Equilibrium segregation of sulfur to the free surface of single crystalline titanium
Equilibrium segregation of sulfur to the free surface of single crystalline titanium
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DOI：
10.1088/0953-8984/13/35/301
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发表时间：
2001-09
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影响因子：
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通讯作者：
Z. Cao
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文献类型：
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作者：
Z. Cao
硫在560{？} 800.第800章？利用俄歇电子能谱（AES）测量研究了C。为了描述硫覆盖层中的浓度演变，通过向浓度梯度添加局部函数df（x）/dx来修改Fick第一定律，以驱动从初始均匀分布开始的偏析。由此导出的扩散方程在f（x）= asexp（-x/ds）的情况下求解。有人发现，该解决方案导致AES强度演变的偏析，IS（t）= IS？(1-e? erfc（？）1/2）），？= Dt/ds 2，这与实验结果非常吻合。溅射深度剖析揭示了钛表面下的硫在平衡状态下呈指数衰减分布，这反过来又证明了我们对菲克第一定律的修正。在不参考详细动力学的情况下，通过比较在不同温度下的硫浓度演变来确定活化能Ea = 718 meV/atom。
Equilibrium segregation of sulfur to the free surface of single crystalline titanium from 560{?}C to 800{?}C was investigated using Auger electron spectroscopy (AES) measurements. To describe the concentration evolution in the sulfur overlayer, Fick's first law was modified by adding a local function df(x)/dx, to the concentration gradient to drive the segregation starting from an initially homogeneous distribution. The diffusion equation thus derived was solved for the case f(x) = asexp (-x/ds). It was found that the solution leads to an AES intensity evolution for segregants, IS(t) = IS?(1-e?erfc((?)1/2)), ? = Dt/ds2, which fits the experimental results extremely well. An exponentially decaying distribution of sulfur beneath the titanium surface at equilibrium was revealed by sputter depth profiling, which in turn justifies our modification to Fick's first law. Without referring to the detailed kinetics, an activation energy Ea = 718 meV/atom was determined by comparing the sulfur concentration evolution at different temperatures.