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arXiv 2507.19087physics.chem-phcond-mat.mtrl-sci
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电极/电解质界面处二维离子晶体的电驱动一级相变

Electrically driven first-order phase transition of a 2D ionic crystal at the electrode/electrolyte interface

Federica Angiolari, Alessandro Coretti, Mathieu Salanne, Sara Bonella

AI总结:

本文研究熔盐—金属界面吸附层的电致结晶,揭示预有序与突发单晶化两阶段机制,并通过有限尺寸分析确认后者为一级相变。

摘要:

吸附在金属电极表面的液态电解质会呈现出多种结构,这些结构在组成和局部组织方面都可能与母体体相系统存在显著差异。特别是,实验和模拟研究越来越多地报道了无序—有序或有序—有序转变的存在,并且电极电势被确定为相应的驱动力。然而,人们对该过程的微观机制和阶段仍知之甚少,转变过程中的自由能变化也尚未得到充分表征。为弥补这一空白,我们研究了典型熔盐—金属界面中吸附层的结晶过程。我们证明,从无序结构到有序结构的转变分两个阶段进行。在很宽的电势范围内都观察到预有序效应,导致电极表面形成多晶结构,随后才最终发生突然的有序转变。预有序表现出连续转变的特征。另一方面,有限尺寸效应分析证明了向单晶状态转变的一级相变性质。随着系统尺寸增大,观察到起始施加电压发生偏移,并伴随自由能势垒的显著升高。后者反映在界面电容中:界面电容出现一个峰,并且该峰随系统尺寸增大而变得更加尖锐。

英文摘要:

Liquid electrolytes adsorbed at the surface of metallic electrodes display a multitude of structures that can largely differ from the parent bulk system, both in terms of composition and local organization. In particular, the existence of disorder-order or order-order transitions has been increasingly reported in experimental and simulation studies, and the electrode potential identified as the corresponding driving force. The microscopic mechanisms and the stages of the process are, however, poorly understood, and the free energy variation during the transition remain insufficiently characterized. To fill this gap, we investigate the crystallization of the adsorbed layer in a prototypical molten salt-metal interface. We demonstrate that the transition from the disordered to ordered structures proceeds in two stages. Pre-ordering effects are observed across a wide range of potentials, resulting in the formation of a poly-crystalline structure on the electrode surface, before an abrupt ordering transition finally occurs. The pre-ordering displays signature of a continuous transition. On the other hand, finite-size effects analysis proves the first-order character of the transition towards the mono-crystalline state. Upon increasing the system size, a shift in the onset applied voltage is observed, accompanied by a dramatic increase in the free energy barrier. The latter reflects in the interfacial capacitance, which displays a peak that sharpens with increasing system size.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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