A 109Ag nuclear magnetic resonance investigation was made of the glasses, 0.525Ag2S-0.475(0.5B2S3-0.5SiS2), at 230 to 433K. The nuclear magnetic resonance spectra revealed, for the first time, 3 well-resolved lines which corresponded to 3 kinds of chemically speciated Ag ions on sites - having differing chemical shifts - in a macroscopically homogeneous glass. This chemical speciation of the Ag ions was considered with regard to the microstructure of the glass. As the temperature was increased, the 3 lines which originated from the 3 different ion species narrowed, but they existed independently up to 433K. Nuclear spin-lattice relaxation rates were also measured, and 2 relaxation processes were found. One was associated with 2 of the chemically speciated Ag ions, and the other was associated with the other Ag ions. The 2 different nuclear spin-lattice relaxations gradually approached a common value as the temperature was increased, and finally exhibited a common relaxation rate at, and above, 373K. From the nuclear magnetic resonance and nuclear spin-lattice relaxation results, which represented the ion dynamics on different time scales, it was concluded that the Ag ions moved rapidly (much greater than kHz rates) within separate clusters having similar chemical environments, but were exchanged among the 3 different clusters at relatively low rates (less than 100Hz) above 373K.

Chemical and Dynamic Speciation of Mobile Ions in the Glassy Fast Ionic Conductor Ag2S-B2S3-SiS2 - a 109Ag Nuclear Magnetic Resonance Study. T.Akai, S.W.Martin, F.Borsa: Physical Review B, 2001, 63[2], 024303 (7pp)