Thermal diffusivity and conductivity of ceramics based on the GdFeO3– GdCrO3 system

Gadolinium ferrochromites were successfully synthesized as continuous solid solutions in the GdFeO₃ – GdCrO₃ system via solid-state reaction. Structural and microstructure analyses revealed the formation of an orthorhombic perovskite-type phase with isometric chain-like grains. SEM data demonstrated a systematic decrease in the average grain size, from ∼9.0 μm to ∼2.0 μm, as the Cr content increased. The thermal properties, including thermal diffusivity and thermal conductivity, were investigated using the laser-flash diffusivity method. Thermal diffusivity was observed to decrease with increasing Cr substitution, consistent with enhanced phonon scattering induced by finer grains and increased porosity. Compositions with x = 0.50 and 0.77, sintered at 1400 °C for 24 h, exhibited optimal thermal insulation properties, characterized by porosity levels of 44–48 % and thermal conductivities of 0.6–0.7 W/(m∗K) at room temperature. These findings demonstrate that the microstructure and thermal properties of GdFe_1-xCr_xO₃ oxides can be tuned through Cr doping, making them promising candidates for thermal insulation applications in high-temperature conditions.