The glass-forming region in the ternary mixed anion system AgIAg2SO4Ag2SO4Ag2WO4 has been delineated and the enthalpic manifestation of the glass transition has been examined. By selecting compositions along the tie-line 60AgI · (40 - x)Ag2SO4 · xAg2WO4 and varying x it was possible to study the effect of replacing the SO42- ion by the larger WO42- ion, at a fixed AgI content. The glass-to-liquid transition is found to evolve over an unusually wide range of temperature in the ternary glasses relative to the binary ones indicating that the mixing of anions of different sizes leads to a dramatic broadening of the spectrum of structural relaxation times. Consistent with this observation, the DSC scans of annealed ternary samples reveal prominent pre-Tg endothermic peaks which have previously been seen only in polymer melts (such as pure PVC) known for highly non-exponential relaxation. Possible structural origins, and applications of the Tg broadening phenomenon are discussed.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry