A novel route to synthesize cubic ZrW_(2-x)Mo_xO8 (x=0–1.3) solid solutions and their negative thermal expansion properties

摘要

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 - and β-ZrW2O8 structure for 0x0.8 and 0.9x1.3, 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 (i) against the content x of Mo are discussed based on the variation of order degree parameters of ZrW2-xMoxO8.