Preparation of Al₂(WO₄)₃ Powders with Negative Thermal Expansion Performance by Solid Phase Reaction

Negative thermal expansion material Al2(WO4)3 powders were prepared by solid state reaction using aluminum oxide and tungsten trioxide as raw materials.The phase,crystal structure and morphology of the powders were characterized by powder X-ray diffraction(XRD)and scanning electron microscopy(SEM)respectively.The thermodynamic property of the powders was characterized by thermo gravimetric and differential thermal analysis(TG-DTA).The thermal expansion coefficients of Al2(WO4)3 powders were measured by thermal dilatometer.The results show that the sample is Al2(WO4)3 with high purity and orthorhombic structure.The particles have regular morphology and the size distribution is homogeneous,which is 0.6 μm×0.4 μm averagely.The powders have no phase transition and decomposition in the temperature range from room-temperature to the melting point.The average thermal expansion coefficient of the powders is -1.56×10-6 K-1 in the temperature range of 30-900 ℃.