Barium Tellurite Glasses Research Articles

Efficient ~2.0 μm emission from Ho 3+ doped tellurite glass sensitized by Yb 3+ ions: Judd-Ofelt analysis and energy transfer mechanism [Invited

The ~2.0μm emission characteristics of Ho3+ both by direct excitation and through Yb3+ sensitization in barium-tellurite glass are reported. The radiative properties of active ions have been evaluated by applying Judd-Ofelt theory on the measured absorption spectrum. A significant enhancement of Ho3+ emission (2.0μm) observed with 12 fold decrease of Yb3+ emission (1008nm) in co-doped sample entrenched the efficient energy transfer from Yb3+:2F5/2→Ho3+:5I6. The host phonon assistance in the energy transfer process has been conferred by using Dexter model. Comparatively better emission properties (Arad, Δλeff, σem) reveal that, the present material could be promising for laser emission at ~2.0μm.

Zero stress-optic barium tellurite glass

Zero stress-optic glasses are achieved traditionally through a high content of lead oxide or other closely related p-block metal oxide. We have found that the underlying cause for this behavior is the combination of high metallicity and low coordination numbers adopted by compounds such as lead oxide. Here we test this idea by showing that barium tellurite glasses also show zero stress-optic and negative stress-optic response, at very low barium content. This response results from the fact that barium oxide bonds have very high metallicity, and at the same time barium modifies tellurite by lowering the Te coordination number. The two effects together are sufficient to produce zero stress optic response.

Compositional Dependence of Infrared‐to‐Visible Upconversion in Yb3+‐ and Er3+‐Codoped Germanate, Gallate, and Tellurite Glasses

Upconversion fluorescences of the green 4S3/2→4I15/2 and red 4F9/2→4I15/2 transitions of the Er3+ ion are studied for Yb3+‐ and Er3+‐codoped sodium germanate, potassium tantalum gallate, and barium tellurite glasses by InGaAs laser‐diode pumping. The phonon energies of the host glasses are determined by infrared‐reflection measurements. Compositional effects on the Judd—;Ofelt parameters for the Er3+ ion, the spontaneous emission probability (SPE) of the 2F5/2→2F7/2 transition for the Yb3+ ion, and the phonon energy of the glass network are discussed in terms of glass structure. The factors that affect the upconversion fluorescence intensities of the Er3+ ion are discussed, using the phonon energy of the host glass and the SPE for the Yb3+ ion in the germanate, gallate, and tellurite glasses.

Correlation between the structure and glass transition temperature of potassium, magnesium and barium tellurite glasses

The Mossbauer spectrum of tellurite glasses, containing 5 mol% Fe2O3 as a probe, consists of a paramagnetic quadrupole doublet with an isomer shift of 0.39 ± 0.01 mmsec−1. This indicates that Fe3+ ions are present at substitutional sites of Te4+ ions constituting distorted TeO4 trigonal bipyramids, each of which has one oxygen vacancy at an equatorial site. On increasing the K2O content from O to 35 mol%, the quadrupole splitting (Λ) for potassium tellurite glasses decreases continuously from 0.76 to 0.44 mm sec−1. On the other hand, Λ for magnesium and barium tellurite glasses increases with increasing MgO and BaO content, respectively. When the alkali or alkaline earth oxide contents are the same as each other, Λ increases in proportion to the ionic potential (Z/r) of the alkali or alkaline earth metal ion. These results suggest that the glass matrices of alkaliv and alkaline earth tellurite glasses are continuously changed into a chain and a three-dimensional network structure, respectively. Differential thermal analysis studies reveal that there exists a linear relationship between the glass transition temperatureT g and the quadrupole splitting, indicating thatT g is primarily determined by the magnitude of the distortion of TeO4 trigonal bipyramids. This relationship is also applicable to several oxide glasses.