Thermal transport properties of InFeZnO₄-YbFeZnO₄ solid solutions

Thermal transport properties of In_1-xYb_xFeZnO₄ (x = 0, 0.1, 0.2,..., 0.8, 0.9, 1.0) solid solutions ceramics were investigated, which were synthesized by solid state reaction at 1300 °C (1250 °C for YbFeZnO₄) for 30 h. With increasing Yb doping fractions on In site, the solution phase gradually transformed from InFeZnO₄ to YbFeZnO₄ phase, while the two structures belong to the same YbFe₂O₄-type structure in the hexagonal R3m space group. Due to the point defects scattering, the thermal conductivity of In_0.4Yb_0.6FeZnO₄ reached a minimum value of 1.19 W m^-1 K^-1 at 1000 °C, which is much lower than the thermal conductivity (∼2.2 W m^-1 K^-1 at 1000 °C) of 8 wt.% yttria stabilized zirconia (8YSZ) thermal barrier coatings. The present results indicate that In_1-xYb_xFeZnO₄ ceramics are very promising as thermal barrier coatings.