Luminescence properties of Eu³⁺, Bi³⁺ coactivated CaLaNbWO₈ red phosphors under near UV and blue excitations

Abstract

Scheelite type red phosphors CaLa1–xNbWO8: xEu3+ (x = 0.01, 0.03, 0.05, 0.1, 0.15, 0.2, and 0.25) and CaLa0.8–yNbWO8: 0.2Eu3+, yBi3+(y = 0.1, 0.15, and 0.2) were prepared by conventional solid state reaction route. The crystalline structure, morphology and absorbance of these phosphors were characterized by powder X‐ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FT‐IR), and UV–Visible absorption spectroscopy. Investigations on their photoluminescent properties indicated that both Eu3+ doped and Eu3+, Bi3+ coactivated samples emit strong red light at 615 nm under both near UV (394 nm) and blue (465 nm) excitations. Bi3+ codoped system showed broadened charge transfer band (CTB) and stronger excitation peaks at 394 and 465 nm. The red emission intensity of CaLa0.8NbWO8: 0.2Eu3+ phosphor is improved by a factor of 2 as 20 mol% Bi3+ is introduced into the system, and is four times stronger than that of the commercial Y2O3:Eu3+ red phosphor. These phosphors are characterized by sharp red emission with color coordinates closer to the standard red phosphors. Thus, the above phosphors could be a promising red candidate for the phosphor converted white light emitting diodes (pc‐WLEDs).

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