在结合体悬浮液中从混乱到秩序的过渡:X射线测量
概括
合体二氧化颗粒通过重力沉积缓慢缩时形成有序的虹彩晶体. 然而,较快的沉积会导致无形沉积物或玻璃,符合晶体生长理论.
科学领域:
- 体和接口科学科学
- 材料科学是一种材料科学.
- 热力学是一种热力学.
背景情况:
- 体分散与分子系统具有相同的热力学特性.
- 一个关键的现象是硬球的无序到有序的过渡.
- 了解颗粒度的影响对于材料设计至关重要.
研究的目的:
- 为了研究颗粒大小和沉积率对合颗粒排序的影响.
- 用显微镜和X射线测量来描述由此产生的沉积物结构.
- 将实验观测与古典晶体生长理论进行比较.
主要方法:
- 在循环中分散的有机颗粒.
- 重力沉降以集中颗粒.
- 扫描电子显微镜 (SEM) 用于结构分析.
- 用于相位识别的X射线衰减测量.
主要成果:
- 由于缓慢的沉积,小的二氧化颗粒形成了虹彩的,有序的晶体相.
- 较大的颗粒或较快的沉积率导致无形沉积物.
- 在水晶沉积物中,SEM揭示了六边形密集的层.
- X射线测量显示了有序和无形区域之间的边界处的不连续性.
- 迅速形成的沉积物导致了玻璃状的状态.
结论:
- 沉积率和颗粒大小极大地影响着合分散的排序.
- 从有序结构向无形结构的过渡是由沉积率和结晶率之间的竞争决定的.
- 实验结果支持了合体系统中晶体生长的经典理论.
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