Abstract
We report here a conductivity enhancement (similar to 10(1)) at room temperature in a new Ag+ ion conducting composite system. Two silver halides AgI and AgCl, in the mol. wt.(%) ratio 75:25 were taken as first phase host compound for the first time. Inert second phase Al2O3 particles of size < 10 mu m were dispersed in varying molar proportions in the first phase. The highest enhancement in the conductivity (similar to 9.2 X 10(-4)S/cm) was obtained for the ratio:0.7[0.75AgI.0.25AgCl].0.3Al(2)O(3). The plot of electrical conductivity as a function of temperature for the best composition indicated the presence of characteristics beta-->alpha-like transition of AgI or host compound in the composite system with slightly decreased conductivity values from the host in the alpha-phase. The equations governing log sigma versus 1/T for the composite system are represented by: sigma=0.016 exp(-0.074/kT)-->beta-like phase; sigma=0.041 exp(-0.024/kT)-->alpha-like phase give the activation energies as 0.074 eV and 0.024 eV in beta and alpha-like phases, respectively, as compared to the values 0.24 eV and 0.025 eV for the host material. The low activation energy value in the beta-region suggest easy ion migration in the composite system. The ionic mobility mu similar to (2.37+/-1) x 10(-2)cm(2)/Vs) was evaluated at room temperature for the best composition using the transient ionic current (TIC) technique, while the value of the transference number t(ions) is close to unity as obtained by two different techniques, i.e. Wagner's dc polarisation and electrochemical cell potential measurements. For the host material t(ions)similar to 1 and mu similar to (1.5+/-1) x 10(-2).