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The effect of Sn addition on structure and glass transition temperature in Pb-Ge–Se chalcogenide glass

VIVEK MODGIL1,* , V. S. RANGRA1

Affiliation

  1. Department of Physics, Himachal Pradesh University Summerhill Shimla -171005, India

Abstract

Infrared spectroscopy of the quaternary Sn added lead germanate chalcogenide glasses have been carried out in the far infrared spectral range 30cm-1-600 cm-1 at room temperature .Glass transition temperature is decreasing as Sn concentration increases. FIR results support the variation of Tg and theoretically reported results. For all samples, FIR spectra show strong absorption peaks around 112 cm-1,118cm-1 and158 cm-1due to Sn(Se1/2)4. A shift in absorption peaks towards high frequency is observed as x varies from 8 to11. The absorption peaks appear around 197cm-1 for x=8, 12 which are due to GeSe4 and bands around 176 cm-1,185 cm-1due to GeSe2(Raman mode).Here Sn atoms appear to substitute for the germanium atoms in the outrigger sites of Ge(Se1/2)4 tetrahedra up to x=11 as it is reflected in the decrease in absorption bands of Ge(Se1/2)4. With increasing Sn content from x=9 to 11 the reduction in polymeric rings of Se are observed as there is reduction in corresponding absorption bands of Se rings. At x =8, 12 the glasses show a vibrational band of an isolated F2 mode of the Ge-centered tetrahedra outside the clusters. The absorption bands around 127 cm-1,134 cm-1,140 cm-1,150 cm-1 are due to Pb-Se which shifts to high frequency as aspect ratio of Pb-Se varies. The comparatively low bond energies of Pb-Se,Sn-Se than Ge-Se bond and strain effects of Pb,Sn are responsible for decreasing mean bond energy and glass transition temperature. The concentration dependence of the strong FIR features are consistent with that predicted by a network of fourfold-(twofold-) coordinated Sn(Se) and Ge(Se) atoms, with heteropolar bonds favored over homopolar bonds..

Keywords

Quaternary chalcogenide glasses, Far infrared spectroscopy, Glass transistion temperature.

Citation

VIVEK MODGIL, V. S. RANGRA, The effect of Sn addition on structure and glass transition temperature in Pb-Ge–Se chalcogenide glass, Optoelectronics and Advanced Materials - Rapid Communications, 7, 1-2, January-February 2013, pp.30-36 (2013).

Submitted at: Sept. 13, 2012

Accepted at: Feb. 20, 2013