In situ high temperature 27Al NMR study of structure and dynamics in a calcium aluminosilicate glass and melt
In situ high temperature 27Al NMR study of structure and dynamics in a calcium aluminosilicate glass and melt
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DOI：
10.1016/j.jnoncrysol.2007.06.030
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发表时间：
2007-11
影响因子：
3.5
通讯作者：
K. Kanehashi;J. Stebbins
中科院分区：
文献类型：
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作者：
K. Kanehashi;J. Stebbins
用原位高温探针研究了硅酸钙（43.1CaO-12.5Al2O3-44.4SiO2）玻璃及其熔体的27al核磁共振光谱和自旋晶格弛豫时间常数t1的温度依赖性（25 ~ 1400℃），并用环境温度、高场MAS核磁共振对玻璃进行了表征。随着温度的升高，四极卫星运动平均的峰值位置和线宽表现出一致的行为。在玻璃化转变温度Tg附近，t1的随温度下降速率急剧增加，表明核磁共振弛豫过程从振动运动转变为平动运动。在t1最小值（≈1200°C）以上，从t1得到的核磁共振相关时间与从粘度得到的剪切弛豫时间吻合较好，表明微观核自旋弛豫与宏观结构弛豫受相同的动力学控制，因此原子尺度运动与宏观粘性流动密切相关。
The temperature dependence (25–1400°C) of27Al NMR spectra and spin–lattice relaxation time constants T1have been studied for a calcium aluminosilicate (43.1CaO–12.5Al2O3–44.4SiO2) glass and melt using an in situ high temperature probe, and the glass has been characterized by ambient temperature, high field MAS NMR. The peak positions and the line widths show a consistent behavior as motional averaging of the quadrupolar satellites increases with increasing temperature. The rate of decrease with temperature of T1drastically increases near the glass transition temperature Tg, which suggests a change in NMR relaxation process from vibrational to translational motions. Above the T1minimum (≈1200°C), NMR correlation times obtained from T1are in good agreement with shear relaxation times estimated from viscosity, suggesting that microscopic nuclear spin relaxation is controlled by the same dynamics as macroscopic structural relaxation, and thus that atomic-scale motion is closely related to macroscopic viscous flow.