meteoblue

# Registered conference abstracts

The page is gradually updated according to the submissions.

### Registered contributions

Total number of registered contributions: 51

## Registered talks

1. MӦSSBAUER STUDY OF Fe-RICH BERYL
Author(s): Denis Balatskiy, Dedushenko S. K., Gritsenko Yu.D, Perfiliev Yu.D.
Institution: Institute of Chemistry, Far Eastern Branch of Russian Academy of Sciences, Vladivostok
Abstract: Colored beryls are of considerable interest to the jewelry industry because of their high refractive index and rich color. Synthetic beryls are used in optical engineering. Iron is a typical impurity in natural beryls. The color of the mineral is associated not only with the total amount of iron, but also with the ratio of ferric and ferrous iron as well as their positions in the crystal lattice. Mössbauer spectroscopy is the optimal method for determining this parameter. The routine analysis of the Mössbauer spectra of beryls is complicated by the fact that the components of the spectrum (doublets) can be asymmetric [1]. The figure shows the room-temperature Mössbauer spectrum a Fe-rich beryl sample from Pamir containing about 5 wt.% of iron, which we have characterized in detail by several techniques. The spectrum can be satisfactorily described by an asymmetric doublet of iron(II) and a symmetric doublet of iron(III), RTISα-Fe=1.20 +/- 0.06 mm/s−1, RTQS=2.5 +/- 0.1 mm/s−1, FWHML=0.9 +/- 0.1 mm/s−1, FWHMR= 0.5 +/- 0.1 mm/s−1 and RTISα-Fe=0.36 +/- 0.08 mm/s−1, RTQS=0.9 +/- 0.2 mm/s−1, FWHM=1.2 +/- 0.1 mm/s−1 respectively, Fe(II):Fe(III) = 1:1. These parameters are consistent with those known for beryls [2]. However, the accuracy of their determination is not satisfactory from a practical point of view. It is known that the asymmetry may reversibly disappear at low (<14K) and high temperatures (>500oC) [2]. This can be used to simplify modeling. [1] D.C.Price et al. // J. de Phys, 1976, V.37, suppl. to no.12, C6, pp.811-817. [2] R.R.Viana et al. // Hyp. Int., 2001, V.134, pp.193-197.
2. SYNTHESIS, STRUCTURE AND PROPERTIES OF COMPLEX IRON(III) SALTS CONTAINING VARIOUS LIGANDS AND OXIDIZING ANIONS
Author(s): Kende Attila Béres, Ildikó Firalszky, Zoltán Homonnay, Libor Kvitek, Martina Kubikova, László Kótai2
Institution: Eötvös Loránd University, Institute of Chemistry, Budapest, Hungary
Abstract: The aim of our work was –continuing our previous efforts [1-3]– preparation and structural characterization of various iron(III) complexes having different kinds of (reducing) ligands (urea, N-methylurea, N,N- and N,N’-dimethylurea, tetramethylurea) and oxidizing anions (NO3-, MnO4-, ClO4- etc.). Structural characterization has been performed by single crystal X-ray diffraction and various spectroscopic (Mössbauer, IR, Raman) methods.
3. PARAMAGNETIC BEHAVIOUR OF Mn IMPLANTED ZnO
Author(s): Krishanlal Bharuth-Ram, T. B. Doyle, C. Ronning, V. Adoons
Institution: Durban University of Technology, Durban, South Africa
Abstract: Following the prediction of room temperature ferromagnetism in ZnO and GaN doped with ~5 at. % Mn, we have conducted CEMS and VSM studies of ZnO implanted with Mn ions to 3 and 6 at. % concentration. For CEMS measurements, the substrates were co-implanted with 5  1015 cm-2 60 keV 57Fe ions. Data were collected after annealing the samples at temperatures up to 900oC. The implantation damage anneals rapidly, and after the 900oC anneal, the spectra are characterized by paramagnetic doublets with isomer shift consistent with Fe3+, as expected for Fe replacing the Zn2+ in ZnO. The quadrupole splittings are considerably reduced for the 6% implanted sample, reflecting the formation of larger clusters than in the 3% implanted sample. The spectra display no evidence of ferromagnetic behaviour is observed. The magnetization curves collected at temperatures 2k – 30 K and at RT are well represente by the Langevin function and confirm the formation of nano-sized clusters of the implanted ions.
4. APPLICATION OF MÖSSBAUER SPECTROSCOPY TO REAL-WORLD RADIOACTIVE WASTE IMMOBILISATION PROBLEMS
Author(s): Paul A. Bingham, Jessica C. Rigby, James D. Eales and Alex Scrimshire
Institution: College of Business, Technology and Engineering, Sheffield Hallam University, Sheffield, UK
Abstract: Mössbauer spectroscopy is a key technique in the development of solutions for global radioactive waste immobilization problems. Presently ~55M US gallons of radioactive waste is stored in steel tanks at the Hanford site, USA. This waste exists in mixed solid-liquid phases and poses an environmental risk to the immediate area and nearby settlements. The US Dept. of Energy has decided that the waste be vitrified into borosilicate glass using “direct feed” vitrification. A consequence of this approach is that the final waste forms will be highly complex, and the effects of these complexities must be better understood prior to the commencement of the large-scale vitrification efforts. One such complexity is high concentrations of Fe within the waste. Three borosilicate glass series were designed to investigate the composition-property-phase relations in borosilicate glass. Mössbauer spectroscopy was used to show that the iron predominantly exists as Fe3+ in four-coordinated structures with little change as function of Fe-content. However, further study has shown marked differences in the partitioning / clustering of Fe ions as a function of glass matrix. During vitrification, foam evolution must be understood to mitigate risks of blockages. Feeds such as the U.S. Hanford high-iron high-level waste feed, can foam up to 10 times its original volume. This study examined the melting behaviour of the feed and the mechanisms behind gas release and foam creation. Elucidating the structure of iron at distinct temperatures, in the context of evolved gas analysis and feed volume expansion, allowed the precise mechanisms of gas evolution from melting reactions to be understood. During melting the crystalline iron in the feed progressed from Fe2O3 to an Fe3O4-like spinel compound, while the content of iron in the amorphous phase increased. O2 evolution corresponded with these temperatures.
5. Fe-GLUCONATE: STRUCTURE AND PROPERTIES
Author(s): Stanisław M. Dubiel, Łukasz Gondek, Jan Żukrowski
Institution: Faculty of Physics and Applied Computer Science, Academic Center for Materials and Nanotechnology, AGH University of Science and Technology, Kraków, Poland
Abstract: Ferrous gluconate (Fe-gluconate) is a salt of the gluconic acid: C12H22FeO14xH2O with 0  x  2. The compound has mainly applications in medical and food additive industries. Regarding the former it has been satisfactorily used in the cure of hypochromic anemia and sold under various trade names e. g. Ascofer, Fergon and Ferate to list some of them. Respecting the latter, it has been applied for coloring foods, e. g. Black olives and beverages. But Fe-gluconate was also used as an effective inhibitor for carbon steel, gluconate-based electrolytes were also successfully used to electroplate various metals or alloys. The Fe content lies between 11.8 and 12.5 percent, and it is present in two forms: a major ferrous Fe2+ or Fe(II) ion and a minor ferric (Fe3+) or Fe(III) ion. The relative contribution of the minor fraction amounts to 10-15%, as detected by Mössbauer spectroscopy and it seems to decrease with time. We have recently found that, in addition to already known crystalline Fe-gluconate, its amorphous form can be obtained. Furthermore, we revealed that the crystalline Fe-gluconate can have two different crystallographic structures depending on the amount of water: dry sample (x=0) crystallizes in the triclinic unit cell (space group P1), while fully hydrated sample (x=2) exhibits the monoclinic unit cell (space group I2). Results on the dynamics of Fe atoms and indications on low temperature magnetism will be reported, too.
6. HOW MÖSSBAUER SPECTROSCOPY CAN HELP IN ACHIEVEMENT OF VALUABLE FOR INDUSTRY NATURAL RESOURCES FROM EXTRATERRESTRIAL OBJECTS
Author(s): Jolanta Gałązka-Friedman, Martyna Jakubowska, Patrycja Bogusz, Katarzyna Brzózka, Agnieszka Grabias, Rafał Idczak, Robert Konieczny, Tadeusz Szumiata, Marek Woźniak, Łukasz Karwowski
Institution: Warsaw University of Technology, Faculty of Physics, Warsaw, Poland
Abstract: Cosmic agencies are working on the project of bringing down asteroids which contain natural resources valuable for industry. It was determined based on meteorites samples studies that the most useful source of raw materials of our interest could be parent bodies of ordinary chondrites type H. The identification of the type of the ordinary chondrites with the use of classical method (determination of the Fa/Fs ratio (fayalite versus ferrosilite) by measurements made by electron microprobe) cannot be performed on the surface of asteroids for technical reasons. It may, however, be done based on Mössbauer measurements followed by the application of 4M method. The very name of the method – 4M, comes from four words: Meteorites, Mössbauer spectroscopy, Multidimensional Discriminant Analysis and Mahalanobis distance. Following the success of Mössbauer spectroscopy in the mission on Mars, there are suggestions to use the same method for investigation of the surface of asteroids. In our experimental study, in which 4 Mössbauer laboratories took part we assessed objectivity and effectiveness of 4M method by comparison of the results obtained for Mössbauer studies of ordinary chondrites type H, L and LL. In our presentation details of the study and problems related to the effectiveness of the 4M method will be discussed.
7. USE OF IRON OXYHYDROXIDES AS WATER DECONTAMINANTS: THE CASE OF AKAGANEITE
Author(s): Karen Edilma García Tellez, V. Villacorta, A. Valencia Álvarez, D.Y. Gómez Giraldo, J.-M. Greneche, C.A. Barrero Meneses
Institution: University of Antioquia, Faculty of Exact and Natural Sciences, Medellín. Columbia
8. SMART SENSORS FOR CIVIL SECURITY APPLICATIONS
Author(s): Yann Garcia
Institution: UCLouvain, Louvain-la-Neuve
Abstract: In recent years, attention has been focused on the efficient detection of chemical pollutants, especially small volatile organic compounds (VOCs) and hazardous gases (HGs), as well as bacterial agents [1]. This area is very challenging because such molecules are relatively volatile at room temperature, even at low concentration levels. Such species can enter the body through normal breathing, and cause serious health issues [2]. Our investigations led us to focus on a series of azole based coordination polymers [3], for which intriguing iron(II) spin crossover properties were disclosed [4]. In particular, we have recently identified a a new colorimetric chemosensor of formula [Fe(H2btm)2(H2O)2]Cl (1) (H2btm = di(1H-tetrazol-5-yl)methane), allowing to detect at real time, with a high selectivity and ultra-sensitivity, 14 different VOCs and HGs [2]. In particular amines, which are detected very quickly (< 2 min) with very high sensitivity. The detection is accompanied by significant and fast colour changes detectable by the naked-eye at ambient conditions. In addition, different VOCs could be distinguished by simple and intuitive standard chemometric means using a handful smartphone-based analytical method, offering a large colour panel depending on detected molecules. The crystal lattice of (1) reconstructs after adsorbing VOCs vapours, reconstruction which is accompanied by a spin state and a colour change. In addition to its high thermal stability (up to 170 °C), the colorimetric sensor showed excellent reusability by consecutive 7 cycles of adsorption–desorption. This sensor is low-cost, environmentally friendly, easy to use, and shows excellent and fast detection performances. Such features offer attractive prospects for (1) which could be used for in-field detection and food safety control in environmental conditions. In this invited talk, I will review latest advances highlighting the impact of 57Fe Mössbauer spectroscopy for quantitative analysis of spin states of selected iron(II) complexes, used as sensors for various toxic industrial chemicals (TICs) [5-11]. 1. Chkirate K., Karrouchi K., Dege N., Sebbar N. K., Ejjoummany A., Radi S., Adarsh N. N., Talbaoui A., Ferbinteanu M., Essassi E. M., Garcia Y., New. J. Chem. 44 (2020) 2210. Front cover. 2. L. Sun, A. Rotaru, K. Robeyns, Y. Garcia, Ind. Eng. Chem. Res. 60 (2021) 8799. 3. Y. Garcia, Adv. Inorg. Chem. 76 (2020) 121. 4. S. Xue, Y. Guo, Y. Garcia, CrystEngComm 23 (2021) 7899 - 7915. Highlight 5. Y. Guo, S. Xue, M. M. Dîrtu, Y. Garcia, J. Mater. Chem. C 6 (2018) 3895-3900. 6. S. Xue, L. Wang, A. D. Naik, J. Oláh, K. Robeyns, A. Rotaru, Y. Guo, Y. Garcia, Inorg. Chem. Front. 8 (2021) 3532. 7. L. Sun, W. Li, Y. Garcia, Möss. Eff. Ref. Data J. 45 (2022) 47-49. 8. L. Sun, W. Li, Y. Garcia, Willey VCH Book chapter (Y. Garcia, J. Wang, T. Zhang, Eds, 2023). 9. W. Li, L. Sun, Y. Garcia, Hyperfine Interact. 242 (2022) 7. 10. W. Li, L. Sun, C. Liu, A. Rotaru, K. Robeyns, M. L. Singleton, Y. Garcia, J. Mater. Chem. C (2022, in press). Hot paper. 11. L. Sun, A. Rotaru, Y. Garcia, J. Hazardous Mater. (2022, in press).
9. INDUSTRIAL APPLICATIONS OF SUPERPARAMAGNETIC OF IRON OXIDE NANOPARTICLES
Author(s): Vijayendra K Garg, Herojit Singh and Erno Kuzmann
Institution: Institute of Physics, University of Brasília, Brasília, Brazil
Abstract: In 1963, Steve Papell of NASA created ferrofluid for use as rocket fuel. His team of NASA scientists were investigating methods of directing fluids in space and realized that magnetic fluids could be completely controlled by the application and variation of a magnetic field. Ferrofluids are also the focus of current scientific research and have the potential to be used in many medical applications, industrial electric transformers, oil pollution cleaners, memory devices in IT industry. In magnetic drug targeting for example, where drugs could be enclosed by ferrofluid and, once injected into the specific body area requiring treatment, a magnetic field could be applied to keep the drugs in this target area. The localization would limit exposure to the rest of the body and enable the dosage level to be decreased, reducing the adverse side effects experienced by the patient. Hard drives use magnetic memory to store giga- and terabytes of data in computers. Information is written to and read from the storage medium as it moves past devices called read-and-write heads that operate very close (often tens of manometers) over the magnetic surface. The read-and-write head is used to detect and modify the magnetization of the material immediately under it. Magnetite (Fe3O4) and is ferrimagnetic is the most magnetic of all the naturally-occurring minerals. Nanotechnology is an emerging field, with thousand research paper only using Mössbauer spectroscopy, that covers a wide range of new technologies under development in nanoscale (1 to 100 manometers) to produce new products and methodology.
Superparamagnetic iron oxide nanoparticles (SPIONs) with appropriate surface chemistry have numerous applications such as diagnosis, targeted drug delivery, magnetic labelling, magnetic isolations, magnetic carriers, cell separation, magnetic resonance imaging contrast enhancement, tissue repair, immunoassay, detoxification of biological fluids, and hyperthermia. Magnetic nanoparticles can bind to drugs, proteins, enzymes, antibodies, or nucleotides and can also be directed to an organ, tissue, or specific location using an external magnetic field or can be heated in alternating magnetic fields for use in hyperthermia. In the last decade, increased investigations with several types of iron oxides have been carried out in the field of man-sized magnetic particles (mostly maghemite, α-Fe2O3, or magnetite, Fe3O4, single domains of about 5–20 nm in diameter), among which magnetite is a very promising candidate since its biocompatibility has already been proven. Magnetite, Fe3O4, is a common magnetic iron oxide that has a cubic inverse spinel structure with oxygen forming an fcc closed packing and Fe cations occupying interstitial tetrahedral sites and octahedral sites. The electrons can hop between Fe2+ and Fe3+ ions in the octahedral sites at room temperature, rendering magnetite an important class of half-metallic materials. With proper surface coating, these magnetic nanoparticles can be dispersed into suitable solvents, forming homogeneous suspensions (ferrofluids). Such a suspension can interact with an external magnetic field and be positioned to a specific area, facilitating magnetic resonance imaging for medicaldiagnosis, and AC magnetic field-assisted cancer therapy. Because of growing interest preparation of nanoparticles (NPs) to have distinctive properties related to high surface area at volume ratio. The quantum effects of NPs have created notable interest to engineers, biologists, chemists and physicists. Various SPION assisted drug delivery systems and SPIONs are commercially available. Interestingly, naturally occurring nanoparticles (NNPs) are present in all spheres of the Earth (atmosphere, hydrosphere, lithosphere and even in the biosphere). Natural Organic Matter (NOM) could largely contribute to the formation of metal nanoparticles, like by silver and gold nanoparticles (AgNPs and AuNPs) in the environment. The formation of metal nanoparticles entails the reaction of reactive oxygen species and NOM complexes with dissolved metal ions. The formation of AgNPs and AuNPs is enhanced by elevated temperature and/or exposure to light. Water properties (pH, redox conditions, presence of ions/ionic strength, and concentrations are also important factors. Various types of (NOM) determine the growth and stability of NPs in the aquatic environment. Organic matter-coated natural metal nanoparticles display less toxicity than ENPs that are surface coated by polymers and/or surfactants. Different materials have different size and size distribution, applications and advantages. We have synthesized gold, layered double (LDH), and iron-oxide zeolite composite superparamagnetic nanoparticles. Gold- has been used in eastern civilizations for centuries and in west it is still being used in cosmetic surgery. Stabilized gold nanoparticles (AuNPs) Au to buthyldithiol stoichiometry were prepared using modified Brust synthesis. The size of the particles falls into the 1.3–4.0 nm range in which the molecular cluster – metallic particle transition occurred. A Mössbauer study of the effect of pH on Fe valence in iron–polygalacturonate as a medicine for human anaemia was conducted. We have synthesized SPIONs Fe3O4-Zeolite composites. Zeolite can act as a drug carrier and both the constituents of composites are biocompatible. Fe3O4–Zeolite composites in different concentration of Zeolite .Superparamagnetic to ferrimagnetic transitions in cubic iron oxides could be tuned by varying zeolite concentration in composite. Shift of γ-Fe2O3 to α-Fe2O3 phase transition from lower to higher temperature confirmed increase in thermal stability of iron oxide nanoparticles with higher zeolite concentration. Saturation magnetization decreased with increase in Zeolite concentration due to increase in superparamagnetic composition. Above 200 mg of zeolite, the slight decrease in saturation magnetization was due to increase in the zeolite content. We also prepared Fe3O4 –Zeolite composite samples with different incubation, and digestion time but the we could not obtain clean samples giving a paramagnetic doublet.
10. Eh-pH POURBAIX DIAGRAMS OF GREEN RUSTS AND CORTENTM STEEL
Author(s): Jean-Marie R. Génin, Jean-Marc Grenèche, Anne Tanière
Institution: Institut Jean Barriol (FR2843 CNRS-Université de Lorraine), Vandœuvre-lès-Nancy, France
Abstract: Thermodynamically speaking, an obvious similarity does exist between the properties of iron-carbon alloys, i.e. steels, and those of the products of aqueous corrosion of iron and steels. In both cases, one must distinguish between a slow process where stable equilibria are observed and a fast process where metastable equilibria are obtained. Let us firstly consider iron and steel. By slow cooling, many phases form, essentiallty two allotropic phases: bcc, body-centered cubic ferrite (a, b, d)) and fcc, face-centered cubic austenite g whereas carbides such as cementite Fe3C precipitate. In contrast, fast cooling by quenching from high temperature austenite g allows to obtain a body-centered-tetragonal bct martensite a’, which owns a high hardness. The carbides do not form so that the carbon atoms stay trapped inside the a’ lattice, which becomes tetragonal, martensite quenching was invented long ago by Hittites who defeated Ramses II at Qadesh around 1200 BC, thus starting the Age of Iron by leaving the Bronze Age. For giving perennity to the outer envelope of the barrels where are stored the radioactive wastes in Cigéo Center at (F55290) Bure, which are brought from the European Nuclear Reactors, EPRs, that produce nuclear electricity, we propose to choose the weathering CORTENTM steel which cannot be corroded since it is covered by the ferric double layered hydroxycarbonate of formula Fe3+6 O12 H8. n H2O, which is found in soils, the gleys within maritime marshes and named mössbauerite. For drawing the Eh-pH Pourbaix diagram of CORTENTM steel, the in-situ deprotonation reaction becomes GR*(x + dx) + dx H+ + dx e- GR*(x), represented by a straight line according to Nernst’s law, Eh-pH diagrams can be compared for the redox reactions of the two processes, slow dissolution-precipitation versus fast in-situ deprotonation, the fast process is obtained by pouring a strong oxidant such as hydrogen peroxide H2O2, on a coprecipitated GR1(CO32-) with a ferric ionic ratio x of 1/3, inside a glove box with pressurized nitrogen gas. Blackmailing from any gas producer is irrelevant and thanks to all green nuclear electricity by using weathering CORTENTM steel.
11. ORDERING OF Fe3+ CATIONS IN GREEN RUSTS RELATED MINERALS WITHIN GLEYS, MÖSSBAUER SPECTROSCOPY VS. X RAY DIFFRACTION
Author(s): Jean-Marie R. Génin, Jean-Marc Grenèche, Anne Tanière
Institution: Institut Jean Barriol (FR2843 CNRS-Université de Lorraine), Vandœuvre-lès-Nancy, France
Abstract: Corrosion of iron and steels, which is of utmost importance in every day life, depends on the way they form during the oxidation process. In both cases, a blueish-green compound or mineral appears, which is denominated “green rust” because it contains Fe2+ and Fe3+ cations and its color seems that of triclinic clays. The crystal structure displays that of a trigonal double layered hydroxide (DLH), which is the stacking of layers with divalent M1 and trivalent M2 metallic cations, and of interlayers comprising anions and water molecules, its general formula can be written [M12+(1-x) M23+x]x+ [An-](x/n). y H2O. In the case where both cations are those of iron, the formula is now Fe2+6(1-x) Fe3+6x O12 H2(7-3x) CO3. y H2O since the intercalated ion is carbonate CO32-, this hydroxycarbonate (green rust) was identified by Fe57 Mössbauer spectoscopy in hydromorphous gley soils, described firstly by the Ukrainian pedologist Georgii Nikolaiev Vysotskii in 1905. The stacking of a DLH is observed by XRD and Mössbauer spectra revealing a long-range order of Fe3+ ions in layers as due to electrostatic repulsion so that each Fe3+ ion is surrounded by six Fe2+ ions, consequently, the CO32- ions are ordered and do not move during the the oxido-reduction reaction. The similarity between spectra of synthetic samples and those extracted from the field in gleys under the water table allowed the International Mineralogical Association (IMA 2012-049) to name three new minerals (i) fougèrite at x = 1/3, (ii) trébeurdenite at x = 2/3 and (iii) mössbauerite at x = 1, the biogenesis operates in anoxic conditions. The compound at x = 0 has never be found in the field. Finally, there are two oxido-reduction processes of iron, either the slow dissolution-reprecipitation leading to the usual corrosion of iron and steels, or the fast in-situ deprotonation-protonation, Eh-pH Pourbaix diagrams will be discussed later.
12. SURFACE CHANGES INVESTIGATION OF “MASHA” STEEL COMPONENTS BY MÖSSBAUER SPECTROSCOPY
Author(s): Pavel Kohout, P. Kohout, L. Krupa , A.M. Rodin , E.V. Chernysheva, A.V. Gulyaev , A.V. Gulyaeva , J. Kliman , A. Kohoutova, A.B. Komarov , A.S. Novoselov , A. Opichal, J. Pechousek, V.S. Salamatin , S.V. Stepantsov , A.V. Podshibyakin , V.Yu. Vedeneev, S.A. Yukhimchuk
Institution: Joint Institute for Nuclear Research, Dubna, Russia
Abstract: MASHA (Mass Analyzer of Superheavy Atoms) is an experimental setup located on one of the beamlines of U400M synchrotron in Flerov Laboratory of Nuclear reactions, Joint Institute of Nuclear Research in Dubna. It is used for determination of mass of newly produced isotopes of superheavy elements. The defects of steel components of MASHA experimental setup are studied using Mössbauer spectroscopy. The determination the structural changes of surface properties are analyzed in detail. These changes can negatively involve the pathway of primary beam and products in the SHE synthesis and characterization experiments. Vacuum chambers, tubes as well as special chambers (hot catcher, cryo-chambers) surface properties are crucial for attracting the products of SHE experiments due to the changes in electronic properties of phase components, porosity etc. due to the continuous irradiation at high doses. Backscattering 57Fe Mössbauer spectroscopy allows nondestructive material analysis for study of both large and small samples, for determination of iron-bearing phases occurrence with the accuracy below ±1%. MS applications in metallurgy and engineering are significant for determination of residual austenite content. All iron bearing phases can be distinguished i.e. ferrites, oxides, amorphous forms, carbides etc. Phase component changes due to the irradiation are studied also.
13. MÖSSBAUER SPECTROSCOPY OF IRON CATALYSED CARBON NANOSTRUCTURES
Author(s): Michal Korenek, Tatiana Ivanova, Veronika Svacinova and Miroslav Mashlan
Institution: Palacký University, Olomouc, Czech Republic
Abstract: The phase evolution of the trapped iron catalyst in grown up carbon nanostructures was studied. Synthesis was carried out by chemical vapour deposition at temperatures between 700 and 1100 °C using mainly toluene as a carbon precursor. In other cases, a pure ferrocene or ferrocene-toluene so-lution was used as the carbon precursor. Here, Ferrocene also played the role of an iron source for the formation of catalytic particles required in the process of carbon nanostructures growth. Alterna-tively, nanoparticles of zero-valent iron Fe(0) NANOFER STAR (NANO IRON, s. r. o., Czech Republic) were used as catalyst. The phase composition of the final products was analysed by Mössbauer spectroscopy (MS) and X-ray powder diffraction (XRD). Scanning electron microscopy (SEM) in combination with energy dispersive spectroscopy (EDS) was used to visualize the mor-phology of the resulting structures. Analysis by MS of the phase composition of trapped catalytic iron particles revealed four main phases, namely alpha-Fe, gamma-Fe, Fe3C and Fe3O4. The ratio of iron-containing phases differs depending on the catalyst used and the temperature. Alpha-Fe, ce-mentite Fe3C and Fe3O4 phases were identified in the case of direct decomposition of pure ferro-cene at 900 °C. Alpha-Fe, Fe3C and gamma-Fe were identified in the decomposition of the ferro-cene-toluene solution at 850 and 900 °C. In the case of synthesis with zero-valent iron nanoparticles alpha-Fe and Fe3C phase were identified in all products synthetized at temperatures from 700 to 1100 °C. Samples prepared at lower temperatures (700 and 800 °C) contained a Fe3O4 phase. The products of synthesis at higher temperatures (950 and 1100 °C) did not contain the Fe3O4 phase, but instead gamma-Fe. XRD confirmed the presence of the same phases as in MS in all samples. SEM and EDS of the final products confirmed a morphology similar to that of a carbon nano-tube/nanofiber.
14. MICROSTRUCTURE OF HIGH-ENTROPY ALLOYS
Author(s): Dávid Košovský, Marcel Miglierini, Tomáš Kmječ, Marek Bujdoš5, Irena Janotová
Institution: Slovak University of Technology in Bratislava, lovak Spectroscopic Society, member of the Association of Slovak Scientific and Technological Societies, Bratislava, Slovakia
Abstract: In conventional alloys, additional alloying elements are added to the primary (major) element to improve their mechanical, chemical, and physical properties. Since 2018, there has been an increase in interest in high-entropy alloys (HEA) which consist of up to five primary elements. The multi-dimensional compositional space that can be tackled with this approach is practically limitless, and only several types of HEA have been investigated so far. Nevertheless, some HEA have already been shown to possess exceptional properties, exceeding those of conventional alloys. Other outstanding HEA are likely to be discovered in the future. In this work, we analysed mainly microstructural properties of three high-entropy alloys (Fe28Co28Ni28Al8Mn8, Fe20Co20Ni20Al20Mn20 and Fe11Co11Ni11Al33.5Mn33.5). In doing so, less common approach, which makes use of the Mössbauer effect, was adopted. The materials’ subsurface layers were analysed by conversion electron Mössbauer spectroscopy and their bulk was studied by transmission Mössbauer spectroscopy. The composition of HEA was verified using energy dispersive X-ray fluorescence, chemical analysis (F-AAS), and particle-induced X-ray emission technique. We use also X-ray diffraction for determine the crystalline phases present in the investigated HEA.
This work was supported by the projects VEGA 1/0130/20, by the European Regional Development Fund-Project "Centre for Advanced Applied Sciences", grant number CZ.02.1.01/0.0/0.0/16_019/0000778 and by the Slovak Spectroscopic Society, member of the Association of Slovak Scientific and Technological Societies.
15. HIGHLY COVALENT FeIII-O BOND CONFIRMED FROM MÖSSBAUER SPECTRA OF DOMESTIC WASTE MOLTEN SLAG SIMULATED SODA-LIME IRON-SILICATE
Author(s): Shiro Kubuki, Bofan Zhang,Irfan Khan,A. S. Ali,Stjepko Krehula,Mira Ristić,Svetozar Musić,Zoltán Homonnay,Ernő Kuzmann,Shiro Kubuki
Institution: Tokyo Metrpolitan University, Hachi-Oji, Tokyo, Japan
Abstract: The local structure of iron-containing soda-lime aluminosilicate glass and glass-ceramics simulated as domestic waste slag exhausted from municipal waste combustion plants in Japan was investigated by 57Fe-Mössbauer spectroscopy. Photo-Fenton catalytic ability was evaluated by a degradation test using methylene blue aqueous solution (MBaq). The visible-light activated photocatalytic effect was first observed by the MB degradation test of 15Na2O•15CaO•20SiO2•50Fe2O3 (in mass%, abbreviated as 50NCSF) glass which was heat-treated at 1000 oC for 100 min. Under this reaction, MBaq concentration decreased from 10.0 to 0.0 mol•L-1 for 24 h with an apparent rate constant (k) of 4.78•10-4 min-1. RT 57Fe-Mössbauer spectrum of 50NCSF was composed of a paramagnetic doublet with isomer shift (I.S.) of 0.24 mm•s-1 and quadrupole splitting (Q.S.) of 0.99 mm•s-1 due to distorted FeIIIO4 tetrahedra, superimposed on a magnetic sextet with I.S. of 0.36 mm•s-1 and internal magnetic field (Hint) of 51.8 T due to hematite. A larger k value of 9.26•10-3 min-1 was recorded in heat-treated 15Na2O•15CaO•11Al2O3•19SiO2• 40Fe2O3 glass, of which 57Fe-Mössbauer spectrum was composed of a sextet with I.S. and Hint of 0.37 mm s-1 and 51.2 T due to hematite. Very recently, Ali et al. revealed that heat-treated 5Na2O•41.4CaO•20Al2O3•27.6SiO2•6Fe2O3 glass showed a considerably large k value of 115•10-3 min-1 by the introduction of 0.4 mol•L-1H2O2 into this system which was caused by highly covalent distorted FeIIIO4 tetrahedra with I.S. and Q.S. of 0.12 and 1.88 mm•s-1, respectively. The smaller k value of 16.6•10-3 min-1 was evaluated by the catalyst prepared from the domestic waste molten slag in Tokyo. It is concluded that hematite and highly distorted FeIIIO4 tetrahedra with high covalency found in domestic waste molten slag simulated soda-lime iron-silicate achieved highly active Photo-Fenton catalytic ability. This new catalyst prepared by recycling waste slag will be realized by excluding the impurities in domestic waste molten slag in Tokyo.
16. STUDY OF INDUSTRIAL CATALYSTS AND CATALYTIC PROCESSES BY MÖSSBAUER SPECTROSCOPY
Author(s): Károly Lázár
Institution: Centre of Energy Research, ELKH, Budapest, Hungary
Abstract: Conventionally, in large scale production the primary importance lies in the processes themselves, and the study of catalysts is only a partial, however important contribution to the complex interpretation. Usually industrial processes are performed under high pressures and temperatures, less accessible for an experimental Mössbauer assembly. Conventionally, the catalysts are studied before the processes in their pristine states and afterwards in spent forms and conclusions are drawn from comparison of these two states. The operando studies are less available for the method, however they provide essential information when completed in certain studies. The present contribution is based on an overview of the recent literature taking into account the previous consideration as well. Two principal groups of catalysts will be discussed. First catalysts used in real large scale processes will be considered. Among these the conventional iron based catalysts used in Fischer-Tropsch and other hydrocarbon conversion processes are still significant part of recent studies, more related details are revealed in the last years. The oxide, nitride and other composed catalysts play also important role, they will be discussed, too. The other wide group is composed from perspective materials not used currently in large scale, however they might be promising for future applications. The catalytic performances of these substances are evaluated and are compared to currently used catalysts, as well. In certain cases the catalysts and processes are developing in synergy, the wide scale successful application of the process may depend on the development of efficient catalysts.
17. IS TIN AN INTERESTING ELEMENT FOR ENERGY TRANSITION?
Author(s): Pierre-Emmanuel Lippens
Institution: Institut Charles Gerhardt de Montpellier, Montpellier, France
Abstract: The transformation from fossil-based to zero-carbon energy production is essential to reduce the global greenhouse gas emissions. Solar and wind energy sources are of particular importance due to their renewability and sustainability but they both suffer from intermittency. In addition, mobile systems such as electric vehicles or small electronic devices require autonomous and green energy sources. In these different cases, the electrochemical energy storage should be considered as a suitable solution and lithium-ion batteries are actually the best available technology, providing high energy density.
Basically, lithium-ion batteries consist of two electrodes to store both lithium ions and electrons, and an electrolyte for lithium ion transport. The commonly used positive electrode materials are metal oxides or phosphates while the negative electrodes are mainly based on carbon. However, since the first lithium-ion batteries commercialized by Sony in 1991, a tremendous number of works have been devoted to alternative electrode materials such as tin-based negative electrode materials. These include tin-based amorphous composite oxides in the Stalion batteries developed by Fujifilm Celltech Co. in 1997 and tin-based amorphous intermetallics in the Nexelion batteries commercialized by Sony in 2005.
The present talk will show how 119Sn Mössbauer spectroscopy can help to characterize electrode materials, understand the electrochemical mechanisms and improve the battery performance. Some selected examples will be considered that include not only the lithium-ion batteries but also sodium-ion and potassium-ion storage systems. In addition, future prospects on the application of Mössbauer spectroscopy to recently proposed tin-based electrode materials will be presented.
18. ONE POT SYNTHESIS OF Co AND Ni DOPED MAGHEMITE NANOPARTICLES USING ACETYLCETONATE PRECURSORS
Author(s): Marijan Marciuš, Mira Ristić, Jean-Marc Grenèche, Stjepko Krehula, Svetozar Musić
Institution: Ruđer Bošković Institute, Zagreb
Abstract: Spinel ferrites are important materials which find various applications in modern technology. For this reason scientist and engineers show permanent interest in their synthesis and properties. Maghemite (γ-Fe2O3) which shows very interesting magnetic properties is also a semiconductor. Due to the characteristic crystal structure it can be doped in wide range with various cations for fine tuning of semiconducting as well as gas sensing properties. Recently we reported [1] one pot synthesis of Mn-doped maghemite nanoparticles using acetylacetonate precursors. In present work the acetylacetonates of iron and cobalt or nickel were mixed and heated at proper temperatures to form the nickel or cobalt doped maghemite samples or ferrites. The samples produced were characterized with XRD, Mössbauer, FE-SEM and EDS. The changes in crystallographic parameters in dependence on the fraction of cobalt or nickel were measured. Also, the effect of Co2+ and Ni2+ dopant on Mössbauer parameters was noticed. Low temperature (77 K) measurements of Ni doped maghemite samples showed almost no change in Mössbauer parameters with doping level. Electron microscopy (FE-SEM) showed unusual nanosized particles of high uniformity. The high uniformity of nanoparticles is due to the thermal decomposition of acetylacetonate precursors mixture above the melting point.
19. MÖSSBAUER SPECTROSCOPY IN ADDITIVE MANUFACTURING BY SELECTIVE LASER MELTING
Author(s): Miroslav Mashlan
Institution: Department of Experimental Physics, Faculty of Science, Palacký University, Olomouc, Czech Republic
Abstract: Selective laser melting (SLM) is an additive manufacturing technique used primarily for rapid prototyping. In SLM, the surface of the metal powder on the bed is melted by a laser, which scans the cross sections based on a 3D model of the part being manufactured. Once the cross section is fully scanned, the bed is lowered to allow a new layer of powder to be placed on the previous cross section. The laser rescans this layer and the whole process is repeated until the entire 3D model is scanned and the part is completed. Various experimental techniques (XRD, SEM, EDS) were used to improve the SLM process and to inspect the properties (surface morphology, microstructure, elemental composition) of components produced by SLM. Mössbauer spectroscopy is a suitable method for examining iron-based components. CEMS and CXMS allows surface layers to be studied selectively. CXMS contains information from depths of tens of micrometers, CEMS from depths of 0.3 μm. Transmission Mössbauer spectroscopy (TMS) of metal powders. The phase composition of stainless steel metal powders (CL20ES) and maraging steel powders (CL50WS) during annealing was studied in the temperature range of 500 - 1100 °C in air and inert atmosphere. When the CL20ES powder in an inert atmosphere, no phase changes were identified throughout the entire annealing temperature range. The Mössbauer spectra are represented by a narrow doublet (IS = (-0.8 ± 0.02) mm/s, QS = (0.16 ± 0.03) mm/s), which corresponds to austenitic steels. When CL50WS powder in an inert atmosphere, the phase composition of the powder changes depending on the temperature. The Mössbauer spectra consist of two subspectra, which correspond to the austenitic and ferritic phases. The ferritic phase is represented in the Mössbauer spectrum by a sextet with a distribution of a hyperfine magnetic field (IS = (0.00 ± 0.02) mm/s, mean value of B = 29.8 T). The ratio of the austenitic and ferritic phases varies depending on the annealing temperature. α-Fe2O3, Fe3O4 and wüstite were identified for both powders depending on the annealing temperature in an oxidizing atmosphere. CXMS and CEMS of parts made with SLM. CXMS and CEMS showed changes in the phase composition of the parts depending on the annealing temperature and atmosphere. At the same time, some changes occur only in the surface layer with a thickness of approximately 0.5 μm. These are changes in the ratio of the austenitic and ferritic phases. Various iron oxides also occur during surface oxidation. In accordance with XRD and EDS, it has been shown that some phase transformations occur as a result of the diffusion of alloying elements in the surface layers. This process is associated with an affinity of the alloying elements (Cr, Mn) for oxygen that is greater than the affinity of iron for oxygen. SEM shows the formation of a new crystalline layer on the surface of the samples by annealing. EDS confirmed an increase in the concentration of alloying elements (Cr and Mn), and XRD identified Cr2O3 and Mn2NiO4 on the surface. SEM showed an inhomogeneity of the emerging surface layer, which unfortunately results in difficulties in the registration of CEMS spectra.
20. METALLIC ALLOYS IN NUCLEAR INSTALLATIONS
Author(s): Marcel Miglierini
Institution: Slovak University of Technology in Bratislava, Bratislava, Slovakia
Abstract: Metallic alloys used in nuclear installations are frequently exposed to harsh conditions featuring not only elevated temperature, corrosion but also intense ionizing radiation. Because microstructure of materials is sensitive to any external modifications their resulting physical properties might be also affected. Considerable worldwide research effort is dedicated to the design, production, and prediction of resulting properties of especially new compositions that are supposed to be used in extreme environments including those found in nuclear installations. In this respect, knowledge of microstructural arrangement of any materials is crucial as it affects the resulting macroscopic properties. Here, Mössbauer spectrometry, which is able to identify minute modifications in the local atomic arrangement of the resonant atoms, plays an unmatched and very important role.
In this contribution, two types of metallic alloys that are principally different from the point of view of their structural arrangement will be discussed. Namely, stainless steels (SS) with well-defined long-range order and amorphous metallic alloys (AMA) featuring disordered structure. While the former are widely used as constructions materials the latter are perspective materials for the use as magnetic cores of accelerator radio frequency cavities or surface coatings of containers for spent nuclear fuel. We present examinations of various mechanical treatments including hardening, cutting, grinding, and polishing on the microstructure of selected SS samples. In the second part, identification of radiation induced effects (neutrons and ions) upon Fe-based AMA will be discussed.
This work was supported by the projects VEGA 1/0130/20, by the European Regional Development Fund-Project "Centre for Advanced Applied Sciences", grant number CZ.02.1.01/0.0/0.0/16_019/0000778 and by the Slovak Spectroscopic Society, member of the Association of Slovak Scientific and Technological Societies.
21. INDUSTRIAL APPLICATIONS OF HIGHLY CONDUCTIVE VANADATE GLASS CONTAINING IRON(III)
Author(s): Tetsuaki Nishida, Shiro Kubuki, Nobuto Oka
Institution: Environmental Materials Institute, Fukuoka, Japan
Abstract: "Glass is liquid with a mask of solid". When a melt is quenched, it remains as a “supercooled liquid” below the melting point (Tm), and finally becomes “glass” at a glass transition temperature (Tg). A linear relationship, termed Tg-Δ rule, was discovered in different iron(III)-containing oxide glasses between Tg, ranging from 180 to 800 oC, and quadrupole splitting (Δ) of FeIII ranging from 0.44 to 1.30 mm‧s-1. A Tg-vs.-Δ plot yields a straight line with an “identical” slope of 680 K‧mm-1‧s when FeIII atoms occupy distorted tetrahedral sites as network former (NWF) in different oxide glasses. This experimental rule revealed that Tg of oxide glasses could be primarily determined by the local distortion of NWF-oxygen polyhedra. Thermodynamic studies of "polymers", "Adam-Gibbs theory" and "conformer model", could satisfactorily explain the principles of Tg-Δ rule.
Conducting oxide glasses were invented by annealing vanadate glasses at temperatures higher than Tg or crystallization temperature (Tc). Room-temperature DC resistivity (ρ) remarkably decreased from the order of MΩ‧cm to several Ω‧cm after the annealing. These glasses have been applied to the busbar electrode of solar cell, conducting glass paste, discharge needle, etc. Introduction of CuO (Eg: 1.2-1.5 eV) and Cu2O (2.1-2.2 eV) into vanadate glass was effective to achieve a low resistivity of 3.1-5.0 Ω‧cm after the annealing. In the case of ZnO (Eg: 3.3-3.4 eV)- and SnO2 (3.4-3.6 eV)-containing vanadate glasses, low ρ values of 4.8 and 5.0 Ω‧cm were respectively achieved. Conduction mechanism of these glasses could be explained by taking account of the band gap energy (Eg) of each component and that of prepared glass samples. Together with the remarkable decrease in ρ, a marked decrease in Δ of FeIII is generally observed, proving that Mössbauer spectroscopy could be a powerful tool for the development of cutting-edge materials.
22. APPLICATION OF VANADATE GLASSES CONTAINING DIFFERENT METAL OXIDES TO RECHARGEABLE BATTERIES
Author(s): Nobuto Oka, Tetsuaki Nishida
Institution: Kindai University, Fukuoka, Japan
Abstract: Cathode materials with high charge-discharge capacity are expected for Li-ion battery and metal-air battery to be applied to hybrid and electric cars. In this study, new cathode materials for these rechargeable batteries have been developed using conductive vanadate glasses with different metal oxides. Conductivity of barium iron vanadate glass, 20BaO·10Fe2O3·70V2O5, could be "tunable" over a wide range (10-7-10-1 S/cm) when the local distortion of the glass skeleton was diminished by isothermal annealing. In this symposium, we present the results of air-electrode (cathode) catalysts containing vanadate glasses for metal-air rechargeable battery. This rechargeable battery needs bifunctional catalytic material, which involves effective oxygen reduction (ORR)/evolution reactions (OER) at the air electrode at the discharge/charge process. Conductive vanadate glass containing different metal oxides was synthesized by the melt-quench method. Prepared vanadate glasses were annealed at 450 °C for various times. For the preparation of the air electrode, pulverized vanadate glass was mixed with powder of 7.5 mass% of poly(tetrafluoroethylene), which was hot-pressed on the gas diffusion layer over a Ni metal mesh. 8M KOH aqueous solution and a Pt mesh were used as the electrolyte and the counter electrode, respectively. The prepared vanadate glass electrode showed an excellent bifunctional oxygen reduction/evolution activity, being comparable to that of the materials reported in the literature, such as polycrystalline LaNiO3. At the symposium, we will also present the application of the conductive vanadate glass to Li-ion battery.
23. NONDESTRUCTIVE DETERMINATION OF AUSTENITE IN STEELS
Author(s): Jiří Pechoušek, Lukáš Kouřil, Ernö Kuzmann, René Vondrášek
Institution: Palacký University Olomouc, Olomouc
Abstract: Determination of the austenite amount in steels and its products is an important process for the quality description and durability predicting of steel products. Retained austenite occurrence critically affects the steel properties in both positive and negative ways. We can highlight two statements, i.e., (1) as the retained austenite is soft, it is an undesirable constituent of quench-hardened steel. On the other hand, (2) it was shown that higher amount of retained austenite can enhance the ductility in high-strength steels. Nowadays, the microscopic metallography and XRD methods are conventionally used for austenite amount determination in the industry. As non-destructive measurement is one of the main requirements for steel products inspection, the backscattering Mössbauer spectroscopy can be favourably used and provide very valuable information. The industrial applications of the Mössbauer spectroscopy for austenite determination in steels have been known for more than four decades. From the very beginning of use, industrial solutions including experimental setups proposals and approaches of simple data evaluation were published [1,2], i.e. Taking into consideration Mössbauer spectroscopy features, we can ask a question “Why the Mössbauer spectroscopy is still not widespread in an industry?’’ From the author's point of view, there are some disadvantages which can play an important role and will be discussed. In the last years, a new version of Austenitemeter concept was designed [3,4], and applied [5,6] in steels characterization. Also new approaches are under the investigations. References: 1. Zemčík, T.
24. DEVELOPING NOVEL MAGNETS AND ASSOCIATED PROCESSES TO REDUCE OUR DEPENDENCE ON RARE-EARTH ELEMENTS
Institution: Institute of Ceramics and Glass Materials (CSIC), Madrid
Abstract: As a consequence of their capacity to transform mechanical energy into electrical (and viceversa), permanent magnets are key elements in the technologies upon which we rely our sustainable future. Nowadays, green energy generation (wind turbines) and green mobility (hybrid and electric vehicles, E-motors) operate with permanent magnets that contain rare-earth elements (REE) and thus their demand is expected to significantly increase in the next decade. However, REE are critical raw materials that present important environmental, price and supply issues, and an urgent need exists to reduce our current and future dependence. This situation urgently demands innovations that lead to a substitution of REE by noncritical materials in these devices. In this framework, ferrites present important advantages especially in terms of their price and availability, and efforts are being made to already attempt the substitution in wind turbines and E-motors with state-of-the-art ferrites. In this framework, even mild improvements in their performance could lead to a considerable amount of end-users substituting REE by ferrites in their applications. The demand for ferrites is thus expected to increase as well, and ensuring the sustainability of the ferrite value chain is of great importance for the long term sustainable development goals and CO2 emission targets. The main goal of our research is to develop innovative and improved ferrite-based magnets that substitute REE in applications for the green transition, and enhance the recycling rate of current ferrite magnets. Based on recent patented technology, we are focusing on: 1. Design and develop improved magnetically hard-soft composite powders and magnets based on ferrites through establishing the correlation between structure and magnetic properties, 2. Implement new energy efficient consolidation processes in the production of ferrite magnets, 3. Enhance the recycling rate of ferrite magnet production in collaboration with European waste managers and magnet manufacturers.
25. INFLUENCE OF SM AND Y MOLAR FRACTIONS ON THE PROPERTIES OF ELECTROSPUN (FE, SM) AND (FE, Y) OXIDES
Author(s): Marko Robić, Marko Robić, Zoltán Homonnay, Ernő Kuzmann, Petre Badica, Andrei Alexandru-Dinu et al.
Institution: Ruđer Bošković Institute, Zagreb, Croatia
Abstract: Iron oxides (general term for iron-hydroxides, -oxyhydroxides, and -oxides) are widespread and abundant in nature. In addition to oxides found in nature, there are also synthetic iron oxides, which are important materials in advanced technologies. Researchers are trying to pronounce some properties of these materials, such as magnetic, electrical, optical, photocatalytic, and other properties. These properties are strongly influenced by the nano/microstructure of iron oxides, which mostly depends on the preparation method, as well as by doping with various metal cations. In the present work, we report the phase composition and nano/microstructural changes of the thermal decomposition products of electrospun composite nanofibres of polyvinylpyrrolidone (PVP) and Fe(III)-Sm(III) or Fe(III)-Y(III) nitrate. The thermal decomposition products obtained from electrospun precursor composite fibres were determined using XRPD and 57Fe Mössbauer spectroscopy, while fibre morphology was inspected using FE SEM and TEM. Magnetic properties were studied by 57Fe Mössbauer spectroscopy and SQUID magnetometry. Depending on the Sm and Y molar fractions in (Fe, Sm) and (Fe, Y) oxide systems, as well as calcination temperatures, the following crystal phases were formed: a-Fe2O3, g-Fe2O3, Sm3Fe5O12, Y3Fe5O12, SmFeO3, YFeO3, Sm2O3, and Y2O3. In the reference sample (containing only Fe3+ cations) the a-Fe2O3 phase and a minor amount of g-Fe2O3 phase were present. The amount of these crystalline phases in electrospun products depended on the Sm and Y molar fractions with a significant decrease in crystallinity in samples containing a higher content of samarium or yttrium.
26. STUDY OF STAINLESS STEEL SURFACE AFTER ANNEALING IN THE TEMPERATURE RANGE 550 - 1000 °C
Author(s): Anna Sedláčková, Tatiana Ivanova, Radek Fiedler and Miroslav Mashlan
Institution: Palacký University, Olomouc, Czech Republic
Abstract: Conversion electron Mössbauer spectroscopy (CEMS) and conversion X-ray Mössbauer spectroscopy (CXMS) were used as the main methods to study the surface of specimens made from stainless steel powder (CL20ES) by selective laser melting. Other study methods were X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Samples measuring 25x25x2 mm3 were prepared on a Concept Laser M2-cusing system (Concept Laser, Germany) by selective laser melting. After 3D printing, the samples were sandblasted with corundum powder. The samples were annealed in a LE 15/11 furnace (LAC, Czech Republic) at temperatures of 550, 700, 800, 900 and 1000 °C for 0.5, 1, 2, 4, 8, 16 and 32 hours. The CXMS spectra of all samples contained only the narrow doublet of the corresponding austenitic stainless steel (isomer shift, IS = –0.08 mm/s, quadrupole splitting, QS = 0.15 mm/s). These CXMS spectra are identical to the Mössbauer spectra of the starting metal powder (CL20ES) registered in the transmission geometry of the Mössbauer experiment. Changes related to oxidation in the surface layer with a thickness of about 0.3 μm were identified in the CEMS spectra. A doublet with IS = 0.33 mm/s and QS = 0.55 mm/s appears in the CEMS spectra. According to the isomeric shift, this doublet corresponds to Fe3+. CEMS spectra did not register on all samples. This is related to the diffusion of alloying elements to the surface of the samples where they oxidize. This process is associated with an affinity of the alloying elements (Cr, Mn) for oxygen that is greater than the affinity of iron for oxygen. A thin surface layer formed by oxides of alloying elements and this layer prevents the penetration of conversion electrons emitted during deexcitation of 57Fe nuclei. SEM shows a new crystalline layer on the surface of the samples after annealing. At the same time, EDS confirmed an increase in the concentration of alloying elements (Cr and Mn). XRD identified Cr2O3 and Mn2NiO4 on the surface. Transformation of the austenitic phase to the ferritic phase was observed in samples annealed at 550 °C. In the CEMS spectra, the subspectrum of the ferritic phase appears outside the subspectra of the austenitic phase and the oxide phase. The new ferritic phase (IS = 0.02 mm/s and B = 33.5 T) was observed only by CEMS. It was not commonly identified in CXMS spectra. Only in the extremely long period (430 hours) of registration of the CXMS spectrum does an indication of this ferritic phase appear. It is clear that the ferritic phase is present only in the surface layer up to about 1 μm. XRD confirmed the formation of a ferritic phase after annealing at 550 °C.
27. MÖSSBAUER SPECTROSCOPY AS A CRUCIAL TOOL FOR DESIGNING OXIDATION CATALYSTS
Author(s): Edyta Tabor
Institution: J. Heyrovský Institute of Physical Chemistry of the CAS, v. v. i., Orague, Czech Republic
Abstract: Iron zeolites represent one of the most promising types of heterogeneous catalysts. Zeolite-based iron actives sites can effectively eliminate N 2 O, transform alkanes to alkenes or activate O 2 and enable methane oxidation at room temperature. The catalytic performance of iron zeolites is controlled by type of iron species and zeolite matrix. Thus, the determination of iron sites active in a particular reaction is crucial for developing an efficient catalyst. Mössbauer spectroscopy is the best available method for studying iron-containing materials due to the fact that it can reveal all iron forms. Moreover, this method provides the essential information on the local structure of iron sites.
In this contribution, I will first discuss the influence of iron loading on Fe speciation in zeolites with various topologies (FER, *BEA, and MFI). We have shown that using the combination of in situ Mössbauer and FTIR spectroscopies, the structure and oxidation state of active iron centres in Fe-FER, *BEA, and MFI and their role in N2O decomposition can be revealed.Furthermore, we have demonstrated that the activity of Fe-MFI in the oxidation of propane to propene can be controlled by the structure of iron active sites. The Mössbauer spectroscopy proved to be an efficient tool to study the influence of post-synthesis treatment and reaction conditions on the structural changes of iron species.
Last but not least, we have designed a special arrangement of iron cations in the FER matrix. DFT calculations revealed that these Fe(II) ions can cooperate in N2O and O2 splitting, providing the active form of oxygen stabilized on iron cations. The Mössbauer spectroscopy experimentally confirmed that N2O is split over two Fe(II) centres in FER and the stabilized oxygen form exhibits high oxidation potential towards methane. For the first time, we have shown that molecular oxygen can be dissociated over Fe-FER and subsequently used for the oxidation of methane to methanol at room temperature.
28. IN-SITU/OPERANDO MÖSSBAUER SPECTROSCOPIC CHARACTERIZATIONS OF IRON-BASED ELECTROCATALYSTS
Author(s): Junhu Wang
Institution: enter for Advanced Mössbauer Spectroscopy, Mössbauer Effect Data Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
Abstract: The Mössbauer spectroscopy plays important role in study of Fe-based non-noble metal electrocatalysts. Mössbauer spectroscopy with high energy resolution can be applied to identify catalyst phases structure, active sites, catalytic mechanisms, and determining relationship between catalytic activity and coordination structure. The in-situ/operando Mössbauer spectroscopy is a technique based on hyperfine interactions between nucleus and electrons, gives the parameters of isomer shift, quadrupole splitting and magnetic hyperfine field to study oxidation state, electron spin configuration, symmetry, and magnetic information of Fe/Sn sites in catalyst under working conditions. In this talk, the newly developed in-situ/operando Mössbauer spectroscopy for electrochemistry is introduced in detail, including in-situ/operando devices, spectrum measurement and results discussion by using the industrially potential study cases of Ni-Fe oxyhydroxide water oxidation catalyst and Fe-N-C oxygen reduction catalyst.

## Registered posters

1. PHYSICO-CHEMICAL CHARACTERIZATION OF SYNTHETIC HEMOZOIN CRYSTAL
Author(s): Cesar Augusto Barrero Meneses, C.A. Barrero Meneses et al.
Institution: University of Antioquia, Faculty of Exact and Natural Sciences, Medellín
Abstract: Plasmodium is a parasite that is transmitted to man by the bite of a mosquito of the Anopheles genus that causes malaria. In one of the stages of the life cycle of the parasite in the human body, the plasmodium degrades hemoglobin and forms a crystal called hemozoin, as the main protection mechanism. For this reason, a complete understanding of the formation mechanisms and the physical-chemical characteristics exhibited by this crystal are very important to understand and control the malaria disease. Additionally, this crystal is also the target of several antimalarial drugs. An approach for this type of research is to manufacture in the laboratory, under diverse and controlled conditions and in the presence of various drugs, the synthetic analogue of hemozoin, which is called the β-hematin crystal. We present the kinetic studies, in aqueous medium, of conversion of hemin to β-hematin both in pure form and in the presence of chloroquine, a commonly used antimalarial drug. The results suggested that, under the conditions of the present experiments and based on three statistical values for the goodness of the fit, the order from the best to the worst models for all kinetics are: lineal combination of Avrami and first order > Avrami > hyperbolic tangent > order 1 > order 0. Furthermore, all crystals were characterized by X-ray diffraction, Mössbauer and infrared spectroscopy, and transmission electron microscopy.
2. FORMATION OF -FE2O3 CLUSTERS ON FE IMPLANTED AL2O3
Author(s): Krish Bharuth-Ram, C. Ronning, T. B. Doyle
Institution: Durban University of Technology, Durban, South Africa
Abstract: Our earlier study on Al2O3 implanted with 4 at. % Fe by conversion electron Mössbauer spectroscopy (CEMS) and magnetization measurements showed the formation of paramagnetic Fe clusters 2-3 nm in size. Our search for formation of ferromagnetic nanoclusters was now extended to studies on samples implanted with 50 keV Fe to a concentration of 8 at. %. For the as-implanted situation, the CEM spectrum shows the expected presence of implantation induced broad paramagnetic doublets due to incorporated Fe3+ and Fe2+. On annealing at 900oC, the CEMS spectrum evolves into a strong ferromagnetic sextet with parameters consistent with those of -Fe2O3, together with a paramagnetic doublet due to nanoclusters. The magnetization curves show hysteresis loops with a small non-zero coercive field. The Langevin function for superparamagnetic particles is unable to fit the low temperature magnetic isotherms, confirming the finite size of the clusters.
3. SOME FEATURES OF SOLID FERRATES IMPORTANT FOR THEIR APPLICATION IN WATER TREATMENT TECHNOLOGY
Author(s): Sergey Dedushenko, E. O. Fomin, Yu. D. Perfiliev
Institution: Department of Chemistry, Moscow State University, Moscow, Russia
Abstract: Ferrates(VI), (V), (IV), and (III) are currently known. These substances contain the FeO4n- complex ion (n=2, 3, 4, and 5 respectively). Ferrates(IV) and (V) are structurally unstable at ambient temperature. Iron can be completely reduced to trivalent state without the substance changing colour (black). Mössbauer spectroscopy is a unique tool for observing such a process. In particular, it allowed us to establish that the mechanism of decomposition of ferrates is disproportionation.
When put into water, ferrates(VI), (V), and (IV) can give wine-red solutions of ferrate(VI)-ion (FeO42‑) due to the disproportionation. The existence of FeVO43- or FeIVO44- ions in solutions has not been reliably established. When dissolved in water, sodium ferrate(IV) gives a wine-red solution and a brick-red precipitate of iron(III). But when freshly prepared potassium ferrate(V) is put into water, this may not occur. To obtain red solution some ageing could be necessary, which is easily explained by the disproportionation.
Over the years of studying solid-phase interactions in Na-Fe-O, K-Fe-O, and also Cs-Fe-O systems, we have not been able to obtain any sample containing iron(VI) without trivalent iron impurities. This result is easily explained by the mechanism of iron(VI) formation.
Interaction of ferrates with water leads to its alkalization. In addition, the ferrates(IV) and (V) may contain a noticeable excess of an oxidizing agent, such as sodium peroxide or potassium superoxide. This is frequently a problem for their direct application. But ferrates(IV) and (V) can be used for the production of solid ferrates(VI) by the recrystallization from alkaline solutions, which makes it possible to get rid of the use of chlorine-containing oxidizers or of the use of high-current power supply.
Under normal conditions, FeO42‑-solutions start to decompose immediately after their preparation resulting in iron(III) precipitates. However, studying the dissolution of K2FeO4 in deionized water we observed, that part of the iron(III) may stabilize in the dissolved (not colloidal) form. Such solutions are stable for years. This places additional demands on quality control in ferrate technology.
4. SYNTHESIS OF THE COMPOUNDS OF IRON IN HIGH OXIDATION STATES IN SUPERCRITICAL OXYGEN
Author(s): Sergey Dedushenko, V. A. Mukhanov, Yu. D. Perfiliev
Institution: Department of Chemistry, Moscow State University, Moscow, Russia
Abstract: Iron compounds in high oxidation states have potential for industrial use. For example, ferrates have prospects in water treatment. Their use in power sources is also known. But some other iron compounds of this kind, for example, CaFeIVO3 or La2LiFeVO6, are not yet considered for industrial applications. The reason for this is the great difficulty of their synthesis. These substances are obtained in small quantities in belt-apparatuses by compressing small welded capsules of noble metals containing the reaction mixture as well as oxygen donor compounds to pressure of several GPa and heating them for a long time at temperatures of several hundred degrees Celsius.
However, there is another way to create high pressure of oxygen, more attractive for industrial use. It consists of compressing and heating aluminium capsules containing the substance and filled with liquid oxygen in lentil-type apparatuses to the same pressure and temperature. We tested this method by trying to get La2LiFeO6.
he spectrum contains one line with RTISα-Fe=0.41 mm/s, which is characteristic of La2LiFeO6. Its presence is also confirmed by X-ray powder diffraction. The synthesis, together with all the necessary preparatory operations, took several minutes.
This method has several obvious advantages. But the main advantage is the possibility of its adaptation for industrial production. Suffice it to say that abrasive diamonds are produced in a similar way, with similar temperature and pressure.
5. MÖSSBAUER SPECTROSCOPY STUDY OF CHROMIUM RICH BCC α' PHASE PRECIPITATION IN FE20CR ODS ALLOY
Author(s): Jarmila Degmová, Vladimír Kršjak, Stanislac Sojak, Július Dekan, Martin Petriska, Michal Kotvas
Institution: Faculty of Electrical Engineering and Information Technology, Institute of Nuclear and Physical Engineering, Slovak University of Technology in Bratislava, Bratislava and Trnava, Slovakia
Abstract: The ferritic, dual-phase and martensitic steels with the Cr content higher than 12 wt. % are known for their ageing degradation due to so-called "475 C embrittlement", which can significantly influence their mechanical properties and consequently narrow the range of their applications. This phenomenon is attributed to the phase separation of the α-(Fe, Cr) ferrite phase into Fe-rich ferrite (α) and the Cr-rich ferrite (α') phases in the miscibility gap, below 500 C. In the present work, we focus on the determination of α' precipitation in PM2000 (Fe20Cr) steel by the Mössbauer spectroscopy technique. The obtained results are complemented by non-destructive techniques such as magnetic Barkhausen noise (MBN) and positron annihilation spectroscopy (PAS). These non-destructive techniques were used in a complementary manner to determine the α' phase in the PM2000 samples isothermally annealed at 475 C up to 1000 h. The same annealing was performed on T91 (Fe8Cr) steel to compare the differences in the obtained results with the alloys where α' development is not expected. The authors acknowledge the contribution of the Slovak Research and Development Agency under the project APVV-20-0010.
The authors further acknowledge financial contributions from the Scientific Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic and the Slovak Academy of Sciences, grant numbers VEGA 1/0382/20 and VEGA 1/0395/20 and from the European Regional Development Fund, project No. ITMS2014+:313011W085.
6. THE EFFECT OF ANNEALING ATMOSPHERE ON THE STRUCTURAL PROPERTIES OF FeSIBPCu ALLOYS WITH DIFFERENT SILICON CONTENT
Author(s): Július Dekan, Katarína Sedlačková, Beata Butvinová, Milan Pavúk, Patrik Novák, Július Dekan, Stanislav Sojak and Jozef Sitek
Institution: Slovak University of Technology in Bratislava, Institute of Nuclear and Physical Engineering, Bratislava, Slovakia
Abstract: Structural and magnetic properties of the as-cast and nanocrystalline NANOMET-type soft magnetic alloys of two different compositions differing in silicon content, i.e., Fe82Si4B10P3Cu1 and Fe78Si8B10P3Cu1, were studied. Nanocrystalline alloys were prepared by annealing the amorphous precursors at a temperature of 420C for 20 and 60 minutes in vacuum and in Ar atmosphere. The effect of the annealing time and atmosphere on the alloy properties were investigated by Mössbauer spectroscopy (MS), magnetic measurements, atomic force microscopy (AFM) and X-ray diffraction (XRD) for both studied compositions. Mössbauer spectroscopy disclosed the effect of the silicon content on the annealed alloys microstructure, i.e., the lower relative volumetric fraction of the crystalline phase component for the alloy with 8% of Si as compared to the alloy with lower silicon content of 4%. Variations of the parameters reflecting the magnetic microstructure were also observed and are discussed with relation to different annealing times and atmospheres. Magnetic measurements indicated that longer annealing times are reflected in the resulting coercivity. Better soft magnetic properties showed sample with 8% of Si after annealing for 20 minutes whose coercivity was lower as well as the determined magnetization work. The AFM measurements inspecting the morphology of the sample surfaces manifested the differences in the grain height and the number of grain agglomerates for the studied alloy compositions with relation to the annealing duration and atmosphere. The XRD measurements followed the expansion of crystalline phase in annealed samples.
7. MÖSSBAUER AND MAGNETIC PROPERTIES STUDIES OF Fe84.5−xCoxNb5B8.5P2 NANOCRYSTALLINE ALLOYS FOR APPLICATIONS IN HIGH POWER CONVERSION SYSTEMS
Author(s): Agnieszka Grabias, A. Kolano-Burian, P. Zackiewicz, P. Włodarczyk, M. Kowalczyk, Ł. Hawełek
Institution: Łukasiewicz Research Network – Institute of Microelectronics and Photonics, Warsaw, Poland
Abstract: Amorphous and nanocrystalline iron-based soft magnetic materials play an important role in a broad area of energy conversion, especially in miniaturization- and mobility-related applications. Current development of these materials is focused on fabrication of relatively cheap and easy-to-produce materials with a high-set expectation bar as concerns the soft magnetic properties.
The aim of the work was to determine the most optimal alloy’s composition and conditions of thermo-magnetic treatment of Pyroperm-type Fe84.5−xCoxNb5B8.5P2 (x = 0–20 at.%) materials in order to obtain the magnetic parameters suitable for possible applications in induction heating devices. The amorphous ribbons were produced on semi-industrial scale using the melt-spinning equipment. Next, a special thermo-magnetic treatment was applied to obtain nanocrystalline cores with induced transverse magnetic anisotropy. The structure and magnetic properties of the nanocrystalline alloys were investigated by Mössbauer spectroscopy, hysteresis loop analyses and vibrating sample magnetometry. Magnetic parameters, such as saturation induction, remanence, coercivity, magnetic permeability and core losses, were determined.
Mössbauer spectroscopy studies confirmed the presence of Co in the nanocrystalline bcc phase and the influence of the transverse magnetic field during annealing on spin orientation. Conversion electron Mössbauer spectroscopy measurements allowed us to compare surface vs. bulk crystallization of the alloys. As concerns magnetic properties it was found that the maximum value of the induced magnetic anisotropy (637 J/m3) while maintaining a high value of saturation magnetization (1.7 T) was obtained for the heat treatment at 525 °C for 20 min. in the presence of 140 kA/m transverse magnetic field for the alloy with the highest Co content. High-frequency tests performed on the Fe64.5Co20Nb5B8.5P2 cores confirmed high stability of their magnetic parameters as a function of frequency proving that they are suitable for applications in power electronics in high-frequency and high-power conversion systems. As an example, the nanocrystalline Fe64.5Co20Nb5B8.5P2 cores were successfully installed in industrially available mobile heating equipment.
Author(s): Maria Gracheva, et al.
Institution: Institute of Chemistry, Eötvös Loránd University & Centre for Energy Research, Konkoly-Thege Miklós út. 29-33, Budapest, Hungary
Abstract: Iron is an essential cofactor for all livings. Due to environmental factors iron limitation of the agricultural lands of the world is significant. As a consequence, iron deficiency is one of the most challenging limiting factors of crop production. Since plants represent the major iron source in human nutrition, iron deficiency in plants not only leads to a reduced quality and quantity of plant products, but also promotes development of iron deficiency in human bodies, which is recognized as one of the most common nutritional disorder in the world. Despite this, iron metabolism of mesophyll cells has not been fully revealed yet. It is suggested that iron in the xylem is transported as a citrate complex. Therefore, FeIII citrate is widely applied as the standard iron source for plant nutrition. Since leaves as photosynthetic organs are generally exposed to illumination in daytime, photoreaction of ferric species may have biological relevance in iron metabolism, the relevance of which is poorly understood. In present work FeIII citrate transformation during the photodegradation in solution and after foliar application on leaves was studied by Mössbauer analysis directly. Four model solutions of FeIII citrate at different pH values (1.5, 3.3, 5.5, and 7.0) were exposed to light in a plant growth chamber. Highly acidic conditions led to a complete reduction of Fe together with the formation of FeII citrate and hexaaqua complexes in equal concentration. At higher pH, the only product of the photoreduction was FeII citrate, which was later reoxidized, resulting in the formation of polynuclear stable ferric compound. To test biological relevance, leaves of cabbage were treated with FeIII citrate solution. X-ray fluorescence imaging indicated the accumulation of iron in the treated leaf parts. Mössbauer analysis revealed the presence of several ferric species incorporated into the biological structure. The iron speciation observed should be considered in biological systems where FeIII citrate has a ubiquitous role in iron metabolism.
9. Development of polarized 57Fe Mössbauer sources using an electron linear accelerator
Author(s): Tajima Hiroyuki, Shinji Kitao, Yasuhiro Kobayashi, Takumi Kubota, Makoto Seto
Institution: Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Osaka, Japan
Abstract: Fundamental quantum optics studies in the X-ray and γ-ray region have attracted increasing attention, and Mössbauer γ-rays have been applied to various studies in this region such as electromagnetically induced transmission phenomena and coherent waveform control. Compared with visible light, γ rays have high spatial resolution and high penetrability to objects with optical thickness. In particular, Mössbauer γ rays have a high energy resolution as high as $\Delta$E/E~$10^{-13}$ and the polarization and time structure can be controlled by the transmission process of the absorber, therefore it seems to have extremely promising potential. For quantum optics research in the γ-ray region, it is desirable to use polarized γ-ray sources easily. In order to satisfy this requirement, we produced a magnetically split ${}^{57}$Fe Mössbauer source by irradiating natural Ni foil with X-rays at KURNS-LINAC(Kyoto University, Institute for Integrated Radiation and Nuclear Science - Linear Accelerator). This method requires no special chemical treatment for radioactive material and the prepared source is easy to handle, making it highly valuable for practical use. The polarization source is expected to be used for controlling polarization by applying an external magnetic field, implementing quantum bits, and analyzing hyperfine structure in single crystals.
10. MÖSSBAUER SPECTROSCOPY MONITORING OF THE FERRATE(VI) CONTENT OF A POTENTIAL INDUSTRIAL WASTE WATER TREATMENT PRODUCT ON LONG TERM STORAGE
Author(s): Zoltán Homonnay, Ernő Kuzmann, Miklós Kuti, Győző G. Láng, Gyula Záray, József Lendvai
Institution: Eotvos Lorand University, Budapest, Hungary
Abstract: Ferrate(VI) technology for waste water treatment has been in focus for a long time. While ferrate(VI) has several advantages as compared to chlorine containing products (hypochlorite or chlorine gas), the lack of its stability poses a great challenge to researchers in the R&D sector. When potassium ferrate(VI), K2FeO4 is synthesized and brought to a dry solid form, it is thermodynamically stable, but the presence of water vapors and CO2 triggers decay to FeIII compounds. A further problem is that when the dry product is added to water, the most probably close to neutral pH initiates fast decay and self decomposition with the release of oxygen which reduces the efficiency of the removal of organic pollutants from the water. Ferrate ions are stable at high pH, therefore for long term storage of a commercial product high pH conditions may be secured. In our study, ferrate(VI) was synthesized by anodic oxidation of iron metal at high pH, and after precipitation it was filtered off. The precipitate was not dried completely so that some liquid film could cover the solid grains providing high pH. This material was sealed and stored in a refrigerator. Under these conditions the initial ~90 % ferrate content did not change significantly for several months. The ferrate content during storage was monitored by Mössbauer Spectroscopy, and identification of the degradation products was attempted.
11. Study on the mechanism of mechanochemical transformations and their impact on the catalytic properties of waste-derived amorphous alloys
Author(s): Zara Cherkezova-Zheleva, Zara P. Cherkezova-Zheleva, Daniela G. Paneva, Jugoslav Krstić
Institution: Institute of Catalysis, Bulgarian Academy of Sciences , Sofia
Abstract: This paper investigates the potential to apply mechanochemistry toward improvement of photocatalytic properties of damaged ferromagnetic amorphous alloys for waste water remediation. Series of mechanochemical experiments are arranged for treatment of the tested material, Fe81B13.5Si3.5C2 ribbons. Mossbauer spectroscopy was used to study the mechanism of mechanochemical transformations and their impact on the catalytic properties of these waste-derived amorphous alloys. Planetary ball mill PM 100, Retsch GmbH, Germany with a stainless-steel vial, stainless-steel balls and ethanol milling media are used in all mechanochemical experiments. Comparative investigation of the bulk and the surface of samples is made by transmission mode Mössbauer spectroscopy (at room and liquid nitrogen temperature) and by conversion electron Mössbauer spectroscopy (CEMS). Additional information about the changes in studied materials was obtained by X-ray diffraction and SEM/EDX method. The ball milling parameters, where the surface chemical rearrangement and clustering of amorphous alloy is highly beneficial for its catalytic oxidation properties, are established as a result of the study. It was registered, that the mechanism of mechanochemical transformations and the created chemical and structural rearrangement in the amorphous material significantly impact the formation of catalytically active phases in studied materials. So, this study is dealing with application of mechanochemical treatment for both the preparation of highly active catalytic materials and the reuse of waste-derived amorphous alloys. Acknowledgements: The authors gratefully acknowledge the financial support of the Bulgarian National Science Fund at the Ministry of Education and Science - Project № КП-06-КОСТ/18/ 2019. This article is based on the project activities of COST Action CA 18112 “Mechanochemistry for Sustainable Industry” (Mech@SustInd), supported by COST (European Cooperation in Science and Technology). The financial support from the Bulgarian Academy of Sciences (Bilateral grant agreement between BAS and University of Belgrade, ICTM) is also gratefully acknowledged.
12. 57Fe MӦSSBAUER STUDY OF ZN ADDITION IN Co1-xZnxFe2O4 SPINEL NANO FERRITES
Author(s): Shashank Kane, R. Verma (1), V. R. Reddy (2) and F. Mazaleyrat (3)
Institution: (1) School of Physics, D. A. University, Indore, India, (2) UGC-DAE Consortium for Scientific Research, Indore, India, (3) SATIE, ENS Paris-Saclay, Gif‑sur‑Yvette, France
Abstract: Ferrimagnetic spinel nano ferrites exhibit face centered cubic structure, have two inter-penetrating sub-lattices tetrahedral (A), octahedral (B) respectively allocated by divalent, trivalent metal ions, and are represented by formula M2+Fe3+2O4. Control over magnetic properties can be achieved via: presence of specific cations, synthesis technique, thermal treatment, distributions of cations on A, B sites. Thus, tunability of properties makes them attractive in various applications, including those in high frequency devices, bioscience (hyperthermia, MRI), gas sensing, multilayer chip inductor, magnetic cores etc. Present work reports sol gel auto-combustion synthesis of Co1-xZnxFe2O4 (x = 0.0  0.56) ferrites, using nitrate-citrate precursors. Prepared ‘dry gel’ samples were characterized at room temperature by x-ray diffraction (XRD), 57Fe Mössbauer, magnetic measurements. XRD validates the formation of pure spinel phase (grain size: 14.7 nm  29.1 nm), incorporation of Zn2+ ion in the spinel structure evidenced by increase of lattice parameter from 0. 8318 nm to 8394 nm, ascribable to variation of ionic radii of Co2+ (0.072 nm), Zn2+ (0.074 nm). Specific surface area between 38.8 – 75.4 m2/g suggests usefulness of current samples in heterogeneous catalysis. Cationic distribution suggests that while Fe3+, Co2+ ions reside on both A, B sites, but majority of Zn2+, Co2+ ions are populated respectively on A, B sites, leading to modification of: A-A, A-B, B-B super-exchange interaction, inversion degree (0.46 – 0.86), oxygen parameter (0.3786 – 0.3870) suggesting variation of disorder. With increasing Zn-content: i) coercivity reduction, and equivalent grain size suggest that studied ferrites are in single-multi domain overlap regions, ii) decrease of saturation magnetization is attributable to the replacement of a magnetic ion (Co2+) with a non-magnetic ion (Zn2+), shows tunability of magnetic properties. Isomer shift values reveal that Fe has 3+ oxidation state, and component with higher effective internal field (BHF) is assigned to the tetrahedral co-ordination, and shows significant re-distribution of Fe3+ among A, B sites, and reveal increase of paramagnetic doublet area with Zn addition. Data for x  0.16 is analyzed with distribution of hyperfine fields, and shows noticeable changes. BHF decrease shows that more Fe atoms are surrounded by Zn atoms as first-near neighbours Observed changes in magnetic properties are consistent with cation distribution obtained jointly from Mössbauer, XRD, analysis.
13. DEVELOPMENT OF MÖSSBAUER SOURCES FOR 161Dy, 166Er, AND 169Tm
Author(s): Shinji Kitao, Y. Kobayashi, M. Kurokuzu, T. Kubota, M. Seto
Institution: Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Osaka, Japan
Abstract: Mössbauer spectroscopy is one of the most powerful tools for investigation of rare earth elements, since most of rare earth elements include Mössbauer isotopes. To promote their Mössbauer spectroscopy, short-lived Mössbauer sources are necessary to be developed. In this study, several practical sources are reported for 161Dy, 166Er, and 169Tm Mössbauer spectroscopy. The sources are obtained by neutron irradiation at the Kyoto University Reactor(KUR). For the 161Dy Mössbauer spectroscopy, Dy0.5Gd0.5F3 was irradiated at KUR to obtain a 161Tb source. The 161Tb was generated from beta-decay of 161Gd. Gd metal powder irradiated at KUR was also used as another practical 161Tb source. An attempt for alternative source production methods for 161Dy using the electron linear accelerator is discussed. For the 166Er spectroscopy, HoAl2 was irradiated to obtain a 166Ho source. The HoAl2 was used at the temperatures above 40 K, since it shows magnetic broadening below 40 K. For low temperature measurements, a synthesis method of Ho0.4Y0.6H2 was developed using TiH2 as a H2 source. This compound can be used as a 166Ho source even below 40 K. For the 169Tm Mössbauer spectroscopy, Er-Al alloys are used to obtain an 169Er source. Each source was confirmed to show a single-line spectrum by using a single-line absorber. Mössbauer spectra with some typical Dy, Er, and Tm compounds have been measured to demonstrate availability for the application using the obtained sources. These sources are promising for investigations of various materials including Dy, Er or Tm.
14. MOSSBAUER STUDY OF THE MATERIAL OF THE ELECTRIC POWER TRANSFORMERS
Author(s): Yasuhiro KOBAYASHI, Shinji KITAO, Kosuke YUASA，Hiroyuki TAKABAYASHI, Makoto SETO
Institution: Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Osaka-fu, JAPAN
Abstract: Fe-Si alloy is a soft magnetic material used as the core of electric power transformers. One method of molding the core is to press the powdered alloy into the shape of the core. In our study, the X-ray diffraction measurements performed on this processed material, we observed that the peak intensity of ordered phase Fe3Si was decreased in the pressed sample. The amount of ordered phase is important for the magnetic material. We performed Fe-57 Mossbauer spectroscopy to elucidate this decrease in the ordered phase. The Fe-Si alloy powders (Fe-5.0wt%Si and Fe-6.5wt%Si) were prepared by the gas atomizing process. To investigate the influence on the amount of the ordered phase, we pressed the powders at 883MPa and annealed them at 750℃. We used the Co-57 in Rh source and the conventional Mossbauer spectrometer for Mossbauer spectroscopy. The obtained spectra consisted of the spectra of the Fe-Si alloy at low Si concentration and the small spectra of the Fe3Si ordered phase. The obtained Mossbauer spectra were almost unchanged before and after pressing and annealing. There was no change in the amount of Fe3Si, too. The only difference was the full width at half the maximum of the peak, and the pressed sample was broader. This broadening is due to the crystal lattice distortion due to press working. Since there was no change in the intensity ratio of the Mossbauer spectrum, we consider that the percentage of the Fe3Si ordered phase did not change. And we think that the difference in the peak intensity of the X-ray diffraction comes from the distortion, which reduces interference and reduces the peak intensity.
15. INFLUENCE OF SAMARIUM DOPING ON THE PROPERTIES OF HEMATITE (α-Fe2O3) NANORODS
Author(s): Stjepko Krehula, Nina Popov, Mira Ristić, Krešo Zadro, Zoltán Homonnay, Ernő Kuzmann, Svetozar Musić
Institution: Ruđer Bošković Institute, Zagreb, Croatia
Abstract: In addition to being an important source of iron for the steel industry, hematite (α-Fe2O3) is also an important material for some other industrial applications, such as a catalyst in several industrial chemical reactions, particulate pigment for industrial production of paints, coatings, coloured plastic, rubber, ceramics, glass and concrete, as well as for production of magnetic pigments and ferrites. In recent times, synthetic hematite samples have been intensely investigated for usage in several advanced applications such as photoelectrodes for photoelectrochemical hydrogen production using sunlight, sensors for detection of toxic and flammable gases or photocatalysts for the degradation of toxic organic compounds. Properties of hematite samples and their performance in different applications strongly depend on the particle size and shape, as well as on the substitution of Fe3+ ions in crystal structure of hematite by other metal cations. In the present work, the effects of the presence of Sm3+ ions during the synthesis of hematite nanorods on their structural, magnetic and optical properties were investigated. Due to the same charge, but very different radius (95.8 pm), electron configuration (4f5) and magnetic moment (0.85 BM) of Sm3+ ions compared to Fe3+ ions (64.5 pm, 3d5 and 5.92 BM, respectively), it could be possible that Sm3+ ions replace a small amount Fe3+ ions in hematite samples with a measurable change of their properties. Hematite nanorods were prepared by a two-step method which includes hydrothermal synthesis of goethite (α-FeOOH) nanorods and their calcination. Samarium doping caused an increase of the unit cell volume of hematite which indicates a substitution of certain amount of Fe3+ ions by larger Sm3+ ions. Besides, Sm3+ doping of hematite nanorods caused a change of particle shape, decrease of hyperfine magnetic field, lowering of the Morin transition temperature, increased absorption of visible light and decrease of the optical band gap.
16. FABRICATION OF AMORPHOUS Fe BY SWIFT HEAVY ION IRRADIATION
Author(s): Ernő Kuzmann, Sándor Stichleutner, Jiri Pechousek, Lukas Kouril, David Smrcka, Libor Machala, Rene Vondrasek, Vladimir Skuratov, Akio Nakanishi, Kiyoshi Nomura, Shiro Kubuki and Zoltán Homonnay
Institution: Eötcös Loránd University, Institute of Chemistry, Budapest, Hungary
17. Influence of sintering in the structural and magnetic properties of different lithium ferrites
Author(s): José F. Marco, C. Granados-Miralles, A. Serrano, G. Gorni, A. Quesada
Institution: Instituto de Química Física "Rocasolano", Madrid, Spain
Abstract: Lithium ferrites (i.e, LiFeO2, LiFe5O8) are materials of great technological interest due to their multiple properties and the varied applications derived. LiFeO2 is an antiferromagnet (AFM) with a rock-salt structure in which both Li+ and Fe3+ share octahedral sites (Oh) while LiFe5O8 crystallizes in a spinel-type structure in which Li+ occupy Oh while Fe3+ distribute between Oh and tetrahedral (Td) positions, yielding a ferrimagnetic structure (FiM). The Li-content on Li ferrites has been seen to have a great influence over some physical properties, therefore conditioning the performance of functional devices based on these materials.
In this paper we have investigated using XRD, XANES, EXFAS and 57Fe Mössbauer spectroscopy at different temperatures the effect that a process of sintering, aimed at producing denser materials, has on the phase composition, structural properties and magnetic ordering temperature of various lithium ferrites with different Fe/Li ratios.
Increasing the Fe/Li ratio in the precursors, produces materials having different crystalline structures, from rock salt LiFeO2 for Fe/Li=1, to mixed rock salt and spinel phases for Fe/Li=3, to spinel LiFe5O8 for Fe/Li=5.
The data have been evaluated using different fitting models in order to gain insight on the nature of the Li and Fe distribution, either ordered or disordered. The different models and their viability are commented in the light of the EXAFS structural results.
18. ENERGY DOMAIN SYNCHROTRON RADIATION MÖSSBAUER SPECTROSCOPY OF EuH2 UNDER A FEW GPa HYDROGEN PRESSURE
Author(s): Ryo Masuda, et al.
Institution: Hirosaki University, Hirosaki, Aomori, Japan
Abstract: Many metals absorb hydrogen and show properties different from their base materials: volume expansion, structural phase transition, and magnetic phase transition, and so forth. Europium metal also absorbs hydrogen, its hydride EuH2 is stable and shows Pnma structure and ferromagnetism, while europium metal shows Imm(bcc) structure and anti-ferromagnetism. Recently, the progress of high-pressure technique enables experiments under high hydrogen pressure. As for europium, some novel hydride phases of EuHx () were found under high hydrogen pressure below 16 GPa. Further phases were theoretically predicted under higher hydrogen pressures of about 100 GPa.
To study the local electronic structure of europium hydrides, 151Eu Mössbauer spectroscopy have been used. It had clearly showed Eu2+ ionic state at EuH2 and Eu2+-like metallic state at Eu metal. Eu hydride phases under high hydrogen pressure were also studied by energy-domain synchrotron radiation based Mössbauer spectroscopy: Eu3+ ionic state was clearly observed at EuHx () phase under 14 GPa hydrogen pressure. These ionicity change was observed through the clear difference in isomer shift in Mössbauer spectroscopy: furthermore, isomer shift is also affected by volume change and minor charge transfer between the europium and hydrogen even in the same ionicity. For the detailed discussion on the local states of europium in hydride phases, it is important to evaluate the shift by the volume and minor charge transfer.
In this presentation, we report our recent results on isomer shift in the EuH2 phase under a few gigapascal hydrogen pressure through the 151Eu energy-domain synchrotron radiation based Mössbauer spectroscopy performed at BL11XU of SPring-8. The relation between isomer shift change and volume change of EuH2 are discussed, compared with that of Eu metal.
19. 57Fe MÖSSBAUER SPECTROSCOPIC ANALYSIS OF Fe-BEARING PHASES IN THE INDUSTRIAL PRODUCTION OF TiO2 WHITE PIGMENT
Author(s): Svetozar Musić, Mira Ristić, Michael Reissner, Cathrine Frandsen, Stjepko Krehula
Institution: Ruđer Bošković Institute, Zagreb
Abstract: Fe-bearing phases, present in the manufacture of TiO2 pigment by sulphate process, were analysed by 57Fe Mössbauer spectroscopy and supporting techniques. XRD analysis of ilmenite ore from Australia showed the presence of crystalline phases: ilmenite (FeTiO3), rutile (TiO2) and pseudorutile (Fe2Ti3O9). Mössbauer spectrum of ilmenite ore at 293 K showed the superposition of three quadrupole doublets, two of them corresponding to Fe2+ and Fe3+ in ilmenite, whereas the third doublet was discussed in the sense of electron charge transfer mechanism. With decreasing temperature, the hyperfine magnetic splitting components appeared. Mössbauer spectrum of ilmenite ore at 18 K showed very complex nature and possible assignations are given. Copperas (FeSO4·7H2O) is waste product in the manufacture of TiO2 pigment by the sulphate process. Mössbauer analysis was also used in the characterization of commercial FeSO4·7H2O (as declared) and the effect of ageing of this hydrated iron(II) sulphate. Also, Mössbauer spectroscopy was applied in the analysis of ash produced by calcination of copperas in the production of H2SO4 as well as in the characterization of iron oxide pigments produced from copperas.
20. Simultaneous detection of gamma radiation transmission, conversion electrons and x-rays in a single Mössbauer experimental setup
Author(s): Jakub Navarik
Institution: Czech Advanced Technology and Research Institute, Palacký University Olomouc, Czechia, Olomouc
Abstract: This poster is illustrating three typical Mössbauer measurements merged into a single setup, which creates the opportunity to run them at once. The technical solution, developed at CATRIN, is based on the combination of two gas flow detectors (CEMS and CXMS) and one scintillation detector (TMS). The main advantages are experimental time savings and perfect match of the experimental results as all data are acquired with exactly the same instrument, the same source activity and thus the same experimental conditions. The poster outlines the main ideas of the technical solution as well as the experimental results.
21. STATUS OF THE DEVELOPMENT OF A REPOSITORY FOR MÖSSBAUER SPECTRA
Author(s): Michael Reissner
Institution: TU Wien, Wien