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Tellurite glasses; Raman spectroscopy; photoluminscence; Stark level splitting; UV visible spectroscopy.

TeO$_2$-based glasses with a general formula 65TeO$_2$−5BaF$_2$−30ZnF$_2$ (TBZ) (in mol%) were prepared by usual melt quenching technique. Three mol% of europium (Eu) or erbium (Er) were added to the prepared glass at the expense of TeO$_2$. Raman, photoluminescence (PL), UV–visible absorption studies were carried out on the glass samples. Raman spectra of the undoped and doped glasses were analysed using the peak shift and the intensity variation along with fullwidth at half-maximum (FWHM). It was found that Eu-doped TBZ glass has a greater tendency towards depolymerizing theglass matrix by influencing the conversion of TeO$_4$ to TeO$_3$ units compared to Er-doped and undoped glasses. PL spectraof the glass samples show emission due to different possible transitions. Position of the peak of the de-convoluted spectrashows the position of the particular Stark component and the FWHM is a measure of the inhomogeneous broadening. TheUV–visible absorption spectra are used to calculate the optical density and to determine the band edge of the glass samplesby fitting to the Mott equation. It is seen that Eu-doped TBZ glass has a lesser bandgap than that of Er-doped glass.

GAJANAN V HONNAVAR^{1 2} K P RAMESH²

1. PES Institute of Technology, Bangalore South Campus, Near Electronic City, Bangalore 560100, India
2. Department of Physics, Indian Institute of Science, Bangalore 560012, India

Manuscript received

14 September 2016

Accepted

30 November 2016