Mechanical and Electronic Properties of CeO <sub>2</sub> Under Uniaxial Tensile Loading: A DFT Study

Abstract

CeO2 is a promising candidate for materials utilized in solid oxide fuel cells (SOFCs) due to its high ionic conductivity. The high operating temperature of SOFCs results in residual thermal stress in the materials. In this work, for the first time, we studied simultaneously the mechanical and electronic behavior of CeO2 under different uniaxial tensile loading directions using density functional theory. CeO2 shows strong anisotropic mechanical and electronic behavior under uniaxial tensile strain that it has the highest ideal strength and fracture strain along [100] direction. Meanwhile, [100] tensile strain also leads to the largest band gap reduction compared with the other two strain directions. The analysis of the mechanism shows that the highest strength along [100] direction is from the highest Young’s modulus and surface energy. While the analysis on the band gap variation using a theoretical model previously developed by us suggest that the largest average bond length and dielectric susceptibility variation leads to the largest band gap reduction when [100] tensile strain is applied to CeO2. Therefore, the current study provides a meaningful insight into the mechanical and electronic properties of CeO2 under stress, which is vital for its application as SOFCs’ materials.