ZnCl₂ Modified Physical and Optical Properties of Barium Tellurite Glasses

Abstract

The optical properties of tellurite based glass systems are composition dependent. For this purpose glass samples of the composition 70TeO₂-(30–x)BaO-xZnCl₂ with x = 5, 10, 15, 20 and 25 have been synthesized by rapid melt quenching technique. Glassy nature has been confirmed by X-ray diffraction pattern. The physical properties like density, molar volume and crystalline volume have been estimated and found that density decreases while the molar volume increases with increase in ZnCl₂ content. The glass transition temperature decreases with increase in halide content due to increase in the non-bridging oxygen contribution. Direct allowed optical transitions are favourable in these glasses and the optical band gap energy (E_opt) has been observed to increase with increase in ZnCl₂ content. The value of Urbach energy of these glasses shows increasing behaviour with ZnCl₂ concentration indicating the breaking of weak bonds into defects. Metallization criterion for these materials shows that these glasses may be potential candidates for non linear applications.

Keywords:

• Amorphous
• Melt quenching technique
• Non-bridging
• DSC
• UV-Vis spectroscopy