Phase formation and spectral evolution of (Sr,Ba) 2 Si(O,N) 4 :Eu 2+ phosphors

Sr 2‐ x B a x Si(O,N) 4 :Eu 2+ ( SB x SON :Eu 2+ ) oxynitridosilicate phosphors were prepared via incorporation of N 3− , Eu 2+ , and Ba 2+ ions into Sr 2 SiO 4 ( SSO ) lattices. X‐ray diffraction patterns of the prepared powders revealed that SB x SON :Eu 2+ was a solid‐solution form of SSO . An increase in x values caused a phase transition and an expansion of the unit cell. The photoluminescence excitation ( PLE ) spectra of SB x SON :Eu 2+ were broad, covering the ultraviolet range to the visible range. Corresponding PL emission spectra strongly depended on the excitation wavelengths and consisted of two emission bands, one in the green‐blue region (A‐band) and the other in the red region (B‐band), which were assigned to Eu(I) and Eu( II ), respectively. The B‐band resulted from a dramatic red‐shift of the green emission band assigned to Eu( II ) of SSO :Eu 2+ , revealing that the nitridation process preferentially affected the Eu( II ) sites. This behavior was explained by crystal field splitting, the fluorescence decay time, and thermal quenching. The Ba 2+ substitution caused evolution of the PL spectra, and its effects on the spectra were discussed under consideration of ionic size and covalence.