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- ItemInteraction between the components in Tm-Cr-Ge system at 1070 K(Ivano-Frankivsʹk : Fizyko-chimičnyj instytut DVNZ "Prykarpatsʹkyj nacionalʹnyj universytet imeni Vasylja Stefanyka", 2022) Romaka, L.; Stadnyk, Y.; Romaka, V.V.; Konyk, M.The phase equilibrium diagram of the Tm-Cr-Ge ternary system was constructed at a temperature 1070 K based on the results of X-ray phase, microstructural analyzes and energy-dispersive X-ray spectroscopy in the whole concentration range. At the temperature of investigation, two new ternary compounds are realized in the system: TmCr6Ge6 (SmMn6Sn6 structure type, space group P6/mmm, a=0.51506(1), c=0.82645(2) nm) and Tm4Cr4Ge7 (Zr4Co4Ge7 structure type, space group I4/mmm, а=1.39005(9), с=0.54441(1) nm). Inclusion of Cr atoms in the structure of the binary germanide TmGe2 (structure type ZrSi2) up to 10 at. % Cr leads to the formation of a solid solution TmCrxGe2 (x = 0-0.33).
- ItemPhase equilibrium diagram of Y-Cu-Sb system at 870 K(Ivano-Frankivsʹk : Fizyko-chimičnyj instytut DVNZ "Prykarpatsʹkyj nacionalʹnyj universytet imeni Vasylja Stefanyka", 2023) Romaka, L.; Stadnyk, Yu.; Romaka, V.V.; Zelinskiy, A.; Klyzub, P.; Horyn, A.The interaction of the components in the Y-Cu-Sb ternary system was investigated using the methods of X-ray phase analysis, microstructure, and energy-dispersive X-ray spectroscopy in the whole concentration range at 870 K. At the temperature of investigation Y-Cu-Sb system is characterized by the formation of three ternary compounds: Y3Cu22Sb9 (Dy3Cu20+xSb11-x structure type, space group F-43m, a=1.6614(3) nm), Y3Cu3Sb4 (Y3Au3Sb4 structure type, space group I-43d, а = 0.95357(5) nm), YCuSb2 (HfCuSi2 structure type, space group P4/nmm, a = 0.42580(1), c = 0.98932(3) nm). The solubility of copper in the binary compound YSb (NaCl structure type) extends up to 8 at. %.
- ItemFloating Zone Growth of Pure and Pb-Doped Bi-2201 Crystals(Basel : MDPI, 2024) Roslova, Maria; Büchner, Bernd; Maljuk, AndreyIn this review, we summarize recent progress in crystal growth and understanding of the influence of crystal structure on superconductivity in pure and Pb-doped Bi2Sr2CuOy (Bi-2201) materials belonging to the overdoped region of high-temperature cuprate superconductors. The crystal growth of Bi-2201 superconductors faces challenges due to intricate materials chemistry and the lack of knowledge of corresponding phase diagrams. Historically, a crucible-free floating zone method emerged as the most promising growth approach for these materials, resulting in high-quality single crystals. This review outlines the described methods in the literature and the authors’ synthesis endeavors encompassing Pb-doped Bi-2201 crystals, provides a detailed structural characterization of as-grown and post-growth annealed samples, and highlights optimal growth conditions that yield large-size, single-phase, and compositionally homogeneous Bi-2201 single crystals.
- ItemThe Weak 3D Topological Insulator Bi12Rh3Sn3I9(Weinheim : Wiley-VCH, 2020) Lê Anh, Mai; Kaiser, Martin; Ghimire, Madhav Prasad; Richter, Manuel; Koepernik, Klaus; Gruschwitz, Markus; Tegenkamp, Christoph; Doert, Thomas; Ruck, MichaelTopological insulators (TIs) gained high interest due to their protected electronic surface states that allow dissipation-free electron and information transport. In consequence, TIs are recommended as materials for spintronics and quantum computing. Yet, the number of well-characterized TIs is rather limited. To contribute to this field of research, we focused on new bismuth-based subiodides and recently succeeded in synthesizing a new compound Bi12Rh3Sn3I9, which is structurally closely related to Bi14Rh3I9 – a stable, layered material. In fact, Bi14Rh3I9 is the first experimentally supported weak 3D TI. Both structures are composed of well-defined intermetallic layers of ∞2[(Bi4Rh)3I]2+ with topologically protected electronic edge-states. The fundamental difference between Bi14Rh3I9 and Bi12Rh3Sn3I9 lies in the composition and the arrangement of the anionic spacer. While the intermetallic 2D TI layers in Bi14Rh3I9 are isolated by ∞1[Bi2I8]2− chains, the isoelectronic substitution of bismuth(III) with tin(II) leads to ∞2[Sn3I8]2− layers as anionic spacers. First transport experiments support the 2D character of this material class and revealed metallic conductivity. © 2020 The Authors. Published by Wiley-VCH GmbH
- ItemSyntheses and Molecular Structures of Liquid Pyrophoric Hydridosilanes(Weinheim : Wiley-VCH, 2020) Gerwig, Maik; Böhme, Uwe; Friebel, Mike; Gründler, Franziska; Franze, Georg; Rosenkranz, Marco; Schmidt, Horst; Kroke, EdwinTrisilane, isotetrasilane, neopentasilane, and cyclohexasilane have been prepared in gram scale. In-situ cryo crystallization of these pyrophoric liquids in sealed capillaries on the diffractometer allows access to the single crystal structures of these compounds. Structural parameters are discussed and compared to gas-phase electron diffraction structures from literature and with the results from quantum chemical calculations. Significantly higher packing indices are found for the silanes compared to the corresponding alkanes. Radiation with ultraviolet light (365 nm) and parallel ESR (EPR) measurement shows that cyclohexasilane is easily split into radicals, which subsequently leads to the formation of branched and chain-like oligomers. The other compounds form no radicals under these conditions. NMR spectra of all four compounds have been recorded. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.