Variations in the thermal conductivity of La2Zr2O7 and Gd2Zr2O7 with variable La/Gd concentrations

The phonon density of states and thermal conductivity of La2Zr2O7 and Gd2Zr2O7 are tuned to get materials with improved thermal insulation properties. In this study, pure and doped models of La2Zr2O7 and Gd2Zr2O7 were developed and simulated based on density functional theory. Doping Gd at La sites in La2Zr2O7 was observed to modify the band structure. The density of states analysis showed that Gd d states were introduced in the band gap. With increasing Gd concentration, the band gap of La2Zr2O7 was initially populated and then, a clear band gap was observed at high Gd/La ratios. Smoothness in the phonon density of states curves was observed with an increase in Gd concentration. However, irregular phonon density of states curves was obtained for the Gd2Zr2O7 system. Among the simulated models, the La16-5Gd5Zr16O56 system with Gd/La ratio of 0.454 provided minimum thermal conductivity.

Automated summary

The phonon density of states and thermal conductivity of La2Zr2O7 and Gd2Zr2O7 were tuned to improve thermal insulation properties. Simulation based on density functional theory showed that doping Gd in La2Zr2O7 can modify the band structure and introduce Gd d states into the band gap, leading to changes in the phonon density of states curves. Among the simulated models, the system with a Gd/La ratio of 0.454 provided the minimum thermal conductivity.