First principle study of electronic, optical properties and Raman spectroscopy of alkali earth metals doped ceria

Abstract

First-principle calculations were used to investigate the electronic and optical properties of ceria doped with alkali earth metals, following the Perdew-Burke-Ernzerhof (PBE-GGA) scheme. The doping of ceria with alkali earth metals leads to the formation of an indirect band gap which is attributed to the differences in symmetry points between ceria and the dopants. Optical properties, including the real and imaginary dielectric constant, refractive index, extinction coefficient, reflectivity, and absorption coefficient, were computed using thermo_pw software connected to Quantum Espresso. Compared to pure ceria, doped ceria with alkali earth metals exhibited the highest absorption peaks in the visible light energy range from 1.63 to 3.26 eV. This suggests that alkali earth metal doping enhances ceria’s optical absorption. The Raman spectroscopy study was employed to investigate the structural and spectral response of alkali earth metals doped ceria. The Raman spectroscopy analysis of alkali earth metals doped ceria revealed three peaks: the main peak characteristic of the ceria structure (~ 445–452 cm^-1), a defect-induced peak (~ 600–630 cm^-1), and a secondary structural mode peak (~ 690–705 cm^-1), respectively. The doping of alkali earth metals in ceria modifies its electronic, optical, and Raman spectroscopic properties, making it promising for technological applications.