The mechanism of porosity formation during solvent-mediated phase transformations
The mechanism of porosity formation during solvent-mediated phase transformations
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DOI：
10.1098/rspa.2010.0469
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发表时间：
2010-06
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影响因子：
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通讯作者：
C. Raufaste;B. Jamtveit;T. John;P. Meakin;D. Dysthe
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文献类型：
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作者：
C. Raufaste;B. Jamtveit;T. John;P. Meakin;D. Dysthe
溶剂介导的固-固相转化通常导致多孔介质的形成，其可以在长时间尺度上稳定或经历熟化和固结。我们采用原位和非原位实验研究了KBr-KCl-H_2O体系的置换过程。在水溶液的存在下，通过产生令人惊讶的稳定的、高度各向异性的和连通的孔结构来促进KBr晶体被K（Br，Cl）固溶体置换，所述孔结构遍布产物相。这种孔结构确保了溶质从本体溶液到反应KBr和K（Br，Cl）表面的有效传输。的K（Br，Cl）固溶体的组成分布表现出显着的不连续性跨盘状空腔中的产品相。类似的转化机制在控制各种自然和人造系统的相变过程和速率方面可能很重要。
Solvent-mediated solid–solid phase transformations often result in the formation of a porous medium, which may be stable on long time scales or undergo ripening and consolidation. We have studied replacement processes in the KBr–KCl–H2O system using both in situ and ex situ experiments. The replacement of a KBr crystal by a K(Br,Cl) solid solution in the presence of an aqueous solution is facilitated by the generation of a surprisingly stable, highly anisotropic and connected pore structure that pervades the product phase. This pore structure ensures efficient solute transport from the bulk solution to the reacting KBr and K(Br,Cl) surfaces. The compositional profile of the K(Br,Cl) solid solution exhibits striking discontinuities across disc-like cavities in the product phase. Similar transformation mechanisms are probably important in controlling phase-transformation processes and rates in a variety of natural and man-made systems.