Influence of Gd2O3 addition on thermophysical properties of La2Ce2O7 ceramics for thermal barrier coatings

In order to develop new candidate ceramic materials for thermal barrier coatings (La1−xGdx)2Ce2O7 ceramics were prepared by pressureless-sintering at 1600 °C for 10 h in air. The phase structure, micro-morphology and thermophysical properties of (La1−xGdx)2Ce2O7 ceramics were investigated, respectively. XRD results revealed that pure (La1−xGdx)2Ce2O7 ceramics with defect fluorite structure were synthesized and SEM showed that their microstructures were dense and no other phases existed among the particles. With the increasing temperature, their thermal expansion coefficients increased, while the thermal conductivities decreased. The thermophysical results indicated that thermal expansion coefficients of these ceramics were higher than that of 8YSZ, and their thermal conductivities were much lower than that of 8YSZ. The lower thermal conductivities of these ceramics were mainly attributed to more oxygen vacancies and substitution atoms. These results imply that the (La1−xGdx)2Ce2O7 ceramics can be explored as candidate materials for the ceramic layer in TBC system.