Study of structure and properties of ZnO–Bi2O3–P2O5 glasses

Glasses of the ternary system ZnO–Bi2O3– P2O5 were prepared and studied in two compositional series 50ZnO–xBi2O3–(50 – x)P2O5 and (50 – y)ZnO– yBi2O3–50P2O5. Two distinct glass-forming regions were found in the 50ZnO–xBi2O3–(50 – x)P2O5 glass series with x = 0–10 and 20–35 mol.% Bi2O3. All prepared Bi2O3- containing glasses reveal a high chemical durability. Small additions of Bi2O3 (~5 mol.%) improve thermal stability of glasses. All glasses crystallize on heating within the temperature range of 505–583 C. Structural studies by Raman and 31P MAS NMR spectroscopies showed the rapid depolymerisation of phosphate chains within the first region with x = 0–15 and the presence of isolated Q0 phosphate units within the second region with x = 20–35. Raman studies showed that bismuth is incorporated in the glass structure in BiO6 units and their vibrational bands were observed within the spectral region of 350–700 cm–1. The evolution of properties and the spectroscopic data are both in accordance with a network former effect of Bi2O3