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Luminescent properties of Tb 3 + activated CsLa(WO4)2 green phosphors from polymeric sol-gel method

Balaji Devakumar 1Durairajan Arulmozhi 1Kavirasu Kallimuthu Moorthy Babu Sridharan 

1. Crystal Growth Centre, Anna University, Chennai, Chennai 600025, India


Rare earth activated inorganic materials are still attracting much attention due to its potential application in various optoelectronic devices such as field emission displays (FEDs), plasma display panels (PDPs), cathode-ray tubes (CRTs) and fabrication of white light-emitting diodes (WLEDs). White light can be generated by the following approaches, combining GaN based LED (465nm blue light) with Ce3+: YAG phosphor (yellow) which has two drawbacks such as lower colour-rendering index (CRI), low colour reproducibility, and poor luminous efficiency. Rare Earth tungstates are of great interest as a host lattice for luminescent ions, due to their excellent properties such as strong covalent interaction, high stability and strong visible luminescence. They have broad and intense charge-transfer (C-T) absorption bands in near UV region and capable of transferring energy to the activators by non-radiative mechanism. In this present work, Tb3+ activated CsLa(WO4)2 was synthesized by polymeric sol-gel process using nitrates, water soluble para tungstates, citric acid (as chelating agent) and ethylene glycol (as binding agent) as precursors. The effect of calcination, crystallanity, surface morphology, tungstate chain formation and luminescence properties were studied. Phase purity has been confirmed by powder XRD. Formation of metal citrate with ethylene glycol resin was confirmed by FT-IR spectrum and the liberation of organics from gel at higher calcination temperature was also analyzed. Raman bands reveal the formation of tungstate chains at higher frequency region. The excitation spectra consist of broad bands due to 4f8→4f75d1 transition and some sharp peaks due to f→f transition within Tb3+ 4f8 configuration. The emission spectra consists of two visible emissions (i.e.) blue (5D37FJ) and green (5D47FJ). The role of different concentration of Tb in CsLW and different synthesis processes on physical and luminescence properties were evaluated. The results will be discussed in detail.


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Related papers

Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 7, by Balaji Devakumar
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-03-28 05:17
Revised:   2013-03-28 10:17