Epitaxial Chemically Derived Lanthanum Aluminate Films for Ba2YCu3O7−x Devices

1993 ◽  
Vol 317 ◽  
Author(s):  
Man Faing ◽  
Michael J. Cima
Keyword(s):  
Substrate Material ◽  
Zero Field ◽  
Ybco Films ◽  
Lanthanum Aluminate ◽  
Transmission Electron ◽  
Nitrate Precursor ◽  
Metalorganic Deposition ◽  
Current Densities ◽  
Higher Temperature ◽  
Lattice Matched

ABSTRACTLanthanum aluminate (LaAlO3) has been used as a substrate material for depositing Ba2YCu3O7−x (YBCO) films. In the present study, chemically derived epitaxial LaAlO3 thin films were used for depositing epitaxial YBCO films. These epitaxial LaAlO3 films were deposited on both (100) SrTiO3 and (100) LaAlO3 single crystal substrates by pyrolysis of a mixed nitrate precursor. Crystallization of LaAlO3 on lattice-Matched substrates occurs at below 650°C, whereas crystallization on non lattice-Matched substrates occurs at much higher temperature. The average surface roughness of these LaAlO3 films can be as low as 7Å. The YBCO films derived from metalorganic deposition of metal trifluoroacetate precursors were deposited on these epitaxial LaAlO3 films on SrTiO3 substrates. The resultant YBCO films have critical current densities of > 2 × 106 A/cm2 at 77K and zero field. Transmission electron microscopy of these films shows that they are highly epitaxial yet have pore of about 15–30 nm in size. Chemically derived LaAlO3 films also were used to planarize stepped substrates.

Crystallization of Epitaxial Lanthanum Aluminate and Spinel Thin Films Derived from Nitrate Precursors

1994 ◽  
Vol 341 ◽  
Author(s):  
Man Fai Ng ◽  
Michael J. Cima
Keyword(s):  
Thin Films ◽  
Epitaxial Film ◽  
Amorphous Film ◽  
Zero Field ◽  
Epitaxial Thin Films ◽  
Lanthanum Aluminate ◽  
Initial Nucleation ◽  
Metalorganic Deposition ◽  
Current Densities ◽  
Higher Temperature

AbstractBoth lanthanum aluminate (LaAIO 3) and spinel (MgAl2O 4) epitaxial thin films have been deposited on either planar and stepped (100) SrTiO3 single crystal substrates by pyrolysis of mixed nitrate precursors. The precursors pyrolyze initially into amorphous films. Nucleation of lanthanum aluminate and spinel occurs at the filnVsubstrate interface at higher temperature. Crystallization of LaAlO3 on SrTiO3 substrates occurs at approximately 650°C, whereas nucleation occurs at approximately 800'C without lattice-matched substrates. Similarly, latticematched substrates reduce the crystallization temperature of spinel to below 700°C. The epitaxial film grows at the expense of the amorphous film after the initial nucleation at the interface. The rapid growth and volume change due to the crystallization leave behind an epitaxial film with nanoporosity of 15 to 30 nm. Nevertheless, the surfaces of these films have roughness of only 6–9 Å. Ba2Ycu3O7-x films derived from metalorganic deposition of metal trifluoroacetate precursors was deposited on these epitaxial LaAlO3 films on both planar and stepped SrTiO3 substrates. The resultant YBCO films on LaAlO3 film on planar SrTiO3 substrate have critical current densities of > 2 × 106 A/cm2 at 77K and zero field.

Issues Concerning the Chemical Synthesis of Ceramic Superconducting Coatings in the Bi-Sr-Ca-Cu-O System with High Critical Current Densities.

1991 ◽  
Vol 249 ◽  
Author(s):  
S. J. Golden ◽  
K. J. Vaidya ◽  
T. E. Bloomer ◽  
F. F. Lange ◽  
D. R. Clarke
Keyword(s):  
Thin Films ◽  
Critical Current ◽  
Zero Field ◽  
Superconducting Thin Films ◽  
Ethyl Hexanoate ◽  
X Ray ◽  
Pole Figures ◽  
Oriented Films ◽  
Metalorganic Deposition ◽  
Current Densities

ABSTRACTSuperconducting thin films of the two Cu-layer phase in the Pb-doped Bi- Sr-Ca-Cu-O system have been fabricated on {100} LaAlO3 single crystals by the metalorganic deposition (MOD) from ethyl hexanoate precursors. Some of the major issues pertinent to the synthesis of high quality films have been studied.Thin films of composition Bi1.8Pb0.3Sr1.6CaCu2Ox given heat treatments in air at 850–860 °C for several hours had sharp resistive transitions with a Tc of 85–89 K. The zero-field transport critical current densities were in the range of 1–4×105 A.cm−2 at 77 K and 106 A.cm−2 at 45 K in 200–300 nm thick films. In contrast to caxis oriented films grown on (100) MgO, X-ray pole figures show that the polycrystalline films grown on (100) LaAlO3 are epitaxial, a result confirmed by electron channeling patterns.

Microstructural Evolution of Epitaxial MgAl2O4 Thin Films Derived From Metal Nitrates and From Metal Alkoxides

1993 ◽  
Vol 317 ◽  
Author(s):  
Man Faing ◽  
Michael J. Cima
Keyword(s):  
Dielectric Material ◽  
Processing Parameters ◽  
Magnesium Aluminate ◽  
Metal Alkoxides ◽  
Average Surface Roughness ◽  
Metal Nitrates ◽  
Nitrate Precursor ◽  
Metalorganic Deposition ◽  
The Relationship ◽  
Lattice Matched

ABSTRACTMagnesium aluminate (MgAl2O4) is a potential dielectric material in Ba2YCu3O7−x (BYC) devices. In the present study, epitaxial MgAl2O4 films were deposited on (100) SrTiO3 single crystal substrates by pyrolysis of chemical precursors. Two precursors were used: one was a mixed nitrate precursor, and the other was MgAl2(OC3H7)8. Crystallization of MgAl2O4 on lattice-Matched substrates is observed at 700°C. The average surface roughness of these MgAl2O4 films is about 6Å. These chemically-derived MgAl2O4 films have demonstrated the potential for planarization by metalorganic deposition. The relationship between the processing parameters and the surface morphology of these MgAl2O4 films will be discussed.

Transmission electron microscopic studies on growth mechanism of YBa2Cu3O7−y films formed by advanced trifluoroacetates metalorganic deposition process

2008 ◽  
Vol 23 (12) ◽  
pp. 3353-3362 ◽  
Author(s):  
J. Matsuda ◽  
K. Nakaoka ◽  
T. Izumi ◽  
Y. Yamada ◽  
Y. Shiohara
Keyword(s):  
Crystallization Process ◽  
Deposition Process ◽  
Electron Microscopic ◽  
Calcination Process ◽  
Ybco Films ◽  
Starting Solution ◽  
Transmission Electron ◽  
Microscopic Studies ◽  
Metalorganic Deposition ◽  
Means Of Transmission

Microstructure evolution of YBa2Cu3O7−y (YBCO) films during the two heat-treatments in the advanced trifluoroacetates metalorganic deposition (TFA-MOD) process has been investigated by means of transmission electron microscopy. In the calcination process, precursor films including nanopores were formed through the shrinkage of the film after a remarkable increase of the thickness due to the thermal decomposition of metalorganic salts in the starting solution. During the crystallization process, the densification and shrinkage of the film occurred after agglomeration of nanopores and coarsening of unreacted phase particles such as Y2Cu2O5, CuO, and Ba–O–F in the precursor films. The YBCO films were then epitaxially grown with the remaining unreacted phase particles in the film, finally pores were generated again by a reaction of these unreacted particles to form YBCO accompanied by the volume reduction. It is important to control the densification of precursor films and coarsening of the unreacted phase particles in the crystallization process, to fabricate YBCO final films with fine crystallinity and high critical current values.

Nucleation of Disorder in Fe3Al Alloys

1967 ◽  
Vol 25 ◽  
pp. 312-313
Author(s):  
P. R. Swann ◽  
W. R. Duff ◽  
R. M. Fisher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Temperature ◽  
Antiphase Domain ◽  
Effect Of Temperature ◽  
Domain Structures ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Higher Temperature ◽  
The One

Recently we have investigated the phase equilibria and antiphase domain structures of Fe-Al alloys containing from 18 to 50 at.% Al by transmission electron microscopy and Mössbauer techniques. This study has revealed that none of the published phase diagrams are correct, although the one proposed by Rimlinger agrees most closely with our results to be published separately. In this paper observations by transmission electron microscopy relating to the nucleation of disorder in Fe-24% Al will be described. Figure 1 shows the structure after heating this alloy to 776.6°C and quenching. The white areas are B2 micro-domains corresponding to regions of disorder which form at the annealing temperature and re-order during the quench. By examining specimens heated in a temperature gradient of 2°C/cm it is possible to determine the effect of temperature on the disordering reaction very precisely. It was found that disorder begins at existing antiphase domain boundaries but that at a slightly higher temperature (1°C) it also occurs by homogeneous nucleation within the domains. A small (∼ .01°C) further increase in temperature caused these micro-domains to completely fill the specimen.

Effect of thermal annealing on grain boundary chemistry of polycrystalline TiBa2Ca2Cu3Oy films

1994 ◽  
Vol 52 ◽  
pp. 968-969
Author(s):  
Z. L. Wang ◽  
C. L. Briant ◽  
J. DeLuca ◽  
A. Goyal ◽  
D. M. Kroeger ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Weak Link ◽  
Zero Field ◽  
Stabilized Zirconia ◽  
Local Texture ◽  
Transmission Electron ◽  
Axis Alignment ◽  
Boundary Chemistry ◽  
Small Misorientation ◽  
Misorientation Angles

Recent studies have shown that spray-pyrolyzed films of the Tl-1223 compound (TlxBa2Ca2Cu3Oy, with 0.7 < × < 0.95) on polycrystalline yttrium stabilized zirconia substrates can be prepared which have critical current density Jc near 105 A/cm2 at 77 K, in zero field. The films are polycrystalline, have excellent c-axis alignment, and show little evidence of weak-link behavior. Transmission electron microscopy (TEM) studies have shown that most grain boundaries have small misorientation angles. It has been found that the films have a nigh degree of local texture indicative of colonies of similarly oriented grains. It is believed that inter-colony conduction is enhanced by a percolative network of small angle boundaries at colony interfaces. It has also been found that Jc is increased by a factor of 4 - 5 after the films were annealed at 600 °C in oxygen. This study is thus carried out to determine the effect on grain boundary chemistry of the heat treatment.

Carbon Film Deposition On Silicon Using Low Energy Ion Beams

1991 ◽  
Vol 223 ◽  
Author(s):  
Qin Fuguang ◽  
Yao Zhenyu ◽  
Ren Zhizhang ◽  
S.-T. Lee ◽  
I. Bello ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ion Beam ◽  
Carbon Film ◽  
Carbon Films ◽  
Film Deposition ◽  
Ion Energy ◽  
Transmission Electron ◽  
Higher Temperature ◽  
Post Implantation ◽  
Beam Deposition

ABSTRACTDirect ion beam deposition of carbon films on silicon in the ion energy range of 15–500eV and temperature range of 25–800°C has been studied using mass selected C+ ions under ultrahigh vacuum. The films were characterized with X-ray photoelectron spectroscopy, Raman spectroscopy, and transmission electron microscopy and diffraction analysis. Films deposited at room temperature consist mainly of amorphous carbon. Deposition at a higher temperature, or post-implantation annealing leads to formation of microcrystalline graphite. A deposition temperature above 800°C favors the formation of microcrystalline graphite with a preferred orientation in the (0001) direction. No evidence of diamond formation was observed in these films.

Chemical Solution Deposition of Lanthanum Zirconate Buffer Layers on Biaxially Textured Ni–1.7% Fe–3% W Alloy Substrates for Coated-conductor Fabrication

2002 ◽  
Vol 17 (6) ◽  
pp. 1543-1549 ◽  
Author(s):  
S. Sathyamurthy ◽  
M. Paranthaman ◽  
T. Aytug ◽  
B. W. Kang ◽  
P. M. Martin ◽  
...  
Keyword(s):  
Sol Gel ◽  
Rf Sputtering ◽  
Cube Texture ◽  
Dip Coating ◽  
Buffer Layers ◽  
Lanthanum Zirconate ◽  
Solution Deposition ◽  
Ybco Films ◽  
Current Densities ◽  
Gel Processing

Sol-gel processing of La2Zr2O7 (LZO) buffer layers on biaxially textured Ni–1.7% Fe–3% W alloy substrates using a continuous reel-to-reel dip-coating unit has been studied. The epitaxial LZO films obtained have a strong cube texture and uniform microstructure. The effects of increasing the annealing speed on the texture, microstructure, and carbon content retained in the film were studied. On top of the LZO films, epitaxial layers of yttria-stabilized zirconia and Ceria (CeO2) were deposited using rf sputtering, and YBa2Cu3Ox (YBCO) films were then deposited using pulsed laser deposition. Critical current densities (Jc) of 1.9 MA/cm2 at 77 K and self-field and 0.34 MA/cm2at 77 K and 0.5 T have been obtained on these films. These values are comparable to those obtained on YBCO films deposited on all-vacuum deposited buffer layers and the highest ever obtained using solution seed layers.

Crystallization of Amorphous Silicon-Aluminum thin Films: IN-SITU Observation and Thermal Analysis.

1991 ◽  
Vol 237 ◽  
Author(s):  
Toyohiko J. Konno ◽  
Robert Sinclair
Keyword(s):  
Activation Energy ◽  
Amorphous Alloys ◽  
Amorphous Matrix ◽  
In Situ Observation ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Higher Temperature ◽  
Sputter Deposited

ABSTRACTThe crystallization of sputter-deposited Si/Al amorphous alloys was examined by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). In-situ high-resolution TEM reveals the existence of an Al layer between the amorphous matrix and the growing crystalline phase. The activation energy for the growth is about 1.2eV, roughly corresponding to the activation energy of Si diffusion in Al. These two observations support the view that a crystallization mechanism, in which an Al buffer layer provides the shortest reaction path, is responsible for the reaction. The product microstructure exhibits secondary crystallization at a higher temperature.

Oxygen Precipitation Along Individual Ion Tracks During High Dose O+ Implantation into Silicon

1987 ◽  
Vol 93 ◽  
Author(s):  
Witold P. Maszara
Keyword(s):  
Silicon Layer ◽  
High Dose ◽  
Regular Array ◽  
Ion Tracks ◽  
Oxygen Precipitation ◽  
Transmission Electron ◽  
Oxygen Gas ◽  
Kinetics Of ◽  
Secondary Ion ◽  
Lattice Matched

ABSTRACTSilicon wafers with and without protective1Ahermil oxide were implanted with oxygen at 150keV with doses 1.6 – 2.0×1018 cm−2. Transmission electron microscopy (TEM) and secondary ion mass spectroscopy (SIMS) were used to study the top silicon layer remaining above the implanted buried oxide. regular array of spheroidal voids filled with oxygen gas was observed only in the samples that were not protected by the oxide. The voids were aligned into individual columns whose crystallographic orientation with respect to the host silicon lattice matched the direction of the implantation. The origin and the kinetics of their formation are discussed.

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