TY - CONF A1 - Yusenko, Kirill A1 - Smekhova, A. A1 - Kuzmin, A. T1 - Extended X-Ray absorption fine structure (exafs) to study local constitution of high-entropy alloys N2 - Modern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties. Herein, peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic (fcc)- and body-centered cubic (bcc)-structured high-entropy Alx-CrFeCoNi alloys (x = 0.3 and 3, respectively) are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges. Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision. T2 - SPP2006: ordering in high-entropy alloys CY - Online meeting DA - 05.10.2021 KW - EXAFS KW - High-entropy alloys PY - 2021 AN - OPUS4-54015 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yusenko, Kirill A1 - Petrushina, M. A1 - Dedova, E. A1 - Portnaygin, A. A1 - Papynov, E. A1 - Filatov, E. A1 - Korenev, S. A1 - Gubanov, A. T1 - Effect of temperature and pressure on mixed oxide solid solutions N2 - A hydrothermal synthesis of ZrW2-xMoxO8 (0 ≤ x ≤ 2) from the corresponding precursors is reported in this paper. High-temperature and high-pressure data are presented for the sample with x = 1.6. An increase in temperature initiates the phase transition from tetragonal precursor to orthorhombic-ZrW2-xMoxO8 (x = 1.6) with the subsequent formation of cubic and trigonal phases. The thermolysis parameter of the disordered cubic ZrW2-xMoxO8 (x = 1.6) phase is 803 K, and the coefficient of thermal expansion is α = -4.6∙10–6 K−1. Data on ZrW2-xMoxO8 (x = 1.6) structure as a function of pressure are obtained for the first time. Pressureinduced changes from cubic to orthorhombic ZrW2-xMoxO8 (x = 1.6) phase at 1.38 GPa are observed. The sample amorphization is irreversible during decompression. KW - Phase transition KW - High-pressure KW - Complex oxides PY - 2020 DO - https://doi.org/10.1016/j.inoche.2020.107965 VL - 117 SP - 107965 PB - Elsevier B.V. AN - OPUS4-50821 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yusenko, Kirill A1 - Petrushina, M. A1 - Dedova, E. A1 - Portnaygin, A. A1 - Papynov, E. A1 - Filatov, E. A1 - Gubanov, A. T1 - Pressure induced change in the ZrWMoO8 N2 - In this paper we report high-pressure synchrotron x-ray powder diffraction data for the cubic ZrWMoO8. For the first time, extensive structural study of ZrWMoO8 solid solution as a function of pressure was performed. This study shows that disordered cubic-ZrWMoO8 (space group Pa) transforms to ordered cubic-ZrWMoO8 (space group P) at low pressure. A further high-pressure influence leads followed by amorphization of the sample at 2.2 GPa. All transformations are irreversible. Our work will have high impact in the design of new composite materials with well-defined thermal expansion, especially for applications under extreme conditions and high mechanic stress. KW - Phase transition KW - High-pressure KW - Complex oxides PY - 2020 DO - https://doi.org/10.1016/j.matpr.2019.12.141 VL - 25 IS - 3 SP - 428 EP - 430 PB - Elsevier Ltd. AN - OPUS4-50822 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yusenko, Kirill A1 - Khandarkhaeva, S. A1 - Bykov, M. A1 - Fedotenko, T. A1 - Hanfland, M. A1 - Sukhikh, A. A1 - Gromilov, S. A1 - Dubrovinsky, L. T1 - Face-centered cubic refractory alloys prepared from single-source precursors N2 - Three binary fcc-structured alloys (fcc–Ir0.50Pt0.50, fcc Rh0.66Pt0.33 and fcc–Rh0.50Pd0.50) were 14 prepared from [Ir(NH3)5Cl][PtCl6], [Ir(NH3)5Cl][PtBr6], [Rh(NH3)5Cl]2[PtCl6]Cl2 and 15 [Rh(NH3)5Cl][PdCl4]·H2O, respectively, as single-source precursors. All alloys were prepared by 16 thermal decomposition in gaseous hydrogen flow below 800 °C. Fcc–Ir0.50Pt0.50 and fcc–Rh0.50Pd0.50 17 correspond to miscibility gaps on binary metallic phase diagrams and can be considered as 18 metastable alloys. Detailed comparison of [Ir(NH3)5Cl][PtCl6] and [Ir(NH3)5Cl][PtBr6] crystal 19 structures suggests that two isoformular salts are not isostructural. In [Ir(NH3)5Cl][PtBr6], specific 20 Br…Br interactions are responsible for crystal structure arrangement. Room temperature 21 compressibility of fcc–Ir0.50Pt0.50, fcc–Rh0.66Pt0.33 and fcc–Rh0.50Pd0.50 has been investigated up to 50 GPa 22 in diamond anvil cells. All investigated fcc-structured binary alloys are stable under compression. 23 Atomic volumes and bulk moduli show good agreement with ideal solutions model. For fcc–24 Ir0.50Pt0.50, V0/Z = 14.597(6) Å3·atom-1, B0 = 321(6) GPa, B0' = 6(1); for fcc–Rh0.66Pt0.33, V0/Z = 14.211(3) 25 Å3·atom-1, B0 =259(1) GPa, B0' = 6.66(9); for fcc–Rh0.50Pd0.50, V0/Z = 14.18(2) Å3·atom-1, B0 =223(4) GPa, 26 B0' = 5.0(3). KW - High-pressure KW - Refractory alloys KW - Platinum group metals KW - Single-source precursors PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508176 DO - https://doi.org/10.3390/ma13061418 VL - 13 IS - 6 SP - 1418 PB - MDPI CY - Basel AN - OPUS4-50817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yusenko, Kirill A1 - Kabelitz, Anke A1 - Schokel, Alexander A1 - Wagner, Ralf A1 - Prinz, Carsten A1 - Kemnitz, E A1 - Emmerling, Franziska A1 - Krahl, Thoralf A1 - de Oliveira Guilherme Buzanich, Ana T1 - Local Structure of Europium-Doped Luminescent Strontium Fluoride Nanoparticles: Comparative X-ray Absorption Spectroscopy and Diffraction Study N2 - Rare-earth based luminescent materials are key functional components for the rational design of light-conversion smart devices. Stable Eu3+-doped strontium fluoride (SrF2) nanoparticles were prepared at room temperature in ethylene glycol. Their luminescence depends on the Eu content and changes after heat treatment. The crystallinity of heat-treated material increases in comparison with as-synthesized samples. Particles were investigated in solution using X-ray diffraction, small-angle X-ray scattering, and X-ray spectroscopy. After heat treatment, the size of the disordered nanoparticles increases together with a change of their local structure. Interstitial fluoride ions can be localized near Eu3+ ions. Therefore, non-radiative relaxation from other mechanisms is decreased. Knowledge about the cation distribution is key information for understanding the luminescence properties of any material. KW - SrF2 KW - EXAFS KW - Eu PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-540094 DO - https://doi.org/10.1002/cnma.202100281 VL - 7 IS - 11 SP - 1221 EP - 1229 PB - Wiley Online Library AN - OPUS4-54009 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yusenko, Kirill A1 - Emmerling, Franziska A1 - de Oliveira Guilherme Buzanich, Ana T1 - X-Ray absorption spectroscopy to study multicomponent materials N2 - Detailed study of multicomponent systems in solid-state as well as in solution using X-ray diffraction and X-ray spectroscopy is one of the most common topics in modern materials chemistry. 5-6 component high-entropy alloys such as fcc- and bcc-structured AlxCoCrFeNi and fluorescent nanoparticles based on fluorite-structured SrF2 doped by rare-earth metals in organic solutions have high complexity and their local structure cannot be resolved using only diffraction. X-ray absorption spectroscopy should be applied to understand peculiarities in their local structure and make a link between structure on short and long ranges and their macroscopic properties. Here, based on two representativee examples, we discuss how a combination of several X-ray absorption edges might give new insights into complex materials. T2 - Virtual meeting of the African Light Source CY - Online meeting DA - 15.11.2021 KW - EXAFS KW - Synchrotron studies PY - 2021 AN - OPUS4-54014 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yusenko, Kirill A1 - Domonov, D. A1 - Pechenyuk, S. A1 - Belyevskii, A. T1 - Formation of Nanostructured Carbon from [Ni(NH3)6]3[Fe(CN)6]2 N2 - The products of thermal decomposition in an argon atmosphere of [Ni(NH3)6]3[Fe(CN)6]2 as a precursor has been studied. Decomposition products were studied up to 800◦C. Above 600◦C, all coordination bonds in the residues are broken with a formation of Ni3Fe, Fe, and free carbon with a small admixture of nitrogen. Elementary carbon can be easily separated from metals by treatment with a water solution of hydrochloric acid. Only carbon is responsible for the specific surface of the composite products. The released carbon has a high degree of graphitization and begins to oxidize in air above 500°C and is completely oxidized above 700°C. KW - Carbon materials KW - Double complex compound KW - Thermal decomposition PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508188 DO - https://doi.org/10.3390/nano10020389 VL - 10 IS - 2 SP - 389 PB - MDPI CY - Basel AN - OPUS4-50818 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yusenko, Kirill A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin T1 - Studies of high-entropy alloys using x-ray absorption fine structure at the bamline N2 - BAM line is multipurpose high-energy beamline. To extend studies of multicomponent alloys using EXAFS we perform own research and user experiments requiring multiedge spectroscopy, high-temperature and chemically aggressive sample environments. Our study of multicomponent alloys and high-entropy alloys open new perspectives in understanding their reactivity, corrosion, phase transformations and local ordering. T2 - SPP2006: large scale facilities CY - Online meeting DA - 02.11.2021 KW - Synchrotron studies KW - High-entropy alloys KW - EXAFS PY - 2021 AN - OPUS4-54016 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yusenko, Kirill T1 - Single-source precursors strategy to access refractory high-entropy alloys for electrocatalytic applications N2 - High-entropy alloys containing up to 6 platinum group metals can be prepared by thermal decomposition of single-source precursors non requiring high temperature. We prepare the first example of a single-phase hexagonal high-entropy alloy. Heat treat- ment up to 1500 K and compression up to 45 GPa do not result in phase changes, a record temperature and pres- sure stability for a single-phase high-entropy alloy. The alloys show pronounced electrocatalytic activity in methanol oxidation, which opens a route for the use of high-entropy alloys as materials for sustainable energy conversion. T2 - HEA2020: first international virtual workshop on high-entropy alloy and complex solid solution nanoparticles for electrocatalysis CY - Online meeting DA - 06.10.2020 KW - High-entropy alloys KW - Single-source precursors PY - 2020 AN - OPUS4-54013 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yusenko, Kirill T1 - Reaction of high-entropy alloys with hydrogen under extreme conditions N2 - In the current study, we investigate an interaction under high-pressure high-temperature of single phase fcc-, hcp- and bcc-structured high-entropy alloys with hydrogen, carbon and nitrogen to obtain high-entropy hydrides, carbides and nitrides. Structural changes in high-entropy alloys upon compression and heating in the presence of these light elements are in the focus of our investigation. An easy route to high-entropy hydrides, carbides and nitrides will open new synthetic horizons in compositionally complex materials. Our study suggests that high-entropy alloys form high- entropy hydrides mainly with a composition close to M:H 1:1 ratio. Hydrides can be obtained under compression with hydrogen as a pressure compression medium or using hydrogen fluid as reactive agent. T2 - Intermetallics 2023 CY - Bad Staffelstein, Germany DA - 03.10.2023 KW - HEA PY - 2023 AN - OPUS4-58555 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -