Registration Number
0215U001224,
0112U001279
, R & D reports
Title
Synthesis, crystal structure, properties of new compounds and phase equilibria in metal systems
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Head
Gladyshevskii Roman Evgenovych,
Registration Date
03-02-2015
Organization
Ivan Franko National University of Lviv
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This research work is part of a long-term ongoing investigation of intermetallic compounds carried out at the Department of Inorganic Chemistry of the Ivan Franko National University of Lviv with the aim to increase our knowledge of this class of substances and synthesize new compounds that may form the basis of future materials with tailored properties. The research work focused on three- or more component systems containing rare-earth metals, transition metals, and p-block elements. The work included physical-chemical investigation of phase diagrams, determination of crystal structures, measurements of selected properties, such as electrical resistivity, thermoelectric power, magnetic susceptibility and magnetization, crystal-chemical analysis, and quantum-chemical calculations. The following experimental methods were commonly used: arc melting, induction melting, heat treatment, microstructure analysis, energy-dispersive X-ray spectroscopy, differential thermal analysis, X-ray powder diffraction, and X-ray single crystal diffraction. Full or partial isothermal sections of the phase diagrams of 47 multicomponent systems were constructed for the first time. A concept of polyangulation was developed for multicomponent systems, considering thermodynamic, size, electronic and crystal-chemical factors. The crystal structures of 212 compounds were determined, 17 of which were found to represent new structure types. The crystal-chemical analysis showed that, according to the concept of topological invariance, the structures belong to 11 different classes, of which the trigonal-prismatic class has the highest number of representatives (44.1 %), whereas according to the concept of modular structures, they can be subdivided into five series, of which the series of two-layer structures alone groups 54.9 %. Electrical, magnetic and other properties were measured for 60 of the compounds and solid solutions synthesized within the research work; most of them showed metallic type of conductivity and Curie-Weiss paramagnetism. Partial replacement of the constituents and addition of alloying elements was carried out to study the effect on the physical properties. Systematization of different kinds of ordered or disordered substitution of the atoms in multicomponent intermetallics was proposed and factors governing the substitution were derived. Algorithms describing the composition-structure-properties relationship were developed for particular groups of intermetallics. Data for 114000 inorganic phases were classified according to their structure types. Results of the scientific research carried out within the project have been published in four PhD theses, two monographs, and 90 scientific articles (59 in journals included in scientometric databases), and presented at national and international conferences (105 conference abstracts of which 66 included in scientometric databases); 3 patents of Ukraine were obtained. The crystallographic data have been included in international databases on inorganic compounds (PCD, USA; ICSD, Germany; ICDD, USA). The results are also used as examples in courses on inorganic chemistry and crystal chemistry for bachelor and master students at the University of Lviv. Among the compounds studied within the research work, certain intermetallic semiconductors with semi-Heusler type structure are promising substances for thermoelectric and thermometric applications. For example, the alloy containing zirconium, nickel and tin, which exhibits a Seebeck coefficient twice as large as that of the prototype, appears to be particularly interesting as a potential material for thermocouples and thermoelements; two UA patents were obtained. The new coordination compound Rh2Se9Br6, which contains a sixdentate crown Se9 ligand, was discovered; its potential use in catalytic processes was evidenced and the synthesis patented. The crystal-chemical peculiarities and crystallographic characteristics of the inorganic compounds synthesized and studied within the research work are of great importance for modeling the interaction of chemical elements and for rationalizing the design of materials with tailored properties, as underlined by representatives of the V.I. Vernadsky Institute of General and Inorganic Chemistry of NAS of Ukraine and I.M. Frantsevich Institute for Problems of Materials Science of NAS of Ukraine.
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Белан Богдана Дмитрівна
Горинь Андрій Маркіянович
Демченко Павло Юрійович
Зелінський Анатолій Вікторович
Маняко Микола Богданович
Пукас Світлана Ярославівна
Ромака Любов Петрівна
Семусьо Наталія Зеновіївна
Стадник Юрій Володимирович
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2020-04-02
