Influence of Er substitution for La on the thermal conductivity of (La1−xErx)2Zr2O7 pyrochlores

Abstract The influences of Er 2 O 3 doping on the structure and thermophysical properties of La 2 Zr 2 O 7 were investigated. The (La 1− x Er x ) 2 Zr 2 O 7 ceramics were synthesized by a solid state reaction method. The XRD results indicate that they all consist of the pure pyrochlore structure. The SEM results show that the microstructure of the sintered ceramics is dense and the grain boundaries are clean. The average thermal expansion coefficients of the (La 1− x Er x ) 2 Zr 2 O 7 ceramics range from 9.57 × 10 −6 K −1 to 9.66 × 10 −6 K −1 . The substitution of Er 3+ for La 3+ effectively reduces the thermal conductivity of La 2 Zr 2 O 7 . With the increasing Er 3+ content, the thermal conductivity significantly decreases at lower temperatures. At higher temperatures, however, the thermal conductivity of the (La 1− x Er x ) 2 Zr 2 O 7 becomes similar, indicating that the thermal conductivity is less sensitive to composition variation. In addition, for the composition with x = 0.10, the thermal conductivity reveals a nearly temperature-independent behavior, which should be ascribed to the strong phonon scattering source (rattlers).