A New Method of Estimating the Superconducting Volume Fraction in High-TcSuperconductors

1990 ◽  
Vol 29 (Part 2, No. 5) ◽  
pp. L770-L771 ◽  
Author(s):  
Yoichi Ando ◽  
Shirabe Akita
Keyword(s):  
Volume Fraction ◽  
New Method ◽  
Superconducting Volume Fraction

A Method for Tracking a Solid Body in a Fluid Field in Immersed Boundary Methods

2018 ◽  
Author(s):  
Guangfa Yao
Keyword(s):  
Level Set ◽  
Solid Body ◽  
Volume Fraction ◽  
Transformation Matrix ◽  
The Body ◽  
New Method ◽  
Immersed Boundary ◽  
Body Interaction ◽  
Level Set Function ◽  
Set Function

Immersed boundary method has got increasing attention in modeling fluid-solid body interaction using computational fluid dynamics due to its robustness and simplicity. It usually simulates fluid-solid body interaction by adding a body force in the momentum equation. This eliminates the body conforming mesh generation that frequently requires a very labor-intensive and challenging task. But accurately tracking an arbitrary solid body is required to simulate most real world problems. In this paper, a few methods that are used to track a rigid solid body in a fluid domain are briefly reviewed. A new method is presented to track an arbitrary rigid solid body by solving a transformation matrix and identifying it using a level set function. Knowing level set function, the solid volume fraction can be derived if needed. A three-dimensional example is used to study a few methods used to represent and solve the transformation matrix, and demonstrate the presented new method.

APPLICATION OF ESR TO HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS IV: ALKALI K DOPING EFFECTS ON THE SUPERCONDUCTING CHARACTERISTICS OF K3C60

1999 ◽  
Vol 13 (02) ◽  
pp. 59-69
Author(s):  
K. SUGAWARA ◽  
N. OHYA ◽  
N. ARAI ◽  
S. ICHIMURA ◽  
K. YAMAMOTO ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Calcination Temperature ◽  
Volume Fraction ◽  
Superconducting Properties ◽  
High Tc Superconductors ◽  
High Tc ◽  
Doping Effects ◽  
Superconducting Volume Fraction ◽  
Vortex Size ◽  
Quartz Tubes

Several samples of K 3 C 60 have been made by the calcination of C 60 powder plus K flakes in evacuated quartz tubes at temperatures between 100°C and 700°C for 24 hours. The non-resonant microwave absorption (NRMA) measurements have been done below T c for these samples. From the linewidths and intensities of the NRMA signals, the superconducting properties (T c superconducting volume fraction and vortex size) have been studied as a function of the calcination temperature.

EFFECT OF COOLING RATE ON THE TRANSITION TEMPERATURE IN Bi–Pb–Sr–Ca–Cu–O SYSTEM

1990 ◽  
Vol 04 (04) ◽  
pp. 293-299
Author(s):  
YUGUI WANG ◽  
JINSONG WANG ◽  
NANLIN WANG ◽  
XINPING JIAO ◽  
GUCHANG HAN ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Specific Heat ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Oxygen Deficiency ◽  
Ac Susceptibility ◽  
Rapid Quenching ◽  
Nominal Composition ◽  
Unit Cell Size ◽  
Superconducting Volume Fraction

The resistance and ac susceptibility measurements show that cooling rate of the cast-annealing samples in heat treatment process has some effect on the 110 K superconducting phase in Bi–Pb–Sr–Ca–Cu–O system. Rapid quenching of the sample in air from 845°C causes oxygen deficiency in lattice and brings about a trifling change of unit cell size along c-axis direction. The dc magnetization and specific heat anomaly ∆c measurements demonstrate that fast cooling rate can reduce the transition temperature of high T c phase and the lower critical field, and weaken the pinning forces for vertex lines. The peak value of specific heat anomaly of the sample with nominal composition of Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 4.5 O y is still small in comparison with YBa 2 Cu 3 O 7. From the magnetization curve we can estimate that the superconducting volume fraction is about 20%.

High Density Bulk Shape Rapid Consolidation of the Yba2Cu307-X Superconductor

1989 ◽  
Vol 169 ◽  
Author(s):  
S. V. Rele ◽  
R. V. Raman ◽  
H. S. Meeks ◽  
R. L. Anderson ◽  
R. N. Shelton ◽  
...  
Keyword(s):  
Volume Fraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Superconducting Volume Fraction ◽  
One Step ◽  
Hollow Cylinders ◽  
Diffraction Patterns ◽  
Set Up ◽  
Cylinders And Spheres ◽  
High Processing

AbstractA novel rapid densification technique for fabrication of bulk shape YBa2Cu307–xsuperconductor is presented. The Ceracon process is a one‐step, quasi‐isostatic consolidation route utilizing conventional P/M equipment and set‐up. The Ceracon technology has enabled successful fabrication of bulk, shapes such as discs, cylinders, hollow cylinders and spheres along with significant increases in the density up to 95‐98% of the theorertical. The superconducting volume fraction is preserved due to short hold times at the operating temperatures and avoidance of high processing temperatures. Results based on densities, microstructure, susceptibility measurements, X‐ray diffraction patterns and TGA measurements are discussed.

Temperature Ramping for Nucleation of Oxygen Precipitates in Silicon

1984 ◽  
Vol 36 ◽  
Author(s):  
R. F. Pinizzotto ◽  
H. F. Schaake ◽  
R. G. Massey ◽  
D. W. Heidt
Keyword(s):  
Volume Fraction ◽  
New Method ◽  
Number Density ◽  
Small Particles ◽  
Ramp Rate ◽  
Czochralski Silicon ◽  
Oxygen Precipitation ◽  
Temperature Ramp ◽  
Oxygen Precipitates ◽  
Precipitate Nucleation

ABSTRACTA new method for the nucleation of oxygen precipitates in Czochralski silicon is described. The temperature is ramped at approximately 100°C/hr from a very low value, near 400°C, to the highest temperature used for subsequent process steps. The technique generates a larger precipitate number density and a greater volume fraction of precipitated oxygen than standard isothermal nucleation anneals. The morphology of the precipitates changes from 0.lum sizéd (100) platelets to small particles unresovable by TEM. The new temperature ramping technique can reduce the time needed for precipitate nucleation by at least a factor of three. The details of oxygen precipitation can be totally controlled by adjusting the temperature ramp rate as a function of time.

Synthesis and Superconducting Properties of Metastable Y(Ba2−xYx)Cu3O7+δ

1987 ◽  
Vol 99 ◽  
Author(s):  
Z. Iqbal ◽  
F. Reidinger ◽  
A. Bose ◽  
N. Cipollini ◽  
H. Eckhardt ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Parent Compound ◽  
Resistive Transition ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Recent Interest ◽  
Superconducting Volume Fraction ◽  
Citrate Precursor ◽  
Reaction Routes

ABSTRACTThe oxygen-deficient orthorhombic oxide YBa2Cu3O7-δ has been the center of intense recent interest because of its high Tc superconducting proper-ties[l-3]. Recently, the structurally related La3Ba3Cu3O15-δ, has received increasing attention[4–9]. The pure Y analog[10,11] cannot be synthesized by usual solid state reaction routes probably because of its metastability near 880°C. Here we report on the successful synthesis of pure tetragonal Y3,Ba3CU6O15-δ (referred to as Y 3–3–6), via the firing of an atomically mixed citrate precursor at a relatively low temperature. X-ray diffraction data characterize Y 3–3–6 to be isostructural with the corresponding La compound[4]. The unit cell composition can then be written as: Y(Ba2−x Yx) CU3O7+δ with the parent compound at x = 0.50. Specimens of Y 3–3–6 at × = 0.50 and 0.375 annealed at 650°C under 1 atmosphere of O2 are non-superconducting. Higher pressure O2 annealing and fluorine-doping leads to a 1–5% superconducting volume fraction with onset at 85K. Annealing near 880°C creates a 10% superconducting fraction which shows near-zero resistivity at 62K and a reproducible, small resistive transition near 260K.

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