• Journal of the Korean Ceramic Society
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• v.24 no.3
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• pp.257-262
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• 1987

The characteristics of cobalt oxide powders prepared by hot petroleum drying method from the cobalt acetate were evaluated by DTA/TGA, XRD, BET, SEM and density measurement. The cobalt oxide powder could be prepared by hot petroleum drying of the emulsion of cobalt acetate salt solution and the subsequent thermal decomposition of the acetate at 300$^{\circ}C$. As the concentration of the salt solution and the calcination temperature of the dried powder increased, the surface area of the synthesized powder decreased due to the particle growth, so that after sintering the density and grain size decreased. For the same concentration of the salt solution, the surface area and sinterability of the powder by hot petroleum drying increased in comparision with those by conventional drying.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4449-4459
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• 2022

In this study, an NF₃ plasma etching reaction with a cobalt oxide (Co₃O₄) films grown on the surface of inorganic compounds using granite was investigated. Experimental results showed that the etching rate can be up to 1.604 mm/min at 380 ℃ under 150 W of RF power. EDS and XPS analysis showed that main reaction product is CoF₂, which is generated by fluorination in NF₃ plasma. The etching rate of cobalt oxide films grown on inorganic compounds in this study was affected by surface roughness and etch selectivity. This study demonstrates that the plasma surface decontamination can effectively and efficiently remove contaminated nuclides such as cobalt attached to aggregate in concrete generated when decommissioning of nuclear power plants.

• Journal of the Korean Ceramic Society
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• v.45 no.8
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• pp.482-485
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• 2008

Composite electrode consisting of carbon nanofiber (CNF) and cobalt oxide was prepared for supercapacitor electrode, and its electrochemical property was investigated by means of cyclic voltammetry. Cyclic voltammetric results for the composite electrode showed it had specific capacitance value of 420 F/g at 5 mV/s, which was higher than capacitance value of 180 F/g for the bare CNF. It is concluded that the capacitive property of CNF can be improved by coating cobalt oxide on it to increase the surface area of cobalt oxide.

• Journal of the Korean Ceramic Society
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• v.45 no.6
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• pp.368-373
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• 2008

An electrode for supercapacitor using 3-dimensional porous nickel foam as a current collector and cobalt oxide as an active material was prepared and characterized in terms of morphology observation, crystalline property analysis, and the investigation of electrochemical property. The electrode surface showed that the cobalt oxide was homogeneously coated as the crystalline phase of $Co_3O_4$. Cyclic voltammetry for the $Co_3O_4$/nickel foam electrode exhibited higher specific capacitance values (445 F/g at 10 mV/s and 350 F/g at 200 mV/s) and excellent capacitance retention ratio (99% after $10^4$ cycles). It was proved that the nickel foam substrate played the roles in reducing the interfacial resistance with cobalt oxide and in improving the electrode density by embedding greater amount of cobalt oxide within it.

• Journal of Powder Materials
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• v.11 no.1
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• pp.28-33
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• 2004

In the present study, the focus is on the analysis of carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fined TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. The synthesized titanium-cobalt-oxygen based oxide powder has a mixture of $TiO_2$ and $CoTiO_3$. This oxide powder was transformed to a mixed state of titanium car-bide and cobalt by solid carbon through four steps of carbothermal reduction steps with increasing temperature; reduction of $CoTiO_3$ to $TiO_2$ and Co, reduction of $TiO_2$, to the magneli phase($Ti_nO_{2n-1}$, n>3), reduction of the mag-neli phase($Ti_nO_{2n-1}$, n>3) to the $Ti_nO_{2n-1}$(2$\leq$n$\leq$3) phases, and reduction and carburization of the $Ti_nO_{2n-1}$(2$\leq$n$\leq$3) phases to titanium carbide.

• Korean Journal of Materials Research
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• v.15 no.11
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• pp.722-729
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• 2005

The electrical and dielectric stability of zinc oxide-based varistors were investigated with the cobalt oxide contents in the range of $0.5\~5.0 mo\l%$. As cobalt oxide contents increased, the ceramic density increased in the range of $5.25\~5.55g/cm^3$ and the varistor voltage decreased in the range of $235.3\~86.0V$. The varistor with on addition of cobalt oxide $1.0 mol\%$ exhibited good nonlinearity. in which the nonlinear exponent is 66.6 and the leakage current is $1.2{\mu}A$. Furthermore, the varistors exhibited the highest electrical and dielectric stability, with $\%{\Delta}V_{1mA}=-1.9\%,\;\%{\Delta}{\alpha}=-10.5\%,\;\%{\Delta}I_L=+275.0\%,\;and\;\%{\Delta}tna{\delta}=+55.6\%$, under DC accelerated aging $0.95V_{1mA}/150^{\circ}C/24h$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.93-96
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• 2001

We have reported to make nanostructured cobalt oxide electrode that have large capacitance over than 400F/g (specific capacitance) and good cycleability. But, It had serious demerits of low voltage range under 0.5V and low power density. Therefore, we need to increase voltage range of cobalt oxide electrode. we report here on the electrochemical properties of sol-gel-derived nanoparticulate cobalt xerogel in 1M KOH solution and aqueous polymeric gel electrolyte. In solution electrolyte, cobalt oxide electrode had over than 250F/g capacitance consisted of EDLC and pseudocapacitance. In gel electrolyte, cobalt oxide electrode had around l00F/g capacitance. This capacitance was only surface EDLC. In solution electrolyte, potassium ion as working ion reacted with both of layers easily. However, In gel electrolyte, reacted with only surface-active layer. Its very hard to reach resistive layer. So, we have studied on pretreatment of electrode to contain working ions easily. We'll report more details.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.93-96
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• 2001

We have reported to make nanostructured cobalt oxide electrode that have large capacitance over than 400F/g (specific capacitance) and good cycleability. But, It had serious demerits of low voltage range under 0.5V and low power density. Therefore, we need to increase voltage range of cobalt oxide electrode. we report here on the electrochemical properties of sol-gel-derived nanoparticulate cobalt xerogel in 1M KOH solution and aqueous polymeric gel electrolyte. In solution electrolyte, cobalt oxide electrode had over than 250F/g capacitance consisted of EDLC and pseudocapacitance. In gel electrolyte, cobalt oxide electrode had around 100F/g capacitance. This capacitance was only surface EDLC. In solution electrolyte, potassium ion as working ion reacted with both of layers easily. However, In gel electrolyte, reacted with only surface-active layer. Its very hard to reach resistive layer. So, e have studied on pretretmetn of electrode to contain working ions easily. We'll report more details.

• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.871-875
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• 2001

Cobalt silicidation at sidewall spacer edge of Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) with post annealing treatment for capacitor forming process has been investigated as a function of dopant species. Cobalt silicidation of nMOSFET with n-type Lightly Doped Drain (LDD) and pMOSFET with p-type LDD produces a well-developed cobalt silicide with its lateral growth underneath the sidewall spacer. In case of pMOSFET with n-type LDD, however, a void is formed at the sidewall spacer edge with no lateral growth of cobalt silicide. The void formation seems to be due to a retarded silicidation process at the LDD region during the first Rapid Thermal Annealing (RTA) for the reaction of Co with Si, resulting in cobalt mono silicide at the LDD region. The subsequent second RTA converts the cobalt monosilicide into cobalt disilicide with the consumption of Si atoms from the Si substrate, producing the void at the sidewall spacer edge in the Si region. The void formed at the sidewall spacer edge serves as a resistance in the current-voltage characteristics of the pMOSFET device.

• Korean Journal of Materials Research
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• v.30 no.6
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• pp.273-278
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• 2020

This research is conducted to analyze the compatibility of used monomers and produce the high functional hydrogel ophthalmic polymer containing silane and nanoparticles. VTMS (vinyltrimethoxysilane), TAVS [Triacetoxy(vinyl)silane] and cobalt oxide nanoparticles are used as additives for the basic combination of SilM (silicone monomer), MMA (methyl methacrylate) and MA (methyl acrylate). Also, the materials are copolymerized with EGDMA (ethylene glycol dimethacrylate) as cross-linking agent, AIBN (thermal polymerization initiator) as the initiator. It is judged that the lenses of all combinations are optically excellent and thus have good compatibility. Measurement of the optical and physical characteristics of the manufactured hydrophilic ophthalmic polymer are different in each case. Especially for TAVS, the addition of cobalt oxide nanoparticles increases the oxygen permeability. These materials are considered to create synergy, so they can be used in functional hydrogel ophthalmic lenses.