• 한국전기화학회:학술대회논문집
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• 2001.10a
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• pp.41-41
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• 2001

• Korean Journal of Materials Research
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• v.10 no.11
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• pp.732-737
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• 2000

Plasma enhanced chemical vapor deposition of $TiO_{2$\pm}{\delta}$ has been carried out using TEMAT [tetrakis(ethylmethylamido) titanium] and $H_2$. Increasing the power from 300 W to 500 W produced the high density plasma, leading to the formation of TiO$_2$films with an increased ratio of Ti to O and a negligible amount of C and N. Applying the bias of 30W to the substrate in creased the growth rate of the film with a slightly increased content of Ti in the film. In addition, $H_2O$ was from either the residual gas in the gase pressure or $H_2(/He)$ gas and actively participated in the formation of $TiO_2$ films. Consequently, Ti ions created in the plasma could be a main contributor to $TiO_2$ formation with a slight amount of $H_2O(~10^{-4}Toor)$ in the ambient, which provided the dissociation of TEMAT.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.45-50
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• 2006

Oxygen-deficient anatase and rutile titanium dioxide $(TiO_{2-\delta})$ thin films were prepared by a sol-gel method and their structural, electronic, and magnetic properties were investigated. Both anatase and rutile $TiO_{2-\delta}:Fe$ Fe films exhibited ferromagnetism at room temperature for a limited range of Fe doping. For the same amount of Fe doping, the anatase sample exhibited a higher magnetic moment than the rutile one. Result of conversion electron Mossbauer spectroscopy measurements indicates that $Fe^{3+}$ ions substituting the octahedral $Ti^{4+}$ sites mainly contribute to the room-temperature ferromagnetism. Some of the anatase $TiO_{2-\delta}:Fe$ films exhibited p-type character but the observed feromagnetism turns out to be independent of the hole concentration. The room-temperature ferromagnetism can be explained in terms of a direct ferromagnetic coupling between two neighboring $Fe^{3+}$ ions via an electron trapped in oxygen vacancy in $TiO_{2-\delta}:Fe$.

• Membrane Journal
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• v.22 no.1
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• pp.8-15
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• 2012

Tubular $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ membranes with $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$ porous coating layer were prepared by extrusion and dip coating technique. XRD and SEM result showed the tubular membrane possessed the perovskite structure and porouscoating layer (thickness= about $2{\mu}m$) in surface. The oxygen permeation test was measured at condition of ambient air (feed side) and vacuum (permeate side) in the temperature range from 750 to $950^{\circ}C$. The oxygen permeation flux of $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ tubular membrane with $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$ porous coating layer reached maximum $3.2mL/min{\cdot}cm^2$ at $950^{\circ}C$ and was higher than non-coated $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ tubular membrane. Long-term stability test result indicated that the oxygen permeation flux was quite stable during the 11 day.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.131-134
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• 2002

The effect of the addition on the densification, low temperature sintering, and microwave dielectric properties of the Ca[($Li_{1/3}Nb_{2/3}$)$_{1-x}$$Ti_{x}$]$O_{3-{\delta}}$/(CLNT) was investigated. $Bi_2O_3$ additives improved the dencification and reduced the sintering temperature from $1150^{\circ}C$ to $900^{\circ}C$ of CLNT microwave dielectric ceramics. As increasing $Bi_2O_3$ contents, the dielectric constants and bulk density were increased. The quality factor, however, was decreased slighty. The temperature coefficients of the resonant frequency shifted positive value as increasing $Bi_2O_3$ contents. The dielectric properties of Ca[($Li_{1/3}Nb_{2/3}$)$_{1-x}$$Ti_{x}$]$O_{3-{\delta}}$ and Ca[($Li_{1/3}Nb_{2/3}$)$_{0.8}Ti_{0.2}$]$O_{3-{\delta}}$ with 5wt% $Bi_2O_3$ sintered at $900^{\circ}C$ for 3h were $\varepsilon_{r}$=20, 35 Q.$f_{0}$=6500, 11,000 GHz, $\tau_{f}$=4, 13 ppm/$^{\circ}C$, respectively.

• Journal of the Korean Ceramic Society
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• v.33 no.9
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• pp.1045-1049
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• 1996

Pressureless-sintered polycrystalline alumina and carbon steel were joined with Ag-33.5Cu-1.5Ti (wt%) brazing alloy. SEM observation revealed that two reaction layers with different thicknesses were continuously formed between the alumina and the brazing alloy. A thick layer formed on the brazing alloy side was identified as Ti3(Cu0.93Al0.07)3O phase with diamond cubic structure. Another thin layer adjacent to the alumina was revealed as $\delta$-TiO phase of which the crystal structure was HCP with a lattice parameter of a0=0.419 nm and c0=0.284 nm. It was confirmed using XPS analysis that $\delta$-TiO was formed directly by a redox reaction of alumina with titanium ir, molten brazing alloy.

• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.109-112
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• 2005

Electronic and magnetic properties of $Ti_{1-x}M_xO_{2-\delta}$ (M=Co and Fe) thin films grown by sol-gel method have been investigated. Anatase and rutile $Ti_{1-x}Co_xO_{2-\delta}$ films were successfully grown on $Al_2O_3$ (0001) substrates and exhibited p-type electrical conductivity while the undoped films n-type conductivity. Room temperature vibrating sample magnetometry measurements on the anatase and rutile $Ti_{1-x}Co_xO_{2-\delta}$ films with same x ($=4.8 at.{\%}$) showed quite similar magnetic hysteresis curves with the saturation magnetic moment of $\~4 {\mu}_B$ per Co ion despite their differences in structural and electronic properties. Such giant magnetic moment is attributable to the unquenched orbital moment of the $Co^{2+}$ ions substituting the octahedral $Ti^{4+}$ sites. Similar ferromagnetic behavior was observed for $Ti_{1-x}Fe_xO_{2-\delta}$ films that are highly resistive compared to the Co doped samples. Saturation magnetic moment was found to decrease for higher x, i.e., $\~2$ and $\~1.5 {\mu}_B$ per Fe ion for x=2.4 and 5.8 at. $\%$, respectively. Conversion electron $M\ddot{o}ssbauer$ spectroscopy measurements predicted the coexistence of $Fe^{2+}$ and $Fe^{3+}$ ions at the octahedral sites of $Ti_{1-x}Fe_xO_{2-\delta}$.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.103.1-103.1
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• 2000

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.103.2-103.2
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• 2000

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.108.2-108
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• 2000