• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.7-7
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• 2011

Quantum beam technology has been expected to develop breakthroughs for nanotechnology during the third basic plan of science and technology (2006~2010). Recently, Green- or Life Innovations has taken over the national interests in the fourth basic science and technology plan (2011~2015). The NIMS (National Institute for Materials Science) has been conducting the corresponding mid-term research plans, as well as other national projects, such as nano-Green project (Global Research for Environment and Energy based on Nanomaterials science). In this lecture, the research trends in Japan and NIMS are firstly reviewed, and the typical achievements are highlighted over key nanotechnology fields. As one of the key nanotechnologies, the quantum beam research in NIMS focused on synchrotron radiation, neutron beams and ion/atom beams, having complementary attributes. The facilities used are SPring-8, nuclear reactor JRR-3, pulsed neutron source J-PARC and ion-laser-combined beams as well as excited atomic beams. Materials studied are typically fuel cell materials, superconducting/magnetic/multi-ferroic materials, quasicrystals, thermoelectric materials, precipitation-hardened steels, nanoparticle-dispersed materials. Here, we introduce a few topics of neutron scattering and ion beam nanofabrication. For neutron powder diffraction, the NIMS has developed multi-purpose pattern fitting software, post RIETAN2000. An ionic conductor, doped Pr2NiO4, which is a candidate for fuel-cell material, was analyzed by neutron powder diffraction with the software developed. The nuclear-density distribution derived revealed the two-dimensional network of the diffusion paths of oxygen ions at high temperatures. Using the high sensitivity of neutron beams for light elements, hydrogen states in a precipitation-strengthened steel were successfully evaluated. The small-angle neutron scattering (SANS) demonstrated the sensitive detection of hydrogen atoms trapped at the interfaces of nano-sized NbC. This result provides evidence for hydrogen embrittlement due to trapped hydrogen at precipitates. The ion beam technology can give novel functionality on a nano-scale and is targeting applications in plasmonics, ultra-fast optical communications, high-density recording and bio-patterning. The technologies developed are an ion-and-laser combined irradiation method for spatial control of nanoparticles, and a nano-masked ion irradiation method for patterning. Furthermore, we succeeded in implanting a wide-area nanopattern using nano-masks of anodic porous alumina. The patterning of ion implantation will be further applied for controlling protein adhesivity of biopolymers. It has thus been demonstrated that the quantum beam-based nanotechnology will lead the innovations both for nano-characterization and nano-fabrication.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1693-1697
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• 2013

This study develops a novel method to remove the free cations created during the synthesis of ionic liquid. The cations are removed from the ionic liquid by size-selective adsorption onto chemically surface-modified Zeolite. The porous crystal nano-structure of Zeolite has several electron-rich Al sites to attract cations. While large cations of an ionic liquid cannot access the Zeolite nano-structure, small cations like $Na^+$ have ready access and are adsorbed. This study confirms that: $Na^+$ can be removed from ionic liquid effectively using Zeolite; and, in contrast to the conventional and extensively applied ion exchange resin method or solvent extraction methods, this can be done without changing the nature of the ionic liquid.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1090-1094
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• 2004

Studies on porous oxide electrode, dye and electrolyte for dye-sensitized solar cells have been intensively carried out until now. However, counter electrode have not been much studied so far. Accordingly, it is needed to investigate new counter electrode materials with superior catalyst property and to substitute for Pt electrode. In this case, carbon nano-tubes (CNTs) are one of alternatives for counter electrodes as following merits: low resistivity, excellent electron emission property, large surface area and low cost due to development of mass production technique. Such advantages gave us to select multiwalled CNTs (MWCNT) as counter electrode for dye-sensitized solar cell. Also, cyclic voltammetry and impedance spectroscopy were used to investigate electrochemical properties of both CNT electrode and Pt electrode. It was found that sheet resistance of CNT electrode was similar to that of Pt electrode, also, electrochemical properties of CNT electrode was superior to that of Pt electrode on the basis on the measurement of CV and impedance spectrum. It was found that CNT is likely to be a very promising electrode material for dye solar cells.

• Korean Journal of Materials Research
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• v.17 no.2
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• pp.81-85
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• 2007

Embedded capacitor technology can improve electrical perfomance and reduce assembly cost compared with traditional discrete capacitor technology. To improve the capacitance density of the $Al_2O_3$ based embedded capacitor on Cu cladded fiber reinforced plastics (FR-4), the specific surface area of the $Al_2O_3$ thin films was enlarged and their surface morphologies were controlled by anodization process parameters. From I-V characteristics, it was found that breakdown voltage and leakage current were 23 V and $1{\times}10^{-6}A/cm^2$ at 3.3 V, respectively. We have also measured C-V characteristics of $Pt/Al_2O_3/Al/Ti$ structure on CU/FR4. The capacitance density was $300nF/cm^2$ and the dielectric loss was 0.04. This nano-porous $Al_2O_3$ is a good material candidate for the embedded capacitor application for electronic products.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.327-331
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• 2009

Nano-porous $TiO_2$ powder was fabricated using Acetylene black, applied photo voltaic device based on the Dye-sensitized Solar Cells (DSCs) was investigated experimentally. $TiO_2$-powder was fabricated using Ti-isopropoxide and 2-propanol by sol-gel combustion method. For cases of variable Acetylene black, characteristic of porosity, size of particle and crystallite of obtained $TiO_2$ nano-powder was investigated. The photovoltaic efficiency of the prepared DSCs was measured using $TiO_2$ film which prepared on each different heat treatment temperature($400^{\circ}C{\sim}700^{\circ}C$) with paste of $TiO_2$ powder. The porosity and size of particle of $TiO_2$ powder made with Acetylene black 0.4g was influenced significantly effect to DSCs characteristic. Heat treatment at $500^{\circ}C$ makes the better photovoltaic efficiency which 5.02%($J_{sc}=11.79mA/cm^2$, $V_{oc}=0.73V$, ff=0.58). The sol-gel combustion method was useful to DSCs fabrication.

• Korean Journal of Materials Research
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• v.14 no.2
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• pp.133-140
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• 2004

We carried out anodic aluminum oxide (AAO) on a Si and a sapphire substrate. For anodic oxidation of Al two types of specimens prepared were Al(0.5 $\mu\textrm{m}$)!Si and Al(0.5 $\mu\textrm{m}$)/Ti(0.1 $\mu\textrm{m}$)$SiO_2$(0.1 $\mu\textrm{m}$)/GaN(2 $\mu\textrm{m}$)/Sapphire. Surface morphology of Al film was analyzed depending on the deposition methods such as sputtering, thermal evaporation, and electron beam evaporation. Without conventional electron lithography, we obtained ordered nano-pattern of porous alumina by in- situ process. Electropolishing of Al layer was carried out to improve the surface morphology and evaluated. Two step anodizing was adopted for ordered regular array of AAO formation. The applied electric voltage was 40 V and oxalic acid was used as an electrolyte. The reference electrode was graphite. Through the optimization of process parameters such as electrolyte concentration, temperature, and process time, a regular array of AAO was formed on Si and sapphire substrate. In case of Si substrate the diameter of pore and distance between pores was 50 and 100 nm, respectively. In case of sapphire substrate, the diameter of pore and distance between pores was 40 and 80 nm, respectively

• Journal of Powder Materials
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• v.8 no.1
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• pp.49-54
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• 2001

The synthesis and characteristics of W-Ni-Fe nanocomposite powder by hydrogen reduction of ball milled W-Ni-Fe oxide mixture were investigated. The ball milled oxide mixture was prepared by high energy attrition milling of W blue powder, NiO and $Fe_2O_3$ for 1 h. The structure of the oxide mixture was characteristic of nano porous agglomerate composite powder consisting of nanoscale particles and pores which act as effective removal path of water vapor during hydrogen reduction process. The reduction experiment showed that the reduction reaction starts from NiO, followed by $Fe_2O_3$ and finally W oxide. It was also found that during the reduction process rapid alloying of Ni-Fe yielded the formation of $\gamma$-Ni-Fe. After reduction at 80$0^{\circ}C$ for 1 h, the nano-composite powder of W-4.57Ni-2.34Fe comprising W and $\gamma$-Ni-Fe phases was produced, of which grain size was35nm for W and 87 nm for $\gamma$-Ni-Fe, respectively. Sinterability of the W heavy alloy nanopowder showing full density and sound microstructure under the condition of 147$0^{\circ}C$/20 min is thought to be suitable for raw material for powder injection molding of tungsten heavy alloy.

• Membrane and Water Treatment
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• v.10 no.6
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• pp.451-460
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• 2019

Thin film composite membranes incorporated with nano-sized hydrophilic zeolite -A were successfully prepared via interfacial polymerization (IP) on porous blend PES/PAN support for water desalination. The thin film nanocomposite membranes were characterized by SEM, contact angle and performance test with 7000 ppm NaCl solution at 7bar. The results showed that the optimum zeolite loading amount was determined to be 0.1wt% with permeate flux 29LMH.NaCl rejection was improved from 69% to 92% compared to the pristine polyamide membrane where the modified PA surface was more selective than that of the pristine PA. In addition, there was no significant change in the permeate flux of the thin film nanocomposite membrane compared with that of the pristine PA in spite of the formation of the dense polyamide layer. The stability of the polyamide layer was investigated for 15 days and the optimized membrane presented the highest durability and stability.

• Journal of the Korean Society of Visualization
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• v.19 no.1
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• pp.50-56
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• 2021

With the advances in recent nanotechnology, mass transport phenomena have been receiving large attention both in academic researches and industrial applications. Nonetheless, it is not clearly determined which parameters are dominant at nanoscale mass transport. Especially, membrane is a kind of technology that use a selective separation to secure fresh water. The development of great separation membrane and membrane-based separation system is an important way to solve existing water resource problems. In this study, glass fiber-based membranes which are treated by graphene oxide (GO), poly-styrene sulfonate (GOP) and sodium dodecyl sulfate (GPS) were fabricated. Mass transport parameters were investigated in terms of material-specific and structure-specific dominance. The 3D structural information of GO, GOP, and GPS was obtained by using synchrotron X-ray nano tomography. In addition, electrostatic characteristic and water absorption rate of the membranes were investigated. As a result, we calculated internal structural information using Tomadakis-Sotrichos model, and we found that manipulation of surface characteristics can improve spacer arm effect, which means enhancement of water permeability by control length of ligand and surface charge functionality of the membrane.

• Nano
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• v.13 no.12
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• pp.1850145.1-1850145.8
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• 2018

In this study, a double-solvent radiation method is proposed to prepare silver nanoparticles in the pores of metal-organic framework MIL-101(Cr). The results reveal that well-dispersed silver nanoparticles with a diameter of about 2 nm were successfully fabricated in the cages of monodisperse octahedral MIL-101(Cr) with a particle size of about 400 nm. The structure of MIL-101(Cr) was not destroyed during the chemical treatment and irradiation. The resulting Ag/MIL-101 exhibits excellent catalytic performance for the reduction of 4-nitrophenol. This method can be extended to prepare other single or bimetallic components inside porous materials.