During crystallization a continuum of patterns could emerge due to the interplay of growth kinetics, material or solution chemistry, and crystallographic defects. The coherent twin boundary is widely known to catalyze growth in pristine crystals including polycrystalline Si. Much remains unknown about the impact of changing the chemical environment of the crystallization process through the deliberate addition of trace metallic species—termed chemical modification. Pristine Si has been reported to grow through the classical model of two parallel twin planes acting in concert to enable steady-state propagation of the solid-liquid interfaces. Here, we achieve a vision on the growth process via in situ synchrotron x-ray microtomography and further corroborated by ex situ crystallographic investigation. We find that steady-state growth is impossible in chemically modified alloys that consist of trace (0.1 wt.%) Sr. This is because the Sr modifier poisons the concave re-entrant grooves, thereby deactivating the advantage of the twin-plane re-entrant edge mechanism and leading to a singly-twinned interface. This study may serve as a proxy to chemically modified crystallization pathways of eutectic Si in Al-Si alloys and, more broadly, as a framework for the crystallization-mediated synthesis of materials.

中文翻译：

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化学修饰后单晶硅晶体的生长

在结晶过程中，由于生长动力学，材料或溶液化学以及结晶学缺陷之间的相互作用，可能会出现连续的图案。众所周知，相干孪晶边界可催化包括多晶Si在内的原始晶体的生长。关于通过故意添加痕量金属物质（称为化学修饰）来改变结晶过程的化学环境的影响，目前尚不清楚。据报道，原始硅是通过两个平行的双平面共同作用的经典模型而生长的，以使固液界面能够稳态传播。在这里，我们通过原位同步加速器X射线显微断层摄影术实现了对生长过程的构想，并通过非原位证实了这一点。晶体学研究。我们发现，在由痕量（0.1 wt。％）Sr组成的化学改性合金中不可能实现稳态生长。这是因为Sr改性剂使凹入凹入槽中毒，从而失去了双平面凹入的优势。进入边缘机制，并导致一个单一的接口。这项研究可以作为Al-Si合金中共晶Si的化学修饰结晶途径的替代方法，并且更广泛地作为结晶介导的材料合成的框架。