A novel route to synthesize cubic ZrW2−xMoxO8 (x=0–1.3) solid solutions and their negative thermal expansion properties

Cubic ZrW2−xMoxO8 (c-ZrW2−xMoxO8) (x=0–1.3) solid solutions were prepared by a novel polymorphous precursor transition route. X-ray diffraction (XRD) analysis reveals that the solid solutions are single phase with α- and β-ZrW2O8 structure for 0⩽x⩽0.8 and 0.9⩽x⩽1.3, respectively. The optimum synthesis conditions of ZrWMoO8 are obtained from differential scanning calorimetry–thermal gravimetric analysis (DSC–TGA), XRD and mass loss-temperature/time curves. Following the above experience, the stoichiometric solid solutions of c-ZrW2−xMoxO8 (x=0–1) are obtained within 1 wt% of mass loss. The relationships of lattice parameters (a), phase transition temperatures (Tc) and instantaneous coefficients of thermal expansion (αi) against the content x of Mo are discussed based on the variation of order degree parameters of ZrW2−xMoxO8.

The trigonal precursor (a) is formed by calcining the dried coprecipitate of component oxides at 600 °C for 3 h. Through the trigonal precursor, cubic ZrWMoO8 (c) is synthesized at 913–950 °C for 1 h. According to the novel preparation route, a series of cubic ZrW2-xMoxO8 (x=0–1.3) are synthesized.Figure optionsDownload as PowerPoint slide