Ultrasonic study of (AgI)x(Ag4P2O7)1-x glasses in the region of the glass-transition temperature.

Abstract

Ultrasonic velocity and attenuation have been measured on the superionic-glass system (AgI${)}_{\mathit{x}}$(${\mathrm{Ag}}_{4}$${\mathrm{P}}_{2}$${\mathrm{O}}_{7}$${)}_{1\mathrm{\ensuremath{-}}\mathit{x}}$, with 0.50\ensuremath{\le}x\ensuremath{\le}0.875, from room temperature to 200 \ifmmode^\circ\else\textdegree\fi{}C through the glass-transition temperatures. X-ray diffraction, differential scanning calorimetry, and density measurements were made, besides ultrasonics, to clarify the nature of the supercooled liquid, with or without dispersed crystallites. We observed velocity dispersion and a single attenuation peak for 0.5\ensuremath{\le}x\ensuremath{\le}0.75 glasses, which decreased in location with increasing x in close correlation with the glass-transition temperature, and was assigned as due to relaxation of the supercooled liquid. For more AgI content, 0.80\ensuremath{\le}x\ensuremath{\le}0.875, another attenuation peak(s) and velocity peak(s) were detected and were considered to be due to nucleation and/or crystallization of some unidentified crystal(s).