Anodizing aluminum in a viscous electrolyte to produce one-dimensional photonic crystals

In the paper, the possibility to produce anodic aluminum oxide (AAO) featuring one-dimensional photonic crystal along the normal to the surface is shown. The AAO structure is represented by alternating layers of different porosity and is formed in a viscous electrolyte based on sulfuric acid and ethylene glycol at the periodically varying from high (1.8 mA/cm²) to low (0.4 mA/cm²) current density with a rectangular pulse shape. The pore sizes and interpore distance, pore density and porosity, thickness and period of the AAO structure have been determined. The specular reflection spectra features for single layers that make up the AAO structure and for one-dimensional photonic crystals structures consisting of 165 periods have been studied. An increase in the porosity of the upper layers of the structure due to chemical etching of the pores during the oxide growth is noted. It is shown that the invariance of the spectral position of the photonic band gap for AAO structures is achieved by a 0.1 % decrease in charge at each subsequent anodizing cycle during their formation, which leads to a decrease in the period of the structure in the lower layers, compensating for the increase in the upper layers porosity. The reflection spectra have been analyzed for the incidence angles of 10° and 30° and used to calculate the period of the structure and the effective refractive index. The effective refractive index of the single layers that make up the AAO structure is calculated using the optical Fabry–Perot oscillations. For AAO with the properties of one-dimensional photonic crystal, a green color is observed at normal light incidence, and an iridescent color is observed when the angle changes. AAO can be used as a decorative coating on the housings of electronic devices (tablets, laptops, phones, etc.) and when creating design objects made of aluminum and its alloys.

1. Masuda H., Fukuda K. Ordered metal nanohole arrays made be a two-step replication of honeycomb structures of anodic alumina. Science, 1995, vol. 268, pp. 1466–1471. https://doi.org/10.1126/science.268.5216.1466

2. Lee W. The Anodization of Aluminum for Nanotechnology Applications. Journal of the Minerals, Metals and Materials Society, 2010, vol. 62, no. 6, pp. 57–63. https://doi.org/10.1007/s11837-010-0088-5

3. Santos A. Nanoporous Anodic Alumina Photonic Crystals: Fundamentals, Developments and Perspectives. Journal of Materials Chemistry, C, 2017, vol. 5, no. 23, pp. 5581–5599. https://doi.org/10.1039/C6TC05555A

4. Mukhurov N. I., Gasenkova I. V., Andrukhovich I. M. Ordered Growth of Anodic Aluminum Oxide in Galvanostatic and Galvanostatic-Potentiostatic Mode. JMSN: Journal of Materials Science and Nanotechnology, 2014, vol. 1, iss. 1, pp. S110 (1–6). https://doi.org/10.15744/2348-9812.1.S110

5. Ramana Reddy P., Ajith K. M., Udayashankar N. K. Effect of electrolyte concentration on morphological and photoluminescence properties of free standing porous anodic alumina membranes formed in oxalic acid. Materials Science in Semiconductor Processing, 2020, vol. 106, art. ID 104755. https://doi.org/10.1016/j.mssp.2019.104755

6. Gorelik V. S., Yashin M. M., Dungxue Bi, Guang Tao Fei. Transmission Spectra and Optical Properties of a Mesoporous Photonic Crystal Based on Anodic Aluminum Oxide. Optics and Spectroscopy, 2018, vol. 124, iss. 2, pp. 167–173. https://doi.org/10.1134/S0030400X18020078

7. Gorelik V. S., Sverbil P. P., Filatov V. V., Dongxue Bi, Guang Tao Fei, Shao Hui Xu. Transmission spectra of one-dimensional porous alumina photonic crystals. Photonics and Nanostructures – Fundamentals and Applications, 2018, vol. 32, pp. 6–10. https://doi.org/10.1016/j.photonics.2018.08.004

8. Kushnir, S. E., Pchelyakova T. Yu., Napolskii K. S. Anodizing with voltage versus optical path length modulation: a new tool for the preparation of photonic structures. Journal of Materials Chemistry, 2018, vol. 6, no. 45, pp. 12192–12199. https://doi.org/10.1039/C8TC04246B

9. Chunxin Sun, Hao Shengzhen, Wang Zhijun, Xu Qin, Wang Yongguo, Peng Qi, Lan Tian. Rapid fabrication of iridescent alumina films supported on an aluminium substrate by high voltage anodization. Optical Materials, 2022, vol. 104, art. ID 109937. https://doi.org/10.1016/j.optmat.2020.109937

10. Segawa H., Wada K. Structural colors of laminated alumina films prepared by ac oxidation in oxalic acid solution. Materials Chemistry and Physics, 2020, vol. 250, art. ID 123031. https://doi.org/10.1016/j.matchemphys.2020.123031

11. Yurasov А. N., Yashin М. М. Effective medium theory as a tool for analyzing the optical properties of nanocomposites. Rossiiskii tekhnologicheskii zhurnal [Russian Technological Journal], 2018, vol. 6, no. 2, pp. 56–66 (in Russian). https://doi.org/10.32362/2500-316X-2018-6-2-56-66

12. Acosta L. K., Bertó-Roselló F., Xifre-Perez E., Law C. S., Santos A., Ferré-Borrull J., Marsa L. F. Tunable Nanoporous Anodic Alumina Photonic Crystals by Gaussian Pulse Anodization. ACS Applied Materials and Interfaces, 2020, vol. 12, no. 17, pp. 19778–19787. https://doi.org/10.1021/acsami.9b23354

13. Lim S. Y., Law C. S., Marsal L. F., Santos A. Engineering of Hybrid Nanoporous Anodic Alumina Photonic Crystals by Heterogeneous Pulse Anodization. Scientific Reports, 2018, vol. 8, no. 1, art. ID 9455. https://doi.org/10.1038/s41598-01827775-6

14. Law C. S., Santos A., Nemati M., Losic D. Structural Engineering of Nanoporous Anodic Alumina Photonic Crystals by Sawtooth-like Pulse Anodization. ACS Applied Materials and Interfaces, 2016, vol. 8, no. 21, pp. 13542−13554. https://doi.org/10.1021/acsami.6b03900

15. Napolskii K. S., Noyan A. A., Kushnir S. E. Control of high-order photonic band gaps in one-dimensional anodic alumina photonic crystals. Optical Materials, 2020, vol. 109, art. ID 110317. https://doi.org/10.1016/j.optmat.2020.110317

16. Petukhov D. I., Napolskii K. S., Eliseev A. A. Permeability of anodic alumina membranes with branched channels. Nanotechnology, 2012, vol. 23, no. 33, p. 5601. https://doi.org/10.1088/0957-4484/23/33/335601

17. Zaraska L., Stępniowski W. J., Ciepiela E., Sulka G. D. The effect of anodizing temperature on structural features and hexagonal arrangement of nanopores in alumina synthesized by two-step anodizing in oxalic acid. Thin Solid Films, 2013, vol. 534, pp. 155–161. https://doi.org/10.1016/j.tsf.2013.02.056

18. Alekseev S. A., Lysenko V., Zaitsev V. N., Barbier D. Application of Infrared Interferometry for Quantitative Analysis of Chemical Groups Grafted onto the Internal Surface of Porous Silicon Nanostructures. The Journal of Physical Chemistry C, 2007, vol. 111, no. 42, pp. 15217–15222. https://doi.org/10.1021/jp0712452

19. Manzano C. V., Ramos D., Pethö L., Bürki G., Michler J., Philippe L. Controlling the Color and Effective Refractive Index of Metal-Anodic Aluminum Oxide (AAO)–Al Nanostructures: Morphology of AAO. The Journal of Physical Chemistry C, 2017, vol. 122, no. 1, pp. 957–963. https://doi.org/10.1021/acs.jpcc.7b11131

20. Gorelik V. S., Klimonsky S. O., Filatov V. V., Napolskii K. S. Optical properties of one-dimensional photonic crystals based on porous films of anodic aluminum oxide. Optics and Spectroscopy C, 2016, vol. 120, no. 4, pp. 534–539. https://doi.org/10.1134/S0030400X16040081

21. Sadykov А. I., Leontev A. P., Kushnir S. E., Lukashin A. V., Napolskii K. S. Kinetics of the Formation and Dissolution of Anodic Aluminum Oxide in Electrolytes Based on Sulfuric and Selenic Acids. Russian Journal of Inorganic Chemistry, 2021, vol. 66, no. 2, pp. 258–265. https://doi.org/10.1134/S0036023621020182