First-principle Studies on Enhanced Optical Stability of BaMgAl₁₀O₁₇:Eu²⁺ Phosphor by SiN Doping

Using density functional theory, we studied band structure, density of states, optical proper-ties and Mulliken population of the pure and SiN doped BaMgAl₁₀O₁₇:Eu²⁺(BAM:Eu²⁺) phosphors. Calculation results showed that the bands of BAM:Eu²⁺ were of low band en-ergy dispersion, indicating large joint density of states, hence high performance of optical absorption and luminescence. BAM:Eu²⁺ showed stronger absorption intensity while Eu²⁺ occupied the BR sites instead of the mO sites. The concentration of Eu²⁺ at BR sites increased while that at mO sites decreased after Si-N doping. The influence of the vari-ation of Eu²⁺ distribution on the spectra was stronger than the influence of the decrease of Eu²⁺ PDOS when SiN concentration was lower than 0.25, therefore the absorption andluminescence intensity of BAM:Eu²⁺ were enhanced. Mulliken population of Si-N bond was higher than Al-O bond, while that of Eu-N bond was higher than Eu-O bond as well, indicating that Si-N bonds and Eu-N bonds possessed higher covalence than Al-O bonds and Eu-N bonds respectively. The existence of Si-N bonds and Eu-N bonds enhanced the local covalence of Eu²⁺, hence the optical stability of BAM:Eu²⁺.