Preparation, structural characterization, and photoluminescence of Pb²⁺ ions doped telluro-borate glass–ceramics

The melt-quenching method was used to synthesize the samples of the [(75 − x)B₂O₃–10TeO₂–13SrO–2.0ZnO–xPbO (x = 0.0, 5.0, 10, 15, 25, and 40 mol%)]. The peaks found in the XRD patterns were associated with the crystalline phase, Zn₂Te₃O₈, present in these prepared samples. Substituting B₂O₃ with PbO resulted in a steady density increase from 2.89 to 4.75 g/cm³. The molar volume (Vm) increased from 30.23 to 31.95 cm³/mol as the concentration of PbO went up from 0 to 40 mol%. The Raman analysis confirmed that the increase in PbO content in the compositions led to a conversion from TeO₄ to TeO₃ and the change of bridging oxygens to non-bridging oxygens. The optical band gap energy, Urbach energy, and other optical properties were analyzed to determine the optical transmission data. As more PbO was added, the optical band gap energy decreased from 3.140 to 2.930 eV, and the Urbach energy rose from 0.337 to 0.377 eV. Under 300 nm excitation, the photoluminescence spectra showed emission bands linked to electronic transitions of Pb²⁺.