Synthesis and luminescence property of Bi3+ and Dy3+ ions doped MLa2O4 (M = Ba, Sr and Ca) phosphors for LEDs application

Syntheses of the MLa1.99-xO4:0.01Bi(3+)/xDy(3+) (M = Ba,Sr and Ca, and x = 0,0.02,0.05,0.08) phosphors are carried out by solid state reaction method. The samples are subjected to X-ray powder diffraction technique to determine the structure. According to the results, the Bi3+/Dy3+ ions have been substituted in the host materials in an effective manner. Furthermore, the diffuse reflectance spectroscopy throws light on the absorption spectrum with an observed peak around 300 nm owing to the host absorption band. An analysis of the luminescence properties of the synthesized materials using photoluminescence spectra points to an observed peak in the visible emission which stem from the energy states of F-4(9/2) -> H-6(11/2), H-6(13/2), H-6(15/2) ground configuration of Dy3+ ions under UV excitation. As the concentration of Dy3+ ions increases from 0 to 0.05, an increase in emission peak intensity is observed. However, a further increase in concentration to x = 0.08 results in an abrupt drop in emission peak intensity because of the concentration quenching effect of emission spectra. The chromaticity coordinates are also calculated using CIE (1931), varying the concentration of Dy3+ ions. In a bid to obtain findings relating to decay time of the material, decay curves are drawn.