• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.208-211
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• 2000

We prepared Co-Cr-Ta and Co-Cr-Ta/Ti thin film for perpendicular magnetic recording media by facing targets sputtering system (FTS system). Ti underlayer effects on crystallographic and magnetic characteristics of Co-Cr-Ta perpendicular magnetic recording media have been investigated. Crystallgraphic and magnetic characteristic of prepared thin films were evaluated by x-ray diffractometry(XRD), vibrating sample magnetometer(VSM) and kerr hysteresis loop measurement. The coercivity and anisotropy field increase by introduced Ti underlayer when substrate temperature is higher than 150$^{\circ}C$. The c-axis dispersion angle and grain size of Co-Cr-Ta/Ti thin film is decrease than Co-Cr-Ta when substrate temperature is higher than 100$^{\circ}C$. Consequently, the use of a Ti underlayer highly orientated can be improved crystallographic and magnetic characteristics of Co-Cr -Ta perpendicular media layer.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.11
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• pp.105-111
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• 1996

We have invetigated the characteristics of thermal instability of Co-silicides annealed at 850$^{\circ}$C ~ 1000$^{\circ}$C for 10~90 minutes in a furance with N$_{2}$ ambient. In our experiments, Co-silicides and Co/Ti bilayer silicides were formed by depositing (Co, Ti) films on the clean Si substrates in an E-beam evaporator and performing the RTA annelaing. The sheet resistances of Co-silicides formed form Co exhibited the nearly constant value under the post-annealing time above 900$^{\circ}$C showing the increase of 30% and 60% under the conditions annealed at 900$^{\circ}$C and 1000$^{\circ}$C for 30minutes. On the other hand, there were no remarkable changes in the sheet resistance sof Co-silicides formed form Co/Ti bilayer under the post-annealing conditons below 1000$^{\circ}$C.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.657-662
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• 2018

In this study, the effect of $Pt/TiO_2$ catalysts on the CO oxidation reaction at room temperature was investigated using various $TiO_2$ supports with different physical properties to compare and evaluate $Pt/TiO_2$ catalysts. Physicochemical properties of the catalyst were alanyzed using XPS, CO-chemisorption, BET, and CO-TPD. As a result, when the active particle diameter was smaller, while the metal dispersion and surface area were larger, the CO room temperature oxidation reaction was better. These physical properties increased the number of active sites, causing the target material to increase the adsorption amount of CO. In addition, when the $O_2$-consumption increased, the CO-room temperature oxidation reaction activity increased due to the excellent oxygen-transferring ability.

• Journal of the Korean Ceramic Society
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• v.16 no.4
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• pp.225-236
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• 1979

The effect of $Ti^{+4}$ addition on the sinterability, microstructure, and temperature dependence of electromechanical coupling factor of magnetostrictive Ni-Cu-Co ferrite was investigated. The density of Ni-Cu-Co ferrite slightly increased by 2.0 mole % addition of either $TiO_2$ or $Fe_2TiO_4$, but tended to decrease by more than 2.0 mole % addition of $TiO_2$ or $Fe_2TiO_4$. As the content of either $TiO_2$ or $Fe_2TiO_4$ increased, the magnetocrystalline anisotropy compensation temperature also increased. Microstructure studies showed the stable grains when Ni-Cu-Co ferrite was sintered above 1, 20$0^{\circ}C$.

• Journal of Environmental Science International
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• v.14 no.2
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• pp.221-230
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• 2005

Catalytic wet oxidation of trichloroethylene (TCE) in water has been conducted using $TiO_2-supported$ cobalt oxides at $36^{\circ}C$ with a weight hourly space velocity of $7,500\;h^{-1}.\;5\%\;CoO_x/TiO_2$, prepared by using an incipient wetness technique, might be the most promising catalyst for the wet oxidation although it exhibited a transient behavior in time on-stream activity. Not only could the bare support be inactive for the wet decomposition reaction, but no TCE removal also occurred by the process of adsorption on $TiO_2$ surface. The catalytic activity was independent of all particle sizes used, thereby representing no mass transfer limitation in intraparticle diffusion. XPS spectra of both fresh and used Co surfaces gave different surface spectral features for each $CoO_x,\;Co\;2P_{3/2}$ binding energy for Co species in the fresh catalyst appeared at 781.3 eV, which is very similar to the chemical states of $CoTiO_x$ such as $CO_2TiO_4\;and\;CoTiO_3$. The used catalyst exhibited a 780.3-eV main peak with a satellite structure at 795.8 eV. Based on XPS spectra of reference Co compound, the TCE-exposed Co surfaces could be assigned to be in the form of mainly $Co_3O_4$. XRD patterns for $5\%\;CoO_x/TiO_2$ catalyst indicated that the phase structure of Co species in the catalyst even before reaction is quite comparable to the diffraction lines of external $Co_3O_4$ standard. A model structure of $CoO_x$ present predominantly on titania surfaces would be $Co_3O_4$, encapsulated in thin-film $CoTiO_x$ species consisting of $Co_2TiO_4$ and $CoTiO_3$, which may be active for the decomposition of TCE in a flow of water.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.5
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• pp.390-396
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• 2003

As the design rule of device continued to shrink, the contact resistance in small contact size became important. Although the conventional TiN/Ti structure as a ohmic layer has been widely used, we propose a new TiN/Co film structure. We characterized a contact resistance by using a chain pattern and a KELVIN pattern, and a leakage current determined by current-voltage measurements. Moreover, the microstructure of TiN/ Ti/ silicide/n$\^$+/ contact was investigated by a cross-sectional transmission electron microscope (TEM). The contact resistance by the Co ohmic layer showed the decrease of 26 % compared to that of a Ti ohmic layer in the chain resistance, and 50 ％ in KELYIN resistance, respectively. A Co ohmic layer shows enough ohmic behaviors comparable to the Ti ohmic layer, while higher leakage currents in wide area pattern than Ti ohmic layer. We confirmed that an uniform silicide thickness and a good interface roughness were able to be achieved in a CoSi$_2$ Process formed on a n$\^$+/ silicon junction from TEM images.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3635-3640
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• 2013

We prepared Ni and Pd-modified $TiO_2@SiO_2$ core-shell nanostructures and then analyzed them by scanning electron microscopy, optical microscopy, X-ray diffraction crystallography, FT-IR and UV-Visible absorption spectroscopy. In addition, their CO oxidation performance was tested by temperature-programmed mass spectrometry. The CO oxidation activity showed an order of Ni-$TiO_2@SiO_2$ ($900^{\circ}C$) < Ni-$TiO_2@SiO_2$ ($90^{\circ}C$) < Ni-$TiO_2@SiO_2$ ($450^{\circ}C$) in the first CO oxidation run, and greatly improved activity in the same order in the second run. The $T_{10%}$ (the temperature at 10% CO conversion) corresponds to the CO oxidation rate of $2.8{\times}10^{-5}$ molCO $g{_{cat}}^{-1}s^{-1}$. For Ni-$TiO_2@SiO_2$ ($450^{\circ}C$), the $T_{10%}$ was observed at $365^{\circ}C$ in the first run and at $335^{\circ}C$ in the second run. For the Pd-$TiO_2@SiO_2$ ($450^{\circ}C$), the $T_{10%}$ was observed at a much lower temperature of $263^{\circ}C$ in the first CO oxidation run, and at $247^{\circ}C$ in the second run. The CO oxidation activities of transition metal modified $TiO_2@SiO_2$ core-shell nanostructures presented herein provide new insights that will be useful in developing catalysts for various environments.

• Journal of the Korean Vacuum Society
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• v.9 no.4
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• pp.335-340
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• 2000

We investigated the role of the capping layers in the formation of the cobalt silicide in Co/Si systems with TiN and Ti capping layers and without capping layers. The Co/Si interfacial reactions and the phase transformations by the rapid thermal annealing (RTA) processes were observed by sheet resistance measurements, XRD, SIMS and TEM analyses for the clean silicon substrate as well as for the chemically oxidized silicon substrate by $H_2SO_4$. We observed the retardation of the cobalt disilicide formation in the Co/Si system with Ti capping layers. In the case of Co/$SiO_2$/Si system, cobalt silicide was formed by the Co/Si reaction due to with the dissociation of the oxide layer by the Ti capping layers.

• Proceedings of the Korean Magnestics Society Conference
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• 1999.04a
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• pp.22-23
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• 1999

• Journal of the Korean Magnetics Society
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• v.23 no.1
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• pp.7-11
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• 2013

We investigate the perpendicular magnetic anisotropy in $TiO_2$/Co/Pd on GaAs(100), MgO(100), MgO(111), Si(100), and glass substrates. We find that the roughness of $TiO_2$ depends on the $O_2$ partial pressure in the magnetron sputtering process. The perpendicular magnetic anisotropies are found in all substrates with $TiO_2$ seed layer, and the perpendicular magnetic anisotropy of Co/Pd system is insensitive on the type of the substrate when the thickness of $TiO_2$ seed layer is thicker than 5 nm. However, MgO(111) substrate promotes $TiO_2$ rutile (111) structure, and it causes largest perpendicular magnetic anisotropy in $TiO_2$/Co/Pd(111) structures.