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

摘要

Glasses from xCuO.( 100 - x)[4TeO_2 PbO_2) 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 ([PbO_6] structural units) and some [TeO_4] structural units will be converted to [TeO_3] 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 d_(x~2-y~2) orbital (~2B_(1g) 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.