Effect of Ti substitution for Zr on the thermal expansion property of fluorite-type Gd2Zr2O7

Gd2(Zr1−xTix)2O7 (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 Gd2(Zr1−xTix)2O7 were investigated by the Archimedes method, X-ray diffraction, laser Raman spectroscopy, scanning electron microscopy and high-temperature dilatometry. Gd2Zr2O7 exhibits a defect fluorite-type structure; however, Gd2(Zr1−xTix)2O7 (0.25 ⩽ x ⩽ 1.00) solid solutions have an ordered pyrochlore-type structure. Gd2Zr2O7 and Gd2Ti2O7 are completely soluble. The degree of structural order for Gd2(Zr1−xTix)2O7 solid solutions increases with increasing Ti content. The thermal expansion coefficients of Gd2(Zr1−xTix)2O7 increase with increasing temperature from 30 to 1250 °C. The thermal expansion coefficients of Gd2(Zr1−xTix)2O7 gradually decrease with increasing Ti content at identical temperature levels.