Elasticity and conductivity thresholds in solid electrolyte glasses*

The solid electrolyte glass, AgI, possesses a low mean coordination number [1], and when alloyed in the base oxide glass, AgPO$_{3}$, steadily lowers the connectivity of the alloyed glass, (AgI)x(AgPO3)1-x, as reflected in reduction of glass transition temperatures T$_{g}$(x). Non-reversing enthalpy associated with T$_{g}$s vanish in the 0.10 $<$ x $<$ 0.35 range, the reversibility window, which we identify with the Intermediate elastic phase [2]. Glasses at x $<$ 0.10 belong to the Stressed-Rigid while those at x $>$ 0.35 to the Floppy elastic phase. Electrical conductivity, $\sigma $(x), reveal a mild increase near x = 0.10 as glasses become unstressed, and a pronounced increase near x = 0.35, when glasses become floppy. The correlation between $\sigma $(x) and the elastic phases opens a new paradigm in understanding electrical transport in glasses. Chains of PO$_{4}$ tetrahedra ( Q$^{2})$ present in the pristine oxide are steadily cut and eventually transformed into rings as networks become less connected with increasing x, as revealed by Raman and P$^{31}$ NMR measurements. \newline [1] P. Boolchand and W.J.Bresser, Nature \textbf{410}, 1070 (2001). \newline [2] S.Chakravarty, D.Georgiev, P.Boolchand {\&} M.M.Micoulant, JPCM \textbf{17}, L1-L7 (2005).