Structural changes in the ZnF2-Bi2O3-GeO2 glass system doped with Fe2O3 by spectroscopic and dielectric investigations

作者：Teja P M Vinaya; Babu A Ramesh; Rao P Srinivasa; Vijay R; Rao D Krishna^*

来源：Journal of Physics and Chemistry of Solids, 2013, 74(7): 963-970.

DOI：10.1016/j.jpcs.2013.02.015

• Glasses
• Raman spectroscopy
• Infrared spectroscopy
• Dielectric properties

Transparent glasses 20ZnF(2)-40Bi(2)O(3)-(40 - x)GeO2: xFe(2)O(3); 0 <= x <= 2.5 wt% are prepared by melt quenching technique. The amorphous nature of the glass samples is characterized by X-ray diffraction (XRD) and differential thermal analysis (DTA). Spectroscopic studies like optical absorption, FTIR, Raman and dielectric parameters (epsilon', loss(tan delta) and sigma(ac) over a wide range of frequency and temperature) of these samples have been carried out. Optical absorption data has revealed that the bismuth radicals, observed in pure sample F-0, are decreased with increase in concentration of Fe2O3. The optical absorption and ESR studies indicate Fe2+ and Fe3+ ions occupy octahedral positions at higher dopant concentrations of Fe2O3. From FTIR and Raman studies, the coordination of germanium is changed from GeO4 to GeO6 with increase in the concentration of Fe2O3. Dielectric parameters such as dielectric constant epsilon', loss tan delta, a.c. conductivity sigma(ac), are found to increase and activation energy for a.c. conduction is decreased, hence depolymerise the glass network with increase of divalent iron ion concentration; which is also confirmed by band gap energy (E-g). Density of defect energy states N(E-F) is explained with quantum mechanical tunnelling (QMT) model.

• 出版日期2013-7