Surface dynamics dominated by bulk thermal defects -- the case of NiAl (110).
Surface dynamics dominated by bulk thermal defects -- the case of NiAl (110).
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表面动力学主要受体热缺陷影响——以 NiAl (110) 为例。
DOI：
10.1103/physrevb.71.085421
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发表时间：
2005
影响因子：
3.7
通讯作者：
N. Bartelt
中科院分区：
文献类型：
--
作者：
K. Mccarty;J. Nobel;N. Bartelt
我们发现，微小的温度变化会导致NiAl（110）表面上的台阶移动。我们表明，这种步进运动的发生是因为质量在体和表面之间转移，因为体热缺陷的浓度（即，空位）随温度变化。由于发现岛的面积随温度变化的变化与岛的步长严格成比例，因此热产生的缺陷在非常靠近表面台阶处产生（消除）。为了量化体/表面交换，我们振荡样品温度并测量系统响应的振幅和相位滞后，即，岛屿面积的变化与其周长成正比。使用一个一维模型的缺陷扩散通过在垂直于表面的方向上的散装，我们确定的迁移和形成能量的散装热缺陷。在表面平滑过程中，我们发现，在同一平台上的岛屿之间没有流动的材料，并且堆栈中的所有岛屿以相同的速率收缩。我们的结论是平滑发生通过大量的晶体，而不是通过表面扩散的质量传输。基于岛衰变、缺陷迁移和缺陷形成的活化能的测量相对大小，我们表明在步骤处的附着/脱离是平滑中的速率限制步骤。«少
We find that small temperature changes cause steps on the NiAl(110) surface to move. We show that this step motion occurs because mass is transferred between the bulk and the surface as the concentration of bulk thermal defects (i.e., vacancies) changes with temperature. Since the change in an island's area with a temperature change is found to scale strictly with the island's step length, the thermally generated defects are created (annihilated) very near the surface steps. To quantify the bulk/surface exchange, we oscillate the sample temperature and measure the amplitude and phase lag of the system response, i.e., the change in an island's area normalized to its perimeter. Using a one-dimensional model of defect diffusion through the bulk in a direction perpendicular to the surface, we determine the migration and formation energies of the bulk thermal defects. During surface smoothing, we show that there is no flow of material between islands on the same terrace and that all islands in a stack shrink at the same rate. We conclude that smoothing occurs by mass transport through the bulk of the crystal rather than via surface diffusion. Based on the measured relative sizes of the activation energies for island decay, defectmore » migration, and defect formation, we show that attachment/detachment at the steps is the rate-limiting step in smoothing.« less