• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.5
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• pp.362-366
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• 2000

$Li_{0.44}MnO_2$cathode material has high reversibility during lithium insertion processes and is not easily damaged through over-charging or over-discharging. $Mn_2O_3$is often present as an impurity phase, and reduce the electrochemical capacity of electrode because this phase is electrochemically inert. Adding of excess NaOH reduced the $Mn_2O_3$to the content under undetectable by X-ray diffraction. Because the capacity can be increased in the cathode materials with larger unit cell, some of the manganese was replaced with titanium having larger ion size, and powders with the formula $Li_{0.44}T_{iy}Mn_{1-y}O_2$(where y = 0.11, 0.22, 0.33, 0.44, and 0.55) was synthesized and characterized. A maximum reversible capacity of 150 mAh/g was obtained for $Li/P(EO)_8$LiTFSI/$Li_{0.44}Ti_{0.22}Mn_{0.78}O_2$cells in electrochemical potential spectroscopy (ECPS) experiments. Cells with the titanium-doped manganese oxides exhibited a fade rate of 0.12 % or less per cycle.

• Transactions of the Korean hydrogen and new energy society
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• v.3 no.2
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• pp.25-33
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• 1992

With the aim to obtain $TiO_2$ films with an increased photorespones and absorbance in the visible region of the solar spectrum, the direct oxidation of titanium alloys were performed. In this study, $Ti-Ga_2O_3$ alloy was prepared by mixing, pressing and arc melting of appropriate amounts of titanium and $Ga_2O_3$ powder. Electrochemical measurements were performed in three electrode cell using electrolyte of 1M NaOH solution. The oxide films on $Ti-Ga_2O_3$ alloy was composed of $Ti_2O$, TiO, $TiO_2$, $Ga_2TiO_5$. The free energy efficiency (${\eta}e$) of $Ti-Ga_2O_3$ oxide films had 0.8~1.3 % and were increased with the increase of $Ga_2O_3$ content up to 10wt %. The onset potential ($V_{on}$) had -0.8V~0.9V ranges and were shifted to anodic direction with the increase of $Ga_2O_3$ content. The spectral response of Ti-$Ga_2O_3$ oxides were similar to the response of the $TiO_2$ and their $E_g$ were observed to 2.90~3.0eV. Variations of onset potential($V_{on}$) associated with electrolyte pH were -59mV/pH. This probably reflects the nature of the bonding of $OH^-$ ion to the $TiO_2$ surface, a common phenomena in the transition-metal oxides.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.700-705
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• 2021

A portable and disposable pH sensor based on Ti wire was successfully developed for monitoring hydronium ion concentrations. A sensing electrode was prepared by electrochemically depositing iridium oxide onto a Ti wire, while a reference electrode was fabricated by coating Ag/AgCl ink on a Ti wire. Combining the two electrodes in the pH sensor enabled the collection of open circuit potential signals when the sensor was immersed in solutions of various pH values. The pH sensor exhibited excellent electrochemical sensing performance in terms of sensitivity, response time, repeatability, selectivity, and stability. To demonstrate point-of-measurement applications, the pH sensor was integrated with a wireless electronic module that could communicate with a mobile application. The portable pH sensor accurately measured pH changes in real samples. The results obtained were consistent with those of using a commercial pH meter.

• Membrane Journal
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• v.29 no.1
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• pp.30-36
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• 2019

In this study, we reported a solid-state supercapacitor consisting of titanium nitride (TiN) nanofiber and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS) conducting polymer electrode and poly(vinyl alcohol) (PVA)-based polymer electrolyte membrane. The TiN nanofiber was selected as electrode materials due to high electron conductivity and 2-dimensional structure which is beneficial for scaffold effect. PEDOT-PSS is suitable for organic/inorganic composites due to good redox reaction with hydrogen ions in electrolyte and good dispersion in solution. By synergetic effect of TiN nanofiber and PEDOT-PSS, the PEDOT-PSS/TiN electrode showed higher surface area than the flat Ti foil substrate. The PVA-based polymer electrolyte membrane could prevent leakage and explosion problem of conventional liquid electrolyte and possess high specific capacitance due to the fast ion diffusion of small $H^+$ ions. The specific capacitance of PEDOT-PSS/TiN supercapacitor reached 75 F/g, which was much higher than that of conventional carbon-based supercapacitors.

• Journal of IKEEE
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• v.27 no.4
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• pp.556-560
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• 2023

In this study, the impact of Nitrogen implantation process on deep-level defects and lifetime in 4H-SiC Epi surfaces was comparatively analyzed. Deep Level Transient Spectroscopy (DLTS) and Time Resolved Photoluminescence (TR-PL) were employed to measure deep-level defects and carrier lifetime. As-grown Schottky Barrier Diodes (SBDs) exhibited energy levels at 0.16 eV, 0.67 eV, and 1.54 eV, while for implantation SBD, defects at 0.15 eV were observed. This indicates a reduction in defects associated with energy levels Z_1/2 and EH_6/7, known as lifetime killers, as impurities from nitrogen implantation replace titanium and carbon vacancies.

• Korean Journal of Materials Research
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• v.10 no.12
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• pp.812-818
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• 2000

We studied the effects of Ge preamorphization (PAM) on 0.25$\mu\textrm{m}$ Ti-salicide junctions using comparative study with As PAM. For each PAM schemes, ion implantations are performed at a dose of 2E14 ion/$\textrm{cm}^2$ and at 20keV energy using $^{75}$ /As+and GeF4 ion sources. Ge PAM showed better sheet resistance and within- wafer uniformity than those of As PAM at 0.257m line width of n +/p-well junctions. This attributes to enhanced C54-silicidation reaction and strong (040) preferred orientation of the C54-silicide due to minimized As presence at n+ junctions. At p+ junctions, comparable performance was obtained in Rs reduction at fine lines from both As and Ge PAM schemes. Junction leakage current (JLC) revels are below ~1E-14 A/$\mu\textrm{m}^{2}$ at area patterns for all process conditions, whereas no degradation in JLC is shown under Ge PAM condition even at edge- intensive patterns. Smooth $TiSi_2$ interface is observed by cross- section TEM (X- TEM), which supports minimized silicide agglomeration due to Ge PAM and low level of JLC. Both junction break- down voltage (JBV) and contact resistances are satisfactory at all process conditions.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.1-16
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• 2008

Titanium dioxide ($TiO_2$) is one of the most researched semiconductor oxides that has revolutionised technologies in the field of environmental purification and energy generation. It has found extensive applications in heterogenous photocatalysis for removing organic pollutants from air and water and also in hydrogen production from photocatalytic water-splitting. Its use is popular because of its low cost, low toxicity, high chemical and thermal stability. But one of the critical limitations of $TiO_2$ as photocatalyst is its poor response to visible light. Several attempts have been made to modify the surface and electronic structures of $TiO_2$ to enhance its activity in the visible light region such as noble metal deposition, metal ion loading, cationic and anionic doping and sensitisation. Most of the results improved photocatalytic performance under visible light irradiation. This paper attempts to review and update some of the information on the $TiO_2$ photocatalytic technology and its accomplishment towards visible light region.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.718-722
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• 2015

Techniques for immobilizing effective enzymes on nanoparticles for stabilization of the activity of free enzymes have been developing as a pharmaceutical field. In this study, we examined the effect of three different pH conditions of phosphate buffer, as a dissolving solvent for lysosomal enzymes, on the direct immobilization of lysosomal enzymes extracted from Hen's egg white and Saccharomyces cerevisiae. Titanium(IV) oxide (TiO₂) nanoparticles, which are extensively used in many research fields, were used in this study. The lysosomal enzymes immobilized on TiO₂ under each pH condition were evaluated to maintain the specific activity of lysosomal enzymes, so that we can determine the degree of melanin treatment in lysosomal enzymes immobilized on TiO₂. We found that the immobilization efficiency and melanin treatment activity in both lysosomal enzymes extracted from Hen's egg white and S. cerevisiae were the highest in an acidic condition of phosphate buffer (pH 4). However, the immobilization efficiency and melanin treatment activity were inversely proportional to the increase in pH under alkaline conditions. In addition, enhanced immobilization efficiency was shown in TiO₂ pretreated with a divalent, positively charged ion, Ca²⁺, and the melanin treatment activity of immobilized lysosomal enzymes on TiO₂ pretreated with Ca²⁺ was also increased. Therefore, this result suggests that the immobilization efficiency and melanin treatment activity of lysosomal enzymes can be enhanced according to the pH conditions of the dissolving solvent.

• Analytical Science and Technology
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• v.11 no.4
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• pp.260-265
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• 1998

Spherical, ${\mu}m$-sized particles of barium titanyl oxalate were prepared by thermal decomposition of dimethyl oxalate in acidic barium and titanium solutions. Precipitation was carried out in the presence of several supporting anions. Spherical particles having a specific type of particle size distribution. i.e., unimodal or bimodal distribution, with mean size in the range of $0.2{\sim}3{\mu}m$, were formed depending on the supporting anions, oxalate ion generation rate and aging time. Particles of barium titanyl oxalate settled on the bottom of the beaker at the aging time of 120 min grew to the critical monosize of about $1.5{\sim}3{\mu}m$. XRD spectra and chemical analyses of barium titanate showed that barium titanyl oxalate with high qualities could be synthesized by choosing chloride ion as a supporting anion and increasing the reaction temperatures.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.46-52
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• 1992

$TiO_2/SO_4{^{2-}}$ was prepared by precipitation from the mixed solution of titanium chloride and hydrochloric acid followed by modification with sulfuric acid. The characterization of prepared catalyst was performed by using IR, XPS, XRD and DT-TGA. Infrared spectra of $TiO_2/SO_4{^{2-}}$ showed bidentate sulfate ion coordinated to the surface of $TiO_2$. The acid strength of modified catalyst was at least $H_0{\leq}-14.52$, showing the superacidic properties which are attributed to the double bond nature of S=O of the complex formed by the interaction of $TiO_2$ with sulfate ion. For $TiO_2/SO_4{^{2-}}$, the specific surface area increased and the transition from the amorphous to anatase phase occurred at a higher temperature, as compared with pure $TiO_2$.