Atomistic study of xenon crystal growth via low-temperature atom beam deposition
Atomistic study of xenon crystal growth via low-temperature atom beam deposition
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低温原子束沉积氙晶体生长的原子研究
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
M. Jansen
中科院分区：
文献类型：
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作者：
Nicola Totó;C. Schön;M. Jansen
我们用低温原子束沉积的方法从理论上研究了Xe原子在蓝宝石衬底上的沉积和有序Xe相的生长。这种化学合成方法[D.Fischer和M.Jansen，J.Am化学。SoC。41,1755(2002)]特别适合于合成亚稳态固体化合物。模拟过程包括几个步骤，我们使用经验势来模拟衬底内的相互作用，气相和固体中的Xe-Xe相互作用，以及Xe原子与衬底之间的相互作用。在第一步中，我们确定了在实验条件下，没有Xe团簇在气相中形成，因此沉积过程可以用单个Xe原子在低温下在衬底上的吸附来描述。接下来，我们模拟了Xe的沉积过程，研究了沉积速率、衬底温度等各种合成参数对Xe的生长模式的影响。最后，对沉积的Xe层进行了回火处理，并对所得化合物的结构进行了分析。我们研究了局域有序区域的建立作为时间的函数，在沉积和回火过程中都是如此。我们观察到，最终的构型总是结晶的，尽管可能会形成诸如堆积故障和位错之类的缺陷。通过研究衬底和沉积相表面的扩散和吸附过程，解释了不同生长模式的发生和缺陷的形成。
We studied theoretically the deposition of Xe atoms on a sapphire substrate and the subsequent growth of ordered Xe phases via the low-temperature atom beam deposition method. This chemical synthesis method [D. Fischer and M. Jansen, J. Am. Chem. Soc. 41, 1755 (2002)] is particularly suitable for synthesizing metastable solid compounds. The modeling procedure consisted of several steps, where we used empirical potentials to model the interactions within the substrate, the Xe-Xe interactions in the gas phase and the solid, and the interactions between the Xe atoms and the substrate. In a first step, we established that under the experimental conditions, no Xe clusters formed in the gas phase, and thus the deposition could be described by the adsorption of single Xe atoms on the substrate at low temperatures. Next, we simulated the Xe deposition process and we studied the growth mode depending on various synthesis parameters such as the deposition rate and the temperature of the substrate. Finally, the deposited Xe layers were tempered and the structure of the resulting compound was analyzed. We studied the establishment of locally ordered regions as a function of time, both during the deposition and the tempering. We observed that the final configuration was always crystalline, although defects such as stacking faults and dislocations were likely to form. The occurrence of different growth modes and the formation of defects were explained by studying diffusion and adsorption processes on the surface of both the substrate and the depositing phase.