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

摘要

Bluish coloured glasses are obtained from the composition PbCl$_2$a??PbOa??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 PbCl2 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 environmentaround Cu$^{2+}$ is tetragonally distorted octahedral sites and the orbital $d_{x^2a??y^2}$ is the ground state. The characteristics broad bands in the optical absorption spectra are assigned to the ${}^2B_{1g} o {}^2B_{2g}$ 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.