Zirconium Tungstate

Zirconium tungstate (Zr(WO₄)₂) is a metal oxide with unusual properties. The phase formed at ambient pressure by reaction of ZrO₂ and WO₃ is a metastable cubic phase, which has negative thermal expansion characteristics, namely it shrinks over a wide range of temperatures when heated. In contrast to most other ceramics exhibiting negative CTE (coefficient of thermal expansion), the CTE of ZrW₂O₈ is isotropic and has a large negative magnitude (average CTE of -7.2x10−6K−1) over a wide range of temperature (-273 °C to 777 °C). A number of other phases are formed at high pressures.