• 한국분말재료학회지
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• 제29권6호
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• pp.492-498
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• 2022

N-doped Na₂Ti₆O₁₃@TiO₂ (denoted as N-NTO@TiO₂) composites are successfully synthesized using a simple two-step process: 1) ball-milling of TiO₂ with Na₂CO₃ followed by heat treatment at 900℃; 2) mixing of the prepared Na₂Ti₆O₁₃ with titanium isopropoxide and calcining with urea at 500℃. The prepared composites are characterized using XRD, SEM, TEM, FTIR, and BET. The N-NTO@TiO₂ composites exhibit well-defined crystalline and anatase TiO₂ with exposed {101} facets on the external surface. Moreover, dopant N atoms are uniformly distributed over a relatively large area in the lattice of the composites. Under visible light irradiation, ~51% of the aqueous methylene blue is photodegraded by N-NTO@TiO₂ composites, which is higher than the values shown by other samples because of the coupling effects of the hybridization of NTO and TiO₂, N-doping, and presence of anatase TiO₂ with exposed {101} facets.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.119-120
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• 2013

공구, 다이몰드 등에 널리 쓰이는 TiC, TiN, CrN, TiCrN, TiAlN 코팅의 산화특성을 비교하기 위하여 $600^{\circ}C-900^{\circ}C$에서 대기중 산화시험을 실시하였다. 내산화성은 (TiC, TiN), TiAlN, TiCrN, CrN 코팅의 순서로 증가하였다. 코팅원소중 Ti는 $TiO_2$로, Cr은 $Cr_2O_3$로, Al은 $Al_2O_3$로 산화되었다.

• ETRI Journal
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• 제13권4호
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• pp.58-69
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• 1991

고집적회로에서 A1 금속공정의 diffusion barrier로 널리 사용되는 titanium nitride의 성질을 조사하였다. 실제 회로 구조의 열적 안정성을 관찰하기 위하여 준비된 TiN/Ti다층 barrier를 $600^{\circ}C$까지 열처리하여 x-ray photoelectron spectroscopy (XPS), cross-sectional transmission electron microscopy(XTEM) 등으로 분석하였다. 열처리 온도가 증가됨에 따라 oxygen은 TiN 층의 표면과 pure-Ti 층에 pile up 된다. TiN 층의 표면에서는 $600^{\circ}C$열처리시 TiN이 분해되어 완전히 $TiO_2$가 형성되며, TiN 층 내에서는 oxygen 함량은 열처리 온도의 증가에 따라 커지고 이때 형성되는 Ti-oxide는 $TiO_2$ 보다 TiO, $Ti_2$$O_3$ 상태로 존재하게 된다. Pure-Ti 층은 열처리시 두개의 층으로 나누어 지는 데, 표면에서 침투하는 oxygen과 pure-Ti이 반응하여 Ti-oxide 층이 생기며 실리콘 기판과의 반응으로 Ti-silicide를 형성한다. $600^{\circ}C$에서 모든 Ti 층이 반응으로 소모되고 열적 stress, Ti-silicide의 grain growth, oxygen의 침입으로 TiN 층에 blistering이 발생한다.

• 대한환경공학회지
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• 제27권1호
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• pp.59-66
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• 2005

[ $TiO_2$ ]박막은 DC 마그네트론 스퍼터링법을 이용하여 다양한 스퍼터링 파라미터(전력 $0.6{\sim}5.2\;kw$, 기판온도 실온${\sim}350^{\circ}C$, 산소량 $0{\sim}50\;sccm$($O_2+Ar$ 90 sccm, 압력은 약 1 mtorr))를 통하여 증착되었다. TiO-N박막도 가스의 유량비를 제외하고는 $TiO_2$박막과 같은 스퍼터링 조건하에서 증착되었다. 이러한 스퍼터링 파라미터에서 증착된 박막의 전기적 특성을 분석하기 위하여 시트저항을 측정하였고, 박막의 두께(${\alpha}$-step), 표면 거칠기(AFM), 형성 조직(FE-SEM, XRD)을 분석하여 최적 스퍼터링 파라미터를 도출하였다. 최적 스퍼터링 파라미터에서 제조된($TiO_2$, TiO-N)박막을 이용하여 광활성도를 평가하기 위하여 VOCs물질 중 toluene, 반응성 염료인 Suncion Yellow를 대상 물질로 선정하여 적용성 연구를 수행하였다. 실험에서 광촉매 박막은 적용물질에 대해서 광활성을 양호하게 보였으며, 특히 TiO-N광촉매 박막은 가시광 영역에서도 최대 33%의 톨루엔(5 ppm) 제거 효율을 나타내었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.31.2-31.2
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• 2011

We have investigated frequency dependant conductivity (or permittivity) of low dimensional oxide structures represented by [($Sr_{0.75}$, $La_{0.25}$)$TiO_3$]$_1$/1$[SrTiO_3]_n$ superlattices. The low dimensional oxide superlattice was made by cumulative stacking of one unit cell thick La doped $SrTiO_3$ and $SrTiO_3$ with variable thickness from 1 to 6 unit cell, i,e, [($Sr_{0.75}$, $La_{0.25}$)$TiO_3$]$_1$/$[SrTiO_3]_n$ (n=1, 2, 3, 4, 5, 6). We found two kinds of relaxation when n is 3 and 4, while, inductance component was observed at n=1. This behavior can be explained by electron modulation in ($Sr_{0.75}$, $La_{0.25}$)$TiO_3/SrTiO_3$ superlattices. When n is 1, electrons by La doping well extend to un-doped layer. Therefore, the transport of superlattices follows bulk-like behavior. On the other hand, as n increased, the doped electrons became two types of carrier: one localized and the other extended. These results in two kinds of transport phase. At further increase of n, most of doped electrons are localized at the doped layer. This result shows that dimensionality of the oxide structure significantly affect the transport of oxide nanostructures.

• 공업화학
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• 제9권4호
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• pp.585-590
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• 1998

섬유상의 $Na_xTi_nO_{2n+1}$는 층상구조의 $H_2Ti_4O_9{\cdot}nH_2O$에대한 $H^+/Na^+$의 이온교환에 의해서 합성되었다. 이온교환 반응은 0.5~2.0 M NaOH 용액에서 이루어졌으며, 2.0 M NaOH의 용액에서 이온 교환할 때 73%가 치환되었다. 이 때 길이가 $10{\sim}20{\mu}m$이고 직경이 약 $0.7{\mu}m$인 비교적 균일한 형태의 섬유상을 얻을 수 있었다. 그리고 층상구조의 티탄산나트륨에 대한 상전이는 열분석을 통해 확인하였으며, 이 결과 $Na_xTi_nO_{2n+1}$ 섬유는 $200{\sim}600^{\circ}C$의 온도에서 $Na_2Ti_6O_{13}$과 $TiO_2$로 분해되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.374.2-374.2
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• 2016

Volatile organic compounds (VOCs) in the atmosphere are harmful materials which influence indoor air environment and human health. Titanium dioxide ($TiO_2$) is photocatalyst extensively used in degradation of organic compound. To improve the photocatalytic activity in the visible light region, doping with non-metals element or loading noble metals on the surface of $TiO_2$ is generally proposed. In this study, N- doped $TiO_2$ having photocatalytic activity in visible light region was attached noble metal such as Pt, Ag, Pd, Au by coupling method. Catalytic activities of Noble metal coupled $N-TiO_2$ powders were evaluated by the improvement of their photocatalytic activities and the degradation of VOC gas. A UV-Vis spectrophotometer was used to measure the diffuse reflectance spectra of coupled $N-TiO_2$ sample. The photocatlytic activities of as prepared samples were characterized by the decoloration of aqueous MB solution under Xenon light source (UV and visible light). To measure of decomposition VOCs, ethylbenzene was selected for target VOC material and the concentration was monitored under UVLED irradiation in a closed chamber system. Adjusting the initial concentration of 10~12 ppm, to evaluate the removal characteristics by using the coupled $N-TiO_2$.

• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1269-1274
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• 2012

A visible light responsive N, Mo co-doped $TiO_2$ were prepared by sol-gel method. X-ray diffraction, TEM, $N_2$ adsorption, UV-vis spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy were used to characterize the prepared $TiO_2$ samples. Doping restrained the phase transformation from anatase to rutile and reduced the particle sizes. The band gap was much narrowed after N, Mo co-doping. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activities of doped $TiO_2$ were much higher than that of neat $TiO_2$. The photocatalytic stability of N, Mo co-doped $TiO_2$ was much better than that of N doped $TiO_2$.

• Environmental Engineering Research
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• 제18권1호
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• pp.21-28
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• 2013

In this study, the applicability of visible light-emitting-diodes (LEDs) to the photocatalytic degradation of indoor-level trichloroethylene (TCE) and perchloroethylene (PCE) over N-doped $TiO_2$ (N-$TiO_2$) was examined under a range of operational conditions. The N-$TiO_2$ photocatalyst was calcined at $650^{\circ}C$ (labeled N-650) showed the lowest degradation efficiencies for TCE and PCE, while the N-$TiO_2$ photocatalysts calcined at $350^{\circ}C$, $450^{\circ}C$, and $550^{\circ}C$ (labeled as N-350, N-450, and N-550, respectively) exhibited similar or slightly different degradation efficiencies to those of TCE and PCE. These results were supported by the X-ray diffraction patterns of N-350, N-450, N-550, and N-650. The respective average degradation efficiencies for TCE and PCE were 96% and 77% for the 8-W lamp/N-$TiO_2$ system, 32% and 20% for the violet LED/N-$TiO_2$ system, and ~0% and 4% for the blue LED/N-$TiO_2$ system. However, the normalized photocatalytic degradation efficiencies for TCE and PCE for the violet LED-irradiated N-$TiO_2$ system were higher than those from the 8-W fluorescent daylight lamp-irradiated N-$TiO_2$ system. Although the difference was not substantial, the degradation efficiencies exhibited a decreasing trend with increasing input concentrations. The degradation efficiencies for TCE and PCE decreased with increasing air flow rates. In general, the degradation efficiencies for both target compounds decreased as relative humidity increased. Consequently, it was indicated that violet LEDs can be utilized as energy-efficient light sources for the photocatalytic degradation of TCE and PCE, if operational conditions of N-$TiO_2$ photocatalytic system are optimized.

• 한국응용과학기술학회지
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• 제29권3호
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• pp.466-472
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• 2012

가시광선에 감응하는 광촉매를 제조하기 위하여 $TiO_2$에 질소(N)를 도핑하여 $N-TiO_2$를 제조하였다. 제조한 광촉매의 결정성, 입자 형상 및 도핑 상태는 XRD, FE-SEM 및 XPS를 이용하여 조사하였다. 제조한 광촉매의 활성 평가는 메틸렌블루의 광분해로 조사하였다. 제조한 광촉매는 anatase type이었으며, pH가 높을수록 결정화도가 향상되었다. 제조한 광촉매의 입자 크기는 pH 2.0에서 5.42 nm, pH 4.7에서 5.99 nm, pH 9.0에서 7.58 nm로, 입자 크기는 pH가 증가 할수록 약간씩 증가하였다. 광촉매의 활성은 결정화도에 비례하였다. $TiO_2$에 N를 도핑하여 제조한 $N-TiO_2$가 가시광선 하에서도 활성을 나타냈다. $TiO_2$에 도핑한 N는 격자 속에 존재하는 것이 아니라 표면에 존재하였다.