Dong Sik Bae

Synthesis and Characterization of Nanosized ZnxMn1-xFe2O4 Powders by Glycothermal Process

Nanosized ZnxMn1-xFe2O4 powders were prepared in ethylene glycol solution under mild temperature and pressure conditions by precipitation from metal nitrates. The average size and distribution of the synthesized ZnxMn1-xFe2O4 powders were 10- 20 ㎚ and narrow, respectively. The magnetic property of the synthesized ZnxMn1- xFe2O4 powder was of superparamagnetic character at room temperature.

Fabrication and Microstructure of ZnO-TiO2 Composite Membranes by a Reverse Micelle and Sol-Gel Processing

ZnO-TiO2 nanoparticles were synthesized by a reverse micelle and sol-gel process. The average particle size of the colloid was below 30 nm and well dispersed in the solution. ZnOTiO2 composite membranes were fabricated by using the dip-coating method on a porous alumina support. ZnO-TiO2 composite membranes showed a crack-free microstructure and narrow particle size distribution even after the heat treatment up to 600°C. The average particle size of the membrane was 30-40nm, and the pore size of ZnO-TiO2 composite membrane was below 10 nm.

Synthesis and Microstructure of Al2O3-SiO2 Nanoparticles by a Sol-Gel Processing

Al2O3-SiO2 nanoparticles have been synthesized by a sol-gel processing. Size and composition of the synthesized particles can be controlled by manipulating the relative rates of the hydrolysis and condensation reaction of precursor. The average size of synthesized Al2O3-SiO2 nanoparticles was about in the size range of 50~100nm. The effects of synthesis parameters, such as the molar ratio of water to precursor, the molar ratio of water to surfactant and stirring rate, are discussed.

Synthesis and characterization of CoFe2O4 nanoparticles by glycothermal process

CoFe2O4 nanoparticles were prepared in ethylene glycol solution under mild temperature and pressure conditions by precipitation from metal nitrates. The average size of the synthesized CoFe2O4 nanoparticles was in the range of 5 to 10, and they were narrowly distributed in the crystalline phase. Their magnetic property was of superparamagnetic character at room temperature. The effect of synthesis parameters is discussed such as the pH of starting solutions and reaction temperature.

Fabrication and Microstructure of ZnO-SiO2 Nanoparticles by a Reverse Micelle and Sol-Gel Processing

ZnO-SiO2 nanoparticles were synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles was controlled by manipulating the relative rates of the hydrolysis and condensation reaction of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The average size of synthesized ZnO-SiO2 nanoparticles was in the range of 20-40 nm. The effects of synthesis parameters such as the molar ratio of water to precursor and the molar ratio of water to surfactant are discussed.

Synthesis and Characterization of the ZnO-TiO2 Nanoparticles by a Hydrothermal Processing

Zinc titanate nanoparticles were prepared under high temperature and pressure conditions by precipitation from metal precursors with aqueous ammonium hydroxide. Zinc titanates powders were obtained in the temperature range of 180-230 for 4 h. The phase of synthesized particle with calcined at 800 for 2h. ZnTiO3, Zn2TiO4, Zn2Ti3O8, TiO2, ZnO. The average particle size and distribution of the synthesized zinc titanate nanoparticles were below 100 nm and narrow, respectively.

Synthesis and Characterization of CoMn2O4 Nanopowders by a Reverse Micelle Processing

CoMn2O4 nanoparticles were synthesized by reverse micelle processing from the mixed precursor (consisting of Co (NO3)2 ·6H2O and MnCl2·4H2O). The CoMn2O4 was prepared by mixing the aqueous solution at a molar ratio of Co : Mn = 1 : 2. The synthesized powders were calcined at 600°C for 2h. The average size and distribution of synthesized powders were in the range of 10-20nm and narrow, respectively. The average size of the synthesized powders increased with increasing water to surfactant molar ratio. The XRD diffraction patterns show that the phase of CoMn2O4 was spinel (JCPDS no.77-0471). The synthesized and calcined powders were characterized by thermogravimetry-differential scanning calorimeter (TG-DSC), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The magnetic property of the powder was measured by Vibrating Sample Magneto-meter (VSM) at 298K. The effect of synthesis parameter, such as the molar ratio of water to surfactant, is discussed.

Fabrication and Characterization of Barium Doped Ceria Nanopowders by a Solvothermal Processing

Ba doped CeO2 nanopowders were prepared under mild temperature and pressure conditions by precipitation from metal nitrates with aqueous ammonium hydroxide. Spherical Ba doped CeO2 nanopowders were obtained with reaction at the temperature range of 210°C to 230°C for 6 h. The average size of the synthesized Ba doped CeO2 powders were below 10 nm and its distribution was narrow. The XRD pattern showed that the synthesized Ba doped CeO2 powders were crystalline with cubic phase of CeO2. This study has shown that the synthesis of Ba doped CeO2 nanopowders is possible under mild temperature and pressure conditions in ethylene gylcol solution. The effects of synthesis parameters, such as the solvent ratio of starting solution, pH of starting solution, reaction temperature and time, are discussed.

A Study on Fabrication, Dispersion and Surface Coating of Nanocarbon for MgO-C Refractories

Spherical carbon nanoparticles were synthesized by sol-gel polymerization of resorcinol and formaldehyde in the presence of CTAB(cetyltrimethyl ammonium bromide) and subsequent carbonization at 900 in N2 atmosphere. It is found that the amount of CTAB, water and catalyst showed a significant impact on the morphology and size of carbon nanoparticles. The magnesia-carbon (MgO-C) bricks containing 1~4 wt% nanocarbon were prepared by adding various types of carbon black (CB), multi walled carbon nanotubes (CNT) and synthesized nanocarbon. The mechanical properties, oxidation resistance and corrosion resistance of the MgO-C brick in which the nanocarbon is added was investigated. The MgO-C refractories were characterized by Field Emission Scanning Electron Microscope (FE-SEM, MIRA II LMH), Cold Crush Strength (CCS).

Synthesis and Characterization of Sn Doped SiO2 by Reverse Micelle and Sol-Gel Process

Sn doped SiO2 nanoparticles have been synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles and the thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The properties of the Sn doped SiO2 nanoparticles were studied as a function of various processing parameters such as R and H value. The average size of synthesized Sn doped SiO2 nanoparticles was about in the size range of 20-40 nm and core particle (Sn) 1-5 nm. The Sn doped SiO2 nanoparticles were characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM).