Powellite type molybdate-based red phosphors CaGd 1Àx Nb-MoO 8 : xEu 3+ (x = 0.05, 0.1, 0.15, 0.20, 0.25, and 0.30) were synthesized by a solid-state reaction (SSR) route, and a citrate gel (CG) route. The crystalline structure, morphology, absorbance, and luminescent properties of these phosphors were characterized using powder X-ray diffraction, scanning electron microscopy, UV visible absorption spectroscopy, and photoluminescence spectroscopy. The solid solution formation of the phosphor effectively takes place at a lower temperature by the CG route than the SSR route. Particle morphology of the phosphors prepared by the CG route reveals that they are less agglomerated, more spherical, and homogenous in nature with uniform particle size. Investigations on photoluminescence properties show that these phosphors emit strong red light (614 nm) under both near UV (395 nm), and blue (465 nm) excitations. The morphological variation of the developed phosphors with respect to synthesis method and heat treatment played an important role in their luminescence enhancement. The red phosphors prepared via CG route were characterized by enhanced and sharper red emission with longer life time compared to that of phosphors synthesized via SSR route. The CIE color coordinates of the developed red phosphors are (0.65, 0.34) that are closer to NTSC standard red phosphor. Thus, these phosphors could be a promising red candidate for the phosphor converted white light emitting diode applications.
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).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.