• Journal of the Korean Ceramic Society
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• v.35 no.5
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• pp.451-457
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• 1998

$Li_2$$ZrO_3$ powder which is one of the candidates of breeding materials for the fusion reactor was syn-thesized by a precipitation-combustion process. Although precipitates from the reaction between zirconium nitrate and citric acid were existed in a precursor solution. $Li_2$$ZrO_3$ could easily be obtained by using the mixed fuel of urea and citric acid in stoichiometric composition. The phases of as-synthesized powder con-sisted of $Li_2$$ZrO_3$ and small amounts of $Li_6$$Zr_2O_3$ and $Li_2$$ZrO_3$ The latter phases disappeared after the cal-cination at $1100^{\circ}C$ for 2 h. The primary particle size and the specific surface area of as-synthesized powders were smaller than 20nm and 10-14 $M^2$/g, respectively. The primary particle size of the precipitation-combustion synthesized powders was affected by the size of precipitates present in a precursor solution.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.373-379
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• 1988

$\alpha$-Al2O3-15m/o ZrO2 powder was prepared by a sol-gel method from boehmite and zirconium acetate. The transformation temperature of boehmite to $\alpha$-Al2O3 in the system Al2O3-ZrO2 was increased due to the coupled crystallization. On the other hand, the transformation temperature from boehmite to $\alpha$-Al2O3-15m/o ZrO2 could be prepared at 110$0^{\circ}C$ for 100min. The specific surface area of the product of $\alpha$-Al2O3-15m/o ZrO2 was 13.2$m^2$/g.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.4
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• pp.313-320
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• 2003

볼밀링법을 이용하여 타이타늄 스펀지와 칩 또는 스크랩으로부터 상온애서 직접 타이타늄 수소와 분말을 재조하는 실험을 행하였다. 실험결과 진공중에서 볼링을 행한 타이타늄 스펀지와 칩의 경우 24시간외 후 합금분말의 크기는 약 20 um 정도의 크기를 갖는 것을 확인하였다. 그러나 수소화 분위기에서 볼밀링을 행한 경우에 12시간 후 수소화분말의 입도는 0.1-0.2 um로 극히 미세한 합금 분말이 제조되었다. 수소분위기에서의 볼밀링에 의한 타이타늄 분말제조는 기존의 방법에 비해 열을 가하지 않고 타이타늄 수소화분말을 얻을 수 있다는 장점과 나노크기의 미세한 수소화 분말을 얻을 수 있음을 알 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11A
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• pp.904-908
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• 2009

The PZT(lead, zirconium, titanium) based ceramics which, are reported to be ferroelectric materials have their important applications in the areas of surface acoustic waves (SAW), filters, infrared detectors, actuators, ferroelectric random acess memory, speakers, electronic switches etc. Moreover, these PZT materials possess the large electromechanical coupling factor, large spontaneous polarization, low dielectric loss and low internal stress etc. Hence, keeping in view the unique properties of PZT piezoelectric ceramics we also tried to synthesize indigenously the small sized PZT ceramic powder in the laboratory by using the modified sol-gel approach. In this paper, Propyl alcohol based sol-gel method was used for preparation of PZT piezoelectric ceramic. The powder obtained by this sol-gel process was calcined and sintering to reach a pyrochlore-free crystal phase. The characterization of synthesized material was carried out by the XRD analysis and the surface morphology was determined by high resolution scanning electron microscopy.

• Composites Research
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• v.35 no.4
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• pp.288-297
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• 2022

This study investigated the effect of addition of zirconia(zirconium oxide) powder on the curing behavior of phenolic resins. The heating rate controlled curing and isothermal curing behaviors of the phenol resin according to the content of the zirconia powder were analyzed. The viscosity and thermal decomposition characteristics of the phenolic resin with the zirconia content were also examind. From the DSC analysis, the degree of cure and the rate of cure were obtained. Finally, the activation energy for the cure reaction were calculated from the DSC data of the zirconia added phenolic resin. As a found, the higher the zirconia content, the longer the curing was delayed and the greater the activation energy required for curing. Additionally, the TGA result that as the content of zirconia increased, less weight loss was observed. The surface tackiness of the Carbon/Phenol prepreg was partially changed according to the zirconia content, but had no significant effect.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.714-721
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• 1994

Titanium and zirconium-containing MFI type zeolites have been prepared hydrothermally. Incorporation of titanium or zirconium into the framework of zeolite has been demonstrated by XRD, FT-IR, $^{29}Si$ MAS NMR analysis, and the catalytic benzene hydroxylation or n-hexane oxidation was used for checking the properties of catalysts. Pure titania and zirconia powder showed no catalytic activity at all for these reactions but Ti and Zr modified zeolite had the high activities in both reactions. The catalytic activity strongly depended on the kind of solvents, and the conversion of benzene or n-hexane increased with the increasing content of Ti and Zr in zeolites.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.313-317
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• 2010

Li, Zr doped mesoporous silica was synthesized in one pot and investigated for low temperature $CO_2$ adsorption. Herein CTAB and TEOS are used as structural directing agent and silica source respectively. The characteristics of the material was obtained from FT IR, XRD, SEM, TG and BET results. ICP AES results revealed the presence of lithium and zirconium. The material possesses high surface area ($962.22m^2g^{-1}$) with mono dispersed particles of about 2 nm. The maximum $CO_2$ adsorption capacity is 5 wt % (50 mg/g) of $CO_2$/g of sorbent at $25^{\circ}C$, which is regenerable at $200^{\circ}C$. This regeneration temperature of the adsorbent is lower than the reported lithium zirconium silicate powder. Until now, there is no report for the synthesis of Li, Zr doped mesoporous silica. The performance studies illustrate that Li, Zr doped mesoporous silica is tunable, regenerable, recyclable and selective sorbent and hence found to be a promising candidate for $CO_2$ adsorption.

• Journal of the Korean Applied Science and Technology
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• v.20 no.4
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• pp.358-365
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• 2003

Zirconium nitride powders were synthesized at a relatively lower temperature using methane as a reducing agent in the nitridation of zircoia. $ZrO_2$ powder was prepared by a sol-gel technique. The resulting sol-gel was centrifuged, and the gel was washed with deionized water. Anhydrous ammonia was used as the nitrogen source and methane was used as the reducing agent. Conversion diagrams show the equilibrium solid phase as a function of reagent concentrations for a specific temperature and gas pressure for the reagent system $NH_3-ZrO_2-CH_4$. The reagent concentration ranges within which pure ZrN is formed increase with increasing reaction temperature. Low pressure with an excess of hydrogen decreases the reaction temperature at which pure ZrN is formed. Low pressure together with the introduction of excess hydrogen into the reaction system increases Zr and N conversion efficiency and retards C deposition.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.495-501
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• 2020

In this study, zirconium fumarate of metal-organic framework (MOF-801) was solvothermally synthesized at 130 ℃ and characterized through powder X-ray diffraction (PXRD) analyses and porosity measurements from N₂ sorption isotherms at 77 K. The ability of MOF-801 to act as an adsorbent for the phosphate removal from aqueous solutions at 25 ℃ was investigated. The phosphate removal efficiency (PRE) obtained by 0.05 g/L adsorbent dose at an initial phosphate concentration of 60 ppm after 3 h was 72.47%, whereas at 5 and 20 ppm, the PRE was determined to be 100% and 89.88%, respectively, after 30 min for the same adsorbent dose. Brunauer-Emmett-Teller (BET) surface area and pore volume of the bare MOF-801 sample were 478.25 ㎡/g and 0.52 ㎤/g, respectively, whereas after phosphate adsorption (at an initial concentration of 60 ppm, 3 h), the BET surface area and pore volume were reduced to 331.66 ㎡/g and 0.39 ㎤/g, respectively. The experimental data of kinetic (measured at initial concentrations of 5, 20 and 60 ppm) and isotherm measurements followed the pseudo-second-order kinetic equation and the Freundlich isotherm model, respectively. This study demonstrates that MOF-801 is a promising material for the removal of phosphate from aqueous solutions.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.138.2-138.2
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• 2010

Scandium-doped zirconium, ScSZ-based electrolyte, provides higher oxygen conductivity than YSZ and nano-based electrolyte materials are ideal for fabricating thin film electrolyte membrane of SOFC unit cell. Moreover, it may be applied to anode and cathode as well as electrolyte as ionic conductor. In this report, nano-based ScSZ-based electrolyte powder was prepared by co-precipitation synthesis. The particle size, surface area and morphology of the powder were observed by SEM and BET. Thin film electrolyte of under $10{\mu}m$ was fabricated by tape casting and co-firing using the synthesized ScSZ-based powders, and ionic conductivity and gas permeability of electrolyte film were evaluated. Finally, the SOFC unit cell was fabricated using the anode-supported electrolyte prepared by a tape casting method and co-sintering. Electrochemical evaluations of the SOFC unit cell, including measurements such as power density and impedance, were performed and analyzed.