Physical,optical and structural studies of copper-doped lead oxychloro borate glasses

Bluish coloured glasses are obtained from the composition PbCl(_{2})–PbO–B(_{2})O(_{3}) doped with Cu(^{2+}) ions. Basic physical properties and spectroscopic studies (optical absorption, electron paramagnetic resonance, Fourier transform infrared and Raman spectroscopies) were carried out on these samples. The increase in PbCl(_{2}) content resulted in the decrease in density and increase in molar volume. At optical frequencies, band gaps and Urbach energies were evaluated and their variation is explained. Spin-Hamiltonian parameters (SHP) obtained from the EPR spectra suggest that the ligand environment around Cu(^{2+}) is tetragonally distorted octahedral sites and the orbital (d_{x^{2}-{y}^{2}} ) is the ground state. The characteristics broad bands in the optical absorption spectra are assigned to the (^{2})B(_{mathrm{1g}},rightarrow , {}^{2})B(_{mathrm{2g}}) transition. The bonding coefficient values were evaluated using optical data and SHP. FTIR studies suggested that the glass structure is built up of BO(_{3}) and BO(_{4}) units. The presence of diborate, pyroborate, pentaborate groups, etc. in the glass network was confirmed from Raman spectra.