Abnormal thermal conductivity of [720]-oriented BaTiO3 single crystal

The 3ω ‐scanning thermal microscopy and piezoresponse force microscopy techniques were combined to characterize the local thermal conductivity (λ) of ferroelastic domains in [720]‐oriented and [001]‐oriented BaTiO3 single crystal. The [720]‐oriented BaTiO3 showed a local λ value of 3.39 W/m·K, while it was 5.95 W/m·K for [001]‐oriented BaTiO3. The underlying mechanism for such drastic thermal conductivity reduction in [720]‐oriented BaTiO3 is ascribed to a stronger phonon‐scattering effect due to the high strains appearing in [720]‐oriented BaTiO3 single crystals. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) The underlying mechanism for a reduction of the local thermal conductivity of [720]‐oriented BaTiO3 compared to [001]‐oriented BaTiO3 is investigated. The drastic reduction is ascribed to a stronger phonon‐scattering effect due to the high strains appearing in [720]‐oriented BaTiO3 single crystals.