Influence of Fe3+ ions on optical, structural, thermal and mechanical properties of Li2O–Na2O–K2O–ZnO–B2O3 based glass system

Abstract

The effect of addition of Fe3+ ions in Li<inf>2</inf>O–Na<inf>2</inf>O–K<inf>2</inf>O–ZnO–B<inf>2</inf>O<inf>3</inf> based glass system have been studied. The melt quenching technique is used to prepare the glass samples. The X-ray diffraction studies confirmed the amorphous nature of the samples. DSC thermographs indicate that the T<inf>g</inf> is decreasing as the addition of Fe<inf>2</inf>O<inf>3</inf> content. Increase in thermal stability is observed upon adding K<inf>2</inf>O to the F0 sample and increase in the Fe<inf>2</inf>O<inf>3</inf> content further enhanced the thermal stability up to 187 °C. Optical band gap energy (E<inf>g</inf>) of the studied glass system is found to reduce with increasing Fe<inf>2</inf>O<inf>3</inf> content. A band observed around 450 nm in UV absorption spectra is due to the d-d transition of 6A<inf>1g</inf>(S) ? 4T<inf>2g</inf>(G) which indicates the presence of iron ion in trivalent state (Fe3+) with distorted octahedral symmetry. The oxide ion polarizability values determined using the refractive index and optical band gap energy are found to be increasing monotonically with partial incorporation of K<inf>2</inf>O content and with increasing Fe<inf>2</inf>O<inf>3</inf> content. The FTIR and Raman spectroscopy studies confirmed the network modifier role of Fe<inf>2</inf>O<inf>3</inf>. The radial-median cracks produced due to Vickers indentation were studied and it confirmed the enhancement in brittleness of the samples as Fe<inf>2</inf>O<inf>3</inf> content increased. Further efforts have been made to analyse and establish correlation between the physical and mechanical properties with the structural modification of the studied glass system. © 2019 Elsevier Ltd and Techna Group S.r.l.