HIGH-TEMPERATURE NUCLEAR-MAGNETIC-RESONANCE STUDIES OF OXIDE MELTS

Recently, application of in situ, high temperature nuclear magnetic re sonance (NMR) spectroscopy to study silicate, berate and aluminate mel ts has lead to a variety of findings on structural changes with temper ature (particularly in cation coordination number), and on the dynamic s of exchange and diffusion. New data are presented on chemical shifts and spin-lattice relaxation of Na-23 in a number of silicate liquids to about 1200 degrees C, and these results are discussed in light of o ther recent studies. These results clearly demonstrate the mixed alkal i effect on cation motion. New high temperature magic angle spinning B -11 NMR spectra for a sodium berate liquid are also presented. As in p revious studies of aluminate and silicate melts, the latter data set s uggests that the mechanism of viscous flow is closely tied to local ex change of cationic species.