Structural characterization, energy transfer, and Judd–Ofelt analysis of pure and the Eu3+‐doped Ca2LiMg2V3O12 phosphors

Abstract

AbstractA novel vanadate host Ca2LiMg2V3O12 (CLMV) and the Eu3+‐doped samples were synthesized via a solid‐state reaction method. The phase formation and the morphological analysis were studied in detail. The Rietveld refinement result shows that the host belongs to cubic space group Ia‐3d (230) with lattice parameter, a = 12.3948 Å, V = 1904.23 Å3, and Z = 8. The diffuse reflectance spectroscopy measurement estimated the bandgap of the host and the CLMV:0.05Eu3+ phosphors. The host exhibits a broad absorption band (peak at 345 nm) ranging from 240 to 380 nm, which is attributed to the charge transfer in the O2−–V5+ complex. Under near UV excitation (λexc = 345 nm), the host gives a broad emission band covering the visible region from 400 to 730 nm and the emission is in the bluish–green region of the CIE diagram. When the host is doped with the Eu3+ ions and excited at 345 nm, the emission spectrum depicts the superimposition of the characteristic emission bands (red emission) of the Eu3+ ions corresponding to the f–f transitions over the broad emission band of the host. The calculated color coordinates (9600 to 2280 K) demonstrated the color tuning ability of the phosphor as the dopant concentration is increased in the host. This is because the VO43− group plays the sensitiser role and partially transfers energy with the Eu3+ ions. When the same set of phosphors were excited at the dominant characteristic excitation band (λexc = 394 nm) of the Eu3+, the characteristic emission bands of the Eu3+ in the orange–red region were observed. As the electric dipole transition of the Eu3+ was found to be dominant, the prepared phosphors possessed high color purity (CP). The energy transfer mechanism and the lifetime values were also presented. The temperature‐dependent PL studies showed good thermal stability of the optimum sample. Various radiative transition properties were analyzed by the Judd–Ofelt theory. The photometric results reveal the color tuning ability and CP of the CLMV:xEu3+ phosphors.