Effects of temperature and composition on silicate glass structure and dynamics: SI-29 NMR results
Effects of temperature and composition on silicate glass structure and dynamics: SI-29 NMR results
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DOI：
10.1016/0022-3093(88)90289-x
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发表时间：
1988-12
影响因子：
3.5
通讯作者：
J. Stebbins
中科院分区：
文献类型：
--
作者：
J. Stebbins
The distribution of bridging and non-bridging oxygens is a fundamental aspect of the intermediate range order of silicate glasses and liquids. Disorder in this distribution can be characterized by the relative abundances of Qnspecies, which can be quantified by29Si NMR on both spinning and static samples. We emphasize the latter here, and show that increasing the field strength of the network modifying cation and increasing temperature have similar randomizing effects on this distribution. These changes have a major influence on thermodynamic activities. In the liquid, exchange between sites is rapid, but the exchange rate may become slow enough with decreasing temperature to actually define Tg. In silicate liquids, some kind of high energy, low abundance, defects probably are present to allow this structural change to occur, to account for the bulk of the configurational heat capacity, and to explain the observed spin-lattice relaxation times.
