Structure of (45-x)Na2O-xBaO-5ZnO-50P2O5 glasses studied by DSC and infrared spectroscopy

The properties and structure of (45-x)Na2O-xBaO-5ZnO-50P2O5 (x = 0-45 mol%) glasses were investigated, including density, molar volume and glass transition temperature. The increase of density with increasing BaO content can be interpreted by the differences of masses. The variation in the molar volume of these glasses is small. The glass transition temperature increases as BaO is substituted for Na2O. This behaviour indicates that BaO improves the strength of the cross-links between the phosphate chains of the glasses. Analysis of the infrared spectra reveals that the increase of BaO content decreases the formation of end groups [(PO3)n]n-. 24 refs.