G. D. Tsyrenova

Phase formation in the Ag2MoO4-CuO-MoO3 system and the crystal structure of the new double molybdate Ag2Cu2(MoO4)3

Subsolidus phase relations in the Ag2MoO4-CuO-MoO3 oxide-salt ternary system were determined. T-x diagram was plotted for the Ag2MoO4-CuMoO4 quasi-binary join. Double molybdate Ag2Cu2(MoO4)3 was found to exist on this join. This compound is a superstructure derived from orthorhombic Li3Fe(MoO4)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 P212121. A characteristic feature of the Ag2Cu2(MoO4)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 CuO6 octahedra form zigzag ribbons extended in the same direction. MoO4 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.

Phase formation in Cs2MoO4-MMoO4-Zr(MoO4)2 (M = Mn, Mg, Co, Zn) systems and crystal structure of new double molybdates Cs2MnZr2(MoO4)6 and Cs2MnZr(MoO4)4

AbstractSubsolidus phase relations in the Cs2MoO4-MMoO4-Zr(MoO4)2 (M = Mn, Zn) ternary systems were determined, and two groups of new isostructural triple molybdates were synthesized: Cs2MZr(MoO4)4 and Cs2MZr2(MoO4)6 (M = Mn, Mg, Co, Zn). Cs2MnZr2(MoO4)6 and Cs2MnZr(MoO4)4 crystals were grown by spontaneous flux crystallization and used in structure solution for both groups of compounds. The Cs2MnZr2(MoO4)6 structure (a =13.4322(2) Å, c = 12.2016(3) Å, group R3, Z = 3, R = 0.0367) is a new structure type characterized by a mixed three-dimensional framework built of corner-sharing MoO4 tetrahedra and (M, Zr)O6 octahedra where large channels are occupied by cesium cations. Cs2MnZr2(MoO4)4 (a =5.3890(1) Å, c = 8.0685(3) Å, space group P

Phase formation in the systems Ag2MoO4–MO–MoO3 (M=Ca, Sr, Ba, Pb, Cd, Ni, Co, Mn) and crystal structures of Ag2M2(MoO4)3 (M=Co, Mn)

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New molybdenum oxides Ag4M2Zr(MoO4)6 (M=Mg, Mn, Co, Zn) with a channel-like structure

m1, Z = 0.5, R = 0.0247) has the layered glaserite-like KAl(MoO4)2 type structure, where Al3+ octahedral positions are randomly occupied by a 0.5M2+ + 0.5Zr4+ mixture.

New ferroelastic K2Sr(MoO4)2: Synthesis, phase transitions, crystal and domain structures, ionic conductivity

Abstract New molybdenum oxides Ag4 M 2 Zr(MoO4)6 ( M = Mg , Mn, Co, Zn) have been synthesised by the solid state method. The structure of Ag4Mn2Zr(MoO4)6 has been studied by single-crystal X-ray and electron diffraction, high-resolution electron microscopy and second harmonic generation (SHG) technique. Ag4Mn2Zr(MoO4)6 crystallises in the orthorhombic space group P 2 1 2 1 2 1 with unit cell parameters: a = 5.3632 ( 1 ) A , b = 18.9463 ( 3 ) A , c = 21.3621 ( 4 ) A . The 3D framework is formed by MnO6, ZrO6 octahedra and MoO4 tetrahedra connected via common vertices. The structure contents extensive channels along the [100] direction formed by four MnO6 octahedra and six MoO4 tetrahedra. Silver cations are located in these channels. The Ag4 M 2 Zr(MoO4)6 ( M = Mg , Co, Zn) compounds are isotypical with Ag4Mn2Zr(MoO4)6.