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H. Masuda - One of the best experts on this subject based on the ideXlab platform.
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Fabrication of Anodic Porous Alumina
Encyclopedia of Interfacial Chemistry, 2018Co-Authors: H. Masuda, T. Yanagishita, T. KondoAbstract:Anodic Porous Alumina plays an important role in various application fields. In addition to its wide variety of uses in the surface finishing of Al, anodic Porous Alumina has recently become increasingly important as a starting material for functional nanodevices owing to its unique geometrical structures with nanometer dimensions. In this article, the basics of the formation of Porous structures of anodic Porous Alumina, the preparation of self-ordered structures, and the modification process for the Porous structures are described. In addition, examples of typical functional applications of ordered anodic Porous Alumina are introduced.
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Anodic Porous Alumina with elliptical apertures
Electrochemistry Communications, 2018Co-Authors: T. Kondo, T. Yanagishita, Hayato Miyazaki, H. MasudaAbstract:Abstract The fabrication of anodic Porous Alumina with anisotropic structures, i.e., an anisotropic hole arrangement and anisotropic elliptical hole shape, was demonstrated. Through the optimization of the pattern used for the pretexturing and the anodizing conditions, anodic Porous Alumina with holes having an elliptical cross section could be satisfactory obtained. The diameter of the elliptical nanoholes could be controlled by an additional wet-etching process. The obtained anodic Porous Alumina with elliptical nanoholes is expected to be applied to various functional optical devices, such as localized plasmonic devices, requiring control of the anisotropy of the incident light.
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Selective through-holing of anodic Porous Alumina membranes with large area
RSC Advances, 2018Co-Authors: T. Yanagishita, T. Kondo, Yuki Okubo, H. MasudaAbstract:Anodic Porous Alumina membranes with site controlled through-holes were prepared by the formation of a masking layer on the surface of anodic Porous Alumina and subsequent selective second anodization in concentrated sulfuric acid to form a readily soluble layer. After the anodization, the residual Al substrate was removed, and the highly soluble Alumina layer formed in concentrated sulfuric acid was dissolved selectively by wet etching. An advantageous point of this process is the controllability of the pattern of through-holes, and the preparation of large samples with selective through-holes is possible. The pattern of through-holes was controlled by changing the mask pattern formed on the surface of anodic Porous Alumina. The Alumina membranes obtained by this process are expected to be used for various applications that require Porous Alumina membranes with site controlled through-holes.
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Anodic Porous Alumina with square holes through lattice conversion of naturally occurring ordered structures
Journal of Vacuum Science & Technology B Nanotechnology and Microelectronics: Materials Processing Measurement and Phenomena, 2017Co-Authors: T. Kondo, T. Yanagishita, Hayato Miyazaki, H. MasudaAbstract:Anodic Porous Alumina with square cells and square holes was fabricated through the conversion of the triangular lattice of naturally occurring anodic Porous Alumina to a square lattice. A pattern of a triangular lattice obtained from an ordered anodic Porous Alumina lattice was converted to a pattern of a square lattice by modifying the ratio of the lattice through the anisotropic deformation of a polymer sheet with a triangular pattern transferred from Porous Alumina. The obtained pattern of a square lattice on the polymer sheet was transferred to a metal mold using a template process, and the pretexturing of Al using the obtained mold generated anodic Porous Alumina with square cells and square holes. The process allows the fabrication of anodic Porous Alumina with square cells and square holes without the use of a lithographic technique. The obtained Porous Alumina was applied to the fabrication of a surface-enhanced Raman scattering (SERS) substrate with a square Au nanodot array.
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Surface-enhanced Raman scattering on gold nanowire array formed by mechanical deformation using anodic Porous Alumina molds
Applied Physics Express, 2015Co-Authors: T. Kondo, T. Yanagishita, Naoya Kitagishi, H. MasudaAbstract:The fabrication of Au nanowire arrays by mechanical deformation using anodic Porous Alumina was studied. Porous Alumina was pressed onto a Au surface so that Au entered the nanoholes of the Porous Alumina. The Au nanowire arrays were obtained by dissolving the Porous Alumina. For the efficient fabrication of nanowires, a nanoimprinting process was applied, which enabled the nanowires to be reproducibly obtained. The Porous Alumina used as the nanoimprinting mold could be reused. The nanowire arrays could be used as substrates for surface-enhanced Raman scattering measurements owing to the enhancement of the light intensity based on localized surface plasmon resonance.
Yuji Iwamoto - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of castables incorporating highly Porous Alumina aggregates fabricated by high-temperature evaporation method
Ceramics International, 2019Co-Authors: Muto Daimu, Sawao Honda, Shinobu Hashimoto, Yusuke Daiko, Yuji IwamotoAbstract:Abstract Porous Alumina aggregates were prepared for use in adiabatic refractories via a high-temperature evaporation method. The mechanical and thermal characteristics of the Porous Alumina bodies and of castable refractories made using the Alumina as an aggregate were investigated. Specimens were produced by adding boron hydroxide, sodium carbonate and water glass to aluminum hydroxide powder compacts in varying proportions, followed by heating at 1700 °C for 1 h in a reducing atmosphere to form Porous Alumina bodies. During heating, these additives formed a Na2O-B2O3-SiO2 liquid glass phase that promoted the growth of Alumina platelets. These platelets subsequently formed a “house of cards” structure. The porosity and compressive strength of the resulting Porous Alumina were 69.8% and 1.8 MPa, while the thermal conductivity of this material was 0.23 W m−1·K−1 at 1000 °C. A castable incorporating the Porous Alumina aggregate exhibited improved mechanical strength, higher heat resistance and greater FeO corrosion resistance than a sample made using a CA6 (CaO∙6Al2O3) aggregate. The Porous Alumina castable exhibited similar thermal conductivity to that of the CA6 castable at high temperatures, with a value of 0.85 W m−1·K−1 at 1400 °C. Hence, the Porous Alumina aggregate fabricated in this study can be expected to have practical applications.
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Improvement on characteristics of Porous Alumina from platelets using a TEOS treatment
Ceramics International, 2013Co-Authors: Sawao Honda, Shinobu Hashimoto, Y. Ito, H. Hirano, Ryuta Hanai, Yuji IwamotoAbstract:Abstract A Porous Alumina body was synthesized from anisotropic Alumina particles, namely platelets. When green compacts, which had been uniaxially pressed at 1 MPa, were heated at 1200 and 1500 °C for 1 h, the average porosity of the resulting Alumina bodies was 75.5 and 71.0%, respectively. The thermal conductivity of the Porous Alumina fabricated at 1400 °C for 1 h with 72.3% in porosity was 0.8 W m −1 K −1 . In an attempt to increase the compressive strength of the Porous Alumina bodies, TEOS (tetraethyl orthosilicate) solution treatment was carried out, followed by reheating to 1400 °C for 1 h. The compressive strength of the Porous Alumina body increased from 3.8 MPa (without TEOS solution treatment) to 10.2 MPa (with three rounds of TEOS treatment), with the porosity decreasing to 65.5% and the thermal conductivity increasing to1.2 W m −1 K −1 .
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Synthesis and mechanical properties of Porous Alumina from anisotropic Alumina particles
Journal of the European Ceramic Society, 2010Co-Authors: Shinobu Hashimoto, Sawao Honda, S. Horita, Y. Ito, H. Hirano, Yuji IwamotoAbstract:A Porous Alumina body was synthesized from anisotropic Alumina particles (platelets). The uniaxial pressure in fabricating the green compact body had an influence on the relative density of the Alumina body after heating. When green compacts, which had been uniaxially pressed at 1 and 3 MPa, were heated at 1400 °C for 1 h, the relative densities of the resulting Alumina bodies were 25.0% and 35.5%, respectively. The compressive strength of compacts that were uniaxially pressed at 1 and 3 MPa were 0.8 and 4.3 MPa, respectively. In an attempt to increase the compressive strength of these Porous Alumina bodies, aluminum nitrate and magnesium nitrate solution treatments were performed, followed by reheating to 1400 °C for 1 h. When a 0.5 mol/l aluminum nitrate solution was used, the compressive strength of the Porous Alumina body uniaxially pressed at 1 MPa changed from 0.8 MPa (without solution treatment) to 1.5 MPa. Furthermore, when 0.1 mol/l magnesium nitrate solution was used, the compressive strength of the Porous Alumina increased to 1.7 MPa. Thus, solution treatment of the Porous Alumina body had a strong positive effect on its mechanical strength.
Chude Feng - One of the best experts on this subject based on the ideXlab platform.
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Formation of Porous Alumina with oriented pores
Journal of the European Ceramic Society, 2002Co-Authors: Xiang-jin Ding, J P Zhang, Ruoding Wang, Chude FengAbstract:Abstract Adopting the theories describing the bubble forming in the metal–hydrogen solidification process, Porous Alumina with oriented pores was prepared by combining a foaming method with sol-gel technology. The bubble forming process in the sol-gel is different from that in the metal–hydrogen system. Samples were calcined at temperature from 800 to 1200C. The volume-shrinkage and compressive-strength increased with increasing calcination temperature. The Porous Alumina exhibited a bimodal pore structure when prepared below 1200°C.
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A novel preparation of Porous Alumina with parallel channels
Materials Letters, 2001Co-Authors: Xiang-jin Ding, J P Zhang, Ruoding Wang, Chude FengAbstract:Abstract A Porous Alumina with parallel channels has been prepared by combining a foaming method and sol–get technology. Samples were calcined at 800°C, 1000°C and 1200°C, respectively. The volume shrinkage and compressive strength increased with calcination temperature. The Porous Alumina exhibited a bimodal pore structure when calcined below 1200°C. The formation mechanism for Porous Alumina with parallel channels is discussed.
T. Yanagishita - One of the best experts on this subject based on the ideXlab platform.
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Fabrication of Anodic Porous Alumina
Encyclopedia of Interfacial Chemistry, 2018Co-Authors: H. Masuda, T. Yanagishita, T. KondoAbstract:Anodic Porous Alumina plays an important role in various application fields. In addition to its wide variety of uses in the surface finishing of Al, anodic Porous Alumina has recently become increasingly important as a starting material for functional nanodevices owing to its unique geometrical structures with nanometer dimensions. In this article, the basics of the formation of Porous structures of anodic Porous Alumina, the preparation of self-ordered structures, and the modification process for the Porous structures are described. In addition, examples of typical functional applications of ordered anodic Porous Alumina are introduced.
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Anodic Porous Alumina with elliptical apertures
Electrochemistry Communications, 2018Co-Authors: T. Kondo, T. Yanagishita, Hayato Miyazaki, H. MasudaAbstract:Abstract The fabrication of anodic Porous Alumina with anisotropic structures, i.e., an anisotropic hole arrangement and anisotropic elliptical hole shape, was demonstrated. Through the optimization of the pattern used for the pretexturing and the anodizing conditions, anodic Porous Alumina with holes having an elliptical cross section could be satisfactory obtained. The diameter of the elliptical nanoholes could be controlled by an additional wet-etching process. The obtained anodic Porous Alumina with elliptical nanoholes is expected to be applied to various functional optical devices, such as localized plasmonic devices, requiring control of the anisotropy of the incident light.
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Selective through-holing of anodic Porous Alumina membranes with large area
RSC Advances, 2018Co-Authors: T. Yanagishita, T. Kondo, Yuki Okubo, H. MasudaAbstract:Anodic Porous Alumina membranes with site controlled through-holes were prepared by the formation of a masking layer on the surface of anodic Porous Alumina and subsequent selective second anodization in concentrated sulfuric acid to form a readily soluble layer. After the anodization, the residual Al substrate was removed, and the highly soluble Alumina layer formed in concentrated sulfuric acid was dissolved selectively by wet etching. An advantageous point of this process is the controllability of the pattern of through-holes, and the preparation of large samples with selective through-holes is possible. The pattern of through-holes was controlled by changing the mask pattern formed on the surface of anodic Porous Alumina. The Alumina membranes obtained by this process are expected to be used for various applications that require Porous Alumina membranes with site controlled through-holes.
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Anodic Porous Alumina with square holes through lattice conversion of naturally occurring ordered structures
Journal of Vacuum Science & Technology B Nanotechnology and Microelectronics: Materials Processing Measurement and Phenomena, 2017Co-Authors: T. Kondo, T. Yanagishita, Hayato Miyazaki, H. MasudaAbstract:Anodic Porous Alumina with square cells and square holes was fabricated through the conversion of the triangular lattice of naturally occurring anodic Porous Alumina to a square lattice. A pattern of a triangular lattice obtained from an ordered anodic Porous Alumina lattice was converted to a pattern of a square lattice by modifying the ratio of the lattice through the anisotropic deformation of a polymer sheet with a triangular pattern transferred from Porous Alumina. The obtained pattern of a square lattice on the polymer sheet was transferred to a metal mold using a template process, and the pretexturing of Al using the obtained mold generated anodic Porous Alumina with square cells and square holes. The process allows the fabrication of anodic Porous Alumina with square cells and square holes without the use of a lithographic technique. The obtained Porous Alumina was applied to the fabrication of a surface-enhanced Raman scattering (SERS) substrate with a square Au nanodot array.
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Surface-enhanced Raman scattering on gold nanowire array formed by mechanical deformation using anodic Porous Alumina molds
Applied Physics Express, 2015Co-Authors: T. Kondo, T. Yanagishita, Naoya Kitagishi, H. MasudaAbstract:The fabrication of Au nanowire arrays by mechanical deformation using anodic Porous Alumina was studied. Porous Alumina was pressed onto a Au surface so that Au entered the nanoholes of the Porous Alumina. The Au nanowire arrays were obtained by dissolving the Porous Alumina. For the efficient fabrication of nanowires, a nanoimprinting process was applied, which enabled the nanowires to be reproducibly obtained. The Porous Alumina used as the nanoimprinting mold could be reused. The nanowire arrays could be used as substrates for surface-enhanced Raman scattering measurements owing to the enhancement of the light intensity based on localized surface plasmon resonance.
R R Koropecki - One of the best experts on this subject based on the ideXlab platform.
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Optical performance of hybrid Porous silicon–Porous Alumina multilayers
Journal of Applied Physics, 2018Co-Authors: Luisa Guadalupe Cencha, Luisina Forzani, Raul Urteaga, C. Antonio Hernández, R R KoropeckiAbstract:In this work, we study the optical response of structures involving Porous silicon and Porous Alumina in a multi-layered hybrid structure. We performed a rational design of the optimal sequence necessary to produce a high transmission and selective filter, with potential applications in chemical and biosensors. The combination of these Porous materials can be used to exploit its distinguishing features, i.e., high transparency of Alumina and high refractive index of Porous silicon. We assembled hybrid microcavities with a central Porous Alumina layer between two Porous silicon Bragg reflectors. In this way, we constructed a Fabry-Perot resonator with high reflectivity and low absorption that improves the quality of the filter compared to a microcavity built only with Porous silicon or Porous Alumina. We explored a simpler design in which one of the Bragg reflectors is replaced by the aluminium that remains bound to the Alumina after its fabrication. We theoretically explored the potential of the proposal and its limitations when considering the roughness of the layers. We found that the quality of a microcavity made entirely with Porous silicon shows a limit in the visible range due to light absorption. This limitation is overcome in the hybrid scheme, with the roughness of the layers determining the ultimate quality. Q-factors of 220 are experimentally obtained for microcavities supported on aluminium, while Q-factors around 600 are reached for microcavities with double Bragg reflectors, centred at 560 nm. This represents a four-fold increase with respect to the optimal Porous silicon microcavity at this wavelength.In this work, we study the optical response of structures involving Porous silicon and Porous Alumina in a multi-layered hybrid structure. We performed a rational design of the optimal sequence necessary to produce a high transmission and selective filter, with potential applications in chemical and biosensors. The combination of these Porous materials can be used to exploit its distinguishing features, i.e., high transparency of Alumina and high refractive index of Porous silicon. We assembled hybrid microcavities with a central Porous Alumina layer between two Porous silicon Bragg reflectors. In this way, we constructed a Fabry-Perot resonator with high reflectivity and low absorption that improves the quality of the filter compared to a microcavity built only with Porous silicon or Porous Alumina. We explored a simpler design in which one of the Bragg reflectors is replaced by the aluminium that remains bound to the Alumina after its fabrication. We theoretically explored the potential of the proposal ...
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optical performance of hybrid Porous silicon Porous Alumina multilayers
Journal of Applied Physics, 2018Co-Authors: Luisa Guadalupe Cencha, Antonio C Hernandez, Luisina Forzani, Raul Urteaga, R R KoropeckiAbstract:In this work, we study the optical response of structures involving Porous silicon and Porous Alumina in a multi-layered hybrid structure. We performed a rational design of the optimal sequence necessary to produce a high transmission and selective filter, with potential applications in chemical and biosensors. The combination of these Porous materials can be used to exploit its distinguishing features, i.e., high transparency of Alumina and high refractive index of Porous silicon. We assembled hybrid microcavities with a central Porous Alumina layer between two Porous silicon Bragg reflectors. In this way, we constructed a Fabry-Perot resonator with high reflectivity and low absorption that improves the quality of the filter compared to a microcavity built only with Porous silicon or Porous Alumina. We explored a simpler design in which one of the Bragg reflectors is replaced by the aluminium that remains bound to the Alumina after its fabrication. We theoretically explored the potential of the proposal and its limitations when considering the roughness of the layers. We found that the quality of a microcavity made entirely with Porous silicon shows a limit in the visible range due to light absorption. This limitation is overcome in the hybrid scheme, with the roughness of the layers determining the ultimate quality. Q-factors of 220 are experimentally obtained for microcavities supported on aluminium, while Q-factors around 600 are reached for microcavities with double Bragg reflectors, centred at 560 nm. This represents a four-fold increase with respect to the optimal Porous silicon microcavity at this wavelength.In this work, we study the optical response of structures involving Porous silicon and Porous Alumina in a multi-layered hybrid structure. We performed a rational design of the optimal sequence necessary to produce a high transmission and selective filter, with potential applications in chemical and biosensors. The combination of these Porous materials can be used to exploit its distinguishing features, i.e., high transparency of Alumina and high refractive index of Porous silicon. We assembled hybrid microcavities with a central Porous Alumina layer between two Porous silicon Bragg reflectors. In this way, we constructed a Fabry-Perot resonator with high reflectivity and low absorption that improves the quality of the filter compared to a microcavity built only with Porous silicon or Porous Alumina. We explored a simpler design in which one of the Bragg reflectors is replaced by the aluminium that remains bound to the Alumina after its fabrication. We theoretically explored the potential of the proposal ...
