A non-vacuum, room-temperature process for the application of solderable contacts to ceramic high-Tc Superconductors

1989 ◽  
Vol 151 ◽  
pp. 481-486
Author(s):  
A. Lorenz ◽  
E. Bochenek ◽  
R. Fischer ◽  
R. Schneider
Keyword(s):  
Room Temperature ◽  
High Tc Superconductors ◽  
High Tc

scholarly journals Fermi-Bose Mixtures and BCS-BEC Crossover in High-Tc Superconductors

2019 ◽  
Vol 4 (2) ◽  
pp. 51 ◽  
Author(s):  
Maxim Yu. Kagan ◽  
Antonio Bianconi
Keyword(s):  
Room Temperature ◽  
High Tc Superconductors ◽  
High Tc ◽  
Magnetic Traps ◽  
Unconventional Superconductors ◽  
Topological Superconductors ◽  
Coupling Approach ◽  
Bose Einstein ◽  
Room Temperature Superconductivity ◽  
Twisted Graphene

In this review article we consider theoretically and give experimental support to the models of the Fermi-Bose mixtures and the BCS-BEC (Bardeen Cooper Schrieffer–Bose Einstein) crossover compared with the strong-coupling approach, which can serve as the cornerstones on the way from high-temperature to room-temperature superconductivity in pressurized metallic hydrides. We discuss some key theoretical ideas and mechanisms proposed for unconventional superconductors (cuprates, pnictides, chalcogenides, bismuthates, diborides, heavy-fermions, organics, bilayer graphene, twisted graphene, oxide hetero-structures), superfluids and balanced or imbalanced ultracold Fermi gases in magnetic traps. We build a bridge between unconventional superconductors and recently discovered pressurized hydrides superconductors H3S and LaH10 with the critical temperature close to room temperature. We discuss systems with a line of nodal Dirac points close to the Fermi surface and superconducting shape resonances, and hyperbolic superconducting networks which are very important for the development of novel topological superconductors, for the energetics, for the applications in nano-electronics and quantum computations.

EFFECTS OF CHEMICAL DOPING AND STOICHIOMETRIC VARIATION IN HIGH-Tc SUPERCONDUCTORS

1989 ◽  
Vol 03 (04) ◽  
pp. 573-594 ◽  
Author(s):  
Y. H. KAO ◽  
Y. D. YAO ◽  
L. W. SONG
Keyword(s):  
Room Temperature ◽  
Dopant Concentration ◽  
Order Structure ◽  
Exponential Dependence ◽  
Room Temperature Resistivity ◽  
Chemical Doping ◽  
High Tc Superconductors ◽  
Host Matrix ◽  
High Tc ◽  
Temperature Resistivity

Superconducting properties of various chemically-doped high-T c materials are investigated. By using the results obtained with Cu- and Bi-deficient Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O systems as basis, variations of the transition temperature T c , critical current density J c , room temperature resistivity ρ, and oxygen content are compared for different dopant contents. In several cases, J c and ρ are found to be correlated as both quantities show an exponential dependence on the dopant concentration. Most dopants result in a monotonic decrease of T c and J c , except for Ag, F, and Cl. Substitution of Ag and Pb for Cu and Bi in Bi-Sr-Ca-Cu-O indicates a condition for compatibility between the impurity atom and the local structure in the host matrix. Results suggest that the predominant mechanism for high-T c superconductivity is most likely associated with short-range-order structure in the material.

scholarly journals PASSIVATION PROCESS OF HIGH Tc SUPERCONDUCTORS YBa2Cu3O7−δ BY FLUORINE GAS TREATMENT

1988 ◽  
Vol 02 (10) ◽  
pp. 1183-1188 ◽  
Author(s):  
A. TRESSAUD ◽  
B. CHEVALIER ◽  
B. LEPINE ◽  
J.M. DANCE ◽  
L. LOZANO ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Thin Layer ◽  
Room Temperature ◽  
Meissner Effect ◽  
Shielding Effect ◽  
High Tc Superconductors ◽  
Gas Treatment ◽  
High Tc ◽  
Exchange Processes ◽  
Atmospheric Degradation

The atmospheric degradation of high T c superconductors YBa 2 Cu 3 O 7−δ can be prevented using fluorine gas processings around room temperature. A thin layer of amorphous fluorides (and/or oxyfluorides) is formed at the surface of the particles, which passivates the material against hydrolysis and gas-exchange processes. A fluorination mechanism has been proposed, which can account for both fluorine analysis and weight uptake. The superconductivity onset does not seem to be affected by fluorination. Furthermore, an improvement of the shielding effect-Meissner effect cycle to 91% reversibility is achieved when F 2-treated oxides are heated at 350°C under vacuum.

Room Temperature Impedance and ac Conductivity Studies on Na-, K-Doped Tc-Enhanced High Tc Superconductors

2006 ◽  
Vol 19 (1-2) ◽  
pp. 143-149
Author(s):  
M. Mohammad ◽  
A. Y. Khan ◽  
M. S. Subhani ◽  
Sabahat Yasmeen ◽  
Shahnaz Malik ◽  
...  
Keyword(s):  
Ac Conductivity ◽  
Room Temperature ◽  
High Tc Superconductors ◽  
High Tc

APPLICATION OF ESR TO HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS III: CRYSTAL GROWTH RATES OF Y2BaCuO5 IN THE MELTS OF Y1+2nBa2+nCu3+nOx (n=0–0.4) SUBJECTED TO HIGH TEMPERATURES

1999 ◽  
Vol 13 (02) ◽  
pp. 51-58 ◽  
Author(s):  
K. YAMAMOTO ◽  
N. ARAI ◽  
K. HOTTA ◽  
K. SUGAWARA ◽  
H. HIROSE
Keyword(s):  
Heat Treatment ◽  
Crystal Growth ◽  
Growth Rates ◽  
Heat Treatment Temperature ◽  
Room Temperature ◽  
Atmospheric Condition ◽  
Treatment Temperature ◽  
High Tc Superconductors ◽  
Temperature Quenching ◽  
High Tc

Form the ESR measurements of Cu 2+ in Y 2 BaCuCuO 5, the growth rates of Y 2 BaCuCO 5 generated in the melts of Y 1+2n Ba 2+n Cu 3+n O x (n=0–0.4) have been quantitatively obtained as functions of heat-treatment temperature (1000–1400°C) and heat-treatment period (10–120 minutes). All the melted samples have been prepared by heating them in an atmospheric condition, and room-temperature quenching.

Application of ESR to High-Tc Superconductors and Related Materials: I. ESR Study of Cu2+ as a Probe of Crystal Growth Rates of Y2BaCuOy at High Temperatures

1998 ◽  
Vol 12 (10) ◽  
pp. 363-370 ◽  
Author(s):  
K. Yamamoto ◽  
N. Arai ◽  
K. Hotta ◽  
K. Sugawara ◽  
H. Hirose
Keyword(s):  
Heat Treatment ◽  
Crystal Growth ◽  
Growth Rates ◽  
Concentration Ratio ◽  
Room Temperature ◽  
Treatment Temperature ◽  
High Tc Superconductors ◽  
High Tc ◽  
Systematic Data ◽  
Heat Treated

A number of pellets with nominal concentration ratio of Y:Ba:Cu =2:1:1 have been sintered in air at temperatures between 800°C and 1400°C for 1 min ~24 h. The heat-treated samples were quenched to room temperature and the crystal growth rates of Y 2 BaCuO y≃5 were measured using ESR of Cu 2+. Systematic data on the growth rates were taken as a function of heat-treatment temperature and period.

MICROWAVE ABSORPTION STUDIES ON HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS III: Electron Spin Resonance Studies of Y2Ba1Cu1O5 and Gd2Ba1Cu1O5

1991 ◽  
Vol 05 (13) ◽  
pp. 895-901 ◽  
Author(s):  
K. SUGAWARA ◽  
D. J. BAAR ◽  
Y. SHIOHARA ◽  
S. TANAKA
Keyword(s):  
Electron Spin Resonance ◽  
Microwave Absorption ◽  
Electron Spin ◽  
Room Temperature ◽  
Magnetic Ordering ◽  
High Tc Superconductors ◽  
Néel Temperature ◽  
High Tc ◽  
Spin Resonance ◽  
Absorption Studies

The ESR of Cu 2+ and Gd 3+ ion in Y 2 Ba 1 Cu 1 O 5 and Gd 2 Ba 1 Cu 1 O 5 has been studied at temperatures from 4 K to room temperature. Particular emphasis has been paid to the ESR linewidths (∆H PP ) and g-values of the ions. The ∆H PP and g-values for Y 2 Ba 1 Cu 1 O 5 were found to have anomalous increments near 15 K, close to the Néel temperature of Y 2 Ba 1 Cu 1 O 5. Similarly, ∆H PP for Gd 2 Ba 1 Cu 1 O 5 had peaks near 12 K. Our analysis reveals that the ESR signal from Gd 2 Ba 1 Cu 1 O 5 is dominated by the Gd 3+ ESR. However, the magnetic ordering may be caused by both Gd-Gd and Gd-Cu interactions.

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.

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