• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.620-623
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• 2001

The peculiarities of using Self-propagating High-temperature Synthesis (SHS) and solid state phase synthesis for production of high temperature superconductor materials are discussed. Oxide superconductors with general formula $ReBa_2$$Cu_3$$O_{7-x}$ (Re= Y, Yb, Sm, Nd) have been made with using barium oxide initial powder instead of traditional barium carbonate. X-ray powder diffraction showed a single phase orthorhombic perovskite structure was produced in all reactions. Phenomena observed during the grinding of the reactant mixture are presented. Mechano-chemical activation - as a pretreatment of the reactant mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product.

• Archives of Pharmacal Research
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• 제27권8호
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• pp.811-815
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• 2004

Coumarin and its derivatives occur widely in nature. Many attempts were made for synthesis of various coumarin derivatives because of their interesting biological activities. In this study, solid phase synthetic approach of 3-(4-hydroxyphenyl)coumarin was achieved for combinatorial synthesis of substituted 3-phenylcoumarin analogues. Starting from 4-hydroxyphenylacetic acid methyl ester, release of 3-(4-hydroxypnehyl)coumarin from polymer support was accom-plished.

• 한국분말재료학회지
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• 제12권4호
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• pp.255-260
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• 2005

Direct solid state synthesis by hot pressing has been applied in order to produce high efficiency $Zn_4Sb_3$ bulk specimens. Single phase $Zn_4Sb_3$ with 98.5% of theoretical density was successfully produced by direct hot pressing of elemental powders containing 1.2 at.% excess Zn. Thermoelectric properties as a function of temperature were investigated from room temperature to 600 K and compared with results of other studies. Transport properties at room temperature were also evaluated. Thermoelectric properties of single phase $Zn_4Sb_3$ materials produced by direct synthesis were measured and are comparable to the published data. Direct solid state synthesis by hot pressing provides a promising processing route in this material.

• 한국재료학회지
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• 제15권7호
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• pp.473-479
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• 2005

Thermoelectric $Zn_4Sb_3$ alloys were synthesized by a conventional powder metallurgy process consisting of solid state reaction and hot pressing. Single phase $Zn_4Sb_3$ was successfully produced by the annealing of cold compact starting with the mixed elemental powders, and subsequent hot pressing yielded single phase bulk specimens without microcracks. Phase transformations in this alloy system during synthesis were investigated using XRD, SEM and EDS. Thermoelectric properties as a function of temperature were investigated from room temperature to 600 K and compared with results of analogue studies. Transport properties at room temperature were also evaluated. Thermoelectric properties of single phase $Zn_4Sb_3$ materials produced by this process are comparable to the published data. Synthesis by solid state reaction and hot pressing offers a potential processing route to produce a bulk $Zn_4Sb_3$.ٓ

• 한국세라믹학회지
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• 제54권3호
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• pp.217-221
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• 2017

Improvement studies of existing phosphors are needed for use in light emitting diodes (LEDs). Among the phosphors discovered recently, the SLA ($SrLiAl_3N_4:Eu^{2+}$) is a phosphor that has a narrow width. It is now known as a good red phosphor that meets the industry's needs for warm white (color temperature ranging from 2700 to 4000 K) and high CRI (> 80). However, SLA phosphors are obtained from difficult synthetic methods. All commercially available phosphors should be derived from the general solid state synthesis method. The phosphors produced by difficult synthetic methods will inevitably fall out of price competitiveness and will be scrapped. This study succeeded in synthesizing SLA ($SrLiAl_3N_4:Eu^{2+}$) phosphors by using a general solid phase synthesis method based on the reaction energy obtained from DFT calculations. As a result, we found an optimal solid state synthesis method for SLA phosphors.

• 공업화학
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• 제10권5호
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• pp.772-777
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• 1999

$Y_2Ba_1Cu_1O_5(Y211)$ 분말은 출발물질로서 $Y_2O_3(99.9%)$, $BaCO_3(99.9%)$, and CuO(99.9%) 분말을 사용하여 고상반응법과 발화합성법을 이용하여 제조하였다. $Y_2Ba_1Cu_1O_5(Y211)$ 분말에 대한 상형성과 반응속도는 열처리 온도와 반응시간에 따른 시료들을 X-선 회절분석을 이용하여 연구하였다. X-선 회절선으로부터 측정된 전화율($X_{211}$)과 반응특성으로부터 상 형성속도가 분말의 입자크기에 의해 지배되는 것을 알 수 있었다. 그리고 발화합성법으로 제조된 Y211상의 활성화에너지(${\Delta}E_a$)는 고상반응법에 의해 제조된 것의 149.46 kJ/mol과 비교할 때 136.42 kJ/mol을 나타내었다. $Y_2Ba_1Cu_1O_5$계에서의 활성화에너지 값은 발화합성법이 고상반응법보다 더욱 효율적인 방법임을 보였다.

• Archives of Pharmacal Research
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• 제28권7호
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• pp.756-760
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• 2005

Polyene macrolide amphotericin B (AmB) is the drug of choice for the treatment of disseminated fungal infections. However, because of its pronounced side effects, the drug has limited applicability. There are few interesting reports, which state that co-administration of the drug with homo-peptide of polyaspartic acid reduces the side effects of the drug. In our present study, an approach has been made to systematically synthesize low molecular weight heteropeptides consisting of L-aspartic acid and its derivative. It was hypothesized that such heteropeptides will reduce the toxic side effects of the drug by facile hydrophobic binding between the polymer and the drug. We have employed the strategy of solid phase peptide synthesis (SPPS) to synthesize low molecular weight hetero-peptides by using L-aspartic acid and benzyl-L-aspartic acid to induce the hydrophobic binding between the peptide and the drug. In future, the proposed methodology can be employed to tailor other polypeptides substituted with benzyl groups to reduce the nephrotoxicity of AmB.

• 한국세라믹학회지
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• 제36권7호
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• pp.698-704
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• 1999

Li rich Li1+xMn2-xO4(x=0.07) spinel powders were prepared by an oxalate precipitation of wet chemical methods at temperature lower than $600^{\circ}C$. The FTIR results showed that the powders prepared at $600^{\circ}C$ had high degree of crystal quality comparing with the spinel powders prepared by solid state reaction at 75$0^{\circ}C$ which was the lowest synthesis temperature of the solid state reaction method. The particle size of powders prepared by the oxalate precipitation at $600^{\circ}C$ was smaller than 0.2${\mu}{\textrm}{m}$ and the specific surface area was 11.01 m2/g A heat treatment over 90$0^{\circ}C$ formed second phase in the precipitates. It was shown that there were phase transitions at temperatures. T1,T2 and T2. The transitions involved weight loss and gain during heating and cooling. The low temperature synthesis below $600^{\circ}C$ avoided the second phase formation and the prepared powders showed improved compositional and physical properties for secondary lithium battery applications.

• 한국세라믹학회지
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• 제43권11호
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• pp.680-687
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• 2006

An overview is given to optimize the solid state processes toward phase pure and well-crystallized fine particulates of mixed oxides, serving as electroceramic materials in various genres. Elevation of the reactivity and preservation of stoichiometry of the starting mixture are of universal importance. Mechanical activation is versatile for these purposes, particularly when an oxygen atom as a hinge promotes formation of hetero-bridging bonds between dissimilar cationic species prior to calcination. Case studies carried out recently in the author's laboratory are displayed and compared for ferroelectric materials, i.e. $PbMg_{1/3}Nb_{2/3}O_3$ $xPbTiO_3$(PMN-PT), $(1-y)Pb(Zn_xMg{1-x})_{1/3}$ $yNb_{2/3}O_3$ (PZN-PMN), $BaBi_2Ta_2O_9$ (BBT), $Ba(Mg_{1/3}Ta_{2/3})O_3$ (BMT), and ferromagnetics, i.e. M-, Y-, and Z-phases of Ba-hexaferrites.

• 한국분말재료학회지
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• 제29권6호
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• pp.485-491
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• 2022

Lithium lanthanum titanium oxide (LLTO) is a promising ceramic electrolyte because of its high ionic conductivity at room temperature, low electrical conductivity, and outstanding physical properties. Several routes for the synthesis of bulk LLTO are known, in particular, solid-state synthesis and sol-gel method. However, the extremely low ionic conductivity of LLTO at grain boundaries is one of the major problems for practical applications. To diminish the grain boundary effect, the structure of LLTO is tuned to nanoscale morphology with structures of different dimensionalities (0D spheres, and 1D tubes and wires); this strategy has great potential to enhance the ion conduction by intensifying Li diffusion and minimizing the grain boundary resistance. Therefore, in this work, 0D spherical LLTO is synthesized using ultrasonic spray pyrolysis (USP). The USP method primarily yields spherical particles from the droplets generated by ultrasonic waves passed through several heating zones. LLTO is synthesized using USP, and the effects of each precursor and their mechanisms as well as synthesis parameters are analyzed and discussed to optimize the synthesis. The phase structure of the obtained materials is analyzed using X-ray diffraction, and their morphology and particle size are analyzed using field-emission scanning electron microscopy.