OBSERVATION OF SLOW ATOMIC MOTIONS CLOSE TO THE GLASS-TRANSITION USING 2-D SI-29 NMR

被引:49
作者
FARNAN, I
STEBBINS, JF
机构
[1] Department of Geology, Stanford University, Stanford
关键词
D O I
10.1016/0022-3093(90)90264-M
中图分类号
TQ174 [陶瓷工业]; TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
Experiments were performed to investigate atomic re-arrangements just above the glass transition in potassium tetrasilicate (K2Si4O9). These experiments employed two-dimensional NMR techniques which were developed to study chemical exchange in non-viscous liquids and organic polymers. The major feature of the 29Si 2-D NMR exchange spectra of potassium tetrasilicate above its glass transition was a slow exchange (<1 kHz) between the silicon Q3 and Q4 environments. A similar experiment performed just below the glass transition showed no such exchange, which suggests that this Q species exchange is the motion that is 'frozen out' as a viscous liquid cools through its glass transition. The results are consistent with a very local region of atomic re-arrangement and contradict a polymeric view of silicate liquids. © 1990.
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页码:207 / 215
页数:9
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