High Temperature Superconductors in the La1+xBa2-xCu3Oy System

1987 ◽  
Vol 99 ◽  
Author(s):  
E. M. McCarron ◽  
C. C. Torardi ◽  
J. P. Attfield ◽  
K. J. Morrissey ◽  
A. W. Sleight ◽  
...  
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Ionic Radius ◽  
High Temperature Superconductors ◽  
Oxide System ◽  
Superconducting Properties ◽  
Close Match ◽  
Oxygen Ordering ◽  
Lanthanum Ions ◽  
Superconducting Onset Temperature

ABSTRACTIn the perovskite-related La/Ba/Cu oxide system, the lanthanum ions can substitute on the barium sites due to a close match in the ionic radius of the two. Thus it is possible to make a solid solution La1+xBa2-xCu3Oy where O ∼ x ≤ 0.5 and y ∼ 7. For the Ba-rich end member composition (x ∼ 0). the structure is orthorhombic. but as the La content increases and La begins to substitute on the Ba sites (disordered), the crystal symmetry changes from orthorhombic to tetragonal. In addition, the superconducting properties vary with increasing La content. In particular, the superconducting onset temperature is found to decrease linearly from 80 to 45 K over the compositional (x) range 0.0 → 0.375. In the La-rich limit (x = 0.5). 1/4 of the Ba atoms are replaced by La and superconductivity is lost. A correlation between oxygen ordering (annealing) and high Tc is observed for orthorhombic LaBa2Cu3Oy and inferred in the case of tetragonal La1.25Ba1.75Cu3Oy.

Structural and Superconducting Properties of RE1 - 2xPrxCaxSr0.8Ba1.2Cu3O7 - δ (RE = Er and Gd) High Tc Superconductors

2003 ◽  
Vol 17 (13) ◽  
pp. 2609-2622 ◽  
Author(s):  
N. Charoenthai ◽  
P. Winotai ◽  
R. Suryanarayanan ◽  
I. M. Tang
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Transition Temperature ◽  
Size Effect ◽  
High Temperature Superconductors ◽  
Superconducting Properties ◽  
High Tc Superconductors ◽  
High Tc ◽  
Oxygen Annealing ◽  
Ion Size

We report here on the structural and superconducting properties of RE 1 - 2x Pr x Ca x Sr 0.8 Ba 1.2 Cu 3 O 7 - δ (RE = Er and Gd, 0 ≤ x ≤ 0.2) high temperature superconductors. The transition temperature (Tc) of these compounds decreases when the Pr and Ca concentrations are increased. At constant Pr and Ca concentrations, the Tc of Er 1 - 2x Pr x Ca x Sr 0.8 Ba 1.2 Cu 3 O 7 - δ superconductor system is higher than that observed for the Gd 1 - 2x Pr x Ca x Sr 0.8 Ba 1.2 Cu 3 O 7 - δ system. For the Gd 0.8 Pr 0.1 Ca 0.1 Sr 0.8 Ba 1.2 Cu 3 O 7 - δ sample, after heating in argon followed by oxygen annealing, the orthorhombicity increases accompanied by 10 K increase in Tc. These results show that though our data indicate an ion-size effect, the Tc suppression rate dTc/dx depends very much on the heat treatment adopted to prepare the samples.

HETEROSTRUCTURAL FLUCTUATIONS IN SUPERCONDUCTORS

1992 ◽  
Vol 06 (01) ◽  
pp. 91-107 ◽  
Author(s):  
V. I. YUKALOV
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
High Temperature Superconductors ◽  
Crystallographic Structure ◽  
Superconducting Properties

Superconductors are considered in which there occur fluctuations of one crystallographic structure inside another. The role of these heterostructural fluctuations on superconducting properties are analysed. The occurrence of these fluctuations explains anomalous saggings of Mössbauer factor at phase transition in high-temperature superconductors.

Superconducting Properties of Te-Substituted (Tl2-xTex) Ba2CaCu2O8-δ

2019 ◽  
Vol 290 ◽  
pp. 239-244 ◽  
Author(s):  
Syahrul Humaidi ◽  
Eddy Marlianto ◽  
S. Marhaposan ◽  
Roslan Abd-Shukor
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Normal State ◽  
Electrical Resistance ◽  
High Temperature Superconductors ◽  
Solid State Reaction Method ◽  
Precursor Powder ◽  
Superconducting Properties ◽  
State Behavior ◽  
Reaction Method

The Tl2-xTexBa2CaCu2O8-δ (Tl-2212) high temperature superconductors with x = 0.0-0.5 have been prepared by the standard solid-state reaction method. The precursor powder were sintered at 900°C for 24 h with several grindings and heating. The powder were then pressed into pellets and heated at 910°C in oxygen flow for 4 min followed by furnace cooling. The electrical resistance versus temperature dependence measurements showed metallic normal state behavior for all samples. Substitution of Te at the Tl-site led to multi-phasic samples. The x = 0.4 sample showed the highestTc zero= 98 K and Tconset= 111K. The Tl-2212 phase increased from 50% for x=0 up to 92% in the x= 0.4 sample.

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.

Surface and superconducting properties of cleaved high-temperature superconductors

1990 ◽  
Vol 64 (5) ◽  
pp. 603-606 ◽  
Author(s):  
J. E. Demuth ◽  
B. N. J. Persson ◽  
F. Holtzberg ◽  
C. V. Chandrasekhar
Keyword(s):  
High Temperature ◽  
High Temperature Superconductors ◽  
Superconducting Properties
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