Superconducting phase ofLa2CuO4+δ: A superconducting composition resulting from phase separation

J. D. Jorgensen; B. Dabrowski; Shiyou Pei; D. G. Hinks; L. Soderholm; B. Morosin; J. E. Schirber; E. L. Venturini; D. S. Ginley

doi:10.1103/physrevb.38.11337

Pressure-Induced Superconducting Phase Separation in Oxygen-Doped La2-xSrxCuO4+δ

Frontiers of High Pressure Research II: Application of High Pressure to Low-Dimensional Novel Electronic Materials ◽

10.1007/978-94-010-0520-3_28 ◽

2001 ◽

pp. 371-382

Author(s):

B. Lorenz ◽

Z. G. Li ◽

T. Honma ◽

P.-H. Hor

Keyword(s):

Phase Separation ◽

Superconducting Phase

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Theoretical Studies of Copper Oxide Clusters: Prediction of an Electronically Driven Phase Separation in YBa2Cu3Ox

MRS Proceedings ◽

10.1557/proc-99-95 ◽

1987 ◽

Vol 99 ◽

Cited By ~ 1

Author(s):

L. A. Curtiss ◽

T. O. Brun ◽

D. M. Gruen

Keyword(s):

Phase Diagram ◽

Phase Separation ◽

High Temperature ◽

Copper Oxide ◽

Superconducting Phase ◽

Oxygen Stoichiometry ◽

Molecular Orbital Calculations ◽

Theoretical Studies ◽

Two Phases ◽

Semi Empirical

ABSTRACTOn the basis of semi-empirical extended Hiickel molecular orbital calculations of copper-oxide clusters representing the new superconducting material YBa2Cu3Ox, a phase diagram is proposed which suggests that the 94 K high temperature superconducting phase of YBa2Cu3Ox is characterized by an oxygen stoichiometry near 7.0. The phase diagram predicts that a plateau should exist for Tc in the region x = 0.0 – 0.25 and that in this region two phases are present which are characterized by compositions having oxygen stoichiometries 6.5–6.75 and ca. 7.0.

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Short-range-oxygen order and superconducting phase separation in La2CuO4+x

Physica C Superconductivity ◽

10.1016/s0921-4534(00)00978-3 ◽

2000 ◽

Vol 341-348 ◽

pp. 1747-1750 ◽

Cited By ~ 2

Author(s):

J.Q. Li ◽

L. Chen ◽

Z.X. Zhao ◽

Y. Matsui

Keyword(s):

Phase Separation ◽

Short Range ◽

Superconducting Phase

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Experimental verification of superconducting phase separation model in metallic glass Zr78Co22

Solid State Communications ◽

10.1016/0038-1098(89)90008-2 ◽

1989 ◽

Vol 69 (10) ◽

pp. 981-985

Author(s):

Zhou Xianyi ◽

Liu Zhiguo ◽

Zhu Yuping ◽

Chen Guanghui ◽

Chen Yong ◽

...

Keyword(s):

Phase Separation ◽

Metallic Glass ◽

Experimental Verification ◽

Superconducting Phase ◽

Separation Model

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Bulk standards for low-temperature biological x-ray microanalysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100111525 ◽

1984 ◽

Vol 42 ◽

pp. 282-283

Author(s):

P. Echlin ◽

M. McKoon ◽

E.S. Taylor ◽

C.E. Thomas ◽

K.L. Maloney ◽

...

Keyword(s):

Phase Separation ◽

Low Temperature ◽

Analytical Method ◽

Salt Solutions ◽

Absolute Concentration ◽

Cooling Process ◽

X Ray ◽

The Absolute ◽

Analytical Procedures ◽

Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

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Secondary electron imaging of YBa2Cu3O7-x high-Tc superconductors in Scanning Transmission Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155396 ◽

1989 ◽

Vol 47 ◽

pp. 684-685

Author(s):

D. R. Liu ◽

D. B. Williams

Keyword(s):

Electron Microscope ◽

Secondary Electron ◽

Scanning Transmission Electron Microscope ◽

Superconducting Phase ◽

Contrast Imaging ◽

High Tc ◽

Bright Contrast ◽

Transmission Electron ◽

Scanning Transmission ◽

Electron Imaging

The secondary electron imaging technique in a scanning electron microscope (SEM) has been used first by Millman et al. in 1987 to distinguish between the superconducting phase and the non-superconducting phase of the YBa2Cu3O7-x superconductors. They observed that, if the sample was cooled down below the transition temperature Tc and imaged with secondary electrons, some regions in the image would show dark contrast whereas others show bright contrast. In general, the contrast variation of a SEM image is the variation of the secondary electron yield over a specimen, which in turn results from the change of topography and conductivity over the specimen. Nevertheless, Millman et al. were able to demonstrate with their experimental results that the dominant contrast mechanism should be the conductivity variation and that the regions of dark contrast were the superconducting phase whereas the regions of bright contrast were the non-superconducting phase, because the latter was a poor conductor and consequently, the charge building-up resulted in high secondary electron emission. This observation has since aroused much interest amoung the people in electron microscopy and high Tc superconductivity. The present paper is the preliminary report of our attempt to carry out the secondary electron imaging of this material in a scanning transmission electron microscope (STEM) rather than in a SEM. The advantage of performing secondary electron imaging in a TEM is obvious that, in a TEM, the spatial resolution is higher and many more complementary techniques, e.g, diffraction contrast imaging, phase contrast imaging, electron diffraction and various microanalysis techniques, are available.

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Phase separation in sol gel-derived ceramic films of silica-zirconia, alumina-zirconia, and titania-zirconia system

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170967 ◽

1994 ◽

Vol 52 ◽

pp. 646-647

Author(s):

J. Tong ◽

L. Eyring

Keyword(s):

Fracture Toughness ◽

Phase Separation ◽

Sol Gel ◽

Great Influence ◽

High Strength ◽

Chemical Durability ◽

Separation Method ◽

Toughening Mechanism ◽

Ceramic Films ◽

Zirconia Toughened Alumina

There is increasing interest in composites containing zirconia because of their high strength, fracture toughness, and its great influence on the chemical durability in glass. For the zirconia-silica system, monolithic glasses, fibers and coatings have been obtained. There is currently a great interest in designing zirconia-toughened alumina including exploration of the processing methods and the toughening mechanism.The possibility of forming nanocrystal composites by a phase separation method has been investigated in three systems: zirconia-alumina, zirconia-silica and zirconia-titania using HREM. The morphological observations initially suggest that the formation of nanocrystal composites by a phase separation method is possible in the zirconia-alumina and zirconia-silica systems, but impossible in the zirconia-titania system. The separation-produced grain size in silica-zirconia system is around 5 nm and is more uniform than that in the alumina-zirconia system in which the sizes of the small polyhedron grains are around 10 nm. In the titania-zirconia system, there is no obvious separation as was observed in die alumina-zirconia and silica-zirconia system.

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