Epr of superionic phase transition in Cu-stabilized nanocrystalline gamma-AgI

摘要

EPR probed the zincblende (gamma) to cubic (alpha) AgI structural phase transition in AgI through two intrinsic paramagnetic centers: an Ag2+ based hole center (signal "A") and an Ago based conduction electron center (signal "B") associated with AgI nanocrystallites. A sudden drop in intensity (I-PP), (g), and Delta H-PP was observed at 423 K for pure AgI nanocrystals. Cu in AgI increases the thermal stability of the cation sublattice from 423 K (undoped AgI) to 453 K (Ag0.75Cu0.25I) through the strengthened Ag-I bond. A sudden jump in the reciprocal susceptibility observed at well above the phase transition reflects the local bonding configuration in the gamma-AgI structure.