High Tc Oxide Superconductors

MRS Bulletin ◽  
1990 ◽  
Vol 15 (6) ◽  
pp. 31-33
Author(s):  
M. Brian Maple
Keyword(s):  
Physical Properties ◽  
Energy Gap ◽  
Vortex State ◽  
Oxide Superconductors ◽  
High Tc ◽  
Superconducting Energy Gap ◽  
Consistent Picture ◽  
Novel Processing ◽  
Processing Techniques

This issue of the MRS BULLETIN is devoted to high Tc superconductivity. It is the sequel to a previous series of articles on the same subject which appeared in the MRS BULLETIN in January 1989. While the articles in the January 1989 issue emphasized the families of high Tc superconducting oxides known at that rime, as well as novel processing techniques and thin films, the papers in this issue focus on the physical properties of high Tc oxide superconductors.The quality of polycrystalline and single-crystal bulk and thin-film materials has improved to the point where researchers can now make reliable measurements of many physical properties representative of the intrinsic behavior of these materials. As a result, a broad spectrum of important issues such as the nature of the electronic structure, the type of superconducting electron pairing, the magnitude and temperature dependence of the superconducting energy gap, the behavior of fluxoids in the vortex state, etc., can be addressed meaningfully. Presently emerging is a consistent picture of the physical properties of the high Tc oxides, which will form the foundation to eventually developing an appropriate theory for the normal and superconducting states of these remarkable materials.

scholarly journals Novel Materials in the Preparation of Edible Films and Coatings—A Review

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 674 ◽  
Author(s):  
Sabina Galus ◽  
Emine Aytunga Arik Kibar ◽  
Małgorzata Gniewosz ◽  
Karolina Kraśniewska
Keyword(s):  
Food Packaging ◽  
Edible Films ◽  
Plant Residues ◽  
The Novel ◽  
Coating Technology ◽  
Film Forming ◽  
Quality Of Food ◽  
Novel Processing ◽  
Processing Techniques

The development of edible films and coatings has seen remarkable growth in recent decades and is expected to have an important impact on the quality of food products in the coming years. This growth is attributed to the increasing knowledge of edible films and edible coating technology, as well as advances in material science and processing technology. Packaging is used in order to reduce synthetic packaging and can play a role as an eco-friendly biodegradable package or a protective coating on the food surface. A large amount of bio-based polymers have been used in the production of edible films and coatings. Novel sources of edible materials, as well as the novel processing techniques, are a subject of great interest due to their promising potential as innovative food packaging systems. This paper presents the concept and potential for application of new film-forming materials and management of food wastes from the fruit and vegetable industry, which can encounter problems in appropriate disposal. It summarizes the extensive knowledge about the new film-forming materials such as plant residues, flours and gums to show their protective effectiveness and suitability in various types of foods.

THE ENERGY GAP IN THE HIGH-Tc COPPER OXIDE SUPERCONDUCTORS

1993 ◽  
Vol 07 (03) ◽  
pp. 143-153 ◽  
Author(s):  
YONGHONG LI ◽  
CHARLES M. LIEBER
Keyword(s):  
Transition Temperature ◽  
Energy Loss ◽  
High Temperature Superconductor ◽  
Energy Gap ◽  
Low Energy ◽  
Oxide Superconductors ◽  
High Tc ◽  
Resolution Electron ◽  
Copper Oxide Superconductors ◽  
Electron Energy Loss

We briefly review high-resolution electron energy loss spectroscopy (HREELS) studies of the low energy excitations in the high-temperature superconductor Bi 2 Sr 2 CaCu 2 O 8. HREELS has been used to determine the magnitude and temperature dependence of the energy gap (2Δ) for Bi 2 Sr 2 CaCu 2 O 8 single crystals. Below the transition temperature low-energy excitations are detected in the energy loss spectra. Because the energy loss spectra are proportional to the real part of the frequency dependent resistivity, ρR(ω), the energy gap can be determined directly from the HREEL data. At low temperature 2Δ = 6kT c and Δ develops sharply for T < T c . The constraints that these new results place on potential mechanisms of superconductivity are discussed.

Analysis of Superconducting Oxide by 7 MeV Alpha Particle Backscattering Analysis

1989 ◽  
Vol 156 ◽  
Author(s):  
Hiroki Yonezawa ◽  
Yoshikazu Hidaka ◽  
Minoru Suzuki ◽  
Toshio Shigematsu
Keyword(s):  
Alpha Particle ◽  
Resonance Scattering ◽  
High Energy ◽  
Oxide Superconductors ◽  
Quality Estimation ◽  
High Tc ◽  
Ion Backscattering ◽  
Particle Backscattering ◽  
Backscattering Analysis

ABSTRACTHigh energy Ion backscattering analysis in combination with recently-developed resonance scattering analysis Is described, with a stress on precise and quantitative oxygen analysis and its successful application to the characterization and quality estimation of high Tc oxide superconductors. Particularly, the present status of high energy ion backscattering analysis, the review of analytical results for YBa2Cu3O7−x, the estimation of composition and crystalline quality of (La1−xSrx)2CuO4 by 7 MeV alpha particle backscattering analysis are described.

A Tunneling Study of Superconducting YBa2 Cu3Oy By Contact Junctions At 77 K

1987 ◽  
Vol 99 ◽  
Author(s):  
H. Enomoto ◽  
K. Gotoh ◽  
K. Iida ◽  
Y. Takano ◽  
N. Mori ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Electronic Structures ◽  
Energy Gap ◽  
High Tc ◽  
Bcs Model ◽  
High Tc Superconductor ◽  
Derivative Analysis ◽  
Superconducting Energy Gap

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.

A NEW METALLIC NON MAGNETIC SUBSTRATE FOR COATED TAPE SUPERCONDUCTORS

2000 ◽  
Vol 14 (25n27) ◽  
pp. 3134-3138 ◽  
Author(s):  
G. GIUNCHI ◽  
S. CERESARA ◽  
R. CORTI ◽  
T. PETRISOR ◽  
A. MANCINI ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Oxide Superconductors ◽  
Manufacturing Cost ◽  
High Tc Superconductors ◽  
High Tc ◽  
Superconducting Tape ◽  
Production Technologies ◽  
Current Densities ◽  
Structural Compatibility

The high Tc superconductors, realised in form of coated tapes, rely on the quality of the substrate on which they are growing. Furthermore the aim to produce a long superconducting tape, carrying the high engineering current densities typical of the power applications, push the search of a very robust and thin metallic tape as substrate. Looking for a trade off between the mechanical strength at high temperature and the chemical and structural compatibility of the substrate with the growing oxide superconductors, a new metallic alloy is proposed and a systems combining the metallic tape plus one micron thick textured oxide buffer layer is presented. The system fulfils also the demanding characteristics of a low manufacturing cost, being based on production technologies easily scalable at high volumes, like the melt flow casting of the metallic tape and the Electron Beam (EB) evaporation of the oxide film. The main physical characteristic of the new substrate, with the deposited buffer layer, are presented.

A PROPOSED NEW MEASUREMENT OF THE SUPERCONDUCTING GAP IN YBa2Cu3O7

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3290-3293 ◽  
Author(s):  
G. L. ZHAO ◽  
D. BAGAYOKO
Keyword(s):  
Fermi Surface ◽  
Density Functional ◽  
Energy Gap ◽  
Interaction Matrix ◽  
Superconducting Gap ◽  
S Wave ◽  
Minor Variation ◽  
High Tc ◽  
Symmetry Properties ◽  
Superconducting Energy Gap

The superconducting energy gap of YBa 2 Cu 3 O 7 (YBCO) varies strongly with [Formula: see text] and from a sheet of the Fermi surface to another. The strong anisotropic superconducting gap in high Tc materials such as YBCO has led to conflicting d-wave and s-wave interpretations. We have utilized electronic wave functions from the ab-initio density functional calculation and the related electron-phonon interaction matrix elements for the calculation of the superconducting gap values of YBCO. We have found that the superconducting gap on one sheet of the Fermi surface around S-point only shows a minor variation from about 18 meV to 25 meV. Especially, there is no node on this sheet of the Fermi surface around the S-point. We propose a new test measurement of the superconducting gap of YBCO on this sheet of the Fermi surface around the S-point in the Brillouin zone. This measurement is expected to shed light on the gap symmetry properties of high Tc superconductors.

ENHANCEMENT EFFECT DUE TO HOP-ON AND HOP-OFF INTERACTION BETWEEN COOPER PAIR AND BIPOLARON ON THE CHARACTERISTICS OF THE HIGH-Tc CERAMIC SUPERCONDUCTOR

1994 ◽  
Vol 08 (24) ◽  
pp. 3423-3447
Author(s):  
C.C. LAM ◽  
K.N. WONG ◽  
C.M. LEE
Keyword(s):  
Critical Temperature ◽  
Cooper Pair ◽  
Energy Gap ◽  
Enhancement Effect ◽  
Ceramic Superconductor ◽  
High Tc ◽  
Ceramic Superconductors ◽  
Maximum Value ◽  
Superconducting Energy Gap ◽  
Electronegativity Difference

Enhancement in the critical temperature of high-Tc ceramic superconductors has been studied based on the bipolaronic theory which involves the hop-on and hop-off interaction between the Cooper pair and the bipolaron. As a consequence, the BCS energy gap is broadened to a certain extent which is determined by the interaction between the Cooper pair and the bipolaron. The effective superconducting energy gap for the ceramics consists of two parts: the traditional BCS energy gap of the ceramic and the gap broadening contributed by the hop-on and hop-off process. The critical temperature has been formulated from the effective BCS energy gap, and expressed in terms of the electronegativity difference Δχ. Results of our calculation on the critical temperature for MBCO-type, T(n) BCCO , and HBCCO match with the experimental data excellently. For a certain series of ceramic superconductors, the variation of Tc against Δχ traces out a curve having a high enough maximum value, in general.

TUNNELING MEASUREMENTS OF THE ENERGY GAP IN HIGH-Tc SUPERCONDUCTORS

1990 ◽  
Vol 04 (02) ◽  
pp. 201-237 ◽  
Author(s):  
J. R. KIRTLEY
Keyword(s):  
Fermi Level ◽  
Density Of States ◽  
Energy Gap ◽  
Large Energy ◽  
Current Status ◽  
High Tc Superconductors ◽  
High Tc ◽  
Gap Anisotropy ◽  
Consistent Picture ◽  
Coherence Lengths

The current status of tunneling measurements of the superconducting density of states near the Fermi level of high-T c superconductors is reviewed. A number of the characteristics of the tunneling data that had previously been considered to be "non-ideal" follow quite naturally from conventional tunneling theory, if the effects of the unusually large energy gap, often unusually small tunneling barriers, and gap anisotropy and/or inhomogeneity are correctly accounted for. Despite formidable problems in making these measurements, due to both the very short coherence lengths and materials problems in these superconductors, a consistent body of data is emerging. A consistent picture can be drawn from this data with the aid of the new modelling presented here.

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