Defect chemistry and transport characteristics of β-AgI

The defect chemistry and d.c. transport characteristics of beta-AgI are reconsidered by taking into account (i) two structurally different interstitial positions, (ii) short-range interactions via associations, (iii) anisotropy of the wurtzite structure, (iv) long-range defect-defect interactions via Coulomb forces, and (v) formation of highly conducting layers perpendicular to the c-axis via a disordered interface structure with stacking faults. Besides microstructural characterization the analysis relies on the ionic conductivity data by impedance spectroscopy with conventional as well as micro-electrodes, and utilizes recent reports on the defect concentration and defect energies of beta-AgI by molecular dynamics simulations and on AgI:Al2O3 composites. Static valence sum calculations were performed to elucidate the ion conduction pathways and related migration barriers. (C) 2000 Elsevier Science Ltd. All rights reserved.