Synthesis, characterization, and luminescent properties of CaS:Eu phosphor

Europium-doped calcium sulfide phosphor was synthesized by a co-precipitation method using calcium carbonate and ammonium sulfate as the sources for calcium and sulfide, respectively. Reduction of the precipitated CaSO4 into CaS was carried out at 550 degrees, 750 degrees, 950 degrees, and 1150 degrees C at a flow rate of H-2 5 mL/min and N-2 95 mL/min. The formation of crystalline CaS phase was evident by the X-ray diffraction analysis of the fired products. The phosphor yielded red emission of wavelength 634 nm for the excitation wavelength of 465 nm. The emission intensity of the phosphors increased with increasing firing temperature from 550 degrees to 950 degrees C, but firing at 1150 degrees C showed a dramatic decline in emission due to thermal quenching. The study of the effect of Eu loading level showed a decrease in emission with an increase in loading, and the optimum loading for maximum emission was found to be 0.5 mol%. And it can be possible to generate white light of light emitting devices by mixing with SrGa2S4:Eu green phosphor and this phosphor on the 460 nm InGaN blue chip.