Tellurite Glass Lab Report

2.5.1 Fundamental of Tellurite glass

The most stable oxide of tellurite is tellurite glasses (TeO2) which introduces it as a suitable host for crystalline solids and glasses.
Barady (El-Mallawany, 2002) was the first researcher who reported on tellurite oxide glasses in 1957. He noticed that the tellurium dioxide is a poor glass former, meaning that it is necessary to add a modifier to starting TeO2 powder to form the glass. 10 mol% concentration of any modifier is required to form the tellurite glass and he was the first who described the octahedral giometrical structure of tellurium dioxide glasses.
In 1962, Cheremisinov and Zalomanov where the first who synthesized tellurite glass (Cheremisinov and Zlomanov, 1962). They succeeded in melting white crystalline TeO2 powder by chemical synthesis, and they ascertained by X-ray analysis that this melt had a tetragonal lattice. The powder was nearly pure, containing 99.0 to 99.5% tellurium dioxide. An aluminum crucible containing the powdered tellurium dioxide was placed in a furnace, where it

It is more difficult to determine the precise structure of glass than that of crystalline solid. The structure of glass lacks translational symmetry, so that, it is impossible to define a unit cell. The absence of periodicity and symmetry in glass distinguishes it from a crystal. The isotropic vibration properties of glass are consequence of absence of symmetry and the atomic arrangement should be statistically the same in all directions. The structure of TeO2- based glasses is also of interest, because there are two types of basic structure unit, namely TeO4 trigonal bipyramids (tbp) and TeO3 trigonal pyramid (tp) as shown in figure below (Ayuni et al., 2011, Biirger et al.,