Изучены спектры ЯМР (MAS) 6Li, 7Li сложных молибдатов состава Li2Zn2(MoO4)3 и LiRb3Hf2(MoO4)6 с лионситоподобной структурой в интервале температур от 25 до 100°С. Дано отнесение линий ЯМР. Показано, что присутствие в структуре лионсита переходного металла Hf со степенью окисления +4 способствует увеличению подвижности ионов лития по каналам кристаллической структуры.
6Li and 7Li MAS NMR spectra of complex Li2Zn2(MoO4)3 and LiRb3Hf2(MoO4)6 molybdates of lyonsite-type structure are studied at temperatures ranging from 25 to 100°C. NMR signals are attributed to their sources. It is shown that the presence of a transition metal such as Hf in the +4 oxidation state in the structure of lyonsite contributes to the increased mobility of lithium ions along the channels of the crystal structure.
Subsolidus phase relations in the Ag 2 MoO 4 -CuO-MoO 3 oxide-salt ternary system were determined. T-x diagram was plotted for the Ag 2 MoO 4 -CuMoO 4 quasi-binary join. Double molybdate Ag 2 Cu 2 (MoO 4 ) 3 was found to exist on this join. This compound is a superstructure derived from orthorhombic Li 3 Fe(MoO 4 ) 3 . Its structure was solved in terms of a subcell ( a = 5.0749(3), b = 11.300(2), c = 18.127(3) Å, space group Pnma , Z = 4, R = 0.0678). In the true unit cell, the parameter a is tripled; suggested space group is P 2 1 2 1 2 1 . A characteristic feature of the Ag 2 Cu 2 (MoO 4 ) 3 structure is infinite columns (extended along axis a ) of face-sharing oxygen octahedra, in which disordered silver atoms are located (Ag(21), Ag(22), and Ag(23)) with various degrees of irregularity of their octahedral coordination and a strong anisotropy of thermal vibrations. Distorted CuO 6 octahedra form zigzag ribbons extended in the same direction. MoO 4 tetrahedra, which are arranged according to the pseudo-hexagonal law, link the aforementioned major structural elements into a three-dimensional framework. Trigonal-prismatic voids of the framework are occupied by silver atoms Ag (1). Presumably, the disorder of the silver ions in octahedral columns can be responsible for the increased ion conductivity of silver copper molybdate. A partial order of the same ions is the most likely reason for the appearance of superstructure with the tripled unit cell volume.
