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

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 characte...

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Bibliographic Details
Published in:Physica status solidi. A, Applications and materials science Applications and materials science, 2011-09, Vol.208 (9), p.2170-2175
Main Authors: Thomas, Mariyam, Rao, Padala Prabhakar, Mahesh, Sundaresan Pillai Kamalam, Kumari, Leela Sandhya, Koshy, Peter
Format: Article
Language:English
Subjects:
Applied sciences
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Electronics
Exact sciences and technology
Inorganic compounds
luminescence
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Optical properties of bulk materials and thin films
Optoelectronic devices
phosphors
Photoluminescence
Physics
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Structure of solids and liquids
crystallography
Structure of specific crystalline solids
tungstates
white LEDs
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Summary: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).
ISSN:1862-6300
1862-6319
DOI:10.1002/pssa.201026702