NEUTRON-SCATTERING STUDIES ON SUPERIONIC AGI-CSI-(CH3)(4)NI GLASSES

Quasielastic and inelastic neutron scattering from AgI-CsI-(CH3)(4)NI and AgI-CsI-(CD3)(4)NI superionic glasses were measured as a function of temperature. At the lowest temperatures, vibrational modes from internal motion of (CH3N+ or (CD3N+ were observed above 15 meV. Below 20 meV, a broad peak typical of AgI-containing glasses was observed, which showed significant temperature dependence. This mode is attributable to the vibrational motion of localized Ag+ ions. Above 173 K, quasielastic scatterings were seen below 2 meV; these were fitted by the sum of a single Lorentzian, an elastic peak and background components. The half-width at half-maximum (HWHM) of the Lorentzian component was almost a-independent at higher Q values, and its temperature dependence was lower than the value expected from de conductivity. This quasi-elastic component may be attributed to the local hopping of Ag+ in the AgI cluster of the glass and/or the rotational motion of(CD3N+ ions.