Riabov A. Structure chemistry of hydrides of intermetallic compounds of zirconium and REM

Theses are focused on studies of structures of hydrides on IMC on the basis of zirconium (getter materials) and REM (reversible hydrogen absorbers). Structures of 46 hydrides of IMC have been determined for the first time. For saturated Zr3FeD6.7, Zr3CoD6.9, Zr2FeD5 deuterides it has been found that hydrogen atoms fill interstices with sizes in the 0.48…0.53 A range. For Zr2FeD5 and Zr4Al3D2.8 the ordering of hydrogen sublattice with decrease of symmetry has been detected. For the first time it have been refined structures of CeNi3D2.8, LaNi3D2.8, La2Ni7D6.5, Ce2Ni7D4.7 hydrides, which formation is accompanied by anomalous expansion of the lattice in the [001] direction exclusively in the MgZn2 layers. Calculation of electronic structure of hydrides of CeNi3, Ce2Ni7 compounds revealed that expanded fragments of structure are stabilized by the Ni…H…Ni…H framework. For hydrides of Pr(Cu0.75Ni0.25)2 compounds (KHg2 ST) the reversible transition of the structure of saturated orthorhombic hydride into hexagonal Fe2P type hydride has been detected. It is accompanied by desorption of ~1 at. Н/f.u. For the ErMn2H2 compound the structural grounds for low-temperature magnetic transition have been determined. For hydrides of RNiIn (R=La,Ce,Nd) compounds extremely short H...H distances have been detected, under higher hydrogenation pressures the deformed R3NiIn2 octahedron is filled as well. these observation have been confirmed by measurements of TDS and PcT isotherms.