Thermal conductivity of rare-earth scandates in comparison to other oxidic substrate crystals

TL;DR

This study compares high-temperature thermal properties of rare-earth scandates with other oxic substrates, revealing unusual conductivity behavior and proposing a new heat transport mechanism involving migrating ions.

Contribution

It introduces a novel observation of thermal conductivity increase above 900 K in certain scandates and suggests a new heat transport mechanism involving migrating ions.

Findings

DyScO₃ and TbScO₃ show increased thermal conductivity above 900 K

GdScO₃, LSAT, and sapphire exhibit typical decrease in conductivity at high temperatures

Proposes a new heat transport mechanism involving migrating ions

Abstract

High-temperature thermal properties of three neighboring rare-earth scandates DyScO$_3$, TbScO$_3$ and GdScO$_3$ were compared to La$_{0.29}$Sr$_{0.71}$Al$_{0.65}$Ta$_{0.35}$O$_3$ (LSAT) and sapphire. To calculate thermal conductivity, heat capacity and thermal diffusivity were measured by differential scanning calorimetry and laser flash technique, respectively. DyScO$_3$ and TbScO$_3$ showed an untypical rise in the thermal conductivity above 900\,K, while for GdScO$_3$, LSAT and sapphire the expected decrease at elevated temperatures could be observed. These results lead to the proposal of a new type of heat transport by migrating ions.