Effects of Doping and Oxygen Vacancy Concentrations on Oxygen Ion Migration in SmxCe1-xO2-δ: a DFT + U Study掺杂和氧空位浓度对SmxCe1-xO2-δ 中氧离子迁移的影响: DFT U研究chinese journal of chemistryIF10.32019-06-141PRE