Microstructure and Properties of Mixed Yba2Cu3O7-X and Y2Ba4Cu8O16 Thin Films

1989 ◽  
Vol 169 ◽  
Author(s):  
A.F. Marshall ◽  
A. Kapitulnik ◽  
K. Char ◽  
R.W. Barton

AbstractPost-annealed thin films comprised of mixed YBa2Cu3O7-x (123) and Y2Ba4Cu8O16 (248) phases with both faulted and unfaulted microstructures have been characterized by planar and cross-section transmission electron microscopy. The influence of 248-type faults on the 123 structure, possible mechanisms for the higher Tc's of faulted films, and observations of a fourfold ordered structure are discussed.

2010 ◽  
Vol 16 (6) ◽  
pp. 662-669 ◽  
Author(s):  
S. Simões ◽  
F. Viana ◽  
A.S. Ramos ◽  
M.T. Vieira ◽  
M.F. Vieira

AbstractReactive multilayer thin films that undergo highly exothermic reactions are attractive choices for applications in ignition, propulsion, and joining systems. Ni/Al reactive multilayer thin films were deposited by dc magnetron sputtering with a period of 14 nm. The microstructure of the as-deposited and heat-treated Ni/Al multilayers was studied by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) in plan view and in cross section. The cross-section samples for TEM and STEM were prepared by focused ion beam lift-out technique. TEM analysis indicates that the as-deposited samples were composed of Ni and Al. High-resolution TEM images reveal the presence of NiAl in small localized regions. Microstructural characterization shows that heat treating at 450 and 700°C transforms the Ni/Al multilayered structure into equiaxed NiAl fine grains.


1989 ◽  
Vol 4 (4) ◽  
pp. 755-758 ◽  
Author(s):  
J. Yahalom ◽  
D. F. Tessier ◽  
R. S. Timsit ◽  
A. M. Rosenfeld ◽  
D. F. Mitchell ◽  
...  

Copper/nickel multilayered thin-films prepared by electrodeposition have been examined in cross section by electron energy loss spectroscopy and high-resolution transmission electron microscopy. The results of the examinations provide the first direct experimental evidence of the large composition modulation across successive layers in the thin-film structure and the coherent nature of Cu/Ni interfaces.


2003 ◽  
Vol 18 (1) ◽  
pp. 14-26 ◽  
Author(s):  
D. Eyidi ◽  
M. D. Croitoru ◽  
O. Eibl ◽  
R. Nemetschek ◽  
W. Prusseit

CeO2 films are technologically important as buffer layers for the integration of superconducting YBa2Cu3O7−δ films on {100}-biaxially textured Ni substrates, yielding a Ni–CeO2–YBa2Cu3O7−δ layer sequence. The Ni–CeO2 interface is a metal–oxide interface, and the misfit between substrate and film is about 9%. An epitaxial growth model was suggested for this system in the literature. The investigated films were deposited by a reactive thermal evaporation process at substrate temperatures of 650–670 °C with a thickness of 100 nm after deposition. The CeO2 films were characterized by plan-view and cross-section transmission electron microscopy, atomic force microscopy, and scanning electron microscopy. The CeO2 films had a strong {100} biaxial texture with a roughness of approximately 90 nm. No intermediate layer could be found by cross-section transmission electron microscopy at the Ni–CeO2 interface. The films had columnar grains with diameters of 20–50 nm, much smaller than the grain size of the Ni substrate, which was larger than 1 μm. Small-angle grain boundaries and small amounts of 〈111〉-oriented grains were evidenced in plan-view samples by diffraction patterns. The Moiré fringes technique was applied and was ideally suited to image the small rotations (≤3°) of the small CeO2 grains with respect to the Ni substrate. These small rotations of small grains showed that the growth was nonepitaxial, however, biaxially textured. In the CeO2 film samples, nanovoids 5–10 nm in size were observed and were mostly located close to the film surface. A model for the growth of CeO2 thin films on nickel substrates can be proposed on the basis of our results.


Author(s):  
L. Tang ◽  
G. Thomas ◽  
M. R. Khan ◽  
S. L. Duan

Cr thin films are often used as underlayers for Co alloy magnetic thin films, such as Co1, CoNi2, and CoNiCr3, for high density longitudinal magnetic recording. It is belived that the role of the Cr underlayer is to control the growth and texture of the Co alloy magnetic thin films, and, then, to increase the in plane coercivity of the films. Although many epitaxial relationship between the Cr underlayer and the magnetic films, such as ﹛1010﹜Co/ {110﹜Cr4, ﹛2110﹜Co/ ﹛001﹜Cr5, ﹛0002﹜Co/﹛110﹜Cr6, have been suggested and appear to be related to the Cr thickness, the texture of the Cr underlayer itself is still not understood very well. In this study, the texture of a 2000 Å thick Cr underlayer on Nip/Al substrate for thin films of (Co75Ni25)1-xTix dc-sputtered with - 200 V substrate bias is investigated by electron microscopy.


Author(s):  
D. L. Callahan ◽  
Z. Ball ◽  
H. M. Phillips ◽  
R. Sauerbrey

Ultraviolet laser-irradiation can be used to induce an insulator-to-conductor phase transition on the surface of Kapton polyimide. Such structures have potential applications as resistors or conductors for VLSI applications as well as general utility electrodes. Although the percolative nature of the phase transformation has been well-established, there has been little definitive work on the mechanism or extent of transformation. In particular, there has been considerable debate about whether or not the transition is primarily photothermal in nature, as we propose, or photochemical. In this study, cross-sectional optical microscopy and transmission electron microscopy are utilized to characterize the nature of microstructural changes associated with the laser-induced pyrolysis of polyimide.Laser-modified polyimide samples initially 12 μm thick were prepared in cross-section by standard ultramicrotomy. Resulting contraction in parallel to the film surface has led to distortions in apparent magnification. The scale bars shown are calibrated for the direction normal to the film surface only.


Author(s):  
C. Ewins ◽  
J.R. Fryer

The preparation of thin films of organic molecules is currently receiving much attention because of the need to produce good quality thin films for molecular electronics. We have produced thin films of the polycyclic aromatic, perylene C10H12 by evaporation under high vacuum onto a potassium chloride (KCl) substrate. The role of substrate temperature in determining the morphology and crystallography of the films was then investigated by transmission electron microscopy (TEM).The substrate studied was the (001) face of a freshly cleaved crystal of KCl. The temperature of the KCl was controlled by an electric heater or a cold finger. The KCl was heated to 200°C under a vacuum of 10-6 torr and allowed to cool to the desired temperature. The perylene was then evaporated over a period of one minute from a molybdenum boat at a distance of 10cm from the KCl. The perylene thin film was then backed with an amorphous layer of carbon and floated onto copper microscope grids.


Author(s):  
L. D. Peachey ◽  
J. P. Heath ◽  
G. Lamprecht

Biological specimens of cells and tissues generally are considerably thicker than ideal for high resolution transmission electron microscopy. Actual image resolution achieved is limited by chromatic aberration in the image forming electron lenses combined with significant energy loss in the electron beam due to inelastic scattering in the specimen. Increased accelerating voltages (HVEM, IVEM) have been used to reduce the adverse effects of chromatic aberration by decreasing the electron scattering cross-section of the elements in the specimen and by increasing the incident electron energy.


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).


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