Preparation of BaAl2-xGaxSi2O8:Ce3+, M+ (Li, Na, K) blue-cyan phosphors based on charge compensation and cation substitution strategies and luminescence performance study

Highly efficient blue-cyan phosphors can fill the cyan gap in conventional white light-emitting diode (LED) devices to improve the spectral continuity while effectively increasing the white LED colour rendering index (Ra). In this study, Ba 0·94 Al 2- x Ga x Si 2 O 8 :0.06Ce 3+ , M + (Li, Na, K, x  = 0–0.8) blue-cyan phosphors with a feldspar structure were prepared by a high-temperature solid-phase method using charge compensation and cation substitution strategies. The barium (Ba) vacancy due to the charge-imbalance substitution of Ce 3+ is compensated by the different charge compensators Li + , Na + , and K + . The charge compensators affect the luminescence performance of the samples, with the K + -compensated samples showing the greatest enhancement, with intensities up to 1.8 times that of the uncompensated samples. The cation substitution strategy using Ga 3+ to partially replace Al 3+ further improves the luminescence performance of the Ba 0·94 Al 2 Si 2 O 8 :0.06Ce 3+ , 0.04 K + sample, and the excitation band is also improved. In this case, the luminescence intensity of the Ba 0·94 Al 2 Si 2 O 8 :0.06Ce 3+ luminescent material is increased by a factor of 6, and a broadband blue-cyan phosphor with a full-width at half-maximum of 118 nm containing blue, cyan and green is obtained. The co-doping of charge compensators and partial cation substitution improved the luminescence performance of phosphors. The representative sample Ba 0·94 Al 1.6 Ga 0.4 Si 2 O 8 :0.06Ce 3+ , 0.04 K + has a luminescence intensity at a temperature of 150 °C that is 83.2% of that at room temperature and good thermal stability . The combination of 365 nm near-ultraviolet (NUV) LED chips with Ba 0·94 Al 1.6 Ga 0.4 Si 2 O 8 :0.06Ce 3+ , 0.04 K + and the commercial red powder (Ca, Sr)AlSiN 3 :Eu 2+ yields a white LED device with an Ra of up to 93 and a correlated colour temperature (CCT) of 4825 K. These results show that the blue-cyan phosphor complements the cyan component while simplifying the manufacturing process of white LEDs.