揭示水合盐脱水机制的多尺度研究

中文摘要 AI 辅助

理解水合盐的脱水机制在固态化学中仍具有根本重要性，因为它们的行为影响从储热到文物保护再到药物结晶等多个领域。结合拉曼共聚焦显微镜、动态失重测量、扫描电子显微镜（SEM）和显微CT，我们证明十水硫酸钠（芒硝）的脱水动力学通过两个阶段展开：初始的成核控制阶段，其中原子重排驱动二维横向生长，遵循指数规律；随后是相界控制阶段，其中生长向晶体内部推进，受限于水合-脱水界面处的水空位形成。生成的无水芒硝产物表现出约35%的收缩，形成多孔的层状双孔隙纳米晶结构，且相对湿度直接决定晶体尺寸。将该分析扩展至其他硫酸盐水合物表明，水合相与无水相之间的晶体对称性变化决定了表面形貌，将微观结构与机制关联起来。这一多尺度框架揭示了体相测量无法捕捉的动力学，并提出结构指标可预测其他水合盐家族的脱水途径，为无需 exhaustive 实验筛选即可设计热能存储材料开辟了途径。

英文摘要

Understanding the dehydration mechanism of hydrated salts remains fundamentally important in solid state chemistry, as their behavior affect fields ranging from heat storage to heritage conservation and pharmaceutical crystallization. Combining Raman confocal microscopy, dynamic weight loss measurements, SEM, and micro CT, we show that dehydration kinetics of sodium sulfate decahydrate (mirabilite) unfold through two regimes: an initial nucleation controlled phase, where atomic rearrangement drives two dimensional lateral growth following an exponential law, and a subsequent phase boundary controlled regime, where growth advances into the crystal depth, limited by water vacancy formation at the hydrated dehydrated interface. The resulting thenardite product shows around 35 percent shrinkage and forms a porous, layered dual porosity nanocrystalline structure, with relative humidity directly governing crystal size. Extending this analysis to other sulfate hydrates reveals that crystallographic symmetry changes between hydrate and anhydrous phases dictate surface morphology, linking microstructure to mechanism. This multiscale framework uncovers dynamics hidden from bulk measurements and suggests structural indicators could predict dehydration pathways in other hydrated salt families, and opening route toward designing thermal energy storage materials without exhaustive experimental screening.

发表机构

• Institute of Physics, University of Amsterdam（阿姆斯特丹大学物理研究所）
• Universite de Pau et des Pays de l’Adour, CNRS, LFCR, DMEX（波尔多阿基坦大学，法国国家科学研究中心，LFCR，DMEX）

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