Ion-conduction and rigidity/flexibility of glasses

The (AgI)$_{x}$(AgPO$_{3})_{1-x }$ solid electrolyte glass system has been examined extensively although a consensus on the increase of electrical conductivity with x data has been elusive. Here we show that the variability of the data is likely due to water contamination. Our work is on specifically prepared \textit{dry} samples which display glass transition temperatures T$_{g}$(x) that are at least 50\r{ }to 100\r{ }C higher than those reported hitherto. In Raman scattering the frequency of the P-O$_{t}$ bonds in PO$_{4}$ tetrahedra of long chains is found to systematically red-shift with increasing x, and to display thresholds near x= x$_{c}$(1) =0.095(3)(stress-transition) and x =x$_{c}$(2) = 0.379(5)(rigidity transition). Calorimetric measurements show a reversibility window in the 0.09 $<$ x $<$ 0.38 range. Room temperature electrical conductivity, $\sigma $(x), increases with x to display thresholds near x$_{c}$(1) and x$_{c}$(2), and a logarithmic increase at x$>$ x$_{c}$(2) with a power-law $\mu $ = 1.78(10) that is in good agreement with theoretical predictions$^{1}$. Properties of flexibility and rigidity of backbones commonplace in covalent systems$^{2}$ is a concept that extends to solid electrolyte glasses as well. \newline $^{1}$Richard Zallen, Physics of Amorphous Solids \newline $^{2}$ P. Boolchand et al. Phil. Mag 85, 3823 (2005)