11B MAS NMR spectroscopic study of structural relaxation, aging, and memory effect at the atomic scale in a borosilicate glass.
Relaxation kinetics of boron coordination environments in a borosilicate glass in response to temperature jumps has been monitored using (11)B magic-angle spinning (MAS) NMR spectroscopy. The relaxation time scale of the BO4/BO3 ratio is found to be closely comparable with those of the bulk properties, namely, refractive index and viscosity, showing a close connection with one another. Samples partially equilibrated at a low temperature, when subjected to a positive temperature jump, display an initial rapid decrease followed by an increase in the BO4/BO3 ratio. This reversal in the trend of the variation of the BO4/BO3 ratio has been interpreted to be the signature of a memory effect, and the implications are discussed within the framework of the potential energy landscape model of glassy dynamics.
Department of Chemical Engineering and Materials Science, University of California at Davis, One Shields Avenue, Davis, California 95616, USA.
Sezen Soyer
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Sabyasachi
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Sen