Fabrication of Zr₂WP₂O₁₂/ZrV_0.6P_1.4O₇ composite with a nearly zero-thermal-expansion property

Sintered bodies of Zr₂WP₂O₁₂ (ZWP) and ZrV_0.6P_1.4O₇ (ZVP) were fabricated, and their linear thermal expansion coefficients (TEC) were found to be -2.92 × 10^-6 and 3.27 × 10^-6 °C^-1, respectively, in the range 25-500 °C. In an attempt to fabricate composites with a zero-thermal-expansion property, sintered ZWP/ZVP composites with ZVP/ZWP volume ratios of 0.5/0.5, 0.53/0.47, 0.55/0.45, and 0.6/0.4 were fabricated. Scanning electron microscopy revealed that sintering of ZVP/ZWP composites progressed well compared with that of ZWP. A porous ZVP/ZWP composite with a relative density of ca. 83% was fabricated at a ZVP/ZWP volume ratio of 0.53/0.47. X-ray diffractometry and energy dispersive X-ray spectrometry clarified that the ZVP/ZWP composite mainly consisted of ZWP and ZVP grains. Thermomechanical analysis confirmed that the ZVP/ZWP composite exhibited very low thermal expansion with a slight hysteresis with a TEC of -0.29 × 10^-7 °C^-1 in the range 25-500 °C.