• 대한화학회지
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• 제39권1호
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• pp.71-75
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• 1995

Tricarbonyl(2-methyl-1-phenylpentadienyl)iron(+1) hexafluorophosphate 양이온이 hexafluorophosphoric acid를 사용한 tricarbonyl(4-methyl-5-hexadien-1-ol)iron의 양성자 첨가반응에 의해 얻어졌다. 그 양이온과 $H_2o$, dimethyl cuprate, diphenylacetylenyl cuprate, 그리고 cyclohexanone의 enolate와의 반응은 그것들에 대응하는 (η4-1,3-diene)Fe(CO)3를 형성시켰다. 친핵체의 공격에 있어서의 위치 선택성은 주로 입체효과의 결과인 것으로 보인다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.1-1
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• 2000

The infinite layer compound $ACuO_2$, (A-Alkaline earth) consists of infinite stacking of $CuO_2$ planes separated only by alkaline earth ions. This compound attracted much attention because it contains only key ingredient of all cuprate high temperature superconductor; $CuO_2$ plane with controllable carrier concentration without charge reservoir block. High pressure synthesis method has been found to be preferable for this system due to its ability of doping various lanthanide ion into A site with larger superconducting volume fraction. But rigorous study on this rudimentary compound has been hindered by insufficient quality of sample. Especially superconductlng volume fraction was often too small to identify its origin. In this presentation, we report high pressure synthesis of $Sr_{0.9}Ln_{0.1}CuO_2$ (Ln=La, Sm). By controlling the heating temperature precisely during high pressure synthesis we could have superconductors with quite high superconducting volume fraction for this compound. The magnetic properties of the graln aligned samples show very different behavior compared to the cuprate high temperature superconductors. Details will be discussed.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2001년도 추계총회 및 학술발표회
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• pp.6-6
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• 2001

• 한국응용과학기술학회지
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• 제17권2호
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• pp.144-148
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• 2000

A modification of the sol-gel method to obtain phase pure superconducting oxides is described. The method starts from organic salts of yttrium, barium and copper, such as acetates, and avoids the sudden and uncontrollable decomposition of the organic fraction which occurs if nitrates are used as starting materials. The aqueous solution obtained with citric acid in an alkaline medium is concentrated under vacuum. The solid so prepared is decomposed at about $300^{\circ}C$ thus giving an oxide precursor containing well dispersed yttrium, barium and copper. Pyrolysis at 850 - $920^{\circ}C$ followed by oxygen annealing gives the superconducting orthorhombic 123 phase. The results of TGA/DTA of the precursor, as well as XRD, electrical and magnetic property measurements on the pyrolysis products are presented and discussed.

• Progress in Superconductivity
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• 제13권3호
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• pp.146-150
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• 2012

We solve the momentum resolved d-wave Eliashberg equation employing the magnetic excitation spectrum from the inelastic neutron scattering on the LSCO superconductors reported by Vignolle et al. The magnetic excitation spectrum exhibits 2 peaks: a sharp incommensurate peak at 18 meV at momentum (${\pi}$, ${\pi}{\pm}{\delta}$) and (${\pi}{\pm}{\delta}$, ${\pi}$) and another broad peak near 40~70 meV at momentum (${\pi}$, ${\pi}$). Above 70 meV, the magnetic excitation spectrum has a long tail that is shaped into a circle centered at (${\pi}$, ${\pi}$) with ${\delta}$. The sign of the real part of the self-energy is determined by the momentum position of the peaks of the magnetic excitation spectrum and bare dispersion. We will discuss the effects of the each component of the magnetic excitation spectrum on the self-energy, the pairing self-energy.

• Progress in Superconductivity
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• 제11권2호
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• pp.83-86
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• 2010

There are theoretical and experimental evidences for the pseudo-gap in electron doped cuprates being due to interaction between electrons and anti-ferromagnetism(AFM). A remaining issue is on how AFM correlates with pseudo-gap, and eventually with superconductivity. To elucidate the issue, we have performed temperature dependent angle-resolved photoemission studies of an e-doped cuprate superconductor $Sm_{2-x}Ce_xCuO_4$(SCCO) x=0.18 at 20K and 150K. In the case of $Nd_{2-x}Ce_xCuO_4$, the most well known e-doped cuprate, pseudo-gap disappears at around 100 K for x=0.17. Our experimental result reveals that the pseudo-gap of SCCO exists even at 150K for x=0.18. This result implies that the AFM of SCCO survives even in x=0.18, which agrees with previously reported phase diagram of SCCO. Yet, the superconductivity disappears around x=0.18 for both NCCO and SCCO in spite of the difference in the magnetic order. This result sheds a light on the disappearance of superconductivity on the over-doped side.

• 한국결정학회지
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• 제16권1호
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• pp.38-42
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• 2005

Bis(ethylenediamine) cuprate(II)$\cdot$dichromate $Cu(C_2H_8N_2)_2{\cdot}Cr_2O_7$의 결정구조는 a=5.682(1), b=8.567(2), c=14.839(3) ${\AA},\;{\alpha}=97.50(2),\;{\beta}=101.06(1),\;{\gamma}=109.38(2)^{\circ}$, 삼사정계(Triclinic), 공간군 P-1, 공간군 번호 2이며, Z=2, V=653.9(2) ${\AA}^3,\;D_c=2.030gcm^{-3},\;{\mu}=3.273mm^{-1}$이었다. 구조분석은 중금속법으로 풀었으며, 최소 자승법으로 정밀화하였고, 최종 신뢰도 값들은 2291개의 회절반점에 대하여 $R_1=0.0256,\;R_w=0.0708,\;R_{all}=0.0316,\;S=1.151$이었다. 구리 착이온의 Cu-N의 평균 거리가 2.010(3) $\AA$이고, 면에 거의 수직으로 Cu-O 평균거리가 2.525(2) $\AA$로써 찌그러진 팔면체 구조를 하고 있다. 두 가지 이온들은 [111]-방향을 따라서 사슬구조를 형성하고, 이 축을 포함한 이차원 (0-11)면상에 놓인 인접한 축들 사이에는 N1-O5와 N3-O1 수소결합으로 연결되어 있다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.192.1-192.1
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• 2007

• 한국초전도ㆍ저온공학회논문지
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• 제18권2호
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• pp.14-17
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• 2016

Annealing as-grown electron-doped cuprates under a low oxygen-partial-pressure condition is a necessary step to achieve superconductivity. It has been recently found that the so-called protect annealing results in much better superconducting properties in terms of the superconducting transition temperature and volume fraction. In this article, we report on angle-resolved photoemission spectroscopy studies of a protect-annealed electron-doped cuprate $Pr_{0.9}La_{1.0}Ce_{0.1}CuO_4$ on annealing condition dependent superconducting and pseudo-gap properties. Remarkably, we found that the one showing a better superconducting property possesses almost no pseudo-gap while others have strong pseudo-gap feature due to an anti-ferromagnetic order.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.121-124
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• 2000

The time dependence of irreversible magnetization of grain aligned infinite layer superconductor Sr$_{0.9}$La$_{0.1}$CuO$_2$ was measured in temperature range of 2 K < T < 30 K for H= 0.5 T, 1.0 T and 1.5 T parallel to c-axis. From this, we calculated normalized flux creep rate S(T) ${\equiv}$ dlnM/dlnt and found that the temperature independent region in S(T) is significantly wide in comparision with other cuprate superconductors. Using the method of Maley et al., we also deduce the current density dependence of pinning potential and glassy exponent ${\mu}$.