Two-Phase Microstructures in the Heavily Pb-Substituted Bi-2212 Single Crystals Serving as Efficient Pinning Centers

1998 ◽  
pp. 285-288 ◽  
Author(s):  
Zenji Hiroi ◽  
Ikusu Chong ◽  
Makoto Izumi ◽  
Mikio Takano
Keyword(s):  
Single Crystals ◽  
Two Phase ◽  
Pinning Centers

The stability of dislocation networks under various oxygen-doping conditions in superconducting Bi2Sr2CaCu2Oy single crystals and their influence on the flux pinning properties

1994 ◽  
Vol 52 ◽  
pp. 802-803
Author(s):  
Y. Feng ◽  
X. Y. Cai ◽  
R. J. Kelley ◽  
D. C. Larbalestier
Keyword(s):  
Single Crystals ◽  
Oxygen Content ◽  
Basal Plane ◽  
Flux Pinning ◽  
Pinning Centers ◽  
Before And After ◽  
Anomalous Peak ◽  
Basal Plane Dislocation ◽  
The Stability ◽  
Further Development

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.

Critical Current of Bi-2212 Single Crystal by Doping Oxides as a Pinning Center

2014 ◽  
Vol 95 ◽  
pp. 175-180
Author(s):  
Takuya Agou ◽  
Hiroya Imao
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Single Crystals ◽  
Crystal Surface ◽  
Rare Earth Oxides ◽  
Pinning Centers ◽  
Current Path ◽  
Pinning Center ◽  
Superconducting Current ◽  
A Current

It is necessary to formpinning centers in superconductors to allow the flow of large currents throughthe specimens. To clarify the properties of pinning centers, it is preferableto investigate single crystals. In this study, heat treatment was used to dopevarious oxides into Bi2Sr2CaCu2Ox(Bi-2212) single crystals prepared by self-flux methods and the criticalcurrent (Ic) was measured. The oxides used in this study were Al2O3and the rare earth oxides Er2O3and Nd2O3. At 77K, Nd2O3and Er2O3 are magnetic, whereas Al2O3is nonmagnetic. The Ic of the samples were measured as a current per width of 1cm (Ics). The resulting Ics of the Bi-2212 single crystal was 2.8A/cm and thatof the Al2O3 doped Bi-2212 sample was 4.5A/cm. Comparedwith these samples, doping the other rare earth oxides gave Ics values inexcess 10A/cm. The results indicated that the doping oxides were effective inoperating as pinning centers in the samples. We assumed the current path in asingle crystal, and calculated the Ics by superconducting current simulation.The results indicated that the oxides permeated from a crystal surface in aporous shape. The oxides increase the current which flow in the Cu-O2planes that are parallel to the a-b plane.

Tensile properties and cold rolling of binary Ni–Al γ/γ′ two-phase single crystals

2008 ◽  
Vol 16 (11-12) ◽  
pp. 1317-1324 ◽  
Author(s):  
Dingqiang Li ◽  
Kyosuke Kishida ◽  
Masahiko Demura ◽  
Toshiyuki Hirano
Keyword(s):  
Cold Rolling ◽  
Tensile Properties ◽  
Single Crystals ◽  
Two Phase

High Temperature Creep Behavior of Single Crystal Gammpraime and Gamm Laloys

1988 ◽  
Vol 133 ◽  
Author(s):  
M. V. Nathal ◽  
J. O. Diaz ◽  
R. V. Miner
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Single Crystals ◽  
Creep Behavior ◽  
Dislocation Motion ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
High Temperature Creep ◽  
Two Phase ◽  
Temperature Creep

ABSTRACTThe creep behavior of single crystals of γ′ and γ alloys were investigated and compared to the response of two phase superalloys tested previously. High temperature deformation in the γ alloys was characteristic of a climb controlled mechanism, whereas the γ′ based materials exhibited glide controlled creep behavior. The superalloys were much more creep resistant than their constituent phases, which indicates the importance of the γ-γ′ interface as a barrier for dislocation motion during creep.

Two-phase intergrowth in Bi2Sr2Ca0.6Y0.4Cu2Oy single crystals

1993 ◽  
Vol 215 (1-2) ◽  
pp. 39-50 ◽  
Author(s):  
X.F. Zhang ◽  
G. Van Tendeloo ◽  
S.L. Ge ◽  
J.H.P.M. Emmen ◽  
V.A.M. Brabers
Keyword(s):  
Single Crystals ◽  
Two Phase

Microsample Testing of Single Crystalline Ti-52 at%Al and Ti-55.5 at%Al

1998 ◽  
Vol 552 ◽  
Author(s):  
Marc Zupan ◽  
D. M. Dimiduk ◽  
K. J. Hemker
Keyword(s):  
Single Crystals ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
High Temperature Stress ◽  
Two Phase ◽  
Single Crystalline ◽  
Al Content ◽  
Float Zone ◽  
Heat Treated ◽  
Solid Foundation

ABSTRACTDislocation activity in two-phase commercial TiAl alloys occurs most readily in the γ-TiAl phase, and measurements of the CRSS of single crystalline γ-TiAl provides a solid foundation for understanding the mechanical performance of these alloys. Single crystals of γ-TiAl with greater than 54.5 at%Al have been grown using the optical float zone crystal growing technique, but single crystals with lower Al content, closer to that of commercial alloys, have not. In the present study, polycrystalline ingots of Ti-52 at%Al have been heat treated to form very large grains, and microsample tensile specimens, which have a nominal gage cross-section of 250μm × 300μm, a gage length of 250μm and an overall length of 3 mm, have been machined from within single grains. Microsample high-temperature stress-strain curves for Ti-55.5 at%Al single crystals oriented along the [001] and [010] are presented. Tensile tests results for Ti-52 at%Al tested at 1073K along the [237], [173] and [344] orientations will also be discussed.

Magnetic resonance spectrum of a two-phase state in single crystals of La0.7Pb0.3MnO3 lanthanum manganite

JETP Letters ◽  
2000 ◽  
Vol 71 (4) ◽  
pp. 144-147 ◽  
Author(s):  
G. A. Petrakovskii ◽  
N. V. Volkov ◽  
V. N. Vasil’ev ◽  
K. A. Sablina
Keyword(s):  
Magnetic Resonance ◽  
Single Crystals ◽  
Phase State ◽  
Resonance Spectrum ◽  
Lanthanum Manganite ◽  
Two Phase
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