The Morphology of YBa2Cu3O7−x Thin Films Grown on Ceramic Substrates

1987 ◽  
Vol 99 ◽  
Author(s):  
L. A. Tietz ◽  
B. C. De Cooman ◽  
C. B. Carter ◽  
D. K. Lathrop ◽  
S. E. Russek ◽  
...  

ABSTRACTThe microstructure of thin films of the high Tc superconductor YBa2Cu3O7−x deposited on SrTiO3 and Y-stabilized cubic-zirconia (YSZ) single-crystal substrates has been characterized by transmission electron microscopy. Films on both substrates were polycrystalline. On {001 }-oriented SrTiO3, the grains are oriented with <110> normal to the substrate surface. On the same orientation of YSZ, two microstructures are observed: one in which grains have their c-axes normal to the substrate surface, the other in which grains have the a- (or b-) axis normal to the substrate surface. Both of these microstructures contain special grain boundaries. Annealing of ion-milled TEM specimens is presented as a means of removing ion-beam damage.

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.


1987 ◽  
Vol 94 ◽  
Author(s):  
S. W. Lu ◽  
C. W. Nieh ◽  
J. J. Chu ◽  
L. J. Chen

ABSTRACTThe influences of implantation impurities, including BF2, B, F, As and P on the formation of epitaxial NiSi2 in nickel thin films on ion-implanted silicon have been investigated by transmission electron microscopy.The presence of BF2, B, and F atoms was observed to promote the epitaxial growth of NiSi2 at low temperatures. Little or no effect on the formation of NiSi2 was found in samples implanted with As or P ions.The results indicated that the influences of the implantation impurities are not likely to be electronic in origin. Good correlation, on the other hand, was found between the atomic size factor and resulting stress and NiSi2 epitaxy at low temperatures.


1990 ◽  
Vol 5 (8) ◽  
pp. 1605-1611 ◽  
Author(s):  
S. J. Golden ◽  
H. Isotalo ◽  
M. Lanham ◽  
J. Mayer ◽  
F. F. Lange ◽  
...  

Superconducting YBaCuO thin films have been fabricated on single-crystal MgO by the spray-pyrolysis of nitrate precursors. The effects on the superconductive behavior of processing parameters such as time and temperature of heat treatment and film thickness were investigated. The superconductive behavior was found to be strongly dependent on film thickness. Films of thickness 1 μm were found to have a Tc of 67 K while thinner films showed appreciably degraded properties. Transmission electron microscopy studies have shown that the heat treatments necessary for the formation of the superconductive phase (for example, 950 °C for 30 min) also cause a substantial degree of film-substrate interdiffusion. Diffusion distances for Cu in the MgO substrate and Mg in the film were found to be sufficient to explain the degradation of the superconductive behavior in films of thickness 0.5 μm and 0.2 μm. From the concentration profiles obtained by EDS analysis diffusion coefficients at 950 °C for Mg into the YBaCuO thin film and for Cu into the MgO substrate were evaluated as 3 × 10−19 m2/s and 1 × 10−17 m2/s, respectively.


1985 ◽  
Vol 54 ◽  
Author(s):  
L. R. Zheng ◽  
L. S. Hung ◽  
J. W. Mayer

ABSTRACTInteractions of evaporated Ni and Si thin films were investigated by a combination of backseat tering spectrometry and transmission electron microscopy. The presence of amorphous Si has no significant effects on Ni2Si and NiSi formation, but it drastically lowers the formation temperature of NiSi. Experiments with evaporated thin markers established that Ni is the dominant diffusing species in the growth of the three suicides. The stability of NiSi was examined by sequential evaporation of Ni34Si66 and Ni50Si50 thin films both on Si(100) and on evaporated Si substrates. The results showed that NiSi2 grows at the expence of NiSi when the stucture is in contact with evaporated Si, while it dissociates into NiSi and Si when in contact with single crystal Si.


Author(s):  
A. Szirmae ◽  
V.U.S. Rao ◽  
R.M. Fisher

A well known catalytic effect of transition metals and particularly iron in contack with carbonaceous carbon exposed to oxidizing or hydrogenating atmospheres (02, CO-CO2, H2-H2O) has been investigated by scanning and high voltage transmission electron microscopy in a program aimed at determining the fundamental mechanisms of the gasification reactions. Samples of polycrystalline planchets and single crystal flakes of graphite were reacted at temperatures from 650°to 1100°C in “wet” and “dry” hydrogen . Quantitative electron microscope observations were supplemented by weight loss measurements and continuous gas chromatograph analysis of the CO and CH4, produced. Prior to exposure to the reacting gases, small particles of metallic iron are formed on the surface of single crystal graphite flakes or pressed carbon planchets by vacuum deposition of thin films ranging from 1 Å to 2000 Å in thickness.


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