Zr(WMo)(1-x/2)VxO8-x/2: Synthesis, Structure and Properties of Thermal Contracting Solid Solutions Substituted by Multi-elements with Different Valences in ZrW2O8 Type Structure

The tetragonal precursors, Zr(WMo)(1-x/2)VxO7-x/2(OH)(2)center dot 2H(2)O (x=0.04, 0.08, 0.10, 0.14, 0.20, 0.22, 0.26, 0.32) were synthesized by acidic steam hydrothermal (ASH) method, and then the cubic Zr (WMo)(1-x/2)VxO8-/2 (x= 0.04, 0.08, 0.10, 0.14, 0.20, 0.22) was prepared from the precursors by high-temperature dehydration and phase transition method. The cubic Zr(WMo)(1-x/2)VxO8-x/2 possesses the space group Pa (3) over bar and the average crystal structures are described stoichiometrically as the superposition of ZrV2O7 and beta-ZrWMoO8 structures with a limited solubility of ZrV2O7 of 11 mol% in cubic ZrWMoO8. The cubic Zr(WMo)(1-x/2)VxO8-x/2 also possesses thermal contraction property at the temperature range of 200 similar to 573 K and the linear thermal expansion coefficients are almost the same in the above temperature range. The phase transition temperature for Zr(WMo)(1-x/2)VxO8-x/2 is lower than 200 K.