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

Abstract

Ceria doped with rare earth ions (Ce _1−x M _x O _2−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, Y ^3+ ions were doped into the lattice of CeO _2 to form Ce _1−x Y _x O _2−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 Y ^3+ ions in CYO films increased from zero, and then the defective fluorite structure transformed into rare earth C-type structure when the proportion of Y ^3+ ions was beyond 0.5. Moreover, at the beginning, the degree of oxygen diffusion showed an uptrend; but after the proportion of Y ^3+ ions reached a certain value, the degree of oxygen diffusion turned into a downtrend.

Keywords

• Ce1-xYxO2-y thin films
• Oxygen diffusion
• Buffer layer
• Rare earth C-type structure