Structural, morphology and luminescence properties of mixed calcium molybdate-tungstate microcrystals doped with Eu3+ ions and changes of the color emission chromaticity

Abstract Microcrystals of the inorganic red emitting phosphors EuxCa1-1.5xMoyW1-yO4 (x = 0.00667, 0.03333, 0.06667; y = 0, 0.1, …, 0.9, 1) were synthesized by a traditional solid-state method. Studied materials were characterized by X-ray diffraction, infrared spectroscopy and luminescence spectroscopy (luminescence spectra and lifetime measurements). The morphology of the phosphors was characterized by scanning electron microscopy. The luminescence excitation spectra of EuxCa1-1.5xMoyW1-yO4 phosphors were mainly attributed to O2− → Mo6+ and O2- → W6+ charge-transfer (CT) bands in the UV region, at ∼ 260–340 nm, and some sharp lines of Eu3+ transitions with the two strongest at 394 nm and 465 nm (in near-UV and visible regions). The EuxCa1-1.5xMoyW1-yO4 phosphors showed intense red luminescence characteristic for the Eu3+ ions and the emission peaks were ascribed to the 5D0 → 7FJ (J = 0, 1, 2, 3, 4) transitions, respectively. The calculated chromaticity coordinates indicate these phosphors as potential candidates of red phosphors for high quality light source, e.g. LEDs.