• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.98-104
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• 2002

CeO$_2$ and NiO buffers for YBCO coated conductors were deposited on biaxially textured Ni substrate by metalorganic chemical vapor deposition(MOCVD) and the deposition behavior were investigated. The degree of texture of deposited CeO$_2$ and NiO films was strongly dependent on the deposition temperature(T$\sub$d/) and oxygen partial pressure(P$\sub$O$_2$/). ($\ell$00) textured films were well deposited at specific deposition temperatures and oxygen partial pressures. The in-plane and out of plane textures estimated form the full width half maximum of the pole figure peaks were less than 10$^{\circ}$. The surface morphology showed that the CeO$_2$ films consisted of columnar grains grown normal to the Ni substrates, while NiO films were slate and clean like a mirror. The surface roughness of both films estimated by atomic force microscopy(AFM) were as smooth as 3-10 m. The growth rate of the films is much faster than that of other physical deposition methods.

• Journal of the Korean Ceramic Society
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• v.32 no.2
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• pp.234-238
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• 1995

MgFe2O4 formation, grain growth in Fe2O3, Fe solid-solution limit in MgO for MgO-Fe2O3 mixture were studied by means of investigating the distribution of phases and compositions in reaction area between MgO and Fe2O3. The reaction area at equlibrium was composed with MgO-FexO matrix and MgFe2O4 precipitation, MgFe2O4 was formed by precipitating from MgO-FexO matrix dependent on oxygen partial pressure. Fe contents was exponentially decreased with diffusion distance in MgO single crystal, and thus Fe solid-solution limitation in MgO was about 4mol%. The grain growth rate in Fe2O3 base was increased with Mg contents diffused from MgO single crystal.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.231-232
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• 2009

• Journal of the Korean Ceramic Society
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• v.28 no.12
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• pp.989-995
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• 1991

By means of the secondary ion mass spectrometer, the tracer diffusion of oxygen in rutile single crystal was measured as function of temperature and oxygen partial pressure. The tracer diffusivity was determined from the depth profile of 18O. The Po2 dependence of D suggests that the dominant defects in TiO2-y are oxygen vacancies (V{{{{ { ‥} atop { o} }}) and interstitial titanium ions (Ti{{{{ {‥‥} atop {i} }}). The doubly ionized oxygen vacancies are prominent at low temperature and Po2. However, the tetravalent interstitial titanium ions predominate at teperature above 120$0^{\circ}C$.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.6
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• pp.886-894
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• 1990

Sinterbility, microstructure, mechenical and electrical properties of yttriastabilized zirkconiz (92 mole % ZrO2 + 8 mole % Y2O3) doped with 0.5 mole % SiO2 and 0-2.O mole% Al2O3 were studied as a functin of Al2O3 addition. Sintered density increased with increasing Al2O3 addition up to o.5 mole%but decreased up to 1.0mole% Al2O3. Vickers hardness is proportional to sintered density. The specimen added 0.5mole% Al2O3 and 0.5mole% SiO2 exhibited a maximum conductivity. And the specimen added 0.5 mole % Al2O3 and 0.5 mole% SiO2 was measured a maximum electromotive force for a characteristics of oxyzen partial pressure.

• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.805-811
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• 2006

The microstructural changes in Ni/YSZ anode substrate and crack formation during Ni oxidation were investigated. The composition of as-sintered anodes was 56 wt% NiO+44 wt% YSZ and that of electrolyte was 8 mol% yttria. After complete reduction, specimens were oxidized in $N_2$ + air at $600\sim800^{\circ}C$. Oxygen partial pressure was controlled in between 0.05 atm and 0.2 atm $O_2$. When the anode was oxidized, at higher than $690^{\circ}C$, three layers were formed in the specimens. The first was fully oxidized layer(NiO/YSZ), the second was a mixed layer and the third, near-intact layer. Under $640^{\circ}C$ such distinctive layers were not observed. Cracks formed at electrolyte layer when weight gain attained at $65\sim75%$ of the total gain due to complete oxidation despite of different oxidation temperature and oxygen partial pressure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.52-53
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• 2005

$Y_2O_3$ film was directly deposited on Ni-3at%W substrate using DC reactive sputtering technique. Metallic yttrium was used for DC sputtering target and water vapor was used for oxidizing the deposited metallic Yttrium atoms on the substrate. The window of the water vapor turned out to be broad. The minimum partial pressure of water vapor was determined by sufficient oxidation of the $Y_2O_3$ film, and the maximum partial pressure of water vapor was determined by the non-oxidation of the target surface. As the sputtering power was increased, The deposition rate increased without narrowing the window. The fabricated $Y_2O_3$ films showed good texture qualities and surface morphologies. The YBCO film deposited directly on the $Y_2O_3$ buffered Ni-3at%W substrate showed $T_c$, $I_c$ (77 K, self field), and $J_c$ (77 K, self field) of 89 K, 64 A/cm and 1.l $MA/cm^2$, respectively.

• Journal of the Korean Chemical Society
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• v.29 no.6
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• pp.608-614
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• 1985

Electrical conductivities of $ZrO_2-Sm_2O_3$ systems containing 10, 20, 30, 40, and 50 mol% of $ZrO_2$ have been measured as a function of temperature and of oxygen partial pressure at temperature from 500 to 1000${\circ}C$ and oxygen partial pressures from 1 ${\times}10^{-5}to 1{\times}10^{-1}$ atm. Plots of log conductivity vs. 1/T are found to be linear with an inflection point at around 650$^{\circ}C$ and the temperature dependence of conductivity shows two different defect structures. The conductivities are increased with increasing pressure, slowing a p-type character. The electrical conductivity dependences on $Po_2$ are found to be ${\sigma}{\propto}Po_2^{1/5.3}$ at 650∼1000$^{\circ}C$ and ${\sigma}{\propto}Po_2^{1/6}$ at 500∼650$^{\circ}C$, respectively, The defect structures are Oi" at 650-1000$^{\circ}C$ and $Vs_m$"' at 500-650$^{\circ}C$. The electron hole is main carrier type, however ionic contribution is found at low temperature portion. Ionic contributions increased with the increasing amount of $ZrO_2$ dopant. In 60mol% $ZrO_2-Sm_2O_3$ system, the conductivity is increased with decreasing oxygen pressure.

• Journal of the Korean Ceramic Society
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• v.34 no.12
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• pp.1221-1226
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• 1997

The effects of sintering atmosphere and dopant addition on the behavior of densification and grain growth of SnO2 ceramics were investigated with consideration of defect chemistry. CoO and Nb2O5 were chosen as dopants, and oxygen and nitrogen were used for controlling of sintering atmospheres. With the decrease of oxygen partial pressure, densification was depressed due to evaporation of SnO2 ceramics. In the case of SnO2 sintering, the addition of CoO, which produced oxygen vacancy in SnO2 ceramics, led to acceleration of densification and grain growth. On the contrary, when Nb2O5 as a dopant producing Sn vacancy was added to SnO2 ceramics, densification and grain growth were simultaneously retarded. As results, it was conformed that diffusion of oxygen ions was rate determinant in densification and grain growth of SnO2 ceramics.

• The Korean Journal of Ceramics
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• v.4 no.2
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• pp.151-155
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• 1998

The total electrical conductivity, ionic conductivity, and nonstoichimetry of a new cathode material $Y_{1-x}Ca_xFeO_{3-\delta}$ (x=0.1) were measured as functions of temperature ($900\leqT/^{\circ}C\leq1100$) and oxygen partial pressure $(10^{-6}\leqPo_2/atm\leq0.21$). Isothermal variations of these properties with $Po_2$ support that the majority type of ionic defects are anti-Frenkel disorder which, however, has seldom been considered for perovskite-based oxides. The results are discussed in comparison with those reported on similar oxides.