Ordered phases and phase transitions of cesium on the Cu(111) surface
Ordered phases and phase transitions of cesium on the Cu(111) surface
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Cu(111)表面铯的有序相和相变
DOI：
10.1116/1.575096
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
A. Ignatiev
中科院分区：
文献类型：
--
作者：
W. Fan;A. Ignatiev
利用低能电子衍射（LEED）实验研究了80 ~ 450 K温度范围内铯原子在Cu（111）表面的有序相和相变。在80-K表面上的铯在覆盖度θ>0.12时形成取向有序的无公度结构（IS）。IS相的覆盖层晶格参数随着覆盖率的增加而不断减小，直到达到比散装铯小7%的Cs-Cs间距。随着温度的升高，IS相经历了几个转变：（i）在135 K时出现较好的有序相，（ii）在θ 0.21时出现无序相，过渡到中间相（“六方”相），（iii）在θ>0.25和T = 260 K时出现（2×2）相，在T = 355 K时出现（6×6）相。表面上的铯还形成反对称金属畴相和（（4）/（3）（3）1/2×（4）/（3）（3）1/2）-R30°和（2×2）共存相。
Low‐energy electron diffraction (LEED) experiments have been carried out to study the ordered phases and phase transitions of cesium on the Cu(111) surface in the temperature region between 80 and 450 K. The cesium on the 80‐K surface forms an orientationally ordered incommensurate structure (IS) at coverage θ>0.12. The overlayer lattice parameter of the IS phase decreases continuously with coverage until a Cs–Cs spacing 7% smaller than in bulk cesium is reached. By increasing the temperature, the IS phase undergoes several transitions as a function of coverage: (i) a better ordered phase at 135 K, (ii) a disordered phase through an intermediate phase (‘‘hexatic’’ phase) at θ 0.21, and (iii) a (2×2) phase at θ>0.25 and T≊260 K and a (6×6) phase at T≊355 K. The cesium on the surface also forms an antisymmetrical metallic domain phase and a coexisting phase of ( (4)/(3) (3)1/2× (4)/(3) (3)1/2)‐R30° and (2×2).