Synthesis and thermal expansion property of Cr2W3O12 doped with WO3

Cr2W3O12, one of the members of the negative thermal expansion family of A2M3O12, is reported to be prepared by the solid-state method with Cr2O3 and WO3, which was impossible before. Here, the synthesis of Cr2W3O12 is carried out by solid-state sintering. The powder mixture of Cr2O3 and WO3 is obtained using Zn(CH3COO)2 · 2H2O as the catalyst. When Zn(CH3COO)2 · 2H2O (0–25 mol. %) is added to the mixture of Cr2O3 and WO3 with 15 and 20 mol. % of excess WO3, much of the Cr2W3O12 is formed especially because of the addition of 10 and 15 mol. % of Zn(CH3COO)2 · 2H2O. For comparison, commercial ZnO is used as an addition, but its catalytic role is much lower than that of Zn(CH3COO)2 · 2H2O. The roles of addition of Zn(CH3COO)2 · 2H2O and excess WO3 are ascribed to compensate the volatility of WO3 and speed up the reaction of Cr2O3 + 3WO3 → Cr2W3O12 by the catalytic action of Zn(CH3COO)2 · 2H2O, respectively. The prepared Cr2W3O12 samples show positive thermal expansion due to the influence of excess WO3.