• Journal of Magnetics
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• v.21 no.1
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• pp.46-50
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• 2016

$Fe_2O_3/TiO_2$ nanocomposite were successfully synthesized by co-precipitation method using $Fe(NO_3)_3{\cdot}9H_2O$ and $Ti(SO_4)_2$ as raw materials. Structural and textural features of the mixed oxide samples were characterized by X-ray diffractometer, field emission scanning electron microscopy and energy-dispersive X-ray. The effects of initial concentration of oxytetracycline (OTC), different competitive ions and organics on the photocatalytic degradation rate of OTC by the $Fe_2O_3/TiO_2$ nanocomposite were analyzed under UV and visible light irradiation. The results indicate that the optimized initial concentration of OTC was 50 mg/L to achieve the best photocatalytic efficiency. $Cu^{2+}$, $NH_4{^+}$, $C_3H_8O$ and EDTA in the aqueous suspension were found to suppress the degradation rate of OTC, whereas the effect of $NO_3{^-}$ and $H_2C_2O_4$ can be ignored.

• Korean Journal of Materials Research
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• v.24 no.2
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• pp.67-72
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• 2014

Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties, including high strength, high hardness, excellent ductility and toughness. In this study, nanopowders of $Al_2O_3$, MgO and $TiO_2$ were prepared as starting materials by high energy ball milling for the simultaneous synthesis and sintering of the nanostructured compound $Mg_4Al_2Ti_9O_{25}$ by high-frequency induction heating process. The highly dense nanostructured $Mg_4Al_2Ti_9O_{25}$ compound was produced within one minute by the simultaneous application of 80MPa pressure and induced current. The sintering behavior, grain size and mechanical properties of the $Mg_4Al_2Ti_9O_{25}$ compound were evaluated.

• Journal of Environmental Health Sciences
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• v.29 no.1
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• pp.51-61
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• 2003

Pollution purification using titanium dioxide (TiO$_2$) photocatalyst has attracted a great deal of attention with increasing number of relent environmental problems. Currently, the application of TiO$_2$ photocatalyst has been focused on purification and treatment of waste water. However. the use of conventional TiO$_2$ powder photocatalyst results in disadvantage of stirring during the reaction and of separation after the reaction. And the usage of artificial UV lamp has made the cost of photocatalyst treatment system high. Consequently, we herein studied the pilot-scale design to aid in optimization of the energy-saving process for more through development and reactor design by solar light/UV lamp/ TiO$_2$system. In this study, we manufactured the TiO$_2$sol by sol-gel method. According to analysis by XRD, SEM and TEM, characterization of TiO$_2$ sol were nano-size (5-6 nm) and anatase type. Inorganic binder (SiO$_2$) was added to TiO$_2$ lot to be coated for support strongly, and support of ceramic bead was used to lower separation rate that of glass bead The influences were studied of various experimental parameters such as TiO$_2$ quantity, pH, flow rate. additives, pollutants concentration, climate condition and reflection plate by means of reaction time of the main chararteristics of the obtained materials. In water treatment system, variable realtor as solar light/ or UV lamp according to climate condition such as sunny and cloudy days treated the phenol and E-coli(Escherichia coli) effectively.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.79.2-79
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• 2003

• Nuclear Engineering and Technology
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• v.38 no.1
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• pp.61-68
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• 2006

CHF characteristics of nano- fluids were investigated with different volumetric concentrations of $TiO_2$ nanoparticles. Pool boiling experiments indicated that the application of nano-fluids, instead of pure water, as a cooling liquid significantly increased the CHF. SEM (scanning electron microscope) observations subsequent to the pool boiling experiments revealed that nanoparticles were coated on the heating surface during pool boiling of nano-fluids. In order to investigate the roles of nanoparticles in CHF enhancement ofb nano-fluids, pool boiling experiments were performed using (a) a nanoparticle-coated heater, prepared by pool boiling of nano-fluids, immersed in pure water and (b) a nanoparticle-coated heater immersed in nano-fluids. The results demonstrated two different roles of nanoparticles in CHF enhancement using nano-fluids: the effect of nanoparticles coated on the heater surface and the effect of nanoparticles suspended in nano- fluids.

• Korean Journal of Materials Research
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• v.22 no.8
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• pp.409-415
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• 2012

$TiO_2$ thin films for high energy density capacitors were prepared by r.f. magnetron sputtering at room temperature. Flexible PET (Polyethylene terephtalate) substrate was used to maintain the structure of the commercial film capacitors. The effects of deposition pressure on the crystallization and electrical properties of $TiO_2$ films were investigated. The crystal structure of $TiO_2$ films deposited on PET substrate at room temperature was unrelated to deposition pressure and showed an amorphous structure unlike that of films on Si substrate. The grain size and surface roughness of films decreased with increasing deposition pressure due to the difference of mean free path. X-ray photoelectron spectroscopy (XPS) analysis revealed the formation of chemically stable $TiO_2$ films. The dielectric constant of $TiO_2$ films was significantly changed with deposition pressure. $TiO_2$ films deposited at low pressure showed high dissipation factor due to the surface microstructure. The dielectric constant and dissipation factor of films deposited at 70 mTorr were found to be 100~120 and 0.83 at 1 kHz, respectively. The temperature dependence of the capacitance of $TiO_2$ films showed the properties of class I ceramic capacitors. $TiO_2$ films deposited at 10~30 mTorr showed dielectric breakdown at applied voltage of 7 V. However, the films of 500~300 nm thickness deposited at 50 and 70 mTorr showed a leakage current of ${\sim}10^{-8}{\sim}10^{-9}$ A at 100 V.

• Advances in nano research
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• v.15 no.4
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• pp.295-304
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• 2023

In this paper, a powerful photocatalyst based on carbon nanocomposite is developed in order to obtain a new material applicable in water treatment and especially for the discoloration of effluents used in the textile industry. For that, TiO₂-graphene nanocomposites have been successfully synthesized by a mixture of Functionalized Graphene Sheet (FGS) and tetrachlorotitanium complexes to form FGS-TiO₂ nanocomposite. In the presence of an anionic surfactant, we used a new chemical process to functionalize graphene sheets in order to make them an excellent medium for blocking and preventing the aggregation of TiO₂ nanoparticles. The components of these nanocomposites are characterized by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), which confirms the successful formation of the FGS-TiO₂ nanocomposite. It was found that the TiO₂ nanoparticles were dispersed uniformly on the graphene plane which possesses better charge separation capability than pure TiO₂. The FGS-TiO₂ nanocomposites exhibited higher photocatalytic activity compared to pure TiO₂ for the removal of three dyes: such as Methylene Blue (MB), Bromophenol Blue (BB) and Alizarin Red-S (AR) in water. The removal process was fast and more efficient with FGS-TiO₂ nanocomposite in daylight (in the absence of UV irradiation) compared to pure TiO₂ nanoparticles without and under UV in all pH range.

• Journal of the Korean Ceramic Society
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• v.51 no.3
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• pp.218-223
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• 2014

The domain structures, dielectric properties, and phase transformation of (001)-oriented $Pb(Mg_{1/3}Nb_{2/3})O_3-x%PbTiO_3$ (PMN-x%PT) crystals for x=20, 30, 35, and 40 mole% have been investigated. PMN-20%PT consists of polar nano-domains (PND) which do not self-assemble into macro-domain plates. PMN-30%PT consists of PNDs which begin to self-assemble into colonies along preferred {110} planes. PMN-35PT consists of miniature polar domains on the nm scale. PMN-40%PT consists of {001} oriented lamella domains on the mm scale that have internal nano-scale heterogeneities. The dielectric properties of poled (001) PMN-x%PT single crystals have been measured for orientations both parallel and perpendicular to the [001] poling direction. The results of the temperature dependence of the dielectric constant and mesh scans for the 30%PT sample demonstrate that the initial monoclinic phase changes to single domain tetragonal phase and to cubic phase with increasing temperature.

• Membrane Journal
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• v.17 no.3
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• pp.219-232
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• 2007

The polyethersulfone(PES)-titanium oxide($TiO_2$) hybrid membranes were prepared by immersion precipitation phase inversion method. The casting solution for the preparation of $PES-TiO_2$ hybrid membrane was provided by adding $TiO_2$ nano particles into the basis polymer solution of 14 wt% and 20 wt% PES/N-methyl-2-pyrrolidone(NMP). The $TiO_2$ loading [wt% ($TiO_2/NMP$)] in eating solution was varied from 0 to 60 wt%. Membrane performance and morphological change of the resulting $PES-TiO_2$ hybrid membranes were discussed in aspect of $TiO_2$ loading, by viscosity, coagulation value and light transmittance of the casting solution, measurement of tensile strength, pore size and contact angle, surface and cross sectional SEM images of the hybrid membrane, and ultrafiltration experiments using the hybrid membrane. According as increase of $TiO_2$ loading in the casting solution, viscosity is increased and coagulation value becomes lower, therefore the thermodynamic instability of the casting solution is increased. It is found that when $TiO_2$ loading is increased, 1) precipitation rate becomes faster while instantaneous demixing is maintained, 2) pure water flux, membrane pore size and compaction stability of the resulting membranes are increased, 3) tensile strength and contact angle are decreased. Dead-end ultrafiltration of bovine serum albumin(BSA) solution using the hybrid membrane shows that membrane performance(flux of BSA solution) enhanced up to 7 times compared with the results obtained using the pure PES membrane(not containing $TiO_2$ particle), due to the increase of hydrophilicity.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.97.2-97.2
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• 2007