Thermal analyses, spectral characterization and structural interpretation of Yb3+ doped TeO2-ZnO-ZnCl2 glasses

Bulk glasses have been prepared in the TeO2-ZnO-ZnCl2 systems. Their characteristic temperatures were determined and analyzed. Raman and FT-IR spectra were used to analyze the effect of ZnCl2 on the structure and spectral properties of tellurite glasses and OH− groups in this glass system. The spectroscopic properties including absorption spectra, emission cross-sections and fluorescence lifetimes of Yb3+ in TeO2-ZnO-ZnCl2 were measured and calculated. It is demonstrated that the progressive replacement less than 20 mol% of TeO2 by ZnCl2 improves the thermal stability, removes the OH− groups, turns TeO4 bi-pyramidal arrangement into TeO3 (and/or TeO3+1) trigonal pyramids structures and results in the decrease of the symmetry of the structure, which increases the emission cross-sections and lifetimes. But when the content of ZnCl2 up to 30 mol%, the glass system becomes more hygroscopic and introduces more OH− groups, which decrease the emission cross-sections and shorten the lifetimes. The results show that the glass system with 69TeO2-10ZnO-20ZnCl2-1Yb2O3 is a desirable component for active laser media for high power generation.