Dual role of the six-coordinated lead and copper ions in structure of the copper–lead-tellurate glasses

Glasses from xCuO·(100 − x)[4TeO2·PbO2] system where x = 0–40 mol% were studied by density measurements, FTIR, UV–vis and EPR spectroscopy in order to obtain information about the changes that appear in the structure of matrix glass with the doping of copper ions.The FTIR data analysis shows that the copper ions will be distributed in the six-coordinated interstices ([PbO6] structural units) and some [TeO4] structural units will be converted to [TeO3] structural units because the lead ions have a strong affinity towards these groups containing non-bridging oxygens, with negative charge.From the EPR studies, we can conclude that Cu+2 ions have an environment elongated along the z-axis and the ground state of the Cu+2 is dx2−y2dx2−y2 orbital (2B1g state). When the concentration of CuO is increased beyond 5 mol%, the intensity and width of both the parallel and perpendicular hyperfine components are observed to increase.

Research highlights▶ Our investigations show that the copper ions will occupy the six-coordinated interstices ([PbO6] structural units). ▶ Then some [TeO4] structural units will convert to [TeO3] structural units because the lead ions have a strong affinity towards these groups containing non-bridging oxygens, which are negative-charged.