Thermal characteristics and short-range structure in TiO2-TeO2 and Bi2O3-TeO2 glasses: A comparative study

Abstract

The glass forming ability of titanium tellurite and bismuth tellurite glasses have been studied and compared. Titanium tellurite glasses require high melt quenching rates and hence, were synthesized by splat-quenching technique while the bismuth tellurite glasses require further high quenching rates owing to which they were synthesized using ice quenching. It is observed that xTiO2-(100-x)TeO2 glasses have poor glass forming ability (GFA), but for bismuth tellurite glasses in addition to their poor ability to form glasses, they have a very limited glass formation range (up to 5-mol %). At high Bi2O3 content (10-mol %) long-range order co-exists with the disturbed short-range order due its anti-glass phase formation. Bi2O3 and TiO2 incorporated jointly into the tellurite network also shows the properties of their anti-glass nature since there exist sharp peak superimposed upon a broad hump in XRD while the vibrational studies show broad bands. However, incorporating B2O3 into the system suppresses the anti-glass phases present and forms purely a glassy sample. Raman studies found a decrease in the Te—O coordination with increase in Bi2O3 and B2O3 concentration while no effect on the Te-O speciation is observed for TiO2 modified tellurite glasses.