Probing the growth and melting pathways of a decagonal quasicrystal in real-time.
Probing the growth and melting pathways of a decagonal quasicrystal in real-time.
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DOI：
10.1038/s41598-017-17821-0
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发表时间：
2017-12-12
影响因子：
4.6
通讯作者：
Shahani AJ
中科院分区：
文献类型：
--
作者：
Han I;Xiao X;Shahani AJ
准晶体是如何生长的？尽管几十年来一直致力于这一研究领域，但它仍然是晶体生长领域的基本难题之一。虽然对准晶体生长的理论研究并不缺乏，但很少有实验研究来检验他们的各种假设。特别是，缺乏从母体液相中原位和三维（3D）生长准晶体的证据。为了填补我们对准晶凝固和熔化途径的理解空白，我们对Al-15at%Ni-15at%Co组成的十角形相进行了基于同步加速器的x射线成像实验。高通量x射线断层扫描使我们能够观察三维准晶体在温度下的生长和熔化形貌。我们确定了在十角准晶体的生长和熔化过程中不存在时间反转对称性。准晶体的生长主要受液相中原子团簇的附着动力学控制，而熔化则是无障碍的，并受到浮力驱动的对流的限制。这些实验结果提供了急需的基准数据，可用于验证涉及这种独特物质相的相变模拟。
How does a quasicrystal grow? Despite the decades of research that have been dedicated to this area of study, it remains one of the fundamental puzzles in the field of crystal growth. Although there has been no lack of theoretical studies on quasicrystal growth, there have been very few experimental investigations with which to test their various hypotheses. In particular, evidence of the in situ and three-dimensional (3D) growth of a quasicrystal from a parent liquid phase is lacking. To fill-in-the-gaps in our understanding of the solidification and melting pathways of quasicrystals, we performed synchrotron-based X-ray imaging experiments on a decagonal phase with composition of Al-15at%Ni-15at%Co. High-flux X-ray tomography enabled us to observe both growth and melting morphologies of the 3D quasicrystal at temperature. We determined that there is no time-reversal symmetry upon growth and melting of the decagonal quasicrystal. While quasicrystal growth is predominantly dominated by the attachment kinetics of atomic clusters in the liquid phase, melting is instead barrier-less and limited by buoyancy-driven convection. These experimental results provide the much-needed benchmark data that can be used to validate simulations of phase transformations involving this unique phase of matter.
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影响因子：
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