Effect of Ti substitution for Zr on the thermal expansion property of fluorite-type Gd 2Zr 2O 7

Abstract

Gd 2(Zr 1− x Ti x ) 2O 7 (0 ⩽ x ⩽ 1.00) solid solutions were synthesized by solid state reaction at 1550–1650 °C for 10 h in air. The relative density, microstructure and thermal expansion property of Gd 2(Zr 1− x Ti x ) 2O 7 were investigated by the Archimedes method, X-ray diffraction, laser Raman spectroscopy, scanning electron microscopy and high-temperature dilatometry. Gd 2Zr 2O 7 exhibits a defect fluorite-type structure; however, Gd 2(Zr 1− x Ti x ) 2O 7 (0.25 ⩽ x ⩽ 1.00) solid solutions have an ordered pyrochlore-type structure. Gd 2Zr 2O 7 and Gd 2Ti 2O 7 are completely soluble. The degree of structural order for Gd 2(Zr 1− x Ti x ) 2O 7 solid solutions increases with increasing Ti content. The thermal expansion coefficients of Gd 2(Zr 1− x Ti x ) 2O 7 increase with increasing temperature from 30 to 1250 °C. The thermal expansion coefficients of Gd 2(Zr 1− x Ti x ) 2O 7 gradually decrease with increasing Ti content at identical temperature levels.