Fabrication and Characterization of Single Phase α-Alumina Membranes with Tunable Pore Diameters

Masuda, Tatsuya; Asoh, Hidetaka; Haraguchi, Satoshi; Ono, Satoshi

doi:10.3390/ma8031350

Cited by 62 publications

(40 citation statements)

References 36 publications

(63 reference statements)

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“…Porous oxide materials have attracted considerable attention due to their potential applications in filters, catalyst support, electronic, magnetic and optical devices. It is also known, α‐Al 2 O 3 membranes due to their biocompatibility and high chemical resistance are of great demand . One of the widely applied methods for alumina formation is aluminum anodizing in aqueous acidic solutions .…”

Section: Introductionmentioning

confidence: 99%

“…In Ref. authors obtained porous α‐Al 2 O 3 membranes of 25 mm diameter without thermal deformation, initial samples were synthesized in oxalic and phosphoric acids. At the same time, sulfuric acid is one of the cheapest electrolytes among the others commercially applied .…”

Section: Introductionmentioning

confidence: 99%

“…It is also known, α-Al 2 O 3 membranes due to their biocompatibility and high chemical resistance are of great demand. [1] One of the widely applied methods for alumina formation is aluminum anodizing in aqueous acidic solutions. [2] However, as-anodized anodic alumina is amorphous, and in fact, it is fragile and susceptible to both acid and base attack.…”

Section: Introductionmentioning

confidence: 99%

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Structural and Fluorescence Studies of Polycrystalline α‐Al₂O₃ Obtained From Sulfuric Acid Anodic Alumina

Chernyakova

Karpicz

Rutkauskas

et al. 2018

Physica Status Solidi (a)

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In the present study, robust α‐Al2O3 specimens (144 µm thick) are obtained by the heat treatment at 1400 °C of free‐standing sulfuric acid anodic alumina. Scanning electron microscopy analysis show that the as‐anodized anodic alumina films possess well‐ordered porous structure with the pore diameter of about 10.2 nm. After heat treatment at 1400 °C the samples lose their porous structure and certain crystallites with average size of 5–6 µm can be observed. These crystallites can be visualized by fluorescence imaging. According to differential scanning calorimetry data accomplished by X‐ray analysis, the first step of crystallization occurs at around 967 °C, producing γ‐Al2O3. The second one takes place at around 1194 °C, which corresponds to the formation of α‐Al2O3. For the as‐anodized and samples treated at temperatures below 1200 °C the band at 420 nm can be attributed to the emission of OH‐related and other impurities centers. The fluorescence at 460 nm relates to emission of oxygen defect centers, such as F and F2 centers, and sharp bands at 678 and 693 nm indicate the formation of highly crystalline alumina. For α‐Al2O3, its fluorescence is caused by both surface defects and oxygen defect centers. The fluorescence spectroscopy can be applied as a cheap, fast, nondestructive method for the identification of amorphous alumina crystallization.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural and Fluorescence Studies of Polycrystalline α‐Al₂O₃ Obtained From Sulfuric Acid Anodic Alumina

Chernyakova

Karpicz

Rutkauskas

et al. 2018

Physica Status Solidi (a)

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“…Porous MgAl 2 O 4 spinel ceramics have attracted a growing interest due to their high melting point (2135 °C), good thermal shock resistance, excellent chemical inertness, and their low thermal conductivity and thermal expansion coefficient; they are widely used for various applications such as gas filters, thermal insulation materials, waste water filters, catalyst supports and separation membranes [1,2,3,4,5]. In order to meet specific requirements of porosity and pore sizes for different applications, various available methods have been developed in recent years, including gel casting, the addition of pore-forming agent, sacrificial templating, in-situ synthesis, and combustion synthesis [6,7,8,9,10].…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Characterization of Porous MgAl2O4 Ceramics via a Novel Aqueous Gel-Casting Process

Yuan

Liu

et al. 2017

Materials

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A novel and aqueous gel-casting process has been successfully developed to fabricate porous MgAl2O4 ceramics by using hydratable alumina and MgO powders as raw materials and deionized water as hydration agent. The effects of different amounts of deionized water on the hydration properties, apparent porosity, bulk density, microstructure, pore size distribution and compressive strength of the samples were investigated. The results indicated that the porosity and the microstructure of porous MgAl2O4 ceramics were governed by the amounts of deionized water added. The porous structure was formed by the liberation of physisorbed water and the decomposition of hydration products such as bayerite, brucite and boehmite. After determining the addition amounts of deionized water, the fabricated porous MgAl2O4 ceramics had a high apparent porosity (52.5–65.8%), a small average pore size structure (around 1–3 μm) and a relatively high compressive strength (12–28 MPa). The novel aqueous gel-casting process with easy access is expected to be a promising candidate for the preparation of Al2O3-based porous ceramics.

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“…There are many chemical reactions to synthesize pseudoboehmite, most of them include heat treatment and result in a powder [2,3]. While in other works high purity Al plates are necessary to growth pseudoboehmite on its surface; in this work, easily available aluminum alloy 6063 (Al-6063) plates were employed to synthesize pseudoboehmite/aluminum, resulting in a low-cost functionalized substrate for the analysis of nanoparticles by Scanning Electron Microscopy (SEM) [3].…”

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confidence: 99%

Low-cost Functionalized Pseudoboehmite/Aluminum Substrates for the Analysis of Nanoparticles by SEM

et al. 2017

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Aluminum is the most common metal element found in earth, one of its crystalline forms is the pseudoboehmite, used mainly as catalyst [1]. There are many chemical reactions to synthesize pseudoboehmite, most of them include heat treatment and result in a powder [2,3]. While in other works high purity Al plates are necessary to growth pseudoboehmite on its surface; in this work, easily available aluminum alloy 6063 (Al-6063) plates were employed to synthesize pseudoboehmite/aluminum, resulting in a low-cost functionalized substrate for the analysis of nanoparticles by Scanning Electron Microscopy (SEM) [3].Al-6063 is a very common and cheap alloy used widely in machine shops. The plates were worked in a grinding machine using 25µm alumina oxide, followed by Brasso metal polisher on a clean cotton fabric. The cotton fabric was replaced until a mirror like ending was obtained. To eliminate the residues of the metal polisher, they were rinsed with acetone and alcohol under sonication for 15min.An electropolish solution was prepared by mixing perchloric acid (Aldrich, 70%) and ethanol (Aldrich, 99.8%) (4:1), this solution was kept at 4C by an ice bath. The Al-6063 plates were immersed in the perchloric acid solution at 25V and 2.5A for 40s. The plates were then rinsed with Milli-Q water, followed by immersion in sodium hydroxide (1.5M, Aldrich) and nitric acid (1.4M, Aldrich) solutions, rinsed again with water, immersed into boiling water for two minutes and finally blow dried with cleaned air.The formation of a pseudoboehmite layer over the Al-6063 was confirmed by X-ray diffraction according to ICDD 00-021-1307 card (XRD, D2 Phaser Bruker, with a Bragg-Brentano geometry and Cu-kα radiation (λ=1.5418Å) and using the following scan: step size = 0.02°, t = 5s, 10° ≤ 2θ ≤ 80°) (Fig. 1A). The hydroxyl groups available in the surface allow the functionalization by immersing the plates in a 20mM (3-Mercaptopropyl)trimethoxysilane (MPTS, Aldrich) methanolic solution (Aldrich) for 15h. In order to eliminate the unbounded MPTS molecules, the plates were rinsed with deionized water and dried in an oven at 120C for 10 min.These functionalized Al-6063 plates allowed a uniform deposit of gold nanoparticles by drop casting (Fig. 1B). As an example, concave gold nanocubes (CGNC) were synthesized in a seed mediated growth method [4,5] and concentrated 40x by centrifugation (1100g). Next, a 3µL nanocubes solution drop was placed on the functionalized Al-6063 plates and left to dry at room temperature. To ensure that the surfactant of the nanoparticles was removed, samples were plasma cleaned (Femto low-pressure plasma system, Diener) for 10min under nitrogen flow. SEM images (JEOL, JSM-7800F, operating in gentle beam mode at 15kV and 3mm working distance) show the mesoporous surface due to the pseudoboehmite and the attached CGNC (Fig. 1C). The functionalized surface of the Al plates allowed the homogeneous deposit of the CGNC (Fig. 1D).Here we have demonstrated that by using a low-cost Al-6063 plates it was possible to synthesize ...

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Fabrication and Characterization of Single Phase α-Alumina Membranes with Tunable Pore Diameters

Cited by 62 publications

References 36 publications

Structural and Fluorescence Studies of Polycrystalline α‐Al₂O₃ Obtained From Sulfuric Acid Anodic Alumina

Structural and Fluorescence Studies of Polycrystalline α‐Al₂O₃ Obtained From Sulfuric Acid Anodic Alumina

Fabrication and Characterization of Porous MgAl2O4 Ceramics via a Novel Aqueous Gel-Casting Process

Low-cost Functionalized Pseudoboehmite/Aluminum Substrates for the Analysis of Nanoparticles by SEM

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Fabrication and Characterization of Single Phase α-Alumina Membranes with Tunable Pore Diameters

Cited by 62 publications

References 36 publications

Structural and Fluorescence Studies of Polycrystalline α‐Al2O3 Obtained From Sulfuric Acid Anodic Alumina

Structural and Fluorescence Studies of Polycrystalline α‐Al2O3 Obtained From Sulfuric Acid Anodic Alumina

Fabrication and Characterization of Porous MgAl2O4 Ceramics via a Novel Aqueous Gel-Casting Process

Low-cost Functionalized Pseudoboehmite/Aluminum Substrates for the Analysis of Nanoparticles by SEM

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Structural and Fluorescence Studies of Polycrystalline α‐Al₂O₃ Obtained From Sulfuric Acid Anodic Alumina

Structural and Fluorescence Studies of Polycrystalline α‐Al₂O₃ Obtained From Sulfuric Acid Anodic Alumina