Theoretical studies on thermodynamic stabilities and luminescent mechanisms of defects and lanthanide ions in BaZrSi3O9

Theoretical studies on thermodynamic stabilities and luminescent properties for the defects and lanthanide ions in the BaZrSi3O9 are performed in order to better understand luminescence mechanisms of undoped and lanthanide-doped BaZrSi3O9. The defect formation energies derived from density functional theory (DFT) cal-culations with the hybrid PBE0 functional are devoted to analyze thermodynamic stabilities of intrinsic (i.e., the vacancies and antisite defects) and Ti-related defects in the host. The experimental excitation spectra of Ce3+- and Eu2+-doped BaZrSi3O9 phosphors are assigned according to 4f -> 5d transition energies obtained from ab-initio calculations at the complete-active-space self-consistent field/complete-active-space second-order pertur-bation theory/restricted-active-space state-interaction spin-orbit (CASSCF/CASPT2/RASSI-SO) level. Moreover, the mechanisms of the charge transfer (CT), thermoluminescence (TL) and long-lasting luminescence (LLL) in the undoped and lanthanide-doped BaZrSi3O9 are reasonably interpreted on the basis of the thermodynamic tran-sition energy levels of the defects in the host.