Two strategies to achieve color adjustment of Eu2+-doped garnet Lu2Mg2Al2Si2O12 phosphors

Abstract

Phosphors with excellent color adjustable properties have always been the research focus of scientific researchers. This work uses two strategies to control the luminescence behavior of Eu2+ ions in the Lu2Mg2Al2Si2O12 (LMAS) matrix. Firstly, by adjusting the Eu2+ ion concentration, the emission spectra of Lu2Mg2Al2Si2O12:Eu2+ (LMAS:Eu2+) could achieve a 39 nm red shift from 451 to 490 nm, which provides a good blue to cyan emission. Secondly, the Lu2Mg2Al2Si2O12:Eu2+,Mn2+ (LMAS:Eu2+,Mn2+) realized the tuning from the cyan to the white region by introducing Mn2+ ions, which is owing to the sensitization process of Eu2+ to Mn2+ enhancing the red-light emission. The energy transfer process was explored in detail, and the energy transfer efficiency was calculated to be more than 60%. Meanwhile, the thermal stability of the material was also studied. The thermal stability illustrates its potential application in white light-emitting diode (WLED). Under 30 mA drive current, the device obtained by using 365 nm ultraviolet (UV) chip with LMAS:0.01Eu2+,0.35Mn2+ phosphor has a color rendering index (Ra) as high as 93.1, R9 = 85, LE = 1.81 lm/W, the color coordinate is (0.3076, 0.3119) and the correlated color temperature (CCT) is 6984 K, which is obviously in the white light area. The above results indicate that LMAS:Eu2+,Mn2+ phosphors with full-visible-spectrum have potential applications in solid-state lighting.