Sodium ion motion in NaI–AgPO3 glasses

Sodium ion motion in NaI–AgPO3 glasses were investigated by electrical conductivity, NMR chemical shift measurements and X-ray diffraction. The fact that AgI crystal is precipitated at the composition x beyond the glass forming region of the (NaI)x(AgPO3)1 − x system, and that the crystallization of NaPO3 occurs by keeping the glass at a temperature near the glass transition suggests preferential formation of a chemical bond between silver and iodide ions rather than between sodium and iodide ions. Although the sodium ion conduction is more negligible than that of silver ions in a vitreous state, we show that the ionic conductivity of sodium increases above the glass transition temperature by the line width of the NMR chemical shift.