Structural studies of boron and tellurium coordination in zinc borophosphate glasses by 11B MAS NMR and Raman spectroscopy

Zinc borophosphate glasses doped with TeO₂ with different B₂O₃/P₂O₅ ratio were prepared, their basic properties were determined and their structure was studied by ¹¹B MAS NMR and Raman spectroscopies. Structural studies were devoted to the investigation of changes in boron coordination in the dependence on changes in TeO₂ content and in B₂O₃/P₂O₅ ratio in the borophosphate glasses. A special attention was devoted to the formation of mixed structural units B(OP)_4?n(OTe)_n in the studied borophosphate glasses, where by the deconvolution of ¹¹B MAS NMR spectra quantitative data on the number of BO₃ and B(OP)_4?n(OTe)_n mixed structural units were obtained. Raman spectra showed shortening of phosphate chains both with increasing TeO₂ and B₂O₃ content. Raman spectra also showed that with the replacement of P₂O₅ by B₂O₃ in the studied glasses TeO₄ units are replaced by TeO₃ units as the number of oxygen atoms in the glass decreases when the B₂O₃/P₂O₅ ratio increases.