Research Article
Open Access
Doping Effect an Optical Band Gap and Luminescence of Pure and Nd-Doped CoWO4Wolframite Nanostructure Synthesized by Chemical Precipitation
Juliet Josephine Joy. J
RRase College of Engineering, Chennai, Tamilnadu, India
Juliet Josephine Joy. J /Int.J. Chemical Concepts. 2015,1(2),pp 44-56.
Abstract
Wolframite type pure andNd-doped CoWO4 were synthesized by easy and effective
chemical precipitation technique. Typical monoclinic phase and crystal structure of the samples were
confirmed from the XRD pattern. Well defined nanocubicalmorphology with round edges of the pure
and doped samples were confirmed from the electron microscopy analysis. UV-Vis spectra for pure
and Nd3+ doped CoWO4 demonstrates that the excellent optical behaviour of the wolframite cobalt
tungstates nanostructure. Optical energy band gap was varied with the doping as well as calcination
temperature ascribes to the changes in the electronic structure. From the band gap calculation it is
confirmed that the observed band gap is direct which is not belongs to the indirect. Further, the red
shift in the absorption edge substantiates the formation of nanacrystalline CoWO4 and thus evidences
the incorporation of Nd into Co lattice site completely. The strong PL emission peak was centered at
455 nm region for all the samples due to the radtiative transition within the [WO4]-4 tetrahedral group.
The relative intensity of the emission band reduced and at 5 mole% doping it is almost no emission
was observed. This luminescent quenching is confirms the lower annihitaion process in doped CoWO4
nanostructure when compared to pure wolframite. Overall, from this study tuning of an electronic
structure by doping will influences on the optical band gap as well as PL emission in the CoWO4
nanostructure.
Keywords
Chemical synthesis, Wolframite, optical band gap, luminescent quenching