Structural study on lithium-barium borophosphate glasses using infrared and raman spectroscopy

Abstract

This paper reported on the structural properties of Lithium-Barium borophosphate glasses. The glasses were prepared through melt quenching technique and studied in the compositional series which was 25Li2O:25BaO:(x)B2O3:(50-x)P2O5 where 0x50 mol% .The aims of this work were to investigate the vibration mode about the local order around phosphorus tetrahedral structures and the boron coordination changed from trigonal to tetrahedral structures. Their basic properties were determined and their structure was studied by Fourier Transform Infrared (FT-IR) and Raman spectroscopy. Both spectroscopy analysis of the sample revealed vibration mode related to the characteristic phosphate bonds and borate bonds especially P-O-P, O-P-O ,P-O-B, BO3 and BO4. Structural studies were devoted to the investigation of changes in boron coordination in the dependence on changes in B2O3 or P2O5 ratio in the borophosphate glasses. The decrease in the strength of the vibrations of the non-bridging PO2 groups seems to indicate a progressive increase in the connectivity of the glass with increasing B2O3 content. It was likely that this connectivity was due to the formation of P-O-B links at 890 cm-1, which replaced the vibration mode P-O-P. The increasing of B2O3 content and decreasing the P2O5 content causes the boron coordination changes from trigonal to tetrahedral and the basic units change from BO3 to BO4. Overall, the high frequency bands corresponding to stretching vibration become broader, less distinct and overlap each other with an increasing B2O3 content and decreasing P2O5 content.