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

The influences of Er2O3 doping on the structure and thermophysical properties of La2Zr2O7 were investigated. The (La1−xErx)2Zr2O7 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 (La1−xErx)2Zr2O7 ceramics range from 9.57 × 10−6 K−1 to 9.66 × 10−6 K−1. The substitution of Er3+ for La3+ effectively reduces the thermal conductivity of La2Zr2O7. With the increasing Er3+ content, the thermal conductivity significantly decreases at lower temperatures. At higher temperatures, however, the thermal conductivity of the (La1−xErx)2Zr2O7 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).