Structural study on lithium-calcium borophosphate glasses doped with transition metal ions using infrared spectroscopy

This paper reported on the structural properties of Lithium-Calcium borophosphate glasses. The glasses were prepared through melt quenching technique and studied in two compositional series which was 25Li(2)O:25CaO:(x)B2O3:(50-x)P2O5 where 0 <= x <= 50 mole % and 25Li(2)O:25CaO:30B(2)O(3):20P(2)O(5): (y) with y was the doped materials (Cr2+, Mn2+ and Fe2+ ions). 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 spectroscopy (FT-IR). FT-IR spectroscopy analysis of the sample revealed vibration mode related to the characteristic phosphate bonds especially P-O-P, O-P-O and P-O-B. 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. Besides that, 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. 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 940cm(-1), which replaced the vibration mode P-O-P. The glasses doped with Cr2+, Mn2+ and Fe2+ ions and the undoped glass were almost the same. The addition of doped glasses shows that the band was slightly shifted to the right side compare to the undoped glass. Besides that, it shows that the intensity of the bands described above increased and the position of the main bands shift to the lower frequencies. It was obviously shows that 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. The addition of doped Cr2+, Mn2+ and Fe2+ ions to the glass slightly shift to the right side compared to the undoped glass.