• Journal of the Korean Magnetics Society
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• v.7 no.1
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• pp.31-37
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• 1997

The magnetoresistance and the saturation field behavior of the Co-Ag nano granular films as a function of the composition and the ferromagnetic underlayer and overlayermaterials were investigated. The maximum magnetoresistance of 23% and the saturation field of 2.3 kOe at room temperature were obtained in the as-deposited 3000$\AA$ $Co_{30}Ag_{70}$ single alloy films. The magnetoresistance and the saturation field of 100$\AA$ $Co_{30}Ag-{70}$ alloy film were 3.65 % and 3.0 kOe respectively. Those of the sandwiched films with 200$\AA$ Fe were 3.3 % and 1.23 kOe respectively. The saturation field of the sandwiched alloy films could be reduced by the exchange coupling between the ferromagnetic layers and the alloy layer. The effective depth of the exchange coupling was approximately 150$\AA$ in each Fe layer. Among the Fe, Co, and FeNi, the most effective materials to reduce the saturation field of the sandwiched alloy films was Fe.

• Journal of the Korean Chemical Society
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• v.17 no.4
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• pp.247-255
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• 1973

The self supported film specimen of Wyoming montmorillonite as a layer silicate saturated by cations,$Li^{+},\;Na^{+},\;K^{+},\;Ca^{2+},\;Ni^{2+},\;Al^{3+}$and$F^{3+}$ were allowed to contact acetone, methyl-ethyl ketone and diethyl ketone within the heatable gas cell. The i.r. spectra between $4000{\sim}1200cm^{-1}$ at different pressures of adsorbates indicated bond formation through carbonyl oxygen. Two types of carbonyl bond shift with maxima at $1713cm^{-1}$ and $1690cm^{-1}$ are attributed as coordinate bond formation of carbonyl with either surface hydroxyl or cationic hydroxyl group. The intensity of the vOH was analyzed and resonance form of cationic hydroxyl was proposed as an adsorption site. The tendency to form coordinate bond was in good agreement with calculated formal charge of carbonyl oxygen in an increasing order, acetone < methyl-ethyl ketone < diethyl ketone. As an additional mechanism of adsorption, weak hydrogen bonding of methyl hydrogen with surface oxygen was observed.

• Journal of Hydrogen and New Energy
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• v.3 no.2
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• pp.55-62
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• 1992

To improve the MCFC performance it is important to distingush between polarization losses occuring in the individual electrodes and other components. In this study a current interruption technique has been applied to a MCFC unit cell having a reference electrode to separately study the contributions of IR loss and other polarization losses. At a current density of $150mA/cm^2$ the IR-free polarization of a Ni anode was about 60mV while that of a NiO cathode was 130mV and the Ohmic loss of the cell was as large as 170mV suggesting that both the cathode and the cell structure need further improvement. The thin-film electrode model was used to simulate the performance of the electrodes. Both andoe data and cathode data were successfully fitted.

• Corrosion Science and Technology
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• v.22 no.5
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• pp.359-367
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• 2023

The localized corrosion resistance of the Ni-based Inconel 718 alloy after solution heat treatment was evaluated using electrochemical techniques in a solution of 25 wt% NaCl and 0.5 wt% acetic acid. Solution heat treatment at 1050 ℃ for 2.5 hours resulted in an increased average grain diameter. Both Ti carbides (10 ㎛ diameter) and Nb-Mo carbides (1 - 9 ㎛ diameter) were distributed throughout the material. Despite heat treatment, the shape and composition of these carbides remained consistent. An increase in solution temperature led to a decrease in pitting potential value. However, the pitting potential value of solution heat-treated Inconel 718 was consistently higher than that of as-received Inconel 718 at all tested temperatures. Localized corrosion initiation occurred at 0.4 V_SSE in a temperature environment of 80 ℃ for both as-received and solution heat-treated Inconel 718 alloys. X-ray photoelectron spectroscopic analysis indicated that the composition of the passive film formed on specimen surfaces remained largely unchanged after solution heat treatment, with O1s, Cr2p_3/2, Fe2p_3/2, and Ni2p_3/2 present. The difference in localized corrosion resistance between as-received and solution heat-treated Inconel 718 alloys was attributable to microstructural changes induced by the heat treatment process.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.211-218
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• 2014

In this paper the magnetic field properties of the soft magnetic alloys (Fe-Si-Cr and Fe-Ni-Cr) are studied in advance for the development of electro-magnetic shielding films, which could be used in the IT Devices (NFC, mobile phone, computer, etc.).As a result each of the selected soft magnetic alloy melts of the corresponding compositions is water-dispersed into the disk-shaped grains, which are soaked in polymer resin, and of which two types of thin film of thickness 0.1mm and 1mm are made by passing through the heating calendar roller. And the magnetic permeability and the shielding effectiveness of the polymer films containing the soft magnetic alloy grains are measured over the whole frequency bands from the low frequency to 10GHz. Before the experiments of the soft magnetic alloy, a special equation is proposed to estimate the permeability of the alloy, and the equation is verified with the pre-published data by MATLAB, and from which the most optimal compositions can be decided. And the SE(Shielding Effectiveness) of the polymer films containing the soft magnetic alloy grains is simulated by the HFSS.

• Journal of the Korean Magnetics Society
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• v.15 no.4
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• pp.226-230
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• 2005

In this research, magnetic properties and annealing effects of the spin valve structures were investigated, which have Ta underlayer deposited with Ar and $N_2$ gas mixture. Also, TaN underlayer as a diffusion barrier and the substrate were investigated. The structure of the spin valve was Si($SiO_2$)/Ta(TaN)/NiFe/CoFe/Cu/CoFe/FeMn/Ta. Deposition rate was decreased and resistivity and roughness of the TaN films were increased as the $N_2$ gas flow was increased. The XRD results after high temperature annealing showed that Silicides were created in Si/Ta layer, but not in Si/TaN layer. Magnetoresistance ratio (MR) and exchange coupling field ($H_{ex}$) were decreased when the $N_2$ gas flow was increased over 4.0 sccm. The MR of the spin valves with Ta and TaN films deposited with up to 4.0 sccm of $N_2$ gas flow was increased about $0.5\%$ until the annealing temperature of up to $200^{\circ}C$ and then, decreased. TaN film deposited with 8.0 sccm of $N_2$ gas flow showed twice the adhesion of the Ta film. The above results indicate that with 3.0 sccm of $N_2$ gas flow during the Ta underlayer deposition, the magnetic properties of the spin valves are maintained, while the underlayer may be used as a diffusion barrier and the adhesion between the Si substrate and the underlayer is increased.

• Journal of the Korean Magnetics Society
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• v.17 no.1
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• pp.22-25
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• 2007

In this research, magnetic properties of spin valve structures using IrMn layers as antiferromagnetic were studied depending on the thickness of the pinned layer. The spin valve structure was Si substrate/$SiO_2(2,000\;{\AA})/Mo(17\;{\AA})NiFe(21\;{\AA})/CoFe(28\;{\AA})/Cu(22\;{\AA})/CoFe(18\;{\AA})/IrMn(t\;{\AA})/Ta(25\;{\AA})$. Also, Mo film was deposited on Si substrates and the thermal annealing effect was analyzed. The resistivity of the Mo film was increased as an annealing temperature was increased up to $600^{\circ}C$. The variations of MR ratio were related with magnetic exchange coupling field of the spin valve structures for various IrMn pinned layer thickness up to 130 ${\AA}$. MR ratio and $H_{ex}$ of spin valves was about 9.05% and 277.5 Oe when the thickness of the IrMn pinned layer was $32.5\;{\AA}(t=32.5\;{\AA})$. It was increased to 9.65% and 337.5 Oe for $t=65\;{\AA}$. For $t=97.5\;{\AA}$, the MR ratio and Hex decreased to 8.2% and 285 Oe, and further decrease was observed up to $t=130\;{\AA}$.

• Korean Journal of Optics and Photonics
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• v.11 no.5
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• pp.323-329
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• 2000

In this study we have calculated an ideal complex refractive index of a TiN trim used in a layer of anl1reilecnon (I\R) coatmg, [air$ISiO_2ITiNIglass$] in the visible. Also we simulated the rellectance of lwo-layer AR coating by varying the thicknesses of TiN and $SiO_2$ layers, respecl1vely. The simolation results show that we can controllhe lowest reflectance and AR band of tile AR coating. The TIN fihns were fabricated by a RF magnetron sputtering apparalus. The chemical, structural and electrical properties of TiN fih11S were inveshgated by the Rutherford backscattering spech'oscopy (RBS), atomic force microscope (AFM) and 4-point probe. The optical properlies were inve,tigated by the spectrophotometer and vanable angle spectroscopic ellipsometer (VASE). The smface roughness of TiN flhns \vas $9~10\AA$. TIle resistivity of TiN films was TEX>$360~730\mu$\Omega $ cm. The ,toichlOllletry of TiN film was 1'1: O:N = I: 0.65 :0.95 and ilic oxygen wa~ found on ilie smface. With these experimental and simu]al1on resulLs, we deposited duo: two-layer AR coating, [air$ISiO_2ITiNIglass$] and the refleClance was under 0.5% ill the regIOn of 440-650 run. 0 run.

• Korean Journal of Materials Research
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• v.3 no.3
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• pp.261-271
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• 1993

Functionally Gradient Materials(FGM) of 4.5Pb($Ni_{1/3}Nb_{2/3})O_3$-55PZT and PLZT(lO/70 /30, 11/60/40) were prepared. Its dielectric and piezoelectric strain properties were investigated. The FGM were pressed into A/B/ A configuration using two kinds of films, one layer(A) was eliminated from FGM by polishing after sintering at $l250^{\circ}C$, 2 hrs. The acrylic binder system was successfully applied for crack free film through doctor blade method. The thickness of gradent layer in FGM was about 30${\mu}$m. Dielectric properties of FGM show the average value of each side layer. The strain-electric field characteristics of FGM were significantly improved comparison with the other single compositions. The prepared FGM piezoelectric actuator shows about 3${\mu}$m/IOOV displacement.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.25-37
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• 2020

In this study, hybridization of graphene oxide and metal was carried out by the functional groups containing oxygen and thermal treatment for reduction in order to enhance the electrical conductivity and magnetic properties of graphene materials. Graphene-metal hybrid materials were synthesized using the oxygen-containing functional groups (-OH, -COOH and so on) on the surface of graphene oxide by replacing them with metal ions via ion exchange method as well as thermal reduction. The metals used in this study were Fe, Ag, Ni, Zn, and Fe/Ag, and it was confirmed that metal particles of uniform size were well dispersed on the graphene surface through SEM, TEM, and EDS. All of the metal particles on the graphene surface had an oxide-crystalline structure. To check the electrical properties, sheet resistance of the rGO-metal hybrid sample was measured on the PET film made by the dip-coating, and the specific resistance was calculated by measuring the thickness of the specimen through SEM. As a result, the specific resistance was in the range of 2.14×10-5 and 3.5×10-3 ohm/cm.