arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0804.3953cond-mat.mtrl-sci
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吸附质小岛中的应变弛豫:O在W(110)上

Strain relaxation in small adsorbate islands: O on W(110)

T. O. Mentes, N. Stojic, N. Binggeli, M. A. Nino, A. Locatelli, L. Aballe, M. Kiskinova, E. Bauer

摘要:

用低能电子衍射测量了W(110)上p(1x 2)有序氧层中应力引起的晶格变化。我们已经观察到,小的氧岛显示出与下面的晶格不匹配。我们的研究结果表明,沿着[1-10],平均失配与岛的大小成反比,对于所有氧覆盖率高达0.5 ML的1/L,而沿着[001],它只对最小的氧岛和岛的大小的反比的更高的幂有意义。沿着[1-10]的行为由一维有限尺寸的Frenkel-Kontorova模型描述。利用这个模型,结合计算的力常数,我们对氧吸附时表面应力的变化作了定量的估计。结果与我们的从头计算一致,其给出沿[1-10]的相对压应力为-4.72 N/m,沿[001]的微小相对张应力为0.15 N/m。沿[001]方向的标度定性地解释为[1-10]方向的晶格弛豫引起的效应。

英文摘要:

The stress-induced lattice changes in a p(1x2) ordered oxygen layer on W(110) are measured by low-energy electron diffraction. We have observed that small oxygen islands show a mismatch with the underlying lattice. Our results indicate that along [1-10] the average mismatch scales inversely with the island size as 1/L for all oxygen coverages up to 0.5 ML, while along [001] it is significant only for the smallest oxygen islands and scales as a higher power of the inverse island size. The behaviour along [1-10] is described by a one-dimensional finite-size Frenkel-Kontorova model. Using this model, together with calculated force constants, we make a quantitative estimate for the change of surface-stress upon oxygen adsorption. The result is consistent with our ab-initio calculations, which give a relative compressive stress of -4.72 N/m along [1-10] and a minute relative tensile stress of 0.15 N/m along [001]. The scaling along [001] is qualitatively explained as an effect induced by the lattice relaxation in the [1-10] direction.

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