Nmr Study of Sodium Ion Mobility in a Single Crystal of Na β”-Alumina and Water Effects in Polycrystalline Samples

ABSTRACTWe measured the temperature dependence of T1 in a Mg-stabilized single crystal of Na β”-alumina. A comparison with earlier measurements on Li-stabilized polycrystalline samples indicates that, below 500K, the sodium ion kinetics are not directly affected by the stabilizing element. Above 500K our measured T1 shows a dependence on sample composition. Observations of NMR linewidth and signal intensity vs. water content indicate that, at low water concentration (< 2%), all sodium is in contact with water in its conduction plane; at higher water concentrations, the additional water may be forming complexes with some of the sodium.