A study was made of an order of magnitude conductivity enhancement, at room temperature, in a new Ag+ ion-conducting composite system which consisted of the 2 silver halides (with a AgI/AgCl mol% ratio of 75:25) plus inert second-phase oxide particles (less than 10). It was found that the greatest enhancement of the conductivity (about 0.00092S/cm) was obtained in the composition,

0.7[0.75AgI•0.25AgCl]•0.3Al2O3

A plot of the electrical conductivity, as a function of temperature, for the best composition indicated the occurrence of a    transition; leading to a slightly decreased conductivity. The temperature dependence of the composite system could be described by:

 (S/cm) = 0.016 exp[-0.074(eV)/kT]

in the case of the  phase, and by:

 (S/cm) = 0.041 exp[-0.024(eV)/kT]

in the case of the  phase. The activation energies of 0.074 and 0.024eV for the -like and -like phases, respectively, were compared with the values of 0.24 and 0.025eV for the host material. It was suggested that the low activation energy in the -phase region reflected easy ion migration in the composite system. A room temperature ionic mobility of about 0.0237cm2/Vs was deduced, for the best composition, by using the transient ionic current technique. The transference number was found to be close to unity when measured by using Wagner's direct current polarization or electrical cell potential techniques. In the case of the host material, the transference number was approximately equal to unity and the mobility was equal to 0.015cm2/Vs.

R.K.Gupta, R.C.Agrawal: Solid State Ionics, 1994, 72, 314-7