Broadly tuning Sm~(3+) emission via crystal field micro-modulation in CdMoO_4 for white-LEDs

摘要

Rare earth activated oxides phosphors have attracted much attention in the field of solid state lighting (SSL) due to their irreplaceable advantages. In this work, a series of CdMoO_4:aSm(3+) and CdMoO_4:aSm~(3+), M~+ (M = Li, Na, K) phosphors were prepared by high temperature solid-state reaction. X-ray diffraction and photoluminescence spectroscopy were utilized to characterize samples properties. The concentration dependent luminescence of Sm~(3+) activated CdMoO_4 sample was investigated in detail. The optimum doping concentration of CdMoO_4:aSm~(3+) was 0.015 (1.5 mol%) and the corresponding concentration quenching mechanism was verified to be the electric dipole-dipole interaction. Also, CdMoO_4:0.015Sm~(3+) phosphor exhibits bright red-orange emission with excellent CIE coordinates (x = 0.5887, y = 0.3908) under the excitation at 346 nm. In addition, it was observed that the luminescence intensity of Sm~(3+) and Na~+ co-doped sample was 3.667 times stronger than that of the Sm~(3+) single doped sample under the same excitation wavelength. Meanwhile, when Na~+ was incorporated into the CdMoO_4 matrix, the color purity of CdMoO_4:Sm~(3+) phosphor was enhanced from 78.0 to 81.3 %. These red-orange phosphors are promising for application in white light emitting diodes.