Low Thermal Conduction Mechanisms in Cation-Deficient Perovskite-Type Oxides

Cation-deficient perovskite-type oxides have received considerable attention as new thermal barrier coating materials because of their extremely low thermal conductivities. In this study, sintered samples produced from RTa₃O₉ (R: Y, La or Yb) powders are examined and the mechanisms behind their low thermal conductivity are investigated. Thermal conductivity was found to vary primarily with the ionic radius of the R element. As ionic radius decreases, nanodomains form via tilting of the TaO₆ octahedra. Phonon scattering at the domain boundaries is thus likely responsible for the low thermal conductivity of cation-deficient perovskite oxides.