Effect of stepwise replacement of LiF by ZnO on structural and optical properties of LiF.B_2O_3 glasses

Authors: SUSHEEL ARORA, VIRENDER KUNDU, DEV RAJ GOYAL, ANUP SINGH MAAN

Abstract: Zinc fluoroborate glasses with compositions xZnO.(40 - x) LiF.60B_2O_3 (x = 0, 5, 10, 15, and 20) were synthesized by the melt-quench method. The amorphous nature of the glassy samples was confirmed by XRD analysis. The nature of the bonds formed and the role of various species in the composition of the glasses were examined using FTIR spectroscopy. FTIR analysis showed shifting of an absorption band with the addition of ZnO. A UV-visible study was carried out to calculate the optical band gap energy, E_gIt was found that E_gdecreased with increase in concentration of ZnO up to x = 15 and increased slightly for x 20 with the stepwise replacement of a nonoxide group (LiF) by an oxide group (ZnO). Urbach tail energy, E_U, was found to increase from x = 0 to x = 15 and then decreased slightly for x = 20}. Theoretical optical basicity, Lambda_{th}, decreased with decrease in concentration of LiF.

Keywords: Fluoroborate glasses, XRD, FTIR, optical band gap energy, optical basicity

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