Excellent red emission via violet-blue excited in aluminate-based phosphors for white LED application
摘要
Three types of CaAl2O4:Li+ phosphors singly doped with Eu3+, Sm3+, and Ho3+ ions were synthesized using high temperature solid-state reaction method, and the effects of rare-earth ions and doping concentration on the crystal structure, thermal stability and luminescence properties were systematically studied. The XRD patterns show that all Ca1 − xAl2O4:0.01Li+, xRe3+ (Re = Eu, Sm, Ho) phosphors are pure monoclinic CaAl2O4 phase. And these phosphors can be effectively excited by the characteristic excitation wavelength of the corresponding rare earth ions. Notably, when the doping concentration is less than 15 mol%, the corresponding luminous intensity increases monotonically with the increase of Ho3+, while the optimal doping amounts for Eu3+ and Sm3+ are 9 mol% and 1 mol%, respectively. Additionally, comparative analysis revealed superior energy transfer efficiency from the matrix to the luminescent center in the CaAl2O4:0.01Li+, Eu3+ relative to Sm3+ and Ho3+ counterparts. More importantly, the Ca0.91Al2O4:0.01Li+, 0.09Eu3+ phosphors also exhibit excellent thermal and ageing stability. Its luminous intensity exhibited minimal deviation (< 16%) across an extended temperature range (208 ~ 448 K). Furthermore, after 320 h of thermal aging at 100 °C, the sample retained over 98% of its initial fluorescence intensity. This study provides theoretical and experimental basis for the development of CaAl2O4-based phosphors for solid-state lighting devices.