ELECTRONIC STATES OF AG IONS IN AGI-BASED SUPERIONIC CONDUCTING GLASSES

Electronic states of AgI-based superionic conducting glasses have been calculated by the DV-X alpha cluster method. The calculation was carr ied out for the AgI4 tetrahedral unit. The NaI4 tetrahedral unit was a lso considered for comparison with the AgI4 unit. The net charge of th e Ag ion in the AgI4 cluster was found to be about +0.08, which was sm aller than that of the Na ion, +0.39, in the NaI4 cluster. The bond or der between the Ag and the I ions, however, was almost the same as tha t between the Na and the I ions in the NaI4 cluster, This result sugge sts that the total interaction between the Ag and the I ions, includin g both ionic and covalent bonding in the AgI4 cluster, is smaller than that between the Na and the I ions in the NaI4 cluster. This characte ristic electronic state of the Ag ion is one of the causes of the fast movement of Ag ions in AgI-based glasses. (C) 1998 Elsevier Science B .V. All rights reserved.