Theoretical and experimental studies on the crystal structure, electronic structure and optical properties of SmTaO₄

The crystal structure, electronic structure and optical properties of SmTaO₄ were identified through an experimental method and first principles calculation. X-ray powder diffraction (XRD) and a spectrophotometer were used to characterize the crystal structure, reflectivity and band gap of this material; furthermore, the electronic structure and optical properties were investigated according to three exchange-correlation potentials, LDA, GGA and GGA + U. Results show that the SmTaO₄ calcined at 1400 °C with the solid-state reaction method is in monoclinic phase in the space group I²/a. In addition, the calculated lattice parameters are consistent with the experimental values. The electron transitions among the O 2p states, Sm 4f states and Ta 5d states play a key role in the dielectric function, refractive index, absorption coefficient and reflectivity of SmTaO₄. The calculation of first principles provides considerable insight into the relationship between the electronic structure and optical properties of this material.