Processing Relationships in YBa2Cu3O7−x Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
W. J. Heber ◽  
L. R. Pederson ◽  
G. D. Maupin ◽  
E. J. Leblanc
Keyword(s):  
Photoelectron Spectroscopy ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Orthorhombic Structure ◽  
Transition Width ◽  
Slow Cooling ◽  
Pressure Oxidation ◽  
Atmosphere Pressure ◽  
X Ray ◽  
Complete Transformation

ABSTRACTSamples of YBa2Cu3O7−x were prepared by solid state reaction of Y2O3, BaO2, and CuO powders mixed in stoichiometric proportions. Powders reacted at 900°C-925°C in air were pressed at 35 MPa into rectangular bars and sintered at 950°C in air for six hours. Slow cooling at 50°C/hour promoted complete transformation to the orthorhombic structure. The effects of subsequent oxidation processing on superconducting properties were also investigated. Oxidation anneals at one atmosphere pressure in flowing O2over the temperature range from 300 to 550°C were performed. Results indicate that oxidation at 450°C optimized the superconducting transition temperature at 91K with a 2-degree transition width. Subsequent high-pressure oxidation (2000 psi O2) at 200°C for one week significantly degraded the superconducting characteristics. Results based on i udometric titration, thermogravimetric analysis, and x-ray photoelectron spectroscopy suggest that the copper valency is about 2.3 and oxygen stoi chiometry is 6.94 (x = 0.06) in samples processed to optimize superconducting properties.

scholarly journals Effect of Sol-Gel Synthesized BiFeO3 Nanoparticle Addition in YBa2Cu3O7–δ (Y123) Superconductor Synthesized by Standard Solid State Reaction Method

2019 ◽  
Vol 290 ◽  
pp. 245-251
Author(s):  
Abdalla Bahboh ◽  
Abdul Halim Shaari ◽  
Hussein Baqiah ◽  
Soo Kien Chen ◽  
Mohd Mustafa Awang Kechik ◽  
...  
Keyword(s):  
Sol Gel ◽  
Solid State Reaction Method ◽  
Superconducting Transition ◽  
Secondary Phases ◽  
Superconducting Properties ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
Scanning Electron Micrograph ◽  
X Ray ◽  
Pure Ybco

The effects of the multiforric BiFO3 nanoparticles addition on the structure and superconducting properties of YBa2Cu3O7–δ (Y123) with different concentrations were systematically investigated using X-ray diffraction (XRD), field emission scanning electron micrograph (FESEM), EDX and four point probe measurement. It was found that the added samples were predominant by Y-123 phase beside small amount of Y-211 and unreacted BiFeO3 secondary phases. Samples with less (wt.%) BFO added YBCO precursor powder preserved the orthorhombic structure similar to the pure YBCO, while samples with higher wt% addition show orthorhombic-to-tetragonal transition tendency. The samples became more porous and their grain size slightly decreased with addition of BiFeO3. The addition of nanoBiFeO3 disturbed the grain growth of Y123, thus resulting in the degradation of superconducting properties of the samples. The superconducting transition temperature (Tc onset) of samples decreased from 92 K for x=0.0 to 44 K for x=10.0 wt. %, which could be attributable to oxygen vacancy disorder.

scholarly journals Synthesis, Characterization and Ageing of MgB2

2001 ◽  
Vol 689 ◽  
Author(s):  
A. Serquis ◽  
R. Schulze ◽  
Y. T. Zhu ◽  
J. Y. Coulter ◽  
D. E. Peterson ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Rietveld Analysis ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Ambient Conditions ◽  
X Ray ◽  
Grain Sizes ◽  
Crystal Strain ◽  
Surface Decomposition ◽  
Meissner Fraction

ABSTRACTWe studied the influence of sample preparation and defects in the superconducting properties samples using atomic ratios of Mg:B=1:1 and Mg:B=1:2. Samples were characterized by SEM, and XRD, and the magnetization properties were examined in a SQUID magnetometer. The presence of Mg vacancies was determined by Rietveld analysis. Most of the samples exhibited sharp superconducting transitions with Tcs between 37–39 K.We found a strong correlation between the crystal strain and the Tc. This strain was related to the presence of Mg vacancies. In addition, results showed that some samples degraded with time when exposed to ambient conditions. In these samples the Tc did not change with time, but the superconducting transition became broader and the Meissner fraction decreased. This effect was only present in samples with poor connectivity between grains and smaller grain sizes. The degradation was related to a surface decomposition as observed by X-ray Photoelectron Spectroscopy. No correlation was found between this effect and the presence of Mg vacancies.

COMPOSITION DEPENDENCE OF SUPERCONDUCTIVITY AND CRYSTAL STRUCTURE IN La(Ba1−xCax)2Cu3O7−y SYSTEM

1989 ◽  
Vol 03 (04) ◽  
pp. 307-311 ◽  
Author(s):  
N. CAO ◽  
J.Q. ZHENG ◽  
X.Y. SHAO ◽  
X.S. CHEN ◽  
W.Y. GUAN
Keyword(s):  
Crystal Structure ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Composition Dependence ◽  
Superconducting Transition ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
Zero Resistance

The composition dependence of superconductivity and crystal structure in La ( Ba 1−x Ca x)2 Cu 3 O 7−y system was determined by the resistivity measurements and X-ray diffraction analysis. The superconducting transition temperature is raised with the increase of Ca content till x=0.6, at which the zero resistance temperature of the sample is 81.5 K. In the meanwhile, the crystal structure of the sample changed from tetragonal (x=0) to orthorhombic structure (x=0.2, 0.4, 0.6). With further increase of Ca content, the superconductivity decrease for the sample of x=0.8 with mixed phases including the orthorhombic oxygen-deficient perovskite-like (ODP) structure and no superconducting transition is found at 4.2 K for the sample of x=1 without the ODP structure. A possible explanation of these experimental results is given.

Deposition of Superconducting Thin Films of Magnesium Di-Boride on Various Substrates by Electroless Plating Process

2010 ◽  
Vol 654-656 ◽  
pp. 1840-1843
Author(s):  
Susil K. Putatunda ◽  
Khurpa S. Vijayaragavan ◽  
Gavin Lawes
Keyword(s):  
Thin Films ◽  
Electroless Plating ◽  
Magnesium Diboride ◽  
Superconducting Thin Films ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Gold Silver

Superconducting thin films of magnesium diboride (MgB2) has been synthesized on various substrates such as gold, silver, copper and silicon using a novel electroless plating technique. The microstructures and the superconducting properties of these films have been characterized using X-ray diffraction, scanning electron microscopy and temperature dependent magnetometry. X-ray diffraction measurements confirm that the films are crystalline magnesium diboride with some impurity phases. Clear evidence for a superconducting transition in the magnetization measurements was observed.

scholarly journals Carbon nanofibers addition on transport and superconducting properties of bulk YBa2Cu3O7−δ material prepared via co-precipitation

2020 ◽  
Vol 31 (19) ◽  
pp. 16983-16990
Author(s):  
Nurul Auni Khalid ◽  
Mohd Mustafa Awang Kechik ◽  
Nur Atikah Baharuddin ◽  
Chen Soo Kien ◽  
Hussein Baqiah ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Carbon Nanofibers ◽  
Precipitation Method ◽  
Superconducting Properties ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
Minor Phase ◽  
X Ray ◽  
Co Precipitation ◽  
A Minor

Abstract The effects of carbon nanofibers addition on transport and superconducting properties of YBa2Cu3O7−δ (Y-123) superconductor were studied. Y-123 was prepared using co-precipitation method for good quality bulk of high temperature superconducting material. Carbon nanofibers with 0.2–0.8 wt% were added into Y-123 superconductors. The samples were characterized using electrical resistance measurement for critical temperature (Tc) and critical current density (Jc), powder X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray analysis. Most of the samples indicated a dominant Y-123 phase of an orthorhombic structure with a minor phase of BaCO3 and Y-124. Onset critical temperature was found to decrease from 90.5 to 80 K with increasing of carbon nanofibers concentration. The Jc for pure sample is 11 A/cm2 at 30 K while the Jc of sample with 0.4 wt% carbon nanofibers is 830 A/cm2 at 30 K. Introduction of carbon nanofibers enhanced Jc significantly. However, further addition of carbon nanofibers in Y-123 superconductor caused degradation in Jc.

Superconducting Properties of Bi-Sr-Ca-Cu-O Crystallized Glass

1999 ◽  
Vol 13 (09n10) ◽  
pp. 985-989
Author(s):  
S. Chudinov ◽  
S. Stizza ◽  
B. Kościelska ◽  
L. Murawski ◽  
W. Sadowski ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Glass Ceramics ◽  
Superconducting Phase ◽  
Superconducting Transition ◽  
Resistive Transition ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Melt Quenching ◽  
X Ray ◽  
Quenching Method

This paper reports the crystallization and superconducting properties of Bi 4 Sr 3 Ca 3 Cu 4 O x glass-ceramics. The glass was prepared using the conventional melt-quenching method. X-ray diffraction pattern has shown that the annealing at temperature of 800°C converted the glass into glass-ceramics with Bi 2 Sr 2 CaCu 2 O x superconducting phase (2212-phase). The superconducing transition exhibits the change in the slope that is characteristic for two different superconducting phases. It is observed that T c (zero) increases from 20 K to 80 K with increasing time of annealing. The influence of magnetic field on the superconducting transition has been investigated. Our studies revealed a remarkable broadening of the resistive transition as a function of temperature with increasing field. The temperature width ( T c-T) of the transition for both phases increases with magnetic field according to Tinkham model.

1212-Molybdo-Cuprates; effect of oxygenation in the structure, properties and electronic states

2014 ◽  
Vol 1655 ◽  
Author(s):  
Sourav Marik ◽  
A. J. Dos santos-Garcia ◽  
Christine Labrugere ◽  
Emilio Morán ◽  
Olivier Toulemonde ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Oxidation Reaction ◽  
Short Range ◽  
Magnetic Measurements ◽  
Electronic States ◽  
The Other ◽  
Superconducting Transition ◽  
X Ray ◽  
Flowing Oxygen ◽  
Structure Properties

ABSTRACTThe influence of oxygenation in the magnetism, superconductivity and electronic states for the Mo0.3Cu0.7Sr2RECu2Oy (RE = Y, Er and Tm) compounds are discussed here. The magnetic measurements on the as-prepared (AP) samples suggest the existence of short-range magnetic correlations due to the presence of the paramagnetic MoV cations in the copper chain site. On the other hand, all the oxygenated samples are not magnetic but superconducting. The high pressure oxygenated sample shows the highest superconducting transition temperature of TC = 84 K. The influence of oxygenation in the electronic states for the Mo0.3Cu0.7Sr2YCu2Oy system associated with an oxidation reaction leading from a non-superconducting to a superconducting state has also been investigated by means of X-ray photoelectron spectroscopy (XPS). XPS measurements show the predominance of the MoV oxidation state over the MoVI one in the AP material; annealing under flowing oxygen enhances both the MoVI and CuII amounts. A detailed study of the electronic states for the Mo0.3Cu0.7Sr2YCu2Oy samples has been performed and is also discussed.

Superconducting properties of mixtures of Y1Ba2Cu3O9−x and Y1.8Ba0.2Cu1O5−y

1988 ◽  
Vol 3 (6) ◽  
pp. 1297-1303 ◽  
Author(s):  
X. W. Wang ◽  
H. S. Kwok ◽  
L. Shi ◽  
J. P. Zheng ◽  
P. Mattocks ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Meissner Effect ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
X Ray ◽  
Heat Treated

The superconducting properties of heat-treated mixtures of Y1Ba2Cu3O9−x (A) and Y1.8Ba0.2Cu1O5−y (B) have been studied. As the concentration of B increases, the Meissner effect decreases, while the resistance jump near the superconducting transition increases. When the fraction of B approaches about 0.5, the superconducting transition disappears. Four different phases are identified in the mixture from the x-ray spectra, i.e., Y1Ba2Cu3O9−x, Y2Ba1Cu1O5–z, Y2Cu2O5, and Y2O3. The results agree well with the published phase diagram of this system.

Sign in / Sign up

Export Citation Format

Share Document