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Structure and properties of Ag2O−GeO2−P2O5 glasses

Authors: Hostinský Tomáš | Mošner Petr | Koudelka Ladislav

Year: 2023

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	Structure and properties of Ag2O−GeO2−P2O5 glasses	Phosphate glasses of the Ag2O−GeO2−P2O5 were studied in two compositional series (50-x)Ag2O−xGeO2−50P2O5 with 0-50 mol% GeO2 and 50Ag2O−xGeO2−(50-x)P2O5 with 0-20 mol% GeO2. Basic physical properties were determined, and thermal properties studied by differential thermal analysis, thermomechanical analysis, and hot-stage microscopy. The glass structure was investigated using Raman spectroscopy and 31P MAS NMR by both 1D and 2D techniques. The electrical properties of the glasses were obtained by using impedance spectroscopy. In both glass series glass transition temperature with GeO2 additions and all glasses containing GeO2 crystallizes in temperature range 500-750 °C. The dependence of the coefficient of thermal expansion in both cases sharply decreased with the addition of GeO2, which is a typical phenomenon when Tg increases, and indicates the strengthening of the structural network of the glass due to the increase in the occurrence of Ge−O bonds. 31P MAS NMR spectra of (50-x)Ag2O−xGeO2−50P2O5 series were dominated by one major resonance which shifts to more negative values with increase of GeO2 content. Position and the shift of the peak indicates that network of the glass is mainly built from Q2 structural units. By using 2D 31P INADEQUATE sequence was confirmed that phosphate chains are gradually shortened due to the formation of Ge−O−P bonds. 31P MAS NMR spectra of 50Ag2O−xGeO2−(50-x)P2O5 consist of multiple peaks that mainly belong to structural units Q1 and Q2. Spectra of this series are also influenced by hygroscopicity of the glasses. Raman spectra of the glasses includes dominant vibrational band in the region 1000−1300 cm-1, changes in this region reveals transformation of phosphate glass network. Another dominant vibrational bands can be found in the region 500-800 cm-1. This region reflects evolution of P‒O‒P connections to P‒O‒Ge and Ge‒O‒Ge connections through the series.