• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1334_1335
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• 2009

In this paper we have presented recent studies concerning the high performance oxide thin film transistor (TFT) with a-IGZO channel and $ZrO_2$ gate dielectrics. The a-IGZO TFT is fully fabricated at room-temperature without any thermal treatments. The $ZrO_2$ is one of the most promising high-k materials with high capacitance originated from the high dielectric constant. The a-IGZO TFT with $ZrO_2$ shows high performance exhibiting high field effect mobility of $39.82\;cm^2$/Vs and high on-current of 2.52 mA at 10V.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.239-239
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• 1999

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.251-251
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• 2002

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.547-553
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• 2013

Zirconium oxide ($ZrO_2$) nano porous membranes were fabricated by electrochemical two-step anodization with an electropolished zirconium substrate in inorganic water-based and organic electrolyte systems containing small amounts of fluoride. Using two-step anodization and organic electrolytes, highly regular and ordered nanotubular $ZrO_2$ oxide layers can be compared with aqueous electrolytes. The morphology and size of the nano porous layers were characterized by FE-SEM (field emission scanning electron microscopy), XRD (X-ray diffraction), and EDS (energy dispersive spectroscopy). Luminescence properties were investigated by photoluminescence measurements.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.269-274
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• 2018

All the $Ni-Co-Ce-ZrO_2$ mixed oxides are prepared by co-precipitations methods. Methanation of CO and $H_2$ reaction is screened tested over different fractions of cerium (2, 4, 7 and 12 wt.%) over $Ni-Co/ZrO_2$ bimetallic catalysts are investigated. The mixed oxides are characterized by XRD, CO-Chemisorption, TGA and screened methanation of CO and $H_2$ at $360^{\circ}C$ for 3000 min on stream at typical ratio $CO:H_2=1:1$. In $Ni-Co/CeZrO_2$ series 2 wt.% Ce loading catalyst shows most promising catalyst for $CH_4$ selectivity than $CO_2$, which directs more stability with less coke formation. The high activity is attributed to the better bimetallic synergy and the well-developed crystalline phases of NiO, $ZrO_2$ and $Ce-ZrO_2$. Other bimetallic mixed oxides NCoZ, $NCoC^{4-12}Z$ has faster deactivation with low methanation activity. Finally, 2 wt.% Ce loading catalyst was found to be optimal coke resistant catalyst.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.86-89
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• 2015

Uniform ZrO₂ nanoballs were synthesized at 700℃ using the inverse replication method through a colloid-imprinted carbon (CIC) template. The structural, dielectric, and conducting properties of the ZrO₂ nanoballs were investigated and compared with those of ZrO₂ film prepared by sol-gel method and powdered ZrO₂ chemical. Both the monoclinic and cubic phases were found in the ZrO₂ balls and film but the ZrO₂ chemical showed a monoclinic phase, where the cubic structure is known to be formed at above 2,300℃. ZrO₂ nanoballs showed the lower dielectric property of k = 21.2 at 1 MHz because the 8-coordinated cubic phase in the ZrO₂ nanoball produced lower polarization than the polarization of the 7-coordinated monoclinic ZrO₂ chemical (k = 23.6). The dielectric stability was maintained in each ZrO₂ ball, film, and chemical under the applied forward and reverse voltage range (−5 to +5 V) at 1 MHz. The ionic conductivities were 7.86 × 10⁻⁸/Ω·cm for ZrO₂ nanoballs, 3.29 × 10⁻⁸/Ω·cm for ZrO₂ chemical, and 6.70 × 10⁻⁵/Ω·cm for the thickness of 1,053 nm ZrO₂ film at room temperature with the electronic contribution being less than 0.006%.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.247-251
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• 1999

Tungsten oxide supported on zirconia was prepared by drying powdered $Zr(OH)_4$ with ammonium metatungstate aqueous solution, followed by calcining in air at high temperature. Upon the addition of only small amount of tungsten oxide (1 wt % $WO_3$) to $ZrO_2$, both the acidity and acid strength of catalyst increased remarkably, showing the presence of $Br{\ddot{o}}nsted$ and Lewis acid sites on the surface of $WO_3$/$ZrO_2$. The high acid strength and large amount of acid sites on $WO_3$/$ZrO_2$ were due to the presence of the W=O bond nature of complex formed by the interaction between $WO_3$ and $ZrO_2$. The catalyst containing 20 wt % $WO_3$, calcined at 973 K, showed the highest catalytic activity for the 2-propanol dehydration, while the catalyst containing 15 wt % $WO_3$, calcined at 1023 K, exhibited the highest catalytic activity for the cumene dealkylation. For the 2-propanol dehydration the catalytic activities of $WO_3$/$ZrO_2$ catalysts were roughly correlated with their acidities.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.513-519
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• 1998

Zr-Si binary alloys containing 0.01 to O.lwt.%Si were prepared to investigate the effect of Si on the corrosion behavior of Zr. Corrosion test was performed in pure water at 36$0^{\circ}C$ under a pressure of 2660psi for 100days. The alloys containing 0.01 wt. % and 0.05wt. %Si had the black and uniform oxide film and didn't show the transition of corrosion rate. However. the alloys containing O.lwt.%Si had white oxide film and showed the trasition of corrosion rate at 70 days corrosion test. The weight gain increased with the increasing Si content from 0.01 to 0.1 wt.%. The variation of Si contents had no effect on changing the oxide structure but had significant effect on the electrical resistivity of oxide. The electrical resistivity decreased with increasing Si content. The fraction of precipitates in the Zr-Si binary alloys. identified as tetragonal $Zr_{3}$Si increased with increasing Si content. The increase of the volume fraction of precipitates is thought to be responsible for the increase of weight gain due to short circuit effect of precipitate.

• Journal of the Korean Magnetic Resonance Society
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• v.4 no.1
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• pp.1-11
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• 2000

Supported vanadium oxides are being used extensively as catalysts for a variety of reactions, including partial oxidations and ammoxidations. A series of vanadium oxide supported on TiO2-ZrO2 was obtained by impregnating ammonium metavanadate slowly into a mixed precipitateof Ti(OH)4-Zr(OH)4, followed by calcining in air at high temperatures. The prepared catalysts were characterized by 51V solid-state NMR. In the calcined catalysts 51V NMR studies indicated the peaks corresponding to distorted tetrahedral vanadia species at low V2O5 contents and octahedral vanadia species at high vanadia loadings. These results illustrate the suitability of 51V NMR as a unique quantitative spectroscopic tool in the structural analysis of vanadium(V) oxide catalytic materials.

• Electrical & Electronic Materials
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• v.16 no.9
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• pp.61.1-61
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• 2003

Stoichiometric, uniform, amorphous ZrO$_2$ films with an equivalent oxide thickness of ∼1.5nm and a dielectric constant of ∼18 were deposited by an atomic layer controlled deposition process on silicon for potential application in meta-oxide-semiconductor(MOS) devices. The conduction mechanism is identified as Schottky emission at low electric fields and as Poole-Frenkel emission at high electric fields. the MOS devices showed low leakage current, small hysteresis(〈50mV), and low interface state density(∼2*10e11/cm2eV). Microdiffraction and high-resolution transmission electron microscopy showed a localized monoclinic phase of ${\alpha}$-ZrO$_2$ and an amorphous interfacial ZrSi$\_$x/O$\_$y/ layer which has a correspondign dielectric constant of 11