Phase equilibrium in the Cs2MoO4-Bi2(MoO4)3-Zn(MoO4)2 system and the crystal structure of new triple molybdate Cs5BiZr(MoO4)6

The subsolidus region of the Cs2MoO4-Bi2(MoO4)3-Zr(MoO4) system was studied by X-ray powder diffraction. Quasi-binary sections were elucidated, and triangulation performed. Triple molybdates with the component ratios 5: 1: 2 (S 1) and 2: 1: 4 (S 2) were prepared for the first time. Crystals of cesium bismuth zirconium molybdate of the 5: 1: 2 stoichiometry (Cs5BiZr(MoO4)6) were grown from fluxed melts with spontaneous nucleation. The composition and crystal structure of this triple molybdate were refined using X-ray diffraction data (collected on X8 APEX automated diffractometer, MoK α radiation, 2348 F(hkl), R = 0.0226). The trigonal unit cell parameters were as follows: a = b = 10.9569(2), c = 39.804(4) A, V = 4138.4(4) A3, Z = 6, space group R \( \bar 3 \) c. The mixed-metal three-dimensional framework in this structure is built of Mo tetrahedra and two sorts of (Bi,Zr)O6 octahedra. Large interstices accommodate two sorts of cesium atoms. The Bi3+ and Zr4+ cation distributions over two positions were refined during structure solution.