• 열처리공학회지
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• 제18권6호
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• pp.362-368
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• 2005

Formation and thermal stability of a quasicrystalline phases in Al-Fe-Mo alloys were investigated by means of melt-spinning process and subsequent heat treatment test. Thermal decomposition and phase transformation process of the as-spun alloys were studied using X-ray diffraction and electron microscopy. The melt-spun Al-Fe-Mo alloys contained an icosahedral quasicrystalline phase with a quasilattice constant of 0.457 nm. Icosahedral phase formed at a composition of $Al_{82.5}Fe_{14}Mo_{3.5}$ as a metastable phase during rapid solidification was transformed into the stable crystalline phases, cubic 1/0 approximant and monoclinic ${\lambda}$-phase, upon heating. A metastable icosahedral and cubic(a = 0.93 nm) phases in as-spun $Al_{65}Fe_{20}Mo_{15}$ alloy were decomposed into two cubic(a = 0.62, 0.31 nm) phases by heat treatment.

• 한국재료학회지
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• 제17권4호
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• pp.236-238
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• 2007

[ 0-3PbTiO_3/P$ ](VDF/TrFE) nanocomposites thin films for passive pyroelectric infrared sensor have been fabricated by two-step spin coating technique. 65 wt% VDF and 35 wt% TrFE was formed to a P(VDF/TrFE) poder Nano size $PbTiO_3$ powder was used. 0-3 connectivity of $PbTiO_3$(VDF/TrFE) composites film is achieved and also observed by SEM photography successfully. The dielectric constant, and pyroelectric coefficient measured and compared with P (VDF/TrFE). A very low dielectric constant (13.48 at 1 kHz) and high enough pyroelectric coefficient (3.101 $nC/cm^2$.k at $50^{circ}C$) neasured. This nanocomposites can be used for a new pyroelectric infrared sensor for better performance.

• 한국재료학회지
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• 제9권4호
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• pp.345-348
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• 1999

The properties of Fe ions in the $ CdFe_2$$O_4$ and $CdFeAlO_4$ were investigated using the Mossbauer spectroscopy, in the temperature range from 300K to 900K. The calculated Debye temperature, recoil free fraction, mean square displacement and velocity are, 476.5K, 0.835, 3.39$\times$10\ulcorner$\textrm{cm}^2$, and 1.11$\times$10\ulcorner$\textrm{cm}^2$sec$^2$for Fe ions in the $CdFe_2$$O_4$ and 369.0K, 0.741, 5.65$\times$10\ulcorner$\textrm{cm}^2$ and 1.33$\times$10\ulcorner$\textrm{cm}^2$/$sec^2$in the $CeFeAlO_4$. The difference of the properties in the two samples were explained by the variation of the Fe\ulcorner-O\ulcorner bonding length with the substituted Al ions.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2002년도 춘계학술발표대회 논문개요집
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• pp.65-70
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• 2002

• 한국자기학회:학술대회 개요집
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• 한국자기학회 1993년도 춘계연구발표회 논문개요집
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• pp.64-65
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• 1993

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2016년도 자성 및 자성재료 국제학술대회
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• pp.64-65
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• 2016

• 한국재료학회지
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• 제19권4호
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• pp.228-231
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• 2009

Phase transition in ferroelectric polymer is very interesting behavior and has been widely studied for real device applications, such as actuators and sensors. Through the phase transition, there is structural change resulting in the change of electrical and optical properties. In this study, we fabricated the Febry-Perot interferometer with the thin film of ferroelectric P(VDF-TrFE) 50/50 mol% copolymer, and thermo-optical properties were investigated. The effective thermo-optical coefficient of P(VDF-TrFE) was obtained as $2.3{\sim}3.8{\times}10^{-4}/K$ in the ferroelectric temperature region ($45^{\circ}C{\sim}65^{\circ}C$) and $6.0{\times}10^{-4}/K$ in the phase transition temperature region ($65^{\circ}C{\sim}85^{\circ}C$), which is a larger than optical silica-fiber and PMMA. The resonance transmission peak of P(VDF-TrFE) with the variation of temperature showed hysteretic variation and the phase transition temperature of the polymer in heating condition was higher than in the cooling condition. The elimination of the hysteretic phase transition of P(VDF-TrFE) is necessary for practical applications of optical devices.

• Bulletin of the Korean Chemical Society
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• 제20권12호
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• pp.1428-1432
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• 1999

[Fe$^{II}$(BLPA)DBCH]BPh₄ (1), a new functional model for the extradiol-cleaving catechol dioxygenases, has been synthesized, where BLPA is bis(6-methyl-2-pyridylmethyl)(2-pyridylmethyl)amine and DBCH is 3,5-di-tert-butylcatecholate monoanion. ¹H NMR and EPR studies confirm that 1 has a high-spin Fe(II) (S = 2) center. The electronic spectrum of 1 exhibits one absorption band at 386 nm, showing the yellow color of the typical [Fe$^{II}$(BLPA)] complex. Upon exposure to O₂, 1 is converted to an intense blue species within a minute. This blue species exhibits two intense bands at 586 and 960 nm and EPR signals at g = 5.5 and 8.0 corresponding to the high-spin Fe(III) complex (S = 5/2, E/D = 0.11). This blue complex further reacts with O₂ to be converted to (μ-oxo)Fe$^{III}_2$ complex within a few hours. Interestingly, 1 affords intradiol cleavage (65%) and extradiol cleavage (20%) products after the oxygenation. It can be suggested that 1 undergoes two different oxygenation pathways. The one takes the substrate activation mechanism proposed for the intradiol cleavage products after the oxidation of the $Fe^II\;to\;Fe^{III}$. The other involves the direct attack of O₂ to $Fe^{II}$ center, forming the $Fe^{III}$-superoxo intermediate which can give rise to the extradiol cleavage products. 1 is the first functional Fe(II) complex for extradiol-cleaving dioxygenases giving extradiol cleavage products.

• 한국양식학회지
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• 제10권3호
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• pp.255-260
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• 1997

어분이 65% 첨가된 사료에 P와 Fe의 보충 효과를 조사하기 위해 인산염($KH_2PO_4$)을 0%, 1%, 2%, 3% 및 4% 첨가한 사료와 철 (Fe-citrate)을 0.022%, 0.044%, 0.066% 및 0.088% 첨가한 실험사료를 설계, 제조하여 조피볼락 치어 (평균 체중 7 g)를 각 수조 ($100\ell$)에 40마리씩 2반복으로 수용하여 각각 21주간 사육실험하였다. 사육실험 결과, 증체율, 사료효율, 영양소축적율, 혈액성상 사료의 P 첨가량에 따른 유의적인 차이가 인정되지 않았다(P>0.05). 조지방의 경우는 사료의 P 함량이 높을수록 감소하여 유의적으로 낮은 값을 보였다(P<0.05). Fe 보충효과 실험에서, 증체율, 사료효율, 영양소축적율, 혈액성상 및 전어체의 일반성분은 Fe를 보충하여도 개선되지 않았으며, 성장률은 오히려 Fe 첨가량이 높은 실험구에서 저하되는 현상을 보였다. 따라서 조피볼락 사료에 어분이 65% 배합될 경우에는 별도의 P와 Fe 첨가는 필요 없을 것으로 판단된다.

• 한국분말재료학회지
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• 제10권2호
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• pp.129-135
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• 2003

Nanocrystalline powders of $MnFeP_{1-x}As_x$(x=0.45-0.6) have been synthesized by mechanochemical reaction at room temperature using high-energy ball milling from mixtures of Mn, Fe, P, and As Powders. It has been found that a mechanically induced self-propagating reaction (MSR) occurs within 2 hours of milling and it produces very fine polycrystalline powder having a hexagonal $Fe_2P$ structure. Further milling up to 24 hours did not change the crystalline and average particle sizes or the phase composition of the milling product. When x is 0.65, no reaction among the reactants has been observed even after 24 hours of milling. As the P content decreases in $MnFeP_{1-x}As_x$, the incubation time for the MSR has increased and the lattice constants in both a and c axes have changed.