Scaling behavior and nearly constant loss effect in AgI–LiPO3 composite glasses

xAgI–(1 − x)LiPO3 composite glass electrolytes were prepared by melt quenching technique by using a twin roller assembly operated at 2000 rpm. The composite glasses with x < 0.2 were completely amorphous. However, in glasses with x > 0.2, micron size cluster particles of γ-AgI nanocrystallytes, embedded in a glass matrix were observed. This was confirmed by XRD and SEM studies. The conductivity of composite glasses increased by several orders of magnitude in comparison to pure LiPO3 glasses. Maximum conductivity of ~ 10− 3 S/cm was found for x = 0.5 composition. FTIR studies suggest that AgI acts as a plasticizing agent which reduces the polymeric chain lengths of phosphate glasses. In addition AgI provides silver ions which contribute to the total ionic conductivity. It was shown by using Summerfield scaling that glasses with x < 0.2 are mixed ion conducting with lithium and silver and both are contributing to the total conductivity. Summerfield scaling was not obeyed by these compositions. However glasses with x > 0.2 obeyed the Summerfield scaling and it was deduced that in these glasses the conduction is predominantly due to silver ions and any conduction due to lithium ions if at all is negligible. Nearly constant loss (NCL) effects were observed in low AgI (x < 0.2) glasses at low temperatures.However no NCL effect was found in high AgI content glasses. It is expected that the presence of NCL is due to lithium ions only as NCL has been found in pure LiPO3.

► The dc conductivity increased by 6 orders in xAgI-(1 - x) LiPO3 composite glasses for x = 0.5 with value of ~ 10–3 S/cm.
► The enhancement in conductivity was attributed to highly mobile silver ions.
► For x < 0.2 a mixed ion conduction due to lithium as well as silver ions was observed.
► For glasses with x < 0.2 Summerfield scaling was not obeyed due to mixed ion conduction.
► Higher AgI glasses with x > 0.2 showed ionic conduction due to silver ions only.