Effect of nanocrystallization on electrical conductivity of glasses and composites of the AgI-Ag2O-B2O3 system

Amorphous and glassy-crystalline samples of the AgI-Ag2O-B2O3 system with high content of AgI were prepared. It was shown that annealing of initially amorphous samples (with AgI content not higher than 60 mol%) leads to formation of crystalline grains of beta-and gamma-AgI and to a conductivity increase to 1.1.10(-2) S cm(-1) at 20 degrees C (for AgI content of 55 mol%). The conductivity enhancement was attributed to interfacial regions surrounding crystalline grains. As-received samples with higher contents of AgI (>= 75 mol% AgI) have high concentration of crystalline grains, mainly of AgI. The temperature dependence of conductivity undergoes step-like changes (close to 150 degrees C on heating and close to 120 degrees C on cooling). These changes are a consequence of the beta-alpha-AgI phase transitions taking place in the crystallites. (c) 2005 Elsevier B.V. All rights reserved.