概括
了解无机材料的玻璃变成液体的转变至关重要. 这项研究表明,局部Si-O键断裂,而不是大型集群运动,即使在高粘度下也控制流动和扩散.
科学领域:
- 材料科学 材料科学 材料科学
- 固态化学 固态化学
- 物理化学 物理化学
背景情况:
- 在无机材料中,控制玻璃转化为液体的原子尺度动力学仍然在很大程度上无法解释.
- 了解这些动态对于预测材料特性和设计新材料至关重要.
研究的目的:
- 研究控制酸 (K2Si4O9) 玻璃变液的原子尺度机制.
- 为了将交换的动态与诸如粘度和扩散等宏观性质相关联.
主要方法:
- 使用了二维魔术角度旋转核磁共振 (2D MAS NMR) 光谱.
- 在温度超过玻璃过渡温度 (Tg) 的情况下收集的光谱,最高达583°C.
- 测量了不同酸盐物种之间的交换速率.
主要成果:
- 量化的汇率,表明Si-O债券断裂,就在玻璃过渡之上.
- 显示了交换时间表和控制粘度的时间表之间的强烈相关性.
- 观察到,局部断裂是宏观流量和扩散的主要因素,即使在非常高的粘度 (10^10 Pa·s) 中也是如此.
结论:
- 局部Si-O键断裂是控制K2Si4O9.9中玻璃变液的关键机制.
- 这种局部键动力学决定了诸如粘度和扩散之类的宏观性质,挑战了大型集群的协同运动是唯一负责的概念.
- 这些发现为无形材料的原子尺度动力学提供了基本的见解.
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