$beta;-NMR studies of spin-lattice relaxation in glassy and layer-crystalline compounds

The method of beta-radiation detected NMR (β-NMR), complementing and extending the potential of conventional NMR, and its experimental realization by the new β-NMR spectrometer at the research reactor of KFA Jülich are described with respect to spin-lattice relaxation (SLR) studies. Recent applications to oxide and electrolyte glasses and a crystalline layered compound are reviewed. It is shown that a deviation from single-exponential SLR is a signature of local disorder in the vicinity of the β-NMR probes. The temperature and, especially, the magnetic field (or frequency) dependence of the SLR rate allow one to trace various dynamic processes, such as thermally activated excitations of disorder modes, anomalous ionic diffusion, molecular motions below and above the glass transition, and low-dimensional diffusion.