Avoiding the intermediate phase Zr2WP2O12 to develop a larger-negative-thermal-expansion-coefficient material Zr2W2P2O15

Zr2W2P2O15 with larger-negative-thermal-expansion-coefficient (NTEC, −4.01×10−6 K−1, 143-673 K) is developed by controlling reaction process to avoid the intermediate phase of Zr2WP2O12, whose smaller NTEC limits its application. From 1473 K to1573 K, Zr2WP2O12 forms easily but the reaction between Zr2WP2O12 and WO3 to generate Zr2W2P2O15 is difficult even followed by heating up to 1673 K. However, putting raw materials of ZrO2, WO3 and NH4H2PO4 into a pipe furnace at sintering temperature 1673 K directly, the Zr2W2P2O15 is formed avoiding the intermediate phase of Zr2WP2O12.