Structure and properties of Sb2O3-containing zinc borophosphate glasses

ZnO–B2O3–P2O5 glasses formulated with Sb2O3 were investigated in the series 50ZnO–10B2O3–40P2O5 + xSb2O3 (x = 0–70 mol%). With increasing Sb2O3 content, the values of glass transition temperature decrease from 492 °C down to 394 °C. The dissolution rate of the glasses reveals a maximum for the glass with x = 15 mol% Sb2O3. Raman spectra with increasing Sb2O3 content reflect the depolymerisation of phosphate chains. Antimony at low Sb2O3 content forms individual SbO3 pyramids manifested in the Raman spectra by a broad vibrational band at ∼520–690 cm−1. In the glasses with a higher Sb2O3 content SbO3 units link into chains and clusters with Sb–O–Sb bridges manifested in the Raman spectra by a strong broad band at 380–520 cm−1. The 31P MAS NMR spectra with increasing Sb2O3 content reflect the depolymerisation of phosphate chains at low Sb2O3 content and only small changes in the PO4 coordination at a high Sb2O3 content. 11B MAS NMR spectra reveal a steady transformation of B(OP)4 units into B(OP)4−x(OSb)x units, accompanied by the transformation of BO4 into BO3 units with increasing Sb2O3 content.