Neutron Diffraction Studies of High TC Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
D. G. Hinks ◽  
B. Dabrowski ◽  
K. Zhang ◽  
C. U. Segre ◽  
J. D. Jorgensen ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Complex Function ◽  
Electronic Effects ◽  
High Tc Superconductors ◽  
High Tc ◽  
Oxygen Ordering ◽  
Powder Neutron Diffraction

ABSTRACTWe have investigated the structure and composition of La2CuO4 (both pure and Sr-doped) and Nd(Ba2−xNdx)Cu3O7 using powder neutron diffraction. In La2−xSrxCuO4, Tc reacnes its maximum at x=0.15, after which vacancies are introduced in the 2D planes and superconductivity is destroyed. Superconductivity in La2CuO4 is not bulk. No evidence for nonstoichlometry in this material can be observed. In the Nd(Ba2−xNdx)Cu3O7 system, Tc is a complex function of oxygen ordering and electronic effects.

Neutron diffraction by the flux lattice in high-Tc superconductors

1992 ◽  
Vol 180-181 ◽  
pp. 377-379 ◽  
Author(s):  
R. Cubitt ◽  
E.M. Forgan ◽  
D.McK. Paul ◽  
S.L. Lee ◽  
J.S. Abell ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
High Tc Superconductors ◽  
High Tc ◽  
Flux Lattice

Superconducting Properties of Substituted Oxides Bi2Sr2−xLaxCuO6+y and Bi2Sr2Ca1−xYxCu2O8+y Neutron Diffraction of Bi2Sr1.6La0.4CuO6+y and Bi2CaLaCuO6+y

1989 ◽  
Vol 156 ◽  
Author(s):  
J. Darriet ◽  
J. A. Alonso ◽  
P. Burlet ◽  
B. Chevalier ◽  
B. Lepine ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Critical Temperature ◽  
Neutron Diffraction ◽  
Positive Charge ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
High Tc Superconductors ◽  
High Tc ◽  
Zero Resistance

ABSTRACTThe substituted oxides Bi2Sr2−xLaxCuO6+y and Bi2Sr2Ca1−xYxCu2O8+y isostructural to the n = 1 and n = 2 members of the high Tc superconductors have been prepared. The solid solution Bi2Sr2−xLaxCuO6+y shows a superconducting transition for 0.2–0.25<x<0.5 with an onset Tc near 30K and zero resistance temperatures which depend on x and the heat treatment. For x = 1 the isostructural phases Bi2ALaCuO6.5+y with A = Ca or Ba have also been synthesized and are not superconducting. A modelfor the localization of the oxygen atoms is proposed based on neutron diffraction of Bi2Sr1.6La0.4CuO6+y and Bi2CaLaCuO6+y.The Bi2Sr2Ca1−xYxCu2O8+y solid solution exhibits a superconducting transition for 0<x <0.7. The critical temperature remains almost constant (85–90K) for 0<x <0.3 and then decreases rapidly. The oxygen content value 8.65 for Bi2Sr2YCu2O8+y agrees well with the increase of the positive charge when calcium is replaced by yttrium.

scholarly journals Oxygen-Ordering Effects in High-Tc Superconductors.

1998 ◽  
Vol 7 ◽  
pp. 425-430 ◽  
Author(s):  
James S. Schilling ◽  
Craig Looney ◽  
Sascha Sadewasser ◽  
Yong Wang
Keyword(s):  
High Tc Superconductors ◽  
High Tc ◽  
Oxygen Ordering ◽  
Ordering Effects

Theory of Oxygen Ordering and Absorption in 1,2,3 High-Tc Superconductors

1988 ◽  
pp. 191-194
Author(s):  
J. P. A. Westerveld ◽  
D. M. R. Lo Cascio ◽  
H. Bakker ◽  
D. O. Welch
Keyword(s):  
High Tc Superconductors ◽  
High Tc ◽  
Oxygen Ordering

A systematic neutron diffraction study of RBa2Cu3O7 (R = yttrium and rare earths) high-Tc superconductors

1993 ◽  
Vol 195 ◽  
pp. 599-602 ◽  
Author(s):  
M. Guillaume ◽  
P. Allenspach ◽  
J. Mesot ◽  
B. Roessli ◽  
U. Staub ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Diffraction Study ◽  
Rare Earths ◽  
Neutron Diffraction Study ◽  
High Tc Superconductors ◽  
High Tc

The many faces of STEM in materials science

1991 ◽  
Vol 49 ◽  
pp. 440-441
Author(s):  
John Silcox
Keyword(s):  
Materials Science ◽  
Auger Spectroscopy ◽  
Dark Field ◽  
High Tc Superconductors ◽  
High Tc ◽  
Acoustic Environment ◽  
Electromagnetic Vibration ◽  
The Many ◽  
Serial Mode

Determination of the microstructure and microchemistry of small features often provides the insight needed for the understanding of processes in real materials. In many cases, it is not adequate to use microscopy alone. Microdiffraction and microspectroscopic information such as EELS, X-ray microprobe analysis and Auger spectroscopy can all contribute vital parts of the picture. For a number of reasons, dedicated STEM offers considerable promise as a quantitative instrument. In this paper, we review progress towards effective quantitative use of STEM with illustrations drawn from studies of high Tc superconductors, compound semiconductors and metallization of H-terminated silicon.Intrinsically, STEM is a quantitative instrument. Images are acquired directly by detectors in serial mode which is particularly convenient for digital image acquisition, control and display. The VG HB501A at Cornell has been installed in a particularly stable electromagnetic, vibration and acoustic environment. Care has been paid to achieving UHV conditions (i.e., 10-10 Torr). Finally, it has been interfaced with a VAX 3200 work station by Kirkland. This permits, for example, the acquisition of bright field (or energy loss) images and dark field images simultaneously as quantitative arrays in perfect registration.

Crystal chemistry of high-Tc superconductors

1990 ◽  
Vol 48 (4) ◽  
pp. 1118-1119
Author(s):  
Maryvonne Hervieu
Keyword(s):  
Oxygen Deficiency ◽  
Large Family ◽  
Copper Oxides ◽  
High Tc Superconductors ◽  
High Tc ◽  
Single Mechanism ◽  
Square Planar ◽  
History Of ◽  
Bismuth Cuprates ◽  
New Compounds

Four years after the discovery of superconductivity at high temperature in the Ba-La-Cu-O system, more than thirty new compounds have been synthesized, which can be classified in six series of copper oxides: La2CuO4 - type oxides, bismuth cuprates, YBa2Cu3O7 family, thallium cuprates, lead cuprates and Nd2CuO4 - type oxides. Despite their quite different specific natures, close relationships allow their structures to be simply described through a single mechanism. The fifth first families can indeed be described as intergrowths of multiple oxygen deficient perovskite slabs with multiple rock salt-type slabs, according to the representation [ACuO3-x]m [AO]n.The n and m values are integer in the parent structures, n varying from 0 to 3 and m from 1 to 4; every member of this large family can thus be symbolized by [m,n]. The oxygen deficient character of the perovskite slabs involves the existence or the co-existence of several types of copper environment: octahedral, pyramidal and square planar.Both mechanisms, oxygen deficiency and intergrowth, are well known to give rise easily to nonstoichiometry phenomena. Numerous and various phenomena have actually been characterized in these cuprates, strongly depending on the thermal history of the samples.

Evidence for magnetic organization of high Tc superconductor YBa 2 Cu8O7 observed by neutron diffraction

1987 ◽  
Vol 48 (10) ◽  
pp. 1623-1625 ◽  
Author(s):  
B. Farnoux ◽  
R. Kahn ◽  
A. Brulet ◽  
G. Collin ◽  
J.P. Pouget
Keyword(s):  
Neutron Diffraction ◽  
High Tc ◽  
High Tc Superconductor
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