Transport and dielectric properties of lisicon

Abstract

The ionic and electronic conductivities of Lisicon with compositions Li₁₄Zn(GeO₄)₄-(A) and Li₁₂Zn₂(GeO₄)₄-(B) have been determined in the temperature range 306-578 K. It has thus been shown that the ionic transport number is nearly unity throughout the temperature range. The activation energies for lithium motion were found to be 0.6 eV and 0.47 eV for compounds A and B. These values are very close to the values of the heat of transport q^∗ _Li+ 0.59 eV and 0.50 eV respectively, obtained from thermoelectric power (θ _t) measurements. The total ionic conductivity of the pellets of Lisicon was found to decrease with increasing average grain size in the range 20-78 µ . Electrode effects on the ionic conductivity are also reported for silver and TiS₂ electrodes. The electron/hole conductivity was studied using the Wagner cell technique. The activation energies for electron and hole transport for A were estimated as 1.02 eV and 1.39 eV and for B as 0.89 eV and 1.49 eV, respectively. The variation of the dielectric parameters ^ε'₁ ^ε" and tan δ have been studied for sample A between 10 Hz-100 kHz. The high frequency dielectric constant (at 100 kHz) was 21.4. The ^ε ' versus ^ε " (Cole-Cole plot) is also presented.