Luminescence properties of Pr^(3+) and Bi^(3+) co-doped NaCaTiNbO_6 phosphor for red-LEDs

This paper investigates the photoluminescence properties of NaCaTiNbO6：Pr^3＋ and NaCaTiNbO6：Pr^3＋,Bi^3＋ phosphors. NaCaTiNbO6：Pr^3＋ and NaCaTiNbO6：Pr^3＋,Bi^3＋ powder were synthesized successfully by solid state reaction method. Phase purity was checked using X-ray powder diffractometry（XRD）. The excitation and emission spectra were recorded to elucidate the photoluminescence properties of NaCaTiNbO6：Pr^3＋ and NaCaTiNbO6：Pr^3＋,Bi^3＋. Furthermore,fluorescence lifetime measurements were performed. The excitation spectra of NaCaTiNbO6：Pr^3＋ show a main band centered at around 357 nm.The luminescence spectra of NaCaTiNbO6：Pr^3＋ exhibit a red emission peak at 615 nm from the ^1 D2→^3 H4 transition of Pr^3＋ ions. With the introduction of the Bi^3＋ ion into NaCaTiNbO6：Pr^3＋, the luminescence intensity is enhanced nearly two times. Meanwhile,the absorption band edge of NaCaTiNbO6：Pr^3＋ is shifted from 380 to 420 nm. Thus, this study shows that the red phosphor NaCaTiNbO6：Pr^3＋ incorporated with Bi^3＋ is advantageous for light-emitting diode applications.