Phase Formation in the K_2MoO_4-Lu_2(MoO_4)-Hf(MoO_4)_2 System and the Structural Study of Triple Molybdate K_5LuHf(MoO_4)_6

摘要

Interactions in the ternary system K_2MoO_4-Lu_2(MoO_4)-Hf(MoO_4)_2 have been studied by X-ray powder diffraction and differential thermal analysis. A new triple (potassium lutetium hafnium) molybdate with the 5:1:2 stoichiometry has been found. Single crystals of this molybdate have been grown. Its X-ray diffraction structure has been refined (an X8 APEX automated diffractometer, MoK_alpha radiation, 1960 F_(hkl), R = 0.0166). The trigonal unit cell has the following parameters: a = 10.6536(1) A, c = 37.8434(8) A, V = 3719.75(9) A, Z = 6, space group R 3 c. The mixed 3D framework of the structure is built of Mo tetrahedra sharing corners with two independent (Lu,Hf)O_6 octahedra. Two sorts of potassium atoms occupy large framework voids.