Determination of temperature-dependent thermal conductivity of a BaSnO3−δ single crystal by using the 3ω method

• This is the first report about thermal conductivity of BaSnO3−δ single crystals.
• We report the successful κ measurement of the crystals by employing the 3ω method.
• The BaSnO3−δ single crystal can be a good perovskite substrate with high κ.
• We found that phonons mainly contribute to the heat transport in BaSnO3−δ.

The single crystal of the electron doped BaSnO3−δ system has been recently found to have high electrical mobility (up to 320 cm2 V−1 s−1) at room temperature and excellent oxygen stability. Although thermal conductivity (κ) of the BaSnO3−δ single crystal is an important physical quantity, the κ measurement by the conventional DC method has been difficult due to the limited crystal size. Herein, we report the first measurement of κ by using the 3ω method from ∼20 to 300 K in the oxygen deficient BaSnO3−δ single crystal with carrier concentration of ∼1018 cm−3. We found that κ is proportional to T−1 above 50 K, indicating that phonons mainly contribute to the heat transport. Moreover, the electronic contribution is determined as ∼4% of the measured κ from the Wiedemann–Franz law. The κ value is 0.132 W cm−1 K−1 at room temperature and is increased progressively at lower temperatures, becoming overall larger than that of the SrTiO3 single crystal. Our results thus point out that BaSnO3−δ can be a good substrate for growing transparent electronic thin films with the perovskite structure.