Nanostructured high-temperature superconductors: Creation of strong-pinning columnar defects in nanorod/superconductor composites

1997 ◽  
Vol 12 (11) ◽  
pp. 2981-2996 ◽  
Author(s):  
Peidong Yang ◽  
Charles M. Lieber
Keyword(s):  
High Temperature ◽  
Critical Current Density ◽  
Defect Structure ◽  
Elevated Temperatures ◽  
High Temperature Superconductors ◽  
Columnar Defect ◽  
Columnar Defects ◽  
The Matrix ◽  
Strong Pinning ◽  
Reference Samples

A chemical approach to the formation of columnar defects involving the growth and incorporation of MgO nanorods into high temperature superconductors (HTS's) has been developed. MgO nanorods were incorporated into Bi2Sr2CaCu2Oz, Bi2Sr2Ca2Cu3Oz, and Tl2Ba2Ca2Cu3Oz superconductors at areal densities up to 2 × 1010/cm2. Microstructural analyses of the composites demonstrate that the MgO nanorods create a columnar defect structure in the HTS matrices, form a compositionally sharp interface with the matrix, and self-organize into orientations perpendicular and parallel to the copper oxide planes. Measurements of the critical current density demonstrate significant enhancements in the MgO nanorod/HTS composites at elevated temperatures and magnetic fields compared with reference samples.

Crystal Growth of High Temperature Superconductors

MRS Bulletin ◽  
1988 ◽  
Vol 13 (10) ◽  
pp. 56-61 ◽  
Author(s):  
H.J. Scheel ◽  
F. Licci
Keyword(s):  
High Temperature ◽  
Critical Current Density ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Large Scale ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Superconducting Transition ◽  
Theoretical Understanding

The discovery of high temperature superconductivity (HTSC) in oxide compounds has confronted materials scientists with many challenging problems. These include the preparation of ceramic samples with critical current density of about 106 A/cm2 at 77 K and sufficient mechanical strength for large-scale electrotechnical and magnetic applications and the preparation of epitaxial thin films of high structural perfection for electronic devices.The main interest in the growth of single crystals is for the study of physical phenomena, which will help achieve a theoretical understanding of HTSC. Theorists still do not agree on the fundamental mechanisms of HTSC, and there is a need for good data on relatively defect-free materials in order to test the many models. In addition, the study of the role of defects like twins, grain boundaries, and dislocations in single crystals is important for understanding such parameters as the critical current density. The study of HTSC with single crystals is also expected to be helpful for finding optimum materials for the various applications and hopefully achieving higher values of the superconducting transition temperature Tc than the current maximum of about 125 K. It seems unlikely at present that single crystals will be used in commercial devices, but this possibility cannot be ruled out as crystal size and quality improve.

scholarly journals Cyclic degradation of titanium–tantalum high-temperature shape memory alloys — the role of dislocation activity and chemical decomposition

2015 ◽  
Vol 08 (06) ◽  
pp. 1550062 ◽  
Author(s):  
T. Niendorf ◽  
P. Krooß ◽  
C. Somsen ◽  
R. Rynko ◽  
A. Paulsen ◽  
...  
Keyword(s):  
High Temperature ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Elevated Temperatures ◽  
Nickel Titanium ◽  
Chemical Decomposition ◽  
Ω Phase ◽  
The Matrix ◽  
Cyclic Degradation

Titanium–tantalum shape memory alloys (SMAs) are promising candidates for actuator applications at elevated temperatures. They may even succeed in substituting ternary nickel–titanium high temperature SMAs, which are either extremely expensive or difficult to form. However, titanium–tantalum alloys show rapid functional and structural degradation under cyclic thermo-mechanical loading. The current work reveals that degradation is not only governed by the evolution of the ω-phase. Dislocation processes and chemical decomposition of the matrix at grain boundaries also play a major role.

STUDY OF KINETIC FRICTION OF SOLID USING DRIVEN LATTICE OF QUANTIZED VORTEX IN HIGH-TEMPERATURE SUPERCONDUCTORS–A NEW ROUTE TO STUDY SOLID-SOLID FRICTION

2005 ◽  
Vol 19 (01n03) ◽  
pp. 463-470 ◽  
Author(s):  
ATSUTAKA MAEDA ◽  
YUKICHI INOUE ◽  
HARUHISA KITANO ◽  
SATORU OKAYASU ◽  
ICHIRO TSUKADA
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Cuprate Superconductors ◽  
High Temperature Superconductors ◽  
Magnetic Vortex ◽  
Kinetic Friction ◽  
Columnar Defects ◽  
Solid Friction ◽  
Ac Current ◽  
Microwave Techniques

We show that quantized magnetic vortex lattice in high-temperature cuprate superconductors driven by dc or ac current is a very good model system for investigating physics of friction of solid. Based on the dc I-V characteristic measurement and viscosity measurement using microwave techniques in Bi 2 Sr 2 CaCu 2 O y and La 1.85 Sr 0.15 CuO 4, the corresponding kinetic friction was obtained as functions of temperature, magnetic field and driving current density. With increasing magnetic field and temperature, velocity dependence of kinetic friction behaves as that at interfaces with weak interaction of solid. This result means that we can control the kinetic friction, and that systematic experiments are available in a reproducible manner with using this system. Behavior of the kinetic friction at higher velocities (~1 km/s) agrees well with a two-class potential model at finite temperatures. Irradiation of the columnar defects was found to move the system closer to the so-called Amontons-Coulomb friction. This suggests that the random potential created by the strong pinning centers plays an important role of the validity of Amontons-Coulomb law.

Modeling the Microstructural and Yield Strength Evolution of an Age-Hardenable Al Alloy for High Temperature Applications

2016 ◽  
Vol 879 ◽  
pp. 380-385 ◽  
Author(s):  
Marco Colombo ◽  
Elisabetta Gariboldi ◽  
Paola Bassani ◽  
Mihaela Albu ◽  
Ferdinand Hofer
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Yield Strength ◽  
Elevated Temperatures ◽  
Age Hardening ◽  
Homogeneous Distribution ◽  
Al Alloy ◽  
Physically Based ◽  
The Matrix ◽  
Physically Based Models

The mechanical properties of Al alloys are strongly affected by their microstructure: the size and shape of precipitates, their homogeneous distribution and their coherency with the matrix are of primary importance for an effective strengthening of the alloys at room and elevated temperatures. Physically-based models are powerful tools to predict the influence of the mentioned parameters on the mechanical properties of the alloy after age hardening, and also to predict the effect of high temperature service conditions on microstructure evolution. Scope of this work is to model the dimensional kinetic evolution of plate shaped precipitates of an Al-based alloy during aging and after different overaging times at elevated temperature, and use these results to estimate the alloy yield strength. The alloy strengthening response is due to three terms, linearly summed: the intrinsic strength of Aluminum, the contribution from solute in solid solution and the contribution arising from precipitates. The consistency of the model is verified with experimental data obtained from a 2014 Al alloy.

Sign in / Sign up

Export Citation Format

Share Document