Figure 2. Analysis of the self-detachment of crystal layers on the SRF surface. (IMAGE)
Caption
Fig. 2. Analysis of the self-detachment of crystal layers on the SRF surface. (a) Defect regions, which are negligibly narrow compared to the size of the crystal layers, cause the non-sticky SRF surface. (b) It also accelerates the detachment of the crystal layers by an elastic restoring force against the curvature of the SRF. (c) The dominant detachment phenomenon of crystal layers around the critical defect area is a collision between the crystal layers, accompanied by divergence or convergence depending on their angle and position. (d) When the defect region is larger than the size of the crystal layers, the growth of the crystal layers is terminated. FEG-SEM images show the self-detaching phenomena of the copper crystal layers from the SRF surface. (e) Self-detachment by the non-sticky surface, (f) the curvature of fiber, (g) and the divergence (inset scale bar: 1 μm) and (h) the convergence of crystal layers. (i) Termination of crystal growth. The purple region expressed on the fiber to distinguish it from the heavy metal crystal layer formed on the SRF surface represents wide defect regions where the crystal layer is not formed. Commonly, new crystals grow on the SRF surface after the existing crystal layer is self-detached. Scale bar: 50 μm. (j) XRD pattern of the SRF including crystals grown from the adsorbed Cu2+. It is matched well with that of a Cu2(NO3)(OH)3 polycrystal (ICDD No.01-075-1779). (k) SEM image of the Cu2+ crystal layers separated from the SRF surface exhibits a form similar to the curved surface of SRF. Scalebar: 200μm. (l) HR-TEM image of the Cu2+ crystal layer displays d-spacing values that match well with the XRD pattern. Scalebar: 10nm.
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Korea Institute of Science and Technology(KIST)
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