• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.998-1003
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• 1998

$BaTiO_3$ thin film was electrochemically deposited on Ti electrode in a 0.4 M $Ba(OH)_2$ solution of $85^{\circ}C$ using a current pulse waveform. Both $BaTiO_3$ crystallinity and faradaic efficiency for the film formation were enhanced with the increase of cathodic current density and pulse time. Based on the surface analysis and electrochemical studies, it was suggested that, during cathodic pulsed, the surface pH increase due to the reduction of $H_2O$ accelerates the structural changes of Ti oxides which were formed during anodic cycle. Prior to experiments, Ti oxides were intentionally grown in 0.1 M $H_2SO_4$ solution and the effect of initial oxide film thickness on the $BaTiO_3$ film formation was investigated. The migration of $Ti^{+4}$ ions through the oxide film was retarded with the increase of film thickness and it was observed that the crystallization of $BaTiO_3$ was only limited to the defect area of surface oxides.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.100-100
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• 2011

Nanomaterial architecture with highly ordered, vertically oriented $TiO_2$ nanotube arrays shows a good promise for diverse technological applications. As inspired from the literature reports that Nickel modification can improve the photocatalytic activity of $TiO_2$, it was planned to coat Ni into the $TiO_2$ matrix. In this study, first $TiO_2$ nanotubes(TiNTs) were prepared by anodization (60V,3min) in HF-free aqueous electrolyte on ultrasonically cleaned polished titanium sheet substrates ($1{\times}7cm^2$). The typical thickness of the sintered TiNT ($500^{\circ}C$for10min) was ~1 micronas confirmed from the FESEM study. In the next part, as-anodized and sintered TiNT/Ti photoanodes were used to coat Ni by AC electrodeposition from aqueous 0.1M nickel sulphate solution. During AC electrodeposition, conditions such as 1V DC offset voltage, 9V amplitude (peak-to-peak) and 750 Hz frequency were fixed constant and the deposition time was varied as 0.5 min, 1 min, 2 min and 10 min. The photoelectrochemical performance of pristine and Ni modified TiNT/Ti photoanodes was measured in 1N NaOH electrolyte under 1 SUN illumination in the potential range of -1V and 1.2V versus Ag/AgCl reference electrode. The photocurrent performance of TiNT/Ti photoanode decreased upon Ni modification and the results were confirmed after repeated experiments. This suggests us that Ni modification inhibits the photoelectrochemical performance of $TiO_2$ nanotubes.

• Journal of Powder Materials
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• v.15 no.6
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• pp.503-508
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• 2008

Ti(C,N) solid solutions in hot-pressed Ti($C_{x}N_{1-x}$) (x=0.0, 0.3, 0.5, 0.7, 1.0) and 40TiC-40TiN-20Ni (in wt.%) cermet were characterized in this study. For hot-pressed Ti(C,N)s, the lattice parameters and hardness values of Ti(C,N) were determined by using XRD (X-Ray Diffraction) and nanoindentation. The properties of hot-pressed Ti(C,N) samples changed linearly with their carbon or nitrogen contents. For the TiC-TiN-Ni cermet, the hardness of the hard phase and binder phase were determined by nanoindentation in conjunction with microstructural observation. The measured hardness values were ${\sim}8.7$ GPa for the binder phase and ${\sim}28.7$ GPa for the hard phase, which was close to the hardness of hot-pressed Ti($C_{0.7}N_{0.3}$).

• Korean Journal of Crystallography
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• v.6 no.2
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• pp.111-117
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• 1995

TiO2 thin films were prepared on a (100)silicon wafer using a chemical vapor deposition(CVD) method. The deposition experiments were performed using the TTIP in the deposition temperature ransing from 200 content. The deposition rate of TiO2 was increased with the substrate temperature and the oxygen content. The thickness of the deposited thin film and the compositional analysis of this thin films with theoxygen content were measured using Ellipsometry, SEM and ESCA, respectively. The deposited thin film was composed of a bilayer, external TiO2 and internal Ti. Carbon as a residual impurity was found to remain when zero sccm O2 was purged into a reaction chamber and the composition of the deposited thin film was found to change Ti into TiO in a deeper layer. However, when 600sccm O2 was supplied to a reaction chamber, it has been found to reside less carbon content than without O2. Finally, in the condition of 1200sccm O2, no impurity level of carbon was observed and a deeper layer consisted of the Ti composite, even though the deposited surface was composed of TiO2.

• The Journal of Advanced Prosthodontics
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• v.1 no.1
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• pp.56-61
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• 2009

STATEMENT OF PROBLEM. The success of titanium implants is due to osseointegration or the direct contact of the implant surface and bone without a fibrous connective tissue interface. PURPOSE. The purpose of this study was to evaluate the osteoblast precursor response to titanium-10 tantalum-10 niobium(Ti-Ta-Nb) alloy and its sputtered coating. MATERIAL AND METHODS. Ti-Ta-Nb coatings were sputtered onto the Ti-Ta-Nb disks. Ti6-Al-4V alloy disks were used as controls. An osteoblast precursor cell line, were used to evaluate the cell responses to the 3 groups. Cell attachment was measured using coulter counter and the cell morphology during attachment period was observed using fluorescent microscopy. Cell culture was performed at 4, 8, 12 and 16 days. RESULTS. The sputtered Ti-Ta-Nb coatings consisted of dense nanoscale grains in the range of 30 to 100 nm with alpha-Ti crystal structure. The Ti-Ta-Nb disks and its sputtered nanoscale coatings exhibited greater hydrophilicity and rougher surfaces compared to the Ti-6Al-4V disks. The sputtered nanoscale Ti-Ta-Nb coatings exhibited significantly greater cell attachment compared to Ti-6Al-4V and Ti-Ta-Nb disks. Nanoscale Ti-Ta-Nb coatings exhibited significantly greater ALP specific activity and total protein production compared to the other 2 groups CONCLUSIONS. It was concluded that nanoscale Ti-Ta-Nb coatings enhance cell adhesion. In addition, Ti-Ta-Nb alloy and its nanoscale coatings enhanced osteoblast differentiation, but did not support osteoblast precursor proliferation compared to Ti-6Al-4V. These results indicate that the new developed Ti-Ta-Nb alloy and its nanoscale Ti-Ta-Nb coatings may be useful as an implant material.

• Journal of the Korean Magnetics Society
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• v.15 no.6
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• pp.311-314
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• 2005

We investigated the composition dependence of the tunneling magnetoresistance (TMR) behavior and the stability of the magnetic tunnel junctions (MTJs) with TiAlOx barrier and the microstructural evolution of TiAl alloy films. The TMR ratio increased up to $49\%$ at $5.33\;at\%$ Ti. In addition, a significant tunneling magnetoresistance (TMR) value of $20\%$ was maintained after annealing at $450^{\circ}C$, and the breakdown voltage ($V_B$) of and 1.35 V were obtained in the MTJ with $5.33\;at\%$ Ti-alloyed AlOx barrier. These results were closely related to the enhanced quality of the barrier material microstructure in the pre-oxidation state. Ti alloying enhanced the barrier/electrode interface uniformity and reduced microstructural defects. These structural improvements enhanced not only the TMR effect but also the thermal and electrical stability of the MTJs.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.130.1-130.1
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• 2013

We made attempts to improve photocatalytic activity of $TiO_2$ nanoparticles under visible light exposure by combining two additional treatments. N-doping of $TiO_2$ by ammonia gas treatment at $600^{\circ}C$ increased absorbance of visible light. By coating thin film of polydimethylsiloxane (PDMS), and subsequent vacuum-annealing at $800^{\circ}C$, $TiO_2$, became more hydrophilic, thereby enhancing photocatalytic activity of $TiO_2$. Four types of $TiO_2$ samples were prepared, bare-$TiO_2$, hydrophilic-modified $TiO_2$ ($h-PDMS/TiO_2$), N-doped $TiO_2$ ($N/TiO_2$) and hydrophilic-modified and N-doped $TiO_2$ ($h-PDMS/N/TiO_2$). Adsorption capability was evaluated under dark condition and photocatalytic activity of $TiO_2$ was evaluated by photodegradation of MB under blue LED (400 nm< ${\lambda}$) irradiation. N-doping on $TiO_2$ was characterized using XPS and hydrophilic modification of $TiO_2$ surface was analyzed by FT-IR spectrometer. It was found that N-doping and hydrophilic modification both had positive effect on enhancing adsorption capability and photocatalytic activity of $TiO_2$ at the same time. Particularly, N-doping enhanced visible light absorption of $TiO_2$, whereas hydrophilic surface modification increased MB adsorption capacity. By combining these two strategies, photocatalytic acitivity under visible light irradiation became the sum of individual effects of N-doping and hydrophilic modification.

• Journal of the Korean GEO-environmental Society
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• v.12 no.11
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• pp.31-37
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• 2011

This study investigated on the adsorption and photocatalysis of Reactive Black 5(RB5) by the hydroxyapatite(HAP)/Titanium dioxide($TiO_{2}$) media. The adsorption of RB5 on $TiO_{2}$, HAP and $TiO_{2}$/HAP was investigated during a series of batch adsorption experiments. The amounts adsorbed at equilibrium were measured. Langmuir and Freundlich isotherm models were tested for their applicability. The result of equilibrium studies of $TiO_{2}$, HAP and $TiO_{2}$/HAP adsorbent were found to follow Langmuir isotherm model. The adsorbed amounts(Qmax) were found to be 5.28mg/g on single $TiO_{2}$, 12.45mg/g on single HAP and 9.03mg/g on $TiO_{2}$/HAP, respectively. The experimental data were analysed using the pseudo-first-order adsorption and photocatalysis kinetic models. According to these models, RB5 degradation by $TiO_{2}$/HAP was affected by interaction effect of photocatalysis and adsorption.

• Korean Journal of Metals and Materials
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• v.46 no.10
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• pp.691-699
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• 2008

Electrochemical characteristics of Ti-30Ta-xZr alloys coated with HA/TiN by using magnetron sputtering method were studied. The Ti-30Ta containing Zr(3, 7, 10 and 15wt%) were 10 times melted to improve chemical homogeneity by using a vacuum furnace and then homogenized for 24hrs at $1000^{\circ}C$. The specimens were cut and polished for corrosion test and coating, and then coated with HA/TiN, respectively, by using DC and RF-magnetron sputtering method. The analyses of coated surface and coated layer were carried out by using optical microscope(OM), field emission scanning electron microscope(FE-SEM) and X-ray diffractometer(XRD). The electrochemical characteristics were examined using potentiodynamic (-1,500 mV~ + 2,000 mV) and A.C. impedance spectroscopy(100 kHz ~ 10 mHz) in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The microstructure of homogenized Ti-30Ta-xZr alloys showed needle-like structure. In case of homogenized Ti-30Ta-xZr alloys, a-peak was increased with increasing Zr content. The thickness of TiN and HA coated layer showed 400 nm and 100 nm, respectively. The corrosion resistance of HA/TiN-coated Ti-30Ta-xZr alloys were higher than that of the non-coated Ti-30TaxZr alloys, whic hindicate better protective effect. The polarization resistance($R_p$) value of HA/TiN coated Ti-30Ta-xZr alloys showed $8.40{\times}10^5{\Omega}cm^2$ which was higher than that of non-coated Ti-30Ta-xZr alloys.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.6
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• pp.52-54
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• 1982

p·Si-전해질 접합을 전해질로 6N H2SO4, 6N H2SO4(Ti3+), 6N H2SO4(Ti4+), 6N H2SO4(Ti4+/Ti3+)을 사용하여 만들었다. 이들 전해질중 6N H2SO4(Ti4-/Ti3+)을 사용할 때 p·Si 광음극이 안정하게 동학하며 높은 광전 감도를 가지고 있었다. p·Si-electrolyte junction are prepared by using p·Si photocatode in four different electrolytes such as 6N H2SO4, 6N H2SO4(Ti3+), 6N H2SO4(Ti4+), 6N H2SO4(Ti4+/Ti3+) respectively. Among those electrolytes 6N H2SO4(Ti4-/Ti3+) shows very good results, in which p·Si photocathode is stable.