Photoluminescence properties and site-preferable distribution of Ce3+ in Na2Ca1-xSrxSi2O6 (x = 0–1) blue-emitting phosphors.

Two Ce 3+ doped sodium strontium (calcium) silicates, Na 2 SrSi 2 O 6 :Ce 3+ and Na 2 CaSi 2 O 6 :Ce 3+ , were prepared by high temperature solid state reaction. They both crystallize in trigonal crystal system with space group R 3 ¯ m. Substitution of three independent Ca 2+ sites for Ce 3+ ions yields blue emission when excited by UV light (λ e x  = 352 nm). Accordingly, Ce 3+ ions occupying two distinct Sr 2+ sites generate UV to blue light under 300-nm UV excitation. A series of Na 2 Ca 1- x Sr x Si 2 O 6 :Ce 3+ ( x  = 0–1) were prepared. All the samples form solid solutions and are isotypic confirmed by Rietveld refinements. Increasing Sr 2+ content leads to asymmetrical blue shift of PL spectra. Refinement results clarify preferable site occupancy of Sr 2+ in Na 2 CaSi 2 O 6 compound which results in the irregular shift. The migration of Ce 3+ ions between M3 and M4 sites is the key point of this phenomenon. This mechanism could be a guideline to optimize the emissions of emitting centers with multiple sites. [ABSTRACT FROM AUTHOR]