Ionic noise measurement in polymer electrolytes

Electrical noise associated with ion transport (termed as “ionic noise”) has been measured at different temperatures, using a lock-in amplifier and dynamic signal analyzer for a polymer electrolyte PEO:NH₄I and its CdS dispersed composite. The ionic noise suddenly increases as the polymer passes through its phase transition at T _g and T _m. The T _g-peak in the noise measurement appears more clearly than what it does in DTA/DSC or conductivity measurements. Therefore, we suggest the noise technique as a good probe for studying phase transitions in ion conducting solid electrolytes. Further, the present noise measurements also confirm the known results of DTA/DSC studies that both T _g and T _m of polymer electrolytes shift on the formation of composites.