Physical and structural properties of glasses in the TeO_2-TiO_2-Nb_2O_5 system

摘要

Twelve glasses in the TeO_2-TiO_2-Nb_2O_5 system have been prepared. The glass forming region in the TeO_2-TiO_2-Nb_2O_5 ternary system was determined. The structural role of each component was studied by FTIR and some of their physical properties (density, molar volume, oxygen molar volume, transition temperature, thermal expansion coefficient, optical absorption and energy gap) were determined. The glass structure is mainly built by [TeO_4] groups, while Nb~(5+) and Ti~(4+)-ions play as network modifiers. As the Nb_2O_5 and TiO_2 concentration increases, [TeO_4] groups progressively change to [TeO_3] groups as a consequence of the network opening. The contribution of the three ions to the oxygen molar volume follows the order: Te~(4+) >Ti~(4+) >Nb~(5+). TiO_2 incorporation and even more Nb_2O_5 improve the glasses thermal stability and the network reinforcement. TiO_2 is the component which contributes in the highest extent to decrease the glass energy gap.