Photoluminescence properties of anodic aluminium oxide films formed in a mixture of malonic acid and oxalic acid

Li, Shou‐Yi; Liu, Zheng‐Lai; Xiang, Gen‐Xiang; Ma, Bao‐Hong

doi:10.1002/bio.4363

Cited by 3 publications

(1 citation statement)

References 51 publications

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“…Meanwhile, Huang et al [ 27 ] suggested that the PL in AAO membrane originates from oxygen ion defect states (F center) within the AAO membrane, with emission peaks located at 413 nm and 430 nm. The PL effect of AAO has been explored in many studies [ 28 , 29 , 30 , 31 ], among which Zheng et al [ 31 ] investigated the variation in PL intensity of AAO under different anodizing voltages. It was found that the PL intensity of AAO significantly decreases at high voltages of 130 V compared with traditional MA at 40 V [ 31 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Normal-to-High Anodizing Voltage on AAO Surface Hardness from 1050 Aluminum Alloy in Oxalic Acid

Ku,

Wu,

Hung

et al. 2024

Micromachines

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Anodic aluminum oxide (AAO) has been widely applied for the surface protection of electronic component packaging through a pore-sealing process, with the enhanced hardness value reaching around 400 Vickers hardness (HV). However, the traditional AAO fabrication at 0~10 °C for surface protection takes at least 3–6 h for the reaction or other complicated methods used for the pore-sealing process, including boiling-water sealing, oil sealing, or salt-compound sealing. With the increasing development of nanostructured AAO, there is a growing interest in improving hardness without pore sealing, in order to leverage the characteristics of porous AAO and surface protection properties simultaneously. Here, we investigate the effect of voltage on hardness under the same AAO thickness conditions in oxalic acid at room temperature from a normal level of 40 V to a high level of 100 V and found a positive correlation between surface hardness and voltage. The surface hardness values of AAO formed at 100 V reach about 423 HV without pore sealing in 30 min. By employing a hybrid pulse anodization (HPA) method, we are able to prevent the high-voltage burning effect and complete the anodization process at room temperature. The mechanism behind this can be explained by the porosity and photoluminescence (PL) intensity of AAO. For the same thickness of AAO from 40~100 V, increasing the anodizing voltage decreases both the porosity and PL intensity, indicating a reduction in pores, as well as anion and oxygen vacancy defects, due to rapid AAO growth. This reduction in defects in the AAO film leads to an increase in hardness, allowing us to significantly enhance AAO hardness without a pore-sealing process. This offers an effective hardness enhancement in AAO under economically feasible conditions for the application of hard coatings and protective films.

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Section: Introductionmentioning

confidence: 99%

Influence of Normal-to-High Anodizing Voltage on AAO Surface Hardness from 1050 Aluminum Alloy in Oxalic Acid

Ku,

Wu,

Hung

et al. 2024

Micromachines

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Enhanced photoluminescence of hexamolybdenum cluster by anodic aluminum oxide photonic crystals

Kim Ngan Nguyen,

Segawa,

Grasset

et al. 2024

Materials Letters

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Anodic alumina/carbon composite films: extraction and characterization of the carbon-containing component

Chernyakova,

Matulaitienė,

Charkova

et al. 2024

J. Phys. Mater.

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Alumina/carbon composites are modern nanomaterials used as adsorbents, catalysts, catalyst supports, supercapacitors, and electrode materials for fuel cells. Among other methods, aluminum anodizing is fairly fast and inexpensive for producing anodic alumina/carbon composites with controllable properties. In the present study, the morphology and composition of carbon-enriched anodic alumina films were obtained during aluminum anodic oxidation in formic acid with ammonium heptamolybdate (C content is ca. 5.0 mass%) or oxalic acid (C content 3.4 mass%) additives. The anodic alumina films have a wide blue fluorescence in the 400–650 nm wavelength range with a maximum at ca. 490 nm. The fluorescence decay is nonexponential and has an average lifetime of 1.54 and 1.59 ns for ammonium heptamolybdate and oxalic acid additives, respectively. As samples obtained in sulfuric acid (i.e., without carbon) do not possess detectable fluorescence in the 400–650 nm wavelength range, it was concluded that carbon-containing inclusions are responsible for the fluorescence properties of the films. The initial samples were dissolved in the hot aqueous HCl solution and then dialyzed to extract the carbon-containing component. It was shown that the solutions contain nanoparticles of amorphous carbon with a 20–25 nm diameter. Carbon nanoparticles also exhibit an excitation-dependent emission behavior at 280–450 nm excitation wavelengths with average lifetimes of 7.25–8.04 ns, depending on the composition of the initial film. Carbon nanoparticle fluorescence is caused by the core of CNPs and various emission centers on their surface, such as carbonyl, carboxyl, and hydroxyl groups. As CNPs could be exceptional candidates for detection technologies, the biocompatibility assays were performed with living COS-7 mammalian cells, showing a minimal negative impact on the living cells.

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Photoluminescence properties of anodic aluminium oxide films formed in a mixture of malonic acid and oxalic acid

Cited by 3 publications

References 51 publications

Influence of Normal-to-High Anodizing Voltage on AAO Surface Hardness from 1050 Aluminum Alloy in Oxalic Acid

Influence of Normal-to-High Anodizing Voltage on AAO Surface Hardness from 1050 Aluminum Alloy in Oxalic Acid

Enhanced photoluminescence of hexamolybdenum cluster by anodic aluminum oxide photonic crystals

Anodic alumina/carbon composite films: extraction and characterization of the carbon-containing component

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