Microstructural evolution and its influence on oxygen diffusion in yttrium-doped ceria thin films

Abstract

Ceria doped with rare earth ions (Ce1−xMxO2−y (y = x/2)), which contain many oxygen vacancies, have become excellent electrolyte materials for solid oxide fuel cells and important buffer layers for coated conductors. In this paper, Y3+ ions were doped into the lattice of CeO2 to form Ce1−xYxO2−y (CYO) thin films regarded as buffer layers to reduce oxygen diffusion on silicon substrates. It was revealed that the CYO films gradually transformed from a complete fluorite structure into a defective fluorite structure with more and more oxygen vacancies as the proportion of Y3+ ions in CYO films increased from zero, and then the defective fluorite structure transformed into rare earth C-type structure when the proportion of Y3+ ions was beyond 0.5. Moreover, at the beginning, the degree of oxygen diffusion showed an uptrend; but after the proportion of Y3+ ions reached a certain value, the degree of oxygen diffusion turned into a downtrend.