High temperature nuclear magnetic resonance studies of oxide melts

Recently, application of in situ, high temperature nuclear magnetic resonance (NMR) spectroscopy to study silicate, borate and aluminate melts has lead to a variety of findings on structural changes with temperature (particularly in cation coordination number), and on the dynamics of exchange and diffusion. New data are presented on chemical shifts and spin-lattice relaxation of 23Na in a number of silicate liquids to about 1200°C, and these results are discussed in light of other recent studies. These results clearly demonstrate the mixed alkali effect on cation motion. New high temperature magic angle spinning 11B NMR spectra for a sodium borate liquid are also presented. As in previous studies of aluminate and silicate melts, the latter data set suggests that the mechanism of viscous flow is closely tied to local exchange of cationic species.