Mobility of Zn or Cu ions in anodic alumina films

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1 Mobility of Zn or Cu ions in anodic alumina films
岳仑仑

2 Basic For anodizing of aluminium at 100% current efficiency, about 40% of the film thickness is formed at the film/electrolyte interface, the remainder forming at the metal/film interface AI-Cu , AI-Ti , AI-W and AI-Zn prior oxidation of the aluminium atoms and the accumulation of the alloying element atoms in the alloy at the alloy/film interface occur.

3 Mobility of copper ions in anodic alumina films
35nm Al-O.4 at% Cu alloy Aluminium substrate Constant current density 氧化步奏： aluminium the accumulation of copper in a layer of alloy, 2 nm thick alloy incorporated abruptly into the film and aluminium

4 relative migration rates：ionic radii, valency and metal-oxygen bond energy
Such as aluminium the outer 40% of the film thickness is formed by cation migration

5 60 V 85 V

6 通过测量富集层到氧化层和金属层的距离比，算出，铜移动速度和AL移动速度的比例

7 从图中可以看出，铜离子是在向外移动之中的，但是从另一方面来说，富集层的厚 度却几乎不会发上太大变化，这是否能给我们启示，在氧化锌过程中，如果Zn厚度 过大，那么富集层会扩展过大，而且Al保护层过小就会产生溶解现象 如果我们减小Zn膜厚度会怎么样？ 实验中利用到了Al衬底，而我们使用的就是从原则上看是Zn的衬底，

8 Incorporation and mobility of zinc ions in anodic alumina films
A1-0.2 at% Zn alloy 35 nm thick purity aluminium substrate constant current density

9 the presence of the air-formed film at the alloy surface
the prior oxidation of aluminium on an electropolished AI-0.9 at% Zn alloy is terminated upon achieving an average enrichment of zinc; determined experimentally no 'incorporation of zinc ions into the anodic film is expected

10 Conclusions Cu and zinc atoms are accumulated in a layer of alloy, about 2 nm thick, just beneath the anodic film as a consequence of prior oxidation of the aluminium atoms.No Cu or Zn ions are incorporated into the anodic aIumina film during anodizing of the alloy. When the alloy film is almost totally consumed by anodizing, Cu or Zn atoms in the enriched alloy layer are oxidized and incorporated immediately into the anodic film as a result of the presence of an air-modified , electropolishing film on the aluminium substrate. Then Cu or Zn ions migrate outwards; the migration rate of the zinc ions is about 2.3 times that of A13+ ions， The copper ions 3.2 times that of outwardly mobile Al)+ ions.

11 总结 通过这两种金属离子特别是两种合金的阳极氧化过程中，我们可以得到两种离子在 阳极氧化中发生的过程，这对于我们的实验有很好的参考价值。
本实验其实从原则上来说，是使用了Zn衬底，通过论文中的结论如果富集层的Cu or Zn离子含量超过40%，我们就能观测到分层结构，所以实验中我们可以通过研究 氧化一部分的Zn观测，形成的ZnO层的位置和Al2O3位置还有Al的位置，进而研究 氧化过程。 如果我们将Zn的厚度减少到10nm左右，能否会出现比较好的ZnO和Al2O3的分层。 我们双层金属的阳极氧化过程中我们一定要控制好电压，否则容易形成ZnO运动到 表面层进而溶解，或者我们可以使用一些偏中性的电解液。

12 工作思路 通过设定一定的氧化电压，使得Al完全氧化，Zn部分氧化（氧化厚度设为10nm）， 观测切面的分层情况，根据结果算出电压和Zn氧化厚度的关系。 将Zn的厚度减少到10nm左右，设定适合电压，使得Zn完全氧化，观察切面 调整电流密度，观测对于结果的影响 能否使用其他偏中性或者偏碱性的电解液,在表面形成ZnO层，这是否可行？ XRD 分析结果（掠角XRD）

13 Thanks!