ION DYNAMICS AND DEVITRIFICATION IN 0.75AGI-0.25AG(2)MOO(4) FAST-ION CONDUCTING GLASS - AN XRD, DSC AND AG-109 NMR-STUDY

Structural changes and cation dynamics of a fast ion conducting glass 0.75AgI-0.25Ag(2)MoO(4) have been measured by differential scanning ca lorimetry (DSC), X-ray diffraction (XRD), and Ag-109 solid-state nucle ar magnetic resonance (NMR) both in the glassy and supercooled liquid states. In the glassy state, two Agi populations exist with very diffe rent mobilities which are related to different co-ordination spheres. Above the glass transition temperature, the sample undergoes phase sep aration and gives beta-AgI and 2AgI-Ag2MoO4 (2:1) crystals. Cations dy namics decrease and chemical shift anisotropy structures arise. The io nic conduction is based on Ag+ sites with mixed co-ordination, and no evidence of AgI clustering is found. (C) 1998 Published by Elsevier Sc ience B.V. All rights reserved.