Dynamics of water in the Na0.3CoO2 center dot 1.4H(2)O superconductor

Quasielastic neutron scattering is employed to characterize the diffusion of water molecules that are present between the CoO2 layers in the 4.3 K oxyhydrate superconductor Na0.3CoO2 center dot 1.4H(2)O. Dynamic measurements were performed at temperatures between 3.5 K and 315 K. Significant quasielastic scattering was only observed for temperatures of 235 K and higher where only highly constrained diffusive motion is present, similar to what is seen for water confined in pores. Approximately 80% and 100% (depending on the temperature) of the water molecules remain immobile (i.e., frozen) on the time scale of the measurements (10(-9) s). For the mobile water molecules, a model in which the molecules perform localized jumps between Na sites can be used to describe the data. The dynamics of the mobile water molecules does not show a significant change at the superconducting transition temperature.