Superconducting properties and pinning mechanism of filamentary (Sm,Gd,Dy)–Ba–Cu–O doped with Co

The superconducting properties of air-processed melt-textured growth Sm–Ba–Cu–O samples with addition of small amounts (0.004 wt%, 0.4 wt%, 4 wt%) of nano-sized Sm2BaCuO5 particles (nm211) were studied. The microstructure observations show that the size distribution and morphology of the 211-particles of the nm211-doped samples are similar to that of the control (undoped) samples. However, except for the 4 wt% nm211-doped sample, both Tc (critical temperature) and Jc (H, T) (critical current density) are enhanced in nm211-doped samples, and the Jc–H curves are different from those of control samples. The effect of nm211 particles on Jc enhancement is larger at high magnetic fields (>1 T at 77 K) than at low magnetic fields (0∼1 T). The dominant pinning mechanism by analyzing the Jc (H, T) data using the scaling theory indicate that the nm211-doped samples are originated from Δκ pinning (i.e., Tc variation); on the other hand, the control samples are originated from normal pinning (i.e., nonsuperconducting crystalline defects). It is proposed that nano-sized compositional fluctuations in the RE1+x Ba2−x Cu3O y matrix, which are products of nm211 particles and liquid peritectic reaction, act as the source of Δκ pinning centers.

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ANISOTROPIC SUPERCONDUCTING PROPERTIES OF YBa2Cu3O7 BASED THIN FILMS AND SUPERLATTICES

International Journal of Modern Physics B ◽

10.1142/s0217979293000263 ◽

1993 ◽

Vol 07 (01n03) ◽

pp. 113-122

Author(s):

H. ADRIAN ◽

G. JAKOB ◽

C. TOMÉ-ROSA ◽

M. SCHMITT ◽

P. WAGNER ◽

...

Keyword(s):

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Structural Changes ◽

Model Systems ◽

Superconducting Properties ◽

Pinning Mechanism ◽

Thermally Activated ◽

Field Independent ◽

Activated Flux

Superconductivity in high-Tc oxides originates from the presence of (CuO2)-planes which lead to highly anisotropic normal and superconducting transport properties. The short coherence length ξc ≈ 1 to 3Å causes a spatial variation of the order parameter along the c-direction with dramatic consequences on the vortex dynamics. As model systems to study the influence of structural changes we prepared epitaxial YBa 2( Cu 1−x TM x)3 O 7 films ( TM = Zn and Ni), Bi 2 Sr 2 CaCu 2 O 8 films and coherent YBa 2 Cu 3 O 7/ PrBa 2 Cu 3 O 7 superlattices. Measurements of the critical current density [Formula: see text] clearly reveal the intrinsic pinning mechanism in YBa 2 Cu 3 O 7 for B ⊥ c at low temperatures which disappears approaching Tc. Small transition metal dopings act as pinning centers reducing dissipation due to thermally activated flux movement. The decoupling of the (CuO2)-layers in the superlattices causes a transition from anisotropic 3d to 2d behavior. Therefore the superconducting properties in external magnetic fields, which resemble closely those of Bi 2 Sr 2 CaCu 2 O 8 films, are dominated by the field component parallel to the c-axis. For B ⊥ c the resistive transitions ρ (B, T) and the critical current density jc (B, T) are nearly field independent.

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Characterization of Y-Ba-Cu-O films grown on silicon substrates by sequential evaporation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106399 ◽

1988 ◽

Vol 46 ◽

pp. 866-867

Author(s):

E. L. Hall ◽

A. Mogro-Campero ◽

L. G. Turner ◽

N. Lewis

Keyword(s):

Thin Film ◽

Thin Film Deposition ◽

Superconducting Films ◽

Electron Beam Evaporation ◽

Film Deposition ◽

Silicon Substrates ◽

Superconducting Properties ◽

Sequential Electron ◽

Thin Superconducting Films

There is great interest in the growth of thin superconducting films of YBa2Cu3Ox on silicon, since this is a necessary first step in the use of this superconductor in a variety of possible electronic applications including interconnects and hybrid semiconductor/superconductor devices. However, initial experiments in this area showed that drastic interdiffusion of Si into the superconductor occurred during annealing if the Y-Ba-Cu-O was deposited direcdy on Si or SiO2, and this interdiffusion destroyed the superconducting properties. This paper describes the results of the use of a zirconia buffer layer as a diffusion barrier in the growth of thin YBa2Cu3Ox films on Si. A more complete description of the growth and characterization of these films will be published elsewhere.Thin film deposition was carried out by sequential electron beam evaporation in vacuum onto clean or oxidized single crystal Si wafers. The first layer evaporated was 0.4 μm of zirconia.

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Processing and characterization of YBa2Cu3O7−x/Ag composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173364 ◽

1990 ◽

Vol 48 (4) ◽

pp. 46-47

Author(s):

Jafar Javadpour ◽

Bradley L. Thiel ◽

Sarikaya Mehmet ◽

Ilhan A. Aksay

Keyword(s):

Composite System ◽

Precursor Solution ◽

Microstructural Development ◽

Superconducting Properties ◽

Practical Applications ◽

Nitrate Precursor ◽

Cold Pressed ◽

Tape Cast ◽

Composite Samples

Practical applications of bulk YBa2Cu3O7−x materials have been limited because of their inadequate critical current density (jc) and poor mechanical properties. Several recent reports have indicated that the addition of Ag to the YBa2Cu3O7−x system is beneficial in improving both mechanical and superconducting properties. However, detailed studies concerning the effect of Ag on the microstructural development of the cermet system have been lacking. Here, we present some observations on the microstructural evolution in the YBa2Cu3O7−x/Ag composite system.The composite samples were prepared by mixing various amounts (2.5 - 50 wt%) AgNO3 in the YBa2Cu3O7−x nitrate precursor solution. These solutions were then spray dried and the resulting powders were either cold pressed or tape cast. The microstructures of the sintered samples were analyzed using SEM (Philips 515) and an analytical TEM (Philips 430T).The SEM micrographs of the compacts with 2.5 and 50 wt% Ag addition sintered at 915°C (below the melting point of Ag) for 1 h in air are displayed in Figs. 1 and 2, respectively.

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