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Special Issue "Porous Materials 2011"

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Porous Materials".

Deadline for manuscript submissions: closed (28 February 2011)

Special Issue Editors

Guest Editor
Prof. Dr. Stephen Gray

Institute for Sustainability and Innovation, Victoria University, Werribee Campus, Hoppers Lane, Werribee PO Box 14428, Melbourne, Victoria, 8001, Australia
Website | E-Mail
Phone: +61 3 9919 8097
Guest Editor
Prof. Dr. Helmut Föll

Institute for Materials Science, Christian-Albrechts-University of Kiel, Kaiserstr. 2, D-24143 Kiel, Germany
Website | E-Mail
Phone: +49(0)431/880-6175

Special Issue Information

Dear Colleagues

Porous materials are finding applications in many fields, such as membranes for water purification and gas separation, or the slow release of drugs. For porous (single crystal) semi-conductors, uses are emerging in areas like photonics, sensors, Li ion batteries, MEMS, and bio technology. These applications all require materials with consistent and reliable structures, and pore sizes may range from 0.4 nm in crystalline zeolite structures to 1000 nm in polymeric membrane systems.  In semiconductors pore sizes range form a few nm to well above µm and morpholgies from straight cylinders to fractal.  Similarly there is a wide range of fabrication techniques, such as lithography, phase inversion, templating and vapor deposition, and characterizing such materials has required advances in imaging and spectroscopy.

Given the high level of research interest in, and the importance of porous materials, a special edition of "Materials" has been devoted to this topic. Articles that focus on the characterization, fabrication, performance and modeling of porous materials are welcomed, and organic, inorganic and composite materials systems will be considered.

We look forward to receiving your manuscripts.

Prof. Dr. Stephen Gray
Prof. Dr. Helmut Foell
Guest Editor

Keywords

  • porosity
  • membranes
  • lithography
  • pore
  • templating
  • vapor deposition
  • characterization
  • fabrication

Published Papers (9 papers)

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Research

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Open AccessArticle A Mechanochemical Approach to Porous Silicon Nanoparticles Fabrication
Materials 2011, 4(6), 1023-1033; doi:10.3390/ma4061023
Received: 11 April 2011 / Revised: 26 May 2011 / Accepted: 28 May 2011 / Published: 7 June 2011
Cited by 21 | PDF Full-text (487 KB) | HTML Full-text | XML Full-text
Abstract
Porous silicon samples have been reduced in nanometric particles by a well known industrial mechanical process, the ball grinding in a planetary mill; the process has been extended to crystalline silicon for comparison purposes. The silicon nanoparticles have been studied by X-ray diffraction,
[...] Read more.
Porous silicon samples have been reduced in nanometric particles by a well known industrial mechanical process, the ball grinding in a planetary mill; the process has been extended to crystalline silicon for comparison purposes. The silicon nanoparticles have been studied by X-ray diffraction, infrared spectroscopy, gas porosimetry and transmission electron microscopy. We have estimated crystallites size from about 50 nm for silicon to 12 nm for porous silicon. The specific surface area of the powders analyzed ranges between 100 m2/g to 29 m2/g depending on the milling time, ranging from 1 to 20 h. Electron microscopy confirms the nanometric size of the particles and reveals a porous structure in the powders obtained by porous silicon samples which has been preserved by the fabrication conditions. Chemical functionalization during the milling process by a siloxane compound has also been demonstrated. Full article
(This article belongs to the Special Issue Porous Materials 2011)
Open AccessArticle Study of Ni Metallization in Macroporous Si Using Wet Chemistry for Radio Frequency Cross-Talk Isolation in Mixed Signal Integrated Circuits
Materials 2011, 4(6), 952-962; doi:10.3390/ma4060952
Received: 9 May 2011 / Accepted: 23 May 2011 / Published: 25 May 2011
Cited by 1 | PDF Full-text (703 KB) | HTML Full-text | XML Full-text
Abstract
A highly conductive moat or Faraday cage of through-the-wafer thickness in Si substrate was proposed to be effective in shielding electromagnetic interference thereby reducing radio frequency (RF) cross-talk in high performance mixed signal integrated circuits. Such a structure was realized by metallization of
[...] Read more.
A highly conductive moat or Faraday cage of through-the-wafer thickness in Si substrate was proposed to be effective in shielding electromagnetic interference thereby reducing radio frequency (RF) cross-talk in high performance mixed signal integrated circuits. Such a structure was realized by metallization of selected ultra-high-aspect-ratio macroporous regions that were electrochemically etched in p Si substrates. The metallization process was conducted by means of wet chemistry in an alkaline aqueous solution containing Ni2+ without reducing agent. It is found that at elevated temperature during immersion, Ni2+ was rapidly reduced and deposited into macroporous Si and a conformal metallization of the macropore sidewalls was obtained in a way that the entire porous Si framework was converted to Ni. A conductive moat was as a result incorporated into p Si substrate. The experimentally measured reduction of crosstalk in this structure is 5~18 dB at frequencies up to 35 GHz. Full article
(This article belongs to the Special Issue Porous Materials 2011)
Open AccessArticle Layer Transfer from Chemically Etched 150 mm Porous Si Substrates
Materials 2011, 4(5), 941-951; doi:10.3390/ma4050941
Received: 20 April 2011 / Accepted: 19 May 2011 / Published: 23 May 2011
PDF Full-text (331 KB) | HTML Full-text | XML Full-text
Abstract
We demonstrate for the first time the successful layer transfer of an epitaxially grown monocrystalline Si film from a purely chemically etched porous Si substrate of 150 mm diameter to a glass carrier. The surface conditioning for all Si layer transfer processes based on
[...] Read more.
We demonstrate for the first time the successful layer transfer of an epitaxially grown monocrystalline Si film from a purely chemically etched porous Si substrate of 150 mm diameter to a glass carrier. The surface conditioning for all Si layer transfer processes based on porous Si has been, up to now without exception, carried out by electrochemical etching. In contrast, our chemical stain etching process uses an aqueous HF-rich HF/HNO3 solution. The porosity increases with increasing doping concentration of the Si substrate wafer and with increasing porous layer thickness. In contrast to the electrochemically etched double layers, the porosity profile of the stain etched substrates is highest at the original wafer surface and lowest at the interface between the porous layer and the Si bulk. The epitaxy process is adapted to the high porosity at the surface with regard to the reorganization of the porous layer. Full article
(This article belongs to the Special Issue Porous Materials 2011)
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Open AccessArticle Preparation, Characterization and Performance of Templated Silica Membranes in Non-Osmotic Desalination
Materials 2011, 4(5), 845-856; doi:10.3390/ma4040845
Received: 8 April 2011 / Revised: 18 April 2011 / Accepted: 28 April 2011 / Published: 2 May 2011
Cited by 10 | PDF Full-text (1043 KB) | HTML Full-text | XML Full-text
Abstract
In this work we investigate the potential of a polyethylene glycol-polypropylene glycol-polyethylene glycol, tri-block copolymer as a template for a hybrid carbon/silica membrane for use in the non-osmotic desalination of seawater. Silica samples were loaded with varying amounts of tri-block copolymer and calcined
[...] Read more.
In this work we investigate the potential of a polyethylene glycol-polypropylene glycol-polyethylene glycol, tri-block copolymer as a template for a hybrid carbon/silica membrane for use in the non-osmotic desalination of seawater. Silica samples were loaded with varying amounts of tri-block copolymer and calcined in a vacuum to carbonize the template and trap it within the silica matrix. The resultant xerogels were analyzed with FTIR, Thermogravimetric analysis (TGA) and N2 sorption techniques, wherein it was determined that template loadings of 10 and 20% produced silica networks with enhanced pore volumes and appropriately sized pores for desalination. Membranes were created via two different routes and tested with feed concentrations of 3, 10 and 35 ppk of NaCl at room temperature employing a transmembrane pressure drop of 85% (in most cases >95%) and fluxes higher than 1.6 kg m−2 h−1. Furthermore, the carbonized templated membranes displayed equal or improved performance compared to similarly prepared non-templated silica membranes, with the best results of a flux of 3.7 kg m−2 h−1 with 98.5% salt rejection capacity, exceeding previous literature reports. In addition, the templated silica membranes exhibited superior hydrostability demonstrating their potential for long-term operation. Full article
(This article belongs to the Special Issue Porous Materials 2011)
Open AccessArticle Gold Nanostructures for Surface-Enhanced Raman Spectroscopy, Prepared by Electrodeposition in Porous Silicon
Materials 2011, 4(4), 791-800; doi:10.3390/ma4040791
Received: 18 March 2011 / Revised: 4 April 2011 / Accepted: 11 April 2011 / Published: 14 April 2011
Cited by 14 | PDF Full-text (414 KB) | HTML Full-text | XML Full-text
Abstract
Electrodeposition of gold into porous silicon was investigated. In the present study, porous silicon with ~100 nm in pore diameter, so-called medium-sized pores, was used as template electrode for gold electrodeposition. The growth behavior of gold deposits was studied by scanning electron microscope
[...] Read more.
Electrodeposition of gold into porous silicon was investigated. In the present study, porous silicon with ~100 nm in pore diameter, so-called medium-sized pores, was used as template electrode for gold electrodeposition. The growth behavior of gold deposits was studied by scanning electron microscope observation of the gold deposited porous silicon. Gold nanorod arrays with different rod lengths were prepared, and their surface-enhanced Raman scattering properties were investigated. We found that the absorption peak due to the surface plasmon resonance can be tuned by changing the length of the nanorods. The optimum length of the gold nanorods was ~600 nm for surface-enhanced Raman spectroscopy using a He-Ne laser. The reason why the optimum length of the gold nanorods was 600 nm was discussed by considering the relationship between the absorption peak of surface plasmon resonance and the wavelength of the incident laser for Raman scattering. Full article
(This article belongs to the Special Issue Porous Materials 2011)
Open AccessArticle A Preliminary Study on the Effect of Macro Cavities Formation on Properties of Carbon Nanotube Bucky-Paper Composites
Materials 2011, 4(3), 553-561; doi:10.3390/ma4030553
Received: 19 January 2011 / Revised: 23 February 2011 / Accepted: 8 March 2011 / Published: 10 March 2011
Cited by 3 | PDF Full-text (727 KB) | HTML Full-text | XML Full-text
Abstract
In this study, we focus on processing and characterizing composite material structures made of carbon nanotubes (CNTs) and reproducibly engineering macro-pores inside their structure. Highly porous bucky-papers were fabricated from pure carbon nanotubes by dispersing and stabilizing large 1 μm polystyrene beads within
[...] Read more.
In this study, we focus on processing and characterizing composite material structures made of carbon nanotubes (CNTs) and reproducibly engineering macro-pores inside their structure. Highly porous bucky-papers were fabricated from pure carbon nanotubes by dispersing and stabilizing large 1 μm polystyrene beads within a carbon nanotube suspension. The polystyrene beads, homogeneously dispersed across the thickness of the bucky-papers, were then either dissolved or carbonized to generate macro cavities of different shape and properties. The impact of adding these macro cavities on the porosity, specific surface area and Young’s modulus was investigated and some benefits of the macro cavities will be demonstrated. Full article
(This article belongs to the Special Issue Porous Materials 2011)

Review

Jump to: Research

Open AccessReview Magnetic Nanoparticles Embedded in a Silicon Matrix
Materials 2011, 4(5), 908-928; doi:10.3390/ma4050908
Received: 13 April 2011 / Accepted: 12 May 2011 / Published: 17 May 2011
Cited by 19 | PDF Full-text (1113 KB) | HTML Full-text | XML Full-text
Abstract
This paper represents a short overview of nanocomposites consisting of magnetic nanoparticles incorporated into the pores of a porous silicon matrix by two different methods. On the one hand, nickel is electrochemically deposited whereas the nanoparticles are precipitated on the pore walls. The
[...] Read more.
This paper represents a short overview of nanocomposites consisting of magnetic nanoparticles incorporated into the pores of a porous silicon matrix by two different methods. On the one hand, nickel is electrochemically deposited whereas the nanoparticles are precipitated on the pore walls. The size of these particles is between 2 and 6 nm. These particles cover the pore walls and form a tube-like arrangement. On the other hand, rather well monodispersed iron oxide nanoparticles, of 5 and 8 nm respectively, are infiltrated into the pores. From their size the particles would be superparamagnetic if isolated but due to magnetic interactions between them, ordering of magnetic moments occurs below a blocking temperature and thus the composite system displays a ferromagnetic behavior. This transition temperature of the nanocomposite can be varied by changing the filling factor of the particles within the pores. Thus samples with magnetic properties which are variable in a broad range can be achieved, which renders this composite system interesting not only for basic research but also for applications, especially because of the silicon base material which makes it possible for today’s process technology. Full article
(This article belongs to the Special Issue Porous Materials 2011)
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Open AccessReview Electrochemically Formed Porous Silica
Materials 2011, 4(5), 825-844; doi:10.3390/ma4050825
Received: 7 March 2011 / Revised: 6 April 2011 / Accepted: 20 April 2011 / Published: 26 April 2011
Cited by 4 | PDF Full-text (1209 KB) | HTML Full-text | XML Full-text
Abstract
Controlled electrochemical formation of porous silica can be realized in dilute aqueous, neutral-pH, fluoride medium. Formation of a porous film is initiated by sweeping the potential applied to silicon to values higher than 20 V. Film formation, reaching a steady state, may be
[...] Read more.
Controlled electrochemical formation of porous silica can be realized in dilute aqueous, neutral-pH, fluoride medium. Formation of a porous film is initiated by sweeping the potential applied to silicon to values higher than 20 V. Film formation, reaching a steady state, may be pursued in a wide range of potentials, including lower potentials. The origin of a threshold potential for porous film initiation has been explained quantitatively. All of the films appear mesoporous. Films grown at high potentials exhibit a variety of macrostructures superimposed on the mesoporosity. These macrostructures result from selective dissolution of silica induced by local pH lowering due to oxygen evolution. Films grown at potentials lower than 15 V appear uniform on the micrometer scale. However, all of the films also exhibit a stratified structure on the scale of a few tens of nanometres. This periodic structure can be traced back to the oscillatory behavior observed during the electrochemical dissolution of silicon in fluoride medium. It suggests that periodic breaking of the growing film may be responsible for this morphology. Full article
(This article belongs to the Special Issue Porous Materials 2011)
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Open AccessReview Progress of Application Researches of Porous Fiber Metals
Materials 2011, 4(4), 816-824; doi:10.3390/ma4040816
Received: 1 March 2011 / Revised: 1 April 2011 / Accepted: 12 April 2011 / Published: 19 April 2011
Cited by 17 | PDF Full-text (351 KB) | HTML Full-text | XML Full-text
Abstract
Metal fiber porous materials with intrinsic properties of metal and functional properties of porous materials have received a great deal of attention in the fundamental research and industry applications. With developments of the preparation technologies and industrial requirements, porous fiber metals with excellent
[...] Read more.
Metal fiber porous materials with intrinsic properties of metal and functional properties of porous materials have received a great deal of attention in the fundamental research and industry applications. With developments of the preparation technologies and industrial requirements, porous fiber metals with excellent properties are developed and applied in many industry areas, e.g., sound absorption, heat transfer, energy absorption and lightweight structures. The applied research progress of the metal fiber porous materials in such application areas based on the recent work in our group was reviewed in this paper. Full article
(This article belongs to the Special Issue Porous Materials 2011)
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