Far Infrared Measurements on Single Crystals, Films and Bulk Sintered High Temperature Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
T. W. Noh ◽  
P. E. Sulewski ◽  
S. G. Kaplan ◽  
A. J. Sievers ◽  
D. K. Lathrop ◽  
...  
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
High Temperature Superconductors ◽  
Far Infrared ◽  
Infrared Measurements ◽  
Gap Values

ABSTRACTWe report measurements of the reflectivity of bulk samples, films and single crystals of high Tc materials. The data are fitted with the Mattis-Bardeen theory to obtain gap values. For sintered samples we find 2Δ/kTc = 2.6, while for YBa2Cu3O7-y films and single crystals 2Δ/kTc = 6.4 and 7.7 respectively.

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.

SINGLE CRYSTAL GROWTH OF HIGH TEMPERATURE SUPERCONDUCTORS AND INVESTIGATION OF THEIR PHYSICAL PROPERTIES

1989 ◽  
Vol 03 (02) ◽  
pp. 289-302 ◽  
Author(s):  
V. A. TATARCHENKO ◽  
G. A. EMEL'CHENKO ◽  
N. V. ABROSIMOV ◽  
V. A. BORODIN ◽  
L. Ya. VINNIKOV ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Optical Properties ◽  
Crystal Growth ◽  
High Temperature ◽  
Thermal Treatment ◽  
Physical Properties ◽  
Single Crystals ◽  
High Temperature Superconductors ◽  
Single Crystal Growth ◽  
Superconducting Properties

Part of the phase diagram of the La 2 O 3- CuO system has been studied and single crystals of La 2 CuO 4, (LaSr) 2 CuO 4 (up to 20 × 8 × 6 mm 3), YBa 2 Cu 3 O 7−δ (up to 8 × 6 × 0.1 mm 3) and HoBa 2 Cu 3 O 7-(up to 3 × 2.5 × 1 mm 3) have been grown by the method of spontaneous crystallisation, using a rotational crucible. It has been established that thermal treatment of "123" single crystals under oxygen pressure to 10 bars improves their superconducting properties. Electrical, magnetic, optical properties, and the real structure of the single crystals produced have been studied.

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