• Carbon letters
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• v.11 no.2
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• pp.117-121
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• 2010

The composites of alginate, carbon nanotube, and iron(III) oxide were prepared for the removal of heavy metal in aqueous pollutant. Both alginate and carbon nanotube were used as an adsorbent material and iron oxide was introduced for the easy recovery after removal of heavy metal to eliminate the secondary pollution. The morphology of composites was investigated by FE-SEM showing the carbon nanotubes coated with alginate and the iron oxide dispersed in the alginate matrix. The ferromagnetic properties of composites were shown by including iron(III) oxide additive. The copper ion removal was investigated with ICP AES. The copper ion removal efficiency increased greatly over 60% by using alginate-carbon nanotube composites.

• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.235-237
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• 2016

Oxide/metal/oxide (OMO) thin films were fabricated using amorphous indium-gallium-zinc-oxide (a-IGZO) and an Ag metal layer on a glass substrate at room temperature. The optical and electrical properties of the a-IGZO/Ag/a-IGZO samples changed systemically depending on the thickness of the Ag layer. The transmittance in the visible range tends to decrease as the Ag thickness increases while the resistivity, carrier concentration, and Hall mobility tend to improve. The a-IGZO/Ag (13 nm)/a-IGZO thin film with the optimum Ag thickness showed an average transmittance (T_av) of 71.7%, resistivity of 6.63 × 10⁻⁵ Ω·cm and Hall mobility of 15.22 cm²V⁻¹s⁻¹.

• Progress in Superconductivity
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• v.12 no.2
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• pp.114-117
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• 2011

We report our efforts on the development of Nb-based non-hysteretic Josephson junction fabrication process for quantu device applications. By adopting and modifying the existing Nb-aluminum oxide tunnel junction process, we develop a process for non-hysteretic Josephson junction circuits using metal-silicide as metallic barrier material. We use sputter deposition of Nb and $MoSi_2$, PECVD deposition of silicon oxide as insulator material, and ICP-RIE for metal and oxide etch. The advantage of the metal-silicide barrier in the Nb junction process is that it can be etched in $SF_6$ RIE together with Nb electrode. In order to define a junction area precisely and uniformly, end-point detection for the RIE process is critical. In this paper, we employed thin Al layer for the etch stop, and optimized the etch condition. We have successfully demonstrated that the etch stop properties of the inserted Al layer give a uniform etch profile and a precise thickness control of the base electrode in Nb trilayer junctions.

• Journal of the Korean Solar Energy Society
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• v.33 no.2
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• pp.93-100
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• 2013

Two-step thermochemical cycle using ferrite-oxide($Fe_2O_4$) device was investigated. The $H_2O$(g) was converted into $H_2$ in the first experiment which was performed using a dish type solar thermal system. However the experiment was lasted only for 2 cycles because the metal oxide device was sintered and broken down. Another problem was that the reaction was taken place mainly on a side of the metal oxide device. The m-$ZrO_2$, which was widely known as a material preventing sintering, was applied on the metal oxide device. The ferrite loading rate and the thickness of the metal oxide device were increased from 10.67wt% to 20wt% and from 10mm to 15mm, respectively. The chemical reactor having two inlets was designed in order to supply the reactants uniformly to the metal oxide device. The second-experiment was lasted for 5 cycles, which was for 6 hours. The total amount of the $H_2$ production was 861.30ml. And cerium oxide($CeO_2$) device was used for increasing $H_2$ production rate. $CeO_2$ device had low thermal resistance, however, more $H_2$ production rate than $Fe_2O_4$ device.

• Korean Journal of Materials Research
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• v.19 no.7
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• pp.349-355
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• 2009

Metal thin film patterns on a LTCC substrate, which was connected through inner via and metal paste for electrical signals, were formed by a screen printing process that used electric paste, such as silver and copper, in a conventional method. This method brought about many problems, such as non uniform thickness in printing, large line spaces, and non-clearance. As a result of these problems, it was very difficult to perform fine and high resolution for high frequency signals. In this study, the electric signal patterns were formed with the sputtered metal thin films (Ti, Cu) on an LTCC substrate that was coated with protective oxide layers, such as $TiO_2$ and $SiO_2$. These electric signal patterns' morphology, surface bonding strength, and effect on electro plating were also investigated. After putting a sold ball on the sputtered metal thin films, their adhesion strength on the LTCC substrate was also evaluated. The protective oxide layers were found to play important roles in creating a strong design for electric components and integrating circuit modules in high frequency ranges.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.101-106
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• 2009

In this paper, Thin films of $HfO_2$/Hf were deposited on p-type wafer by Atomic Layer Deposition (ALD). We studied the electrical and material characteristics of $HfO_2$/Hf/Si MOS capacitor depending on thickness of Hf metal layer. $HfO_2$ films were deposited using TEMAH and $O_3$ at $350^{\circ}C$. Samples were then annealed using furnace heating to $500^{\circ}C$. Round-type MOS capacitors have been fabricated on Si substrates with $2000\;{\AA}$-thick Pt top electrodes. The composition rate of the dielectric material was analyzed using TEM (Transmission Electron Microscopy), XRD (X-ray Diffraction) and XPS (X-ray Photoelectron Spectroscopy). Also the capacitance-voltage (C-V), conductance-voltage (G-V), and current-voltage (I-V) characteristics were measured. We calculated the density of oxide trap charges and interface trap charges in our MOS device. At the interface between $HfO_2$ and Si, both Hf-Si and Hf-Si-O bonds were observed, instead of Si-O bond. The sandwiched Hf metal layer suppressed the growing of $SiO_x$ layer so that $HfSi_xO_y$ layer was achieved. And finally, the generation of both oxide trap charge and interface trap charge in $HfO_2$ film was reduced effectively by using Hf metal layer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.3
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• pp.103-107
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• 2024

In this study, nickel, a pure metal material, was proposed as a saggar for synthesizing NCM [Li(Ni_xCo_yMn_z)O₂] cathode active material. Nickel is known as a metal that is resistant to oxidation and has a high melting point. Nickel is one of the main components of NCM cathode material and was expected to be free from problems with contamination from saggar during cathode material synthesis. We sought to confirm the possibility of nickel as a saggar for synthesizing NCM cathode active materials. When a Ni metal crucible and Ni_0.8Co_0.1Mn_0.1(OH)₂ (NCM 811) precursor material were reacted at 900℃ for a long time, the change in the reaction layer on the surface of the crucible over time was analyzed. The nickel crucible reaction layer formed during heat treatment at 900℃ was nickel oxide, and is thought to have been created by simultaneous oxygen diffusion from the cathode precursor oxide and reaction with oxygen in the atmosphere. The change in thickness of the oxide layer appears to slow down after 480 hours, which suggests that the rate of oxygen diffusion from the precursor is reduced. It remained combined without falling out of the crucible until 480 hours. However, it was confirmed that the oxide layer falls off after 720 hours, so it is thought that it can be used as saggar for NCM synthesis only for a certain period of time.

• Journal of Technologic Dentistry
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• v.35 no.4
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• pp.359-364
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• 2013

Purpose: This study was to observe characteristic of metal oxidation and bonding strength according to composition of Ni-Cr alloy for porcelain fused to metal crown. The three kinds of Ni-Cr alloy with different composition ratio of parent metal were observed general properties and chemical properties of each alloy surface and measured the shear bonding strength between ceramic and each alloys. The aim of study was to suggest the material for design of parent metal's composition ratio to development of alloy for porcelain fused to metal crown. Methods: The three kinds of alloy as test specimen was Ni(59wt%)-Cr(24wt%), Ni(67wt.%)-Cr(16wt.%) alloy and Ni(71wt%)-Cr(12wt%)alloy. The oxide on surface was observed by EDX. And the shear test was performed by MTS. Results: The surface property and oxide characteristic analysis of oxide layer, weight percentage of Element O within $Ni_{59}Cr_{24}$ alloy measured 23.03wt%, $Ni_{67}Cr_{16}$ alloy measured 21.13wt% and $Ni_{71}Cr_{12}$ alloy was measured 48.55wt%. And the maximum shear bonding strength was measured 58.02Mpa between $Ni_{59}Cr_{24}$ alloy and vintage halo(H2 group). Conclusion: The surface property and oxide characteristic three kind of Ni-Cr alloy was similar. and shear bonding strength showed the highest bonding strength in H2 specimens.

• Transactions on Electrical and Electronic Materials
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• v.11 no.4
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• pp.178-181
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• 2010

An automotive IC voltage regulator which consists of one-chip based on a metal-oxide semiconductor field effect transistor (MOSFET) is investigated experimentally with three types of packaging. The closed type is filled with thermal silicone gel and covered with a plastic lid on the MOSFET. The half-closed type is covered with a plastic case but without thermal silicone gel on the MOSFET. Opened type is no lid without thermal silicone gel. In order to simulate the high temperature condition in engine bay, the operating circuit of the MOSFET is constructed and the surrounding temperature is maintained at $100^{\circ}C$. In the overshoot the maximum was mainly found at the half-closed packaging and the magnitude is dependent on the packaging type and the surrounding temperature. Also the impressed current decreased exponentially during the MOSFET operation.

• ETRI Journal
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• v.35 no.4
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• pp.617-624
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• 2013

Low power consuming and highly responsive semiconductor-type microelectromechanical systems (MEMS) gas sensors are fabricated for real-time environmental monitoring applications. This subsystem is developed using a gas sensor module, a Bluetooth module, and a personal digital assistant (PDA) phone. The gas sensor module consists of a $NO_2$ or CO gas sensor and signal processing chips. The MEMS gas sensor is composed of a microheater, a sensing electrode, and sensing material. Metal oxide nanopowder is drop-coated onto a substrate using a microheater and integrated into the gas sensor module. The change in resistance of the metal oxide nanopowder from exposure to oxidizing or deoxidizing gases is utilized as the principle mechanism of this gas sensor operation. The variation detected in the gas sensor module is transferred to the PDA phone by way of the Bluetooth module.