Synthesis and photoluminescence properties of CaMTiO3:0.12Eu3+ (M = Mg, Sm) red phosphors for lighting application

Abstract

The xMg2+/ySm3+ ions co-doped CaTiO3:0.12Eu3+ red phosphors were synthesized by solid-state reaction method and their structure, crystalline morphology, luminescent properties, decay curves and quantum efficiency were investigated in detail. The XRD patterns show these phosphors have an orthorhombic perovskite structure when the sintering temperature was 1350 °C. From photoluminescence spectra, two excitation peaks were observed located at 397 nm (7F0 → 5L6) and 465 nm (7F0 → 5D2), and there are two prominent red emission peaks around 595 nm (5D0 → 7F1) and 616 nm (5D0 → 7F2) corresponding to the magnetic dipole transition and electric dipole transition of Eu3+ respectively. The luminescent properties were improved by adjusting Mg2+ and Sm3+ ions co-doping concentration and their optimal doping amount was found to be 7 mol% and 0.5 mol%. At this moment, their internal quantum efficiency was measured to be 52.4% and 47.5% respectively and decay times were 0.64 ms and 0.59 ms. According to concentration quench theory, the critical distance between activators in CaMTiO3:Eu3+ (M = Mg, Sm) were 15.27 A and 15.07 A. CaTiO3:Eu3+ phosphor’s thermal stability has been improved a lot due to Mg2+ introduction. When temperature increases from 248 to 388 K, the red emission intensity of CaMg0.07TiO3:0.12Eu3+ and CaMg0.07TiO3:0.12Eu3+,0.005Sm3+ phosphors have decayed only 12.1% and 15.9% respectively. These experimental results have indicated that the synthesized red phosphors can be used in solid state lighting devices.