The energy gap of the high Tc superconductor La1.85Sr0.15CuO4

ABSTRACTGiaever tunneling measurements have been applied to investigate the electronic structures of the high Tc superconductor YB2Cu3Oy near Tc. The superconducting energy gap of 17 meV was observed in V-dl/dv curve at 77 K. In the light of BCS model, 2Δ0Δ/kBTc was estimated as 3.3. Several dip structures were observed in the bias region up to 0.5 eV in V-dl/dV curve, using the 3rd derivative analysis. Through the temperature dependence, these structures were found to be associated with the superconductivity.

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THE ENERGY GAP AND TWO-COMPONENT ABSORPTION IN A HIGH Tc SUPERCONDUCTOR

High Tc Superconductors ◽

10.1016/b978-0-08-037542-7.50011-9 ◽

1989 ◽

pp. 67-77 ◽

Cited By ~ 4

Author(s):

G.A. Thomas ◽

M. Capizzi ◽

J. Orenstein ◽

D.H. Rapkine ◽

A.J. Millis ◽

...

Keyword(s):

Energy Gap ◽

High Tc ◽

High Tc Superconductor ◽

Two Component

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ENERGY GAP OF HIGH-Tc SUPERCONDUCTOR YBa2Cu3O9−x

International Journal of Modern Physics B ◽

10.1142/s021797928700164x ◽

1987 ◽

Vol 01 (03n04) ◽

pp. 1121-1125

Author(s):

H.J. Ye ◽

W. Lu ◽

Z.Y. Yu ◽

X.C. Shen ◽

B.C. Miao ◽

...

Keyword(s):

Energy Gap ◽

Frequency Range ◽

High Tc ◽

Reflectance Curve ◽

Temperature Range ◽

High Tc Superconductor ◽

Infra Red

The far infra-red (IR) reflectances of the high-Tc superconductor YBa2Cu3O9−x(Tc=90 K) are measured in the frequency range 25–150 cm −1 and the temperature range 4.2–200 K. The reflectance curve at 4.2 K rapidly drops near 125 cm −1, whereas the curves at T>90 K go smoothly. Such a superconductor might have an energy gap 2Δ=15.5 meV , and the ratio 2Δ / kTc=2.0 is close to that of La–Ba–Cu–O and La–Sr–Cu–O superconductors, but well smaller than the BCS value 3.5.

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ENERGY GAP OF HIGH-Tc SUPERCONDUCTOR YBa2Cu3O9−δ

International Journal of Modern Physics B ◽

10.1142/s0217979287000761 ◽

1987 ◽

Vol 01 (02) ◽

pp. 503-507

Author(s):

Ye Hong-juan ◽

Lu Wei ◽

Yu Zhi-yi ◽

Shen Xue-chu ◽

Miao Bai-cai ◽

...

Keyword(s):

Energy Gap ◽

Far Infrared ◽

Frequency Range ◽

High Tc ◽

Reflectance Curve ◽

Temperature Range ◽

High Tc Superconductor

The far infrared reflectances of the high-Tc superconductor YBa2Cu3O9−δ(Tc=90k) are measured in the frequency range 25–150 cm−1 and the temperature range 42k-200k. The reflectance curve with 42k rapidly drops near 125 cm−1, whereas the curves with T>90k go smoothly. It indicates such superconductors have a energy gap 2Δ=15.5 mev, and the ratio 2Δ/kTc=2.0 is close to that of superconductors La-Ba-Cu-O and La-Sr-Cu-O, but well smaller than the BCS value 3.5.

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X -Ray Emission and X -Ray Self-Absorption in the High - Tc Superconductor YBa2Cu3O6.9 and other Copper Oxides

Zeitschrift für Naturforschung A ◽

10.1515/zna-1989-0303 ◽

1989 ◽

Vol 44 (3) ◽

pp. 180-188 ◽

Cited By ~ 14

Author(s):

F. Burgäzy ◽

H. Jaeger ◽

K. Schulze ◽

P. Lamparter ◽

S. Steeb

Keyword(s):

Absorption Spectra ◽

Oxygen Content ◽

Energy Gap ◽

Emission Spectra ◽

Copper Oxides ◽

Ionic Character ◽

High Tc ◽

X Ray ◽

High Tc Superconductor ◽

Superconducting Compound

O-Kα X-ray emission spectra of La2CuO4 and YBa2Cu3O6.9 are compared with calculated spectra. It is shown from O-Kα emission spectra of YBa2Cu3Ox with varying oxygen content (6.0 < X < 6.9) that with heating the superconducting compound (x = 6.9) oxygen atoms are removed from the Cu-O chains. A method for comparing X-ray self-absorption spectra from compounds with different concentrations of the element under consideration is presented. Cu-L selfabsorption spectra of YBa2Cu3Ox (6.0 < x < 6.9) are compared with those of Cu, Cu2O, CuO, and NaCuOn. By this comparison and from O-K., emission spectra, oxygen 2p holes are found to be present in the superconducting compound. The ionic character of the Cu-O bonds in the nonsuperconducting green phase Y2BaCuO5 is shown with O-Kα emission and Cu-L3 self-absorption spectroscopy. The energy gap of Y2BaCuO5 is found to be about 5 e V.

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High resolution STEM imaging study on high Tc superconductor YBa2CuaO7-x

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106478 ◽

1988 ◽

Vol 46 ◽

pp. 882-883

Author(s):

H.-J. Ou ◽

J. M. Cowley

Keyword(s):

Crystal Structure ◽

High Resolution ◽

Grain Boundary ◽

Strong Field ◽

Imaging Study ◽

Structure Defects ◽

High Tc ◽

High Tc Superconductor ◽

Diffraction Patterns ◽

Lattice Planes

Using the dedicate VG-HB5 STEM microscope, the crystal structure of high Tc superconductor of YBa2Cu3O7-x has been studied via high resolution STEM (HRSTEM) imaging and nanobeam (∽3A) diffraction patterns. Figure 1(a) and 2(a) illustrate the HRSTEM image taken at 10' times magnification along [001] direction and [100] direction, respectively. In figure 1(a), a grain boundary with strong field contrast is seen between two crystal regions A and B. The grain boundary appears to be parallel to a (110) plane, although it is not possible to determine [100] and [001] axes as it is in other regions which contain twin planes [3]. Following the horizontal lattice lines, from left to right across the grain boundary, a lattice bending of ∽4° is noticed. Three extra lattice planes, indicated by arrows, were found to terminate at the grain boundary and form dislocations. It is believed that due to different chemical composition, such structure defects occur during crystal growth. No bending is observed along the vertical lattice lines.

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Electron-Probe Quantitative Energy-Dispersive Analysis of Trace Magnesium Concentrations in Ag-Mg Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010016501x ◽

1996 ◽

Vol 54 ◽

pp. 510-511

Author(s):

R. B. Marinenko

Keyword(s):

Electron Probe ◽

Energy Dispersive Spectrometry ◽

Mg Alloys ◽

Energy Dispersive ◽

Energy Dispersive Analysis ◽

High Tc ◽

Alloy Wire ◽

High Tc Superconductor ◽

Eds Analysis ◽

Superior Mechanical Properties

Internally oxidized Ag-Mg alloys are used as sheaths for high Tc superconductor wires because of their superior mechanical properties. The preparation and characteristics of these materials have been reported. Performance of the sheaths depends on the concentration of the magnesium which generally is less than 0.5 wt. percent. The purpose of this work was to determine whether electron probe microanalysis using energy dispersive spectrometry (EDS) could be used to quantitate three different Ag-Mg alloys. Quantitative EDS analysis can be difficult because the AgL escape peak occurs at the same energy (1.25 keV) as the Mg Kα peak. An EDS spectrum of a Ag-Mg alloy wire is compared to a pure Ag spectrum in Fig. 1.

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