Effect of MgO and PVA on the Synthesis and Properties of Negative Thermal Expansion Ceramics of Zr2(WO4)(PO4)2

A green synthesis of Zr2(WO4)(PO4)2 ceramics from ZrO2, WO3 and P2O5 is presented. It is shown that the ceramics can be synthesized by one-step sintering within 60 min. The relative density of the ceramics can be enhanced from about 75% without sintering additives to 99.8% of the theoretical value with 1.0 wt% MgO and 2.0 wt% polyvinyl alcohol. The grain sizes of the ceramics are smaller and more uniform with MgO added in the raw materials than with MgO added in the Zr2(WO4)(PO4)2 powder. The coefficients of thermal expansion are about −2.325 × 10−6, −1.406 × 10−6, −1.509 × 10−6 and −1.384 × 10−6°C−1 for the samples without MgO, with MgO added in the raw materials, with MgO added in the Zr2(WO4)(PO4)2 powder and with MgO and PVA added in the raw materials, respectively.