NMR INVESTIGATIONS OF CATION DIFFUSION IN SOME SOLIDS WITH ANTIFLUORITE STRUCTURE.

Abstract

Spin-lattice relaxation rates and nmr linewidths of **7Li and **2**3Na are measured up to 800 degree C for Li//2S, Li//2O, Na//2S and for Na//2O. Relaxation due to cation diffusion is observed with predominant dipole interactions in Li//2S and Li//2O and quadrupole interactions in Na//2S and Na//2O. Motional narrowing occurs below 300 degree C. For Li//2S, Li//2O and Na//2S cation jump frequencies in the regions of intrinsic and of extrinsic disorder are determined with apparent activation energies of about 1. 4 and 0. 7 eV for Li//2S, 1. 3 and 0. 55 ev for Li//2O and 1. 3 and 0. 7 ev for Na//2S. Ionic conductivities calculated from the nmr data agree with conductivities determined directly within a factor 3.