Influence of micro-structure in the low temperature critical currents of YBa2Cu3O7?? thin films

1996 ◽  
Vol 105 (3-4) ◽  
pp. 1017-1022 ◽  
Author(s):  
J. C. Mart�nez ◽  
B. Dam ◽  
B. St�uble-P�mpin ◽  
G. Doornbos ◽  
R. Surdeanu ◽  
...  
1996 ◽  
Vol 46 (S3) ◽  
pp. 1307-1308
Author(s):  
J. C. Martínez ◽  
B. Stäuble-Pümpin ◽  
G. Doornbos ◽  
R. Surdeanu ◽  
B. Dam ◽  
...  

Author(s):  
M. A. Kirk ◽  
M. C. Baker ◽  
B. J. Kestel ◽  
H. W. Weber

It is well known that a number of compound superconductors with the A15 structure undergo a martensite transformation when cooled to the superconducting state. Nb3Sn is one of those compounds that transforms, at least partially, from a cubic to tetragonal structure near 43 K. To our knowledge this transformation in Nb3Sn has not been studied by TEM. In fact, the only low temperature TEM study of an A15 material, V3Si, was performed by Goringe and Valdre over 20 years ago. They found the martensite structure in some foil areas at temperatures between 11 and 29 K, accompanied by faults that consisted of coherent twin boundaries on {110} planes. In pursuing our studies of irradiation defects in superconductors, we are the first to observe by TEM a similar martensite structure in Nb3Sn.Samples of Nb3Sn suitable for TEM studies have been produced by both a liquid solute diffusion reaction and by sputter deposition of thin films.


Author(s):  
J. T. Sizemore ◽  
D. G. Schlom ◽  
Z. J. Chen ◽  
J. N. Eckstein ◽  
I. Bozovic ◽  
...  

Investigators observe large critical currents for superconducting thin films deposited epitaxially on single crystal substrates. The orientation of these films is often characterized by specifying the unit cell axis that is perpendicular to the substrate. This omits specifying the orientation of the other unit cell axes and grain boundary angles between grains of the thin film. Misorientation between grains of YBa2Cu3O7−δ decreases the critical current, even in those films that are c axis oriented. We presume that these results are similar for bismuth based superconductors and report the epitaxial orientations and textures observed in such films.Thin films of nominally Bi2Sr2CaCu2Ox were deposited on MgO using molecular beam epitaxy (MBE). These films were in situ grown (during growth oxygen was incorporated and the films were not oxygen post-annealed) and shuttering was used to encourage c axis growth. Other papers report the details of the synthesis procedure. The films were characterized using x-ray diffraction (XRD) and transmission electron microscopy (TEM).


Author(s):  
O. Eibl ◽  
G. Gieres ◽  
H. Behner

The microstructure of high-Tc YBa2Cu3O7-X thin films deposited by DC-sputtering on SrTiO3 substrates was analysed by TEM. Films were either (i) deposited in the amorphous state at substrate temperatures < 450°C and crystallised by a heat treatment at 900°C (process 1) or (ii) deposited at around 740°C in the crystalline state (process 2). Cross sections were prepared for TEM analyses and are especially useful for studying film substrate interdiffusion (fig.1). Films deposited in process 1 were polycristalline and the grain size was approximately 200 nm. Films were porous and the size of voids was approximately 100 nm. Between the SrTiO3 substrate and the YBa2Cu3Ox film a densly grown crystalline intermediate layer approximately 150 nm thick covered the SrTiO3 substrate. EDX microanalyses showed that the layer consisted of Sr, Ba and Ti, however, did not contain Y and Cu. Crystallites of the layer were carefully tilted in the microscope and diffraction patterns were obtained in five different poles for every crystallite. These patterns were consistent with the phase (Ba1-XSrx)2TiO4. The intermediate layer was most likely formed during the annealing at 900°C. Its formation can be understood as a diffusion of Ba from the amorphously deposited film into the substrate and diffusion of Sr from the substrate into the film. Between the intermediate layer and the surface of the film the film consisted of YBa2Cu3O7-x grains. Films prepared in process 1 had Tc(R=0) close to 90 K, however, critical currents were as low as jc = 104A/cm2 at 77 K.


2009 ◽  
Vol 94 (22) ◽  
pp. 222110 ◽  
Author(s):  
S. S. N. Bharadwaja ◽  
C. Venkatasubramanian ◽  
N. Fieldhouse ◽  
S. Ashok ◽  
M. W. Horn ◽  
...  

1997 ◽  
Vol 505 ◽  
Author(s):  
Xin Zhang ◽  
Tong-Yi Zhang ◽  
Yitshak Zohar

ABSTRACTFEM simulation of micro-rotating-structures was performed for local measurement of residual stresses in thin films. A sensitivity factor is introduced, studied and tabulated from the simulation results. The residual stress can be evaluated from the rotating deflection, the lengths of rotating and fixed beams, and the sensitivity factor. The micro-structure technique was applied to measure residual stresses in both silicon nitride and polysilicon thin films, before and after rapid thermal annealing (RTA), and further confirmed by wafer curvature method. Residual stresses in polysilicon films at different RTA stages were also characterized by micro-Raman spectroscopy (MRS). The experimental results indicate that micro-rotating-structures indeed have the ability to measure spatially and locally residual stresses in MEMS thin films with appropriate sensitivities.


2021 ◽  
Vol 26 ◽  
pp. 102050
Author(s):  
Mehdi Dehghani ◽  
Ershad Parvazian ◽  
Nastaran Alamgir Tehrani ◽  
Nima Taghavinia ◽  
Mahmoud Samadpour

2004 ◽  
Vol 268 (1-2) ◽  
pp. 24-28 ◽  
Author(s):  
Z. Sefrioui ◽  
J.L. Menéndez ◽  
A. Cebollada ◽  
F. Briones ◽  
A. Hernando

2021 ◽  
Vol 31 (5) ◽  
pp. 1-7
Author(s):  
Mary Ann Sebastian ◽  
Neal A. Pierce ◽  
Iman Maartense ◽  
Gregory Kozlowski ◽  
Timothy J. Haugan

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