Abstract: Glass-ceramic, anti-glass and crystalline samples of two systems: xLa2O3-(100-x)TeO2 (x = 5, 7, 10, 12.5, 15 and 20 mol%) and 2TiO2-xLa2O3-(98-x)TeO2 (x = 5, 7 and 10 mol%) were prepared by melt quenching. Glass-ceramic samples are transparent and contain co-existing glass and anti-glass inclusions. Samples with La2O3 concentration greater than 10 mol% required more rapid splat quenching to prepare transparent glass-ceramics whereas the sample with 20 mol% La2O3 produces crystalline monoclinic La2Te4O11 by slow melt quenching and disordered anti-glass phase with the structure of cubic La2Te6O15 by splat quenching. The addition of TiO2 in xLa2O3-(100-x)TeO2 system reduces the size of the inclusions, but it enhances their concentration and also increases the optical transparency and thermal stability of the glasses. Micro-Raman studies found that the Te-O coordination number decreases with an increase in La2O3 mol% and the co-existing glass and anti-glass phases have the same value of average Te-O speciation.

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