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

Abstract

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.