Effects of nonmetal (F, Si, B, and P) doping on the electronic structure and elastic properties of CeO2: A first-principles study

The electronic structure and elastic properties of pure CeO2 and the nonmetal doped system CeO2-X (X = F, Si, B, and P) were investigated using plane-wave pseudopotential method and generalized gradient approximation (GGA+U) by first-principles. The calculated lattice constant, band gaps and elasticity of pure CeO2 are in good agreement with the experimental results. F-doped CeO2 exhibits increased band gap at the Fermi level and enhanced nonmetal characteristics. Conversely, P-doped CeO2 features reduced nonmetal characteristics. Moreover, Si- and B-doped systems manifest disappearing band gap and metal characteristics. In nonmetal doped systems, the quantity of electric charge transferred by atom decreases, covalent binding is enhanced, and covalent bond length shortens. After nonmetal doping, the system presents mechanical stability and decreased elastic constants (C11, C12, and C44) and elastic moduli (B, G, and E). Si, B, and P doping enhances the ductility of CeO2 and the elastic anisotropy of the system. Furthermore, F doping slightly reduces the ductility but enhances the elastic isotropy of the system.