First-Principles Study on Electronic Properties and Optical Spectra of Ce-Doped La2CaB_(10)O_(19) Crystal

摘要

We report herein a first-principles investigation on electronic properties and 4f → 5d transitions of Ce~(3+) substituted at La~(3+) and Ca~(2+) sites of La2CaB_(10)O_(19) (LCB) crystal, using the hybrid density ftmctional theory (DFT) and the wave function-based embedded cluster calculations, respectively. The hybrid DFT with PBEO functional yields a band gap of 8.1 eV for LCB, in good agreement with the experimentally estimated value of ～8.3 eV. The energy gaps between the occupied Ce~(3+) 4f states and the valence band maximum of the host are predicted to be 1.93 ± 0.12 eV, with a slight dependence on the local environment. Based on the results of embedded cluster calculations at the CASSCF/CASPT2 level with the spin-orbit effect, the experimentally observed excitation bands are identified in association with the two cerium substitutions. The difference between the lowest 4f →5d transition energies of Ce~(3+) located at the two dopant sites are rationalized in terms of the variations in centroid energy and crystal-field splitting of the Sd' configuration with the local environment.