Cationic substitution induced tuning of photoluminescence in Ba2.94-2La Na P4O13: 0.06Eu phosphors for WLEDs

Abstract The cationic substitution of [La3+-Na+] for [Ba2+-Ba2+] pairs in the Eu2+ doped Ba3P4O13 (BPO) phosphors is designed to investigate the effect on Eu valence state and photoluminescence properties. Energy dispersive spectroscopy (EDS) analysis demonstrates the successful incorporation of La3+ and Na+ into BPO, forming Ba2.94-2xLaxNaxP4O13 (BLNPO). Eu3+ ions doped in BLNPO host can only be partly reduced to Eu2+ state under a reducing atmosphere and the reduction mechanism is proposed. BLNPO: Eu exhibits a blue-green broad emission band derived from Eu2+ and a series of sharp emission lines from 570 to 720 nm assigned to the electron transition of 5D0→7FJ (J = 0, 1, 2, 3, 4) of Eu3+. The emission colors of the BLNPO: Eu phosphors can be tuned from blue-green to white and eventually to orange via regulating [La3+-Na+] content. Through this strategy, color-tunable white light emission is successfully achieved and optimized in single-phase BLNPO host, which enables the BLNPO: Eu phosphors to be potential color-tunable phosphor candidates for WLEDs.