Microstructure evolution and cation interdiffusion in thin Gd2O3 films on CeO2 substrates

Thin Gd2O3 films with a thickness of about 150 nm were deposited by pulsed layer deposition on polycrystalline CeO2 substrates to study the structural evolution of the Ce1−xGdxO2−x/2 system with respect to phase formation and cation interdiffusion in the temperature range between 986 °C and 1270 °C. Transmission electron microscopy combined with quantitative energy dispersive X-ray spectroscopy was applied to study the microstructure and to obtain composition profiles across the Gd2O3/CeO2-interface. Gd2O3 was observed to occur in the bixbyite structure up to 1175 °C. The fluorite and the bixbyite phase are found at intermediate compositions without any indication for a miscibility gap. Interdiffusion coefficients were obtained from Gd2O3/CeO2-concentration profiles on the basis of the diffusion-couple solution of the diffusion equation. The activation enthalpy and frequency factor of the diffusion coefficient were derived assuming an Arrhenius-type behavior in the investigated temperature range.