Temperature Effects On Borate Melt Structure And Dynamics: Nmr Studies

Decades of NMR studies of borate glass structure have provided a rich background for NMR studies of the structure and dynamics of the corresponding melts. A number of studies of glasses with varying fictive temperatures have shown that the ratio of three coordinated to four coordinated boron increases with temperature, requiring a corresponding increase in the fraction of non-bridging oxygens. The corresponding effect on dynamics is to increase the rate of exchange among the boron sites, the frequency of which seems to accurately predict the shear correlation time. Dynamics of both network-former and network-modifier cations can also be assessed through spin-lattice relaxation time measurements.