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

Highlights: • Thermal conductivity at high temperature for several substrate crystals measured. • Anisotropy considered, full thermal conductivity tensors were measured. • Some rare earth scandates show a minimum of thermal conductivity around 900 K. High-temperature thermal properties of three neighboring rare-earth scandates DyScO₃, TbScO₃ and GdScO₃ were compared to La_0.29Sr_0.71Al_0.65Ta_0.35O₃ (LSAT) and sapphire. To calculate thermal conductivity, heat capacity and thermal diffusivity were measured by differential scanning calorimetry and laser flash technique, respectively. DyScO₃ and TbScO₃ showed an untypical rise in the thermal conductivity above 900 K, while for GdScO₃, LSAT and sapphire the expected decrease at elevated temperatures could be observed.