Elastic properties and electronic structure of transition metal atoms in CeO 2 solid solution: First principle studies

The elastic properties and electronic structure of the solid solution of CeO2–M (M = Ti, Zr, Hf, V, Nb, Ta) are studied using first principle methods based on density functional theory (DFT). The investigation shows that the elastic constants (B, G, E, C11 and C12) of the solid solution structure of the CeO2–M system have increased, resulting in improved mechanical properties, particularly for CeO2–Zr. The elastic constant C44 in CeO2–Ti and CeO2–V shows a marked reduction. The elastic modulus of CeO2–Nb significantly increased, and its anisotropy is not significantly different from CeO2. By calculating the energy band and density of states, it is shown that CeO2 is an insulator, and there are two band gaps. For transition metal solid solutions, the lattice constant of the CeO2–M system decreases, and the second band gap disappears because the Ce atomic contribution reduces, and there is overlap of the 4f and 5d orbital energies. The valence and conduction bands of the CeO2–M system (Ti, Zr, Hf) were found to shift slightly, with the band gaps reducing to 2.03 eV, 2.477 eV, and 2.44 eV respectively. The band structure of the CeO2–M system (V, Nb, Ta) as a whole moves down, and the second band gap disappears. For bands near the Fermi level, the band gaps are 1.37 eV, 2.51 eV, and 2.73 eV respectively.