Adjustable Thermal Expansion Properties in Zr₂MoP₂O₁₂/ZrO₂ Ceramic Composites

Zr₂MoP₂O₁₂/ZrO₂ composites were successfully synthesized by the solid state method in attempt to fabricate the near-zero thermal expansion ceramics. The phase composition, micromorphology and thermal expansion behavior of the Zr₂MoP₂O₁₂/ZrO₂ composites with different mass ratios were investigated using X-ray diffraction, scanning electron microscopy and thermal mechanical analysis. Results indicate that Zr₂MoP₂O₁₂/ZrO₂ composites can be prepared by pre-sintering at 500°C for 3 h and then sintering at 1050°C for 6 h. The resulting Zr₂MoP₂O₁₂/ZrO₂ composites consisted of orthorhombic Zr₂MoP₂O₁₂ and monoclinic ZrO₂. With increasing content of Zr₂MoP₂O₁₂, the Zr₂MoP₂O₁₂/ZrO₂ ceramics became more compact and the coefficient of thermal expansion decreased gradually. Zr₂MoP₂O₁₂/ZrO₂ composites show an adjustable coefficient of thermal expansion (CTE) from 5.57 × 10^-6 K^-1 to -5.73 × 10^-6 K^-1 by changing the mass ratio of Zr₂MoP₂O₁₂ and ZrO₂. The Zr₂MoP₂O₁₂/ZrO₂ composite with a mass ratio of 2:1 showed near zero thermal expansion, and the average linear thermal expansion coefficient is measured to be 0.0065 × 10^-6 K^-1 in the temperature range from 25 to 700°C.