| An Investigation on the Crystal Growth Studies and Emission line shape in $Er^{3+}$-doped Sodium Tellurite Glasses |
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Purushottam Joshi, Animesh Jha |
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Formerly at the IMR, University of Leeds. Now at the Fibre Optics Laboratory, Raja Ramanna Centre for Advance Technology |
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| Abstract |
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Crystallisation kinetics of the erbium doped soda-tellurite glasses were studied using the differential thermal analysis (DTA) and differential scanning calorimetery (DSC) techniques. The DTA curves in the temperature range of 350 K to 650 K were obtained from isochronal heating rates, chosen in the range of 2 to 20 K/min. DSC isothermal curves were used to calculate the fraction of crystals formed on reheating. The apparent activation energies for devitrification were derived by measuring the shifts in the values of $T_g$ and $T_x$ with heating rates, using the Kissinger method. The derived values of apparent activation energies for isochronal and isothermal methods varied in the range of $190-204;{pm};5;kJ;mol^{-1}$. The X-ray powder diffraction analysis of heat treated and transparent samples showed the presence of nano-scale size sodium-tellurite crystals. These crystallites were found to have a strong influence on the full width of half maxima of the transition in $Er^{3+}:;^4I_{13/2}{
ightarrow}^4I_{15/2}$, which extended from 70 nm in the vitreous materials to 132 nm in glass-ceramic materials. |
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