Search for content and authors

Sol-gel Synthesis and Luminescence studies on Dy3+ Doped NaGd(WO4)2 Yellow Phosphor for Solid State Light Applications

Durairajan Arulmozhi 1Balaji Devakumar 2Kavirasu Kallimuthu Moorthy Babu Sridharan 

1. Anna university, chennai 600025, India
2. Crystal Growth Centre, Anna University, Chennai, Chennai 600025, India


Concentrated efforts were made towards the synthesis of rare-earth activated inorganic oxides based materials for potential applications like solid state lighting (SSL), displays, sensing device and so on. Materials now used in SSL applications like Ce:YAG (excited by blue LED) and tricolour phosphors (excited by UV LED) have their own drawbacks. In this regard as a complimentary materials, NaGd1-xDyx(WO4) (Dy:NGW)   were prepared in sol-gel methods for possible application in SSL devices. Dy:NGW have two principle emission schemes in blue and yellow region corresponding to transitions of 4F9/2-6H15/2 and 4F9/2-6H13/2 at specific wavelengths, 480 and 574 nm.  Sol-gel synthesised Dy:NGW powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infra-red spectroscopy (FT-IR), Raman and spectroflorimeter analysis. The disordered NGW scheelite structure was confirmed by XRD results. SEM images clearly show the surface morphology and size of particles. The formation of tungstate tetrahedral and its corresponding vibration were analyzed with FT-IR and Raman studies. The combined charge transfer band (CTB) of O2--W and O2--Dy3+ were obtained in excitation spectrum. The CTB observed in the region of 230 to 310 nm and high absorption centered at 270 nm and above 310 nm ascribe the various f-f transitions of Dy3+ ions. Compared to CTB at 270 nm the f-f transition at 353 nm has high absorption intensity as observed in the emission spectrum.  The concentration and excitation wavelength dependent luminescence property were analyzed through emission spectrum. Three lines were observed at 480, 575 and 665 nm in blue, yellow and red region corresponding to the transitions of  4F9 to6HJ (J = 15/2, 13/2 and 11/2) in the emission spectrum.  Based on the results, the optimum dopant concentration of Dy3+ ions in NGW has been found to be 7 at% .   


Legal notice
  • Legal notice:

Related papers

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

Submitted: 2013-03-28 05:12
Revised:   2013-03-28 07:47