Preparation, characterization and thermophysical properties of (Sm1−xGdx)2Ce2O7 solid solutions

Sm2Ce2O7 has low thermal conductivity and relatively high thermal expansion coefficient which make it suitable for application as high-temperature thermal barrier coatings. (Sm1−xGdx)2Ce2O7 solid solutions were synthesized by solid state reaction in this paper. The influence of Gd2O3-doping on the phase structure and thermophysical properties were investigated. The synthesized (Sm1−xGdx)2Ce2O7 ceramics exhibit a defect-fluorite structure, which is mainly determined by ionic radius ratio r(Aav3+)/r(B4+). The linear thermal expansion coefficients and thermal conductivities of different (Sm1−xGdx)2Ce2O7 decrease with the increasing value of x in the measuring temperature. Their thermal expansion coefficients are higher than that of 8YSZ, the thermal conductivities of (Sm1−xGdx)2Ce2O7 ceramics at 1000 °C are located within the range of 1.07–1.69 W/m K. The composition dependence of thermal conductivity was discussed by taking into account the phonon scattering by mass and strain fluctuations at the A site.