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In present study glasses of the system Ag 2 O-GeO 2 -P 2 O 5 were studied in the compositional series (50−x)Ag 2 O-xGeO 2 -50P 2 O 5 with x = 0−40 mol%. Ag 2 O substitution by GeO 2 results in a significant increase of both glass transition temperature, T g , and crystallization temperature, T c , up to 628 °C (T g) and 851 °C (T c) at x = 40 mol% GeO 2. The glass structure was investigated from the analysis of 31P MAS NMR and Raman spectra. Both methods show transformation of phosphate glass network formed mainly by Q2 units to germanate-phosphate network formed by Q1 xGe and Q2 1Ge phosphate units and germanate units. Raman spectra, in addition, reveal evolution of P‒O‒P linkages to P‒O‒Ge and Ge‒O‒Ge linkages through the glass series. DC conductivity trend upon GeO 2 addition showed non-monotonic behaviour, which is related to structural changes in the glass-network. • Silver phosphate glasses with a high germanium dioxide content were prepared and studied. • An increase in thermal and chemical stability of glasses by GeO 2 additions was observed. • Structure of glasses was studied by Raman and 31P MAS NMR spectroscopy. • Decreasing Ag 2 O content is associated with higher interconnection of glass network. [ABSTRACT FROM AUTHOR]

Abstract: Zinc borophosphate glasses doped with TeO2 were studied in the compositional series (100− x)[0.5ZnO–0.1B2O3–0.4P2O5]–xTeO2 in a broad concentration range of x =0–80mol% TeO2. The structure of the glasses was studied by Raman and IR spectroscopy and by 31P and 11B MAS NMR spectroscopy. According to the Raman and IR spectra, TeO2 is incorporated in the structural network in the form of TeO3, TeO3+1 and TeO4 structural units. The ratio of TeO4/TeO3 increases with increasing TeO2 content in the glasses. The incorporation of TeO x units into the glass network is associated with the depolymerisation of phosphate chains, as revealed by Raman spectroscopy. The incorporation of TeO2 modifies also the coordination of boron atoms, where B(OP)4 structural units are gradually replaced by B(OP)4−n (OTe) n units. The addition of TeO2 to the parent zinc borophosphate glass results in a decrease of glass transition temperature associated with the replacement of stronger P–O and B–O bonds by weaker Te–O bonds. Chemical durability of glasses reveals a minimum at the glass containing 10mol% TeO2, but with further additions of TeO2 it improves and the glasses with a high TeO2 content reveal better durability than the parent zinc borophosphate glass. [Copyright &y& Elsevier]