Physical and spectroscopic studies of CaF2-Al2O3-Bi2O3-B2O3-CuO glasses

Over the past decade, oxy-fluoride glasses are the subject of investigation by many researchers. Calcium fluoride incorporated alumina-bismuth borate glasses reinforced with minute quantity of copper ions have been synthesized by melt-quenching process and the amorphous nature is approved by X-ray diffraction (XRD) spectra. The samples are further analyzed, to know the effect of Al2O3 on CaF2-Bi2O3-B2O3-CuO glasses, with the help of density, molar volume, optical, electron paramagnetic resonance (EPR), and Raman and Fourier transform infrared (FTIR) spectra. A decreasing trend was observed in density values with increasing Al2O3 even though the relative density of Al2O3 is higher than the CaF2. This decrease in density is attributed to the larger bond length of Al-O in AlO4 units as compared to B-O bond length in BO3 and BO4 units. The bandgap values estimated from optical absorption spectra were found to increase with Al2O3 content, indicating the decrement in the number of non-bridging oxygens. Spin-Hamiltonian parameters g(parallel to)>g(perpendicular to)>g(e) (g(e) = 2.0023) and A(parallel to)>A perpendicular to are of the opinion that the Cu2+ ions were taken the positions of octahedral sites with tetragonal distortion and ground state being d(x2-y2) orbital. FTIR and Raman spectra suggested that these glasses are composed of BiO6, BO3, BO4, and alumina polyhedral.

Automated summary

In this study, the effect of Al2O3 content on calcium fluoride incorporated alumina-bismuth borate glasses was investigated. Various techniques including density, optical, EPR, Raman, and FTIR spectroscopy were employed. The results showed that density decreased and bandgap values increased with increasing Al2O3 content. Cu2+ ions were found to occupy octahedral sites with tetragonal distortion, and the glasses were composed of BiO6, BO3, BO4, and alumina polyhedral structures.