Structure and dynamics of superconductingNaxCoO2hydrate and its unhydrated analog

Neutron scattering has been used to investigate the crystal structure and lattice dynamics of superconducting ${\mathrm{Na}}_{0.3}{\mathrm{CoO}}_{2}\ensuremath{\cdot}1.4(\mathrm{H}/\mathrm{D}{)}_{2}\mathrm{O},$ and the ``parent'' ${\mathrm{Na}}_{0.3}{\mathrm{CoO}}_{2}$ material. The structure of ${\mathrm{Na}}_{0.3}{\mathrm{CoO}}_{2}$ consists of alternate layers of ${\mathrm{CoO}}_{2}$ and Na and is the same as the structure at higher Na concentrations. For the superconductor, the water forms t