Control of meandering grain boundary configurations in YBa2Cu3Oy bicrystal thin films based on deposition rate

1996 ◽  
Vol 11 (10) ◽  
pp. 2440-2449 ◽  
Author(s):  
X. F. Zhang ◽  
D. J. Miller ◽  
J. Talvacchio
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Grain Boundary ◽  
Deposition Rate ◽  
Three Dimensional ◽  
Film Deposition ◽  
Island Growth ◽  
Ybco Films ◽  
Transmission Electron ◽  
Film Deposition Rate

Changing the film deposition rate is shown to be one way to influence the meandering configurations of grain boundaries (GB's) formed in YBa2Cu3Oy (YBCO) bicrystal thin films. The magnitude and wavelength of the meander in YBCO films deposited at two different rates have been characterized by transmission electron microscopy (TEM) and statistically quantified. It has been found that the meander becomes more uniform and considerably less rough in films deposited at lower rates compared to that observed in films deposited at higher rates. A mechanism for the formation of the meandering GB is proposed based on heterogeneous nucleation and three-dimensional (3D) island growth together with overgrowth of the YBCO films across the substrate grain boundary. The different island sizes and tendency for overgrowth induced by changing the film deposition rate are believed to play important roles in controlling the meandering GB configuration. The possible effects of meandering configurations on transport properties are discussed.

Electron Microscopy Studies of The Chemistry And Microstructure of BaF2 / YBa2Cu3O7-x Thin Films

1994 ◽  
Vol 52 ◽  
pp. 796-797
Author(s):  
J. L. Lee ◽  
C. A. Weiss ◽  
R. A. Buhrman ◽  
J. Silcox
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Island Growth ◽  
Multilayer Systems ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Mgo Substrate

BaF2 thin films are being investigated as candidates for use in YBa2Cu3O7-x (YBCO) / BaF2 thin film multilayer systems, given the favorable dielectric properties of BaF2. In this study, the microstructural and chemical compatibility of BaF2 thin films with YBCO thin films is examined using transmission electron microscopy and microanalysis. The specimen was prepared by using laser ablation to first deposit an approximately 2500 Å thick (0 0 1) YBCO thin film onto a (0 0 1) MgO substrate. An approximately 7500 Å thick (0 0 1) BaF2 thin film was subsequendy thermally evaporated onto the YBCO film.Images from a VG HB501A UHV scanning transmission electron microscope (STEM) operating at 100 kV show that the thickness of the BaF2 film is rather uniform, with the BaF2/YBCO interface being quite flat. Relatively few intrinsic defects, such as hillocks and depressions, were evident in the BaF2 film. Moreover, the hillocks and depressions appear to be faceted along {111} planes, suggesting that the surface is smooth and well-ordered on an atomic scale and that an island growth mechanism is involved in the evolution of the BaF2 film.

Preparation and characteristics of 90° rotated biepitaxial Fe3O4 thin films

2002 ◽  
Vol 17 (8) ◽  
pp. 1985-1991 ◽  
Author(s):  
Hiroshi Matsuda ◽  
Hiroshi Sakakima ◽  
Hideaki Adachi ◽  
Akihiro Odagawa ◽  
Kentaro Setsune
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Magnetic Properties ◽  
Electron Diffraction ◽  
Grain Boundary ◽  
Seed Layer ◽  
Tunneling Magnetoresistance ◽  
X Ray ◽  
Transmission Electron

In-plane 90° rotated biepitaxial Fe3O4 thin films have been successfully prepared onto MgO (110) substrates using a CeO2 seed layer and their microstructure, electric, and magnetic properties were investigated. From the x-ray φ-scan measurements, the in-plane epitaxial relations were determined as 〈110〉Fe3O4//〈110〉MgO and 〈001〉Fe3O4//〈001〉MgO for the no-seeded Fe3O4 layer, and 〈001〉Fe3O4//〈110〉MgO and 〈110〉Fe3O4//〈001〉MgO for the CeO2 (110) seeded Fe3O4 layer. The CeO2 seed layer was found to rotate the upper Fe3O4 lattice at 90° upon normal axis to the layer against the no-seeded Fe3O4. The transmission electron microscopy and electron diffraction analyses revealed that the transition region of the biepitaxial Fe3O4 boundary between CeO2-seeded and no-seeded portions consisted of columnarlike polycrystalline grains. The Fe 3O4 films exhibited single-crystallinelike electric and magnetic properties, however, substantial spin-dependent-tunneling magnetoresistance across the 90° grain boundary was not observed even in the antiparallel situation for each Fe3O4 portion.

Quantitative Correlation between Strength, Ductility and Precipitate Microstructures with PFZ in Al-Zn-Mg(-Ag, Cu) Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 431-436 ◽  
Author(s):  
Tomo Ogura ◽  
Shoichi Hirosawa ◽  
Alfred Cerezo ◽  
Tatsuo Sato
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Three Dimensional ◽  
Atom Probe ◽  
The Other ◽  
Proof Stress ◽  
Quantitative Correlation ◽  
Cu Alloys ◽  
Transmission Electron ◽  
Initial Stage

The quantitative correlation between strength, ductility and precipitate microstructures in the vicinity of grain boundaries with precipitate free zones (PFZ) was evaluated for Al-Zn-Mg(-Ag, Cu) alloys using transmission electron microscopy (TEM), three-dimensional atom probe (3DAP) and tensile test. In the Al-Zn-Mg ternary and Cu-added alloys aged at 433K, larger widths of PFZ were observed by TEM and resulted in lower elongations to fracture, independent of the size of grain boundary precipitates. On the other hand, the elongation of the Ag-added alloy was higher, if compared at the same levels of proof stress, due to the much smaller width of PFZ. This strongly suggests that PFZ is harmful to fracture of the investigated alloys. From a 3DAP analysis, furthermore, it was revealed that Ag and Cu atoms are incorporated in the nanoclusters from the initial stage of aging. In this work, the elongation was well correlated to the width of PFZ, size of grain boundary precipitates and the level of proof stress, enabling to predict ductility of the alloys from known microstructural factors.

High temperature epitaxial growth and structure of Nb films on α–Al2O3(0001)

1998 ◽  
Vol 13 (3) ◽  
pp. 693-702 ◽  
Author(s):  
Thomas Wagner
Keyword(s):  
Electron Microscopy ◽  
Growth Temperature ◽  
Basal Plane ◽  
Three Dimensional ◽  
High Energy ◽  
Total Density ◽  
X Ray Diffraction ◽  
Island Growth ◽  
Transmission Electron ◽  
Α Al2o3

Epitaxial Nb thin films were grown via molecular beam epitaxy (MBE) at different substrate temperatures on α–Al2O3(0001) substrates. For temperatures of 900 °C to 1100 °C, it was found that Nb grows in the Volmer–Weber growth mode (formation of three-dimensional crystallites). Depending on the growth temperature, different epitaxial orientations of Nb films can be found. At a growth temperature of 900 °C, the Nb{111} planes are parallel to the sapphire basal plane whereas at 1100 °C the Nb grows with the {110} planes on the basal plane of sapphire. These orientations are present even in the initial stages of growth at both temperatures. The formation of two different epitaxial orientations of thick Nb films can be conclusively explained only by considering both the change in the total density of Nb islands with temperature and the influence of island size on the total energy of the islands. The Nb island growth process has been investigated in situ using reflection high energy electron diffraction (RHEED) and Auger electron spectroscopy (AES). Scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM) were employed to determine the morphology and structure of Nb islands, Nb films, and Nb/α–Al2O3 interfaces.

The Effects of Interfacial Torque on the Geometry of Twin-Grain Boundary Intersections

1971 ◽  
Vol 29 ◽  
pp. 220-221
Author(s):  
R. J. Horylev ◽  
L. E. Murr
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Grain Boundary ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Interfacial Free Energy ◽  
Boundary Misorientation ◽  
Transmission Electron ◽  
Boundary Intersections

The characterization of a grain boundary in a thin film section by transmission electron microscopy has been described previously. In addition, the geometrical configurations resulting from interfacial torque at twin-grain boundary intersections have been described by the use of the electron microscope. There have been, however, no attempts to systematically study the effect of interfacial torque on the geometry of twin-grain boundary intersections in thin metal films. Neither have there been any attempts to systematically study the interrelationships of the degrees of freedom characterizing a grain boundary in a three-dimensional thin section in the electron microscope. The present work describes the relationship of grain boundary misorientation , inclination (θ), and asymmetry (Φ) to relative interfacial free energy; and the dependence of these parameters on relative interfacial torque at twin-grain boundary intersections observed by transmission electron microscopy.

Microstructures and transport properties: A comparison between grain boundaries artificially produced in YBa2Cu3Ov bicrystal thin films and bulk crystals

1996 ◽  
Vol 54 ◽  
pp. 728-729
Author(s):  
X.F. Zhang ◽  
V.R. Todt ◽  
D.J. Miller ◽  
M. St. Louis-Weber ◽  
J. Talvacchio
Keyword(s):  
Thin Films ◽  
Transport Properties ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Bulk Crystals ◽  
Transmission Electron ◽  
Electromagnetic Measurements ◽  
Global Transport ◽  
Film Deposition Rate ◽  
Microstructural Studies

In order to establish the link between grain boundary (GB) structures and transport properties in superconducting materials, electromagnetic measurements and detailed microstructural studies of carefully prepared GBs are required. Frequently, artificially induced GBs prepared by thin film deposition onto bicrystal substrates are used for such studies. Recently, transmission electron microscopy (TEM) studies have revealed a meandering configuration for GBs in YBa2Cu3Oy (YBCO) thin films grown on [001] tilt SrTiO3 bicrystal substrates (Fig. la). The deviation of the meandering GBs away from the underlying substrate GBs varies from a few tens to hundreds of nanometers. We have demonstrated that the magnitude of the meander in terms of amplitude and wavelength can be reduced by lowering the film deposition rate. The meandering GBs were shown to consist of various straight facets which are a few tens to hundreds of nanometers in length. It is possible that the various segments have very different current transport behavior due to a variable misfit dislocation density. Thus, an unambiguous correlation between the microstructure and global transport properties is difficult to attain.

Grain Boundary Migration and Grain Growth Induced by Electromigration in Copper and Aluminum Lines

1995 ◽  
Vol 391 ◽  
Author(s):  
A. Gladkikh ◽  
E. Glickman ◽  
M. Karpovsky ◽  
Y. Lereah ◽  
A. Palevski ◽  
...  
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Migration ◽  
Three Dimensional ◽  
Grain Boundary Migration ◽  
Transmission Electron ◽  
Hillock Formation ◽  
Cu Thin Film

AbstractThe changes of microstructure in Al and Cu thin film lines due to electromigration have been studied using transmission electron microscopy. Grain boundary migration, inclination and dislocation activity were found to be critically involved in the electromigration induced hillock formation that can be described as three dimensional grain growth.

Deciphering the three-dimensional morphology of free-standing block copolymer thin films by transmission electron microscopy

Micron ◽  
2013 ◽  
Vol 44 ◽  
pp. 442-450 ◽  
Author(s):  
Frances I. Allen ◽  
Peter Ercius ◽  
Miguel A. Modestino ◽  
Rachel A. Segalman ◽  
Nitash P. Balsara ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Block Copolymer ◽  
Three Dimensional ◽  
Free Standing ◽  
Transmission Electron

Speeding up Film Deposition Rate: Its Effects on Microstructures of YBa2Cu3Oy Superconducting Thick Films

1999 ◽  
Vol 14 (4) ◽  
pp. 1204-1211 ◽  
Author(s):  
X. F. Zhang ◽  
H. H. Kung ◽  
S. R. Foltyn ◽  
Q. X. Jia ◽  
E. J. Peterson ◽  
...  
Keyword(s):  
Deposition Rate ◽  
Film Growth ◽  
Lattice Mismatch ◽  
Film Deposition ◽  
High Rate ◽  
High Deposition Rate ◽  
Cation Disorder ◽  
Transmission Electron ◽  
Superconducting Thick Films ◽  
Film Deposition Rate

Two very different pulsed laser deposition rates, 192 and 6 Å/s, were used to produce 1 μm thick superconducting YBa2Cu3Ox (YBCO) films on (001) SrTiO3 single-crystal substrates at 790 °C. Transmission electron microscopy (TEM) was used to characterize and compare microstructures between the two films. It has been found that the high deposition rate led to a slight deviation from the expected epitaxial orientations, and extra stress was induced in the films by increased lattice mismatch between the films and the substrates. In addition, misoriented YBCO grains were formed in the high-rate films after a thickness of about 150 nm. Postannealing in oxygen had no visible influence on these defects, although superconducting properties were improved significantly. In contrast to the high-rate films, overall epitaxial orientations have been formed in the low-rate films, and no misoriented YBCO grains were found. However, variations in lattice parameters and columnar voids were observed, although their existence apparently does not have considerable influence on superconducting current density (Jc). Cation disorder was observed in both films. A two-step film growth mechanism is concluded which is responsible for the formation of some defects in the high-deposition rate films.

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