NMR study of sodium ion motion in single crystal beta-alumina

Abstract

The motion of sodium ions in single crystals of beta‐alumina has been studied via its effects on NMR linewidth and electric quadrupole interaction. A single line is seen between −160 and +220 °C at Larmor frequencies from 4 to 19 mHz, indicating rapid ionic motion. The average coupling constant remains almost constant over the temperaure range. The average asymmetry parameter is nonzero and decreases with temperature, reflecting the change in off‐axis site population. An activation energy of about 0.17 eV has been estimated from the linewidth changes in general agreement with that found from diffusion and conductivity measurements.