Preparation and properties of Zr2WP2O12 with negative thermal expansion without sintering additives

Zirconium tungsten phosphate (Zr2WP2O12 denoted as ZWP) is a negative thermal expansion material which can be used as filler in controlling the thermal expansion coefficient of other materials. In this study, dense ZWP ceramics without any additives was prepared via solid-state reaction method, by milling the as-synthesized powder for different times and sintering at 1300°C. The influence of the milling time, i.e. reduced particle sizes, on properties of the Zr2WP2O12 was investigated. The obtained samples were characterized by X-ray diffraction (XRD) method, scanning electron microscopy (SEM), thermal mechanical analysis (TMA), Raman spectroscopy and Vickers hardness tester. The results showed that the milled powders have high crystallinity with single phase orthorhombic structure. The ZWP ceramics exhibits NTE property with high density. With the increase of milling time the coefficient of thermal expansion changed from −2.607 × 10−6 1/K to −3.914 × 10−6 1/K. In addition, the grain sizes decrease and the relative density and HV hardness of the obtained ceramics increase confirming that grinding is an effective method to improve the performance of ZWP ceramics.