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 Al 2 O 3 on CaF 2 -Bi 2 O 3 -B 2 O 3 –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 Al 2 O 3 even though the relative density of Al 2 O 3 is higher than the CaF 2 . This decrease in density is attributed to the larger bond length of Al-O in AlO 4 units as compared to B-O bond length in BO 3 and BO 4 units. The bandgap values estimated from optical absorption spectra were found to increase with Al 2 O 3 content, indicating the decrement in the number of non-bridging oxygens. Spin-Hamiltonian parameters g ‖ > g ⊥ > g e ( g e = 2.0023) and A ‖ > A ⊥ are of the opinion that the Cu 2+ ions were taken the positions of octahedral sites with tetragonal distortion and ground state being d x 2 - y 2 orbital. FTIR and Raman spectra suggested that these glasses are composed of BiO 6 , BO 3 , BO 4 , and alumina polyhedral.