  The synthesis of xAgI(1-x)[Ag2O.B2O3] amorphous superionic conductors is done
via mechanochemical synthesis route (for x = 0.5 and 0.7). Ionic conductivities
of 3 mOhm-1cm-1 for x = 0.5 sample and 5mOhm-1cm-1 for x = 0.7 sample at room
temperature, are observed, which are higher than those of the melt quenched
glassy samples. Impedance plots (Nyquist plots) are found to be depressed
semicircles with a tail at low frequency end. The corresponding equivalent
circuit is postulated and each circuit element is related to a physical
process. The ac conductivity is analyzed in view of the universal dynamic
response (Bode Plots). A unique feature of the mechnochemically synthesized
glasses is that their dc conductivity vs. 1/T behavior exhibit two distinct
regions with different activation energies. The activation energy for dc
conductivity (Edc) and that for ac conductivity (Eac) and the frequency
exponent n are found to satisfy the UDR-relation, Eac= (1-n)Edc in the lower
temperature regime. In the high temperature region, however, this correlation
could not be established due to lack of sac data over the available frequency
domain.

Materials Science