The Preparation of Bulk and Thick Films of YBa2Cu3O7-y Using a Solution Technique

1987 ◽  
Vol 99 ◽  
Author(s):  
P. Barboux ◽  
J. M. Tarascon ◽  
B. G. Bagley ◽  
L. H. Greene ◽  
G. W. Hull ◽  
...  
Keyword(s):  
Solid State ◽  
Thick Films ◽  
Reaction Times ◽  
Microscopic Level ◽  
Solid State Reactions ◽  
Solution Technique ◽  
Particle Sizes ◽  
Large Area ◽  
Size Dispersion ◽  
Technological Interest

ABSTRACTWe have synthesized the high Tc superconducting oxide YBa2Cu3O7-y using a solution technique and compare the resultant properties to materials synthesized by solid state reactions. Because the cations are mixed at the microscopic level, we observe that this solution technique allows lower reaction temperatures and shorter reaction times to obtain the superconducting material. They yield materials with particle sizes of about 1 μm and having a narrow size dispersion (as compared to the typically 50 μm particle sizes obtained by solid state reactions). The smaller, uniform particle sizes yield denser compacts upon sintering. Densities of 90% have been achieved and metallic-like behavior improves and is correlated with increasing density. The solution derived materials superconduct at 91 K and have narrow transition temperatures (0.6K width) which we attribute to sample compositional and structural homogeneity. Because we are able to produce stable, viscous gels, we have investigated the preparation of large area thick films on various substrates of technological interest (e.g. alumina, zirconia.strontium titanate).

scholarly journals Kinetics of Solid-State Reactions in Ni-Zr Thin Films

1991 ◽  
Vol 230 ◽  
Author(s):  
R. B. Schwarz ◽  
J. B. Rubin
Keyword(s):  
Solid State ◽  
Reaction Rate ◽  
High Vacuum ◽  
Reaction Times ◽  
Ultra High Vacuum ◽  
Solid State Reactions ◽  
Platinum Resistance ◽  
Platinum Resistance Thermometers ◽  
Resistance Thermometers ◽  
Kinetics Of

AbstractWe have studied the kinetics of the solid-state amorphizing reaction in thin film multilayers of Ni and Zr. Crystalline Ni and Zr films were deposited in ultra-high vacuum onto platinum resistance thermometers embedded in alumina. An electronic feedback circuit controls the temperature of the substrata by adjusting the power dissipated by the platinum resistors. We find that structural relaxation in the asdeposited Ni and Zr films affects the initial stages of the reaction. For long reaction times there is a discontinuous change in the reaction rate. The time to reach this transition increases with film thickness and depends exponentially on 1/T, with an apparent activation energy of 3 eV atom−1.

On the Photocatalytic Performance of Indium Tantalate and its Modifications

2008 ◽  
Vol 63 (10) ◽  
pp. 1160-1168 ◽  
Author(s):  
Maoiheb Douiheche ◽  
Robert Haberkorn ◽  
Horst P Beck
Keyword(s):  
Solid State ◽  
Profile Analysis ◽  
Sol Gel ◽  
Solid State Reactions ◽  
Particle Sizes ◽  
X Ray ◽  
Co Catalysts ◽  
Sol Gel Process ◽  
Microstructure Parameters ◽  
Uv Lamp

AbstractThe photocatalytic activity of InTaO4 has been studied regarding the effect of a substitution of In by Ni, of the performance of NiO as well as Ag2O as co-catalysts, and especially of the products of different methods of preparation (solid state reaction and/or sol-gel process) and their particle sizes. Solid state reactions and sol-gel procedures were used to synthesise different products for the catalytic reaction in a reactor vessel equipped with amercury UV lamp. The optical properties and the band gap values of the different products were evaluated by reflectance spectroscopy, and the microstructure parameters of the crystalline products were determined by an elaborate profile analysis of the X-ray diagrams. The evolution of H2 and O2 under irradiation was quantified by a GC setup. The causes for the deviations of the performance of these catalysts from the values reported elsewhere are discussed.

Esterification of carboxylic acids on cellulosic material: Solid state reactions

Holzforschung ◽  
2008 ◽  
Vol 62 (2) ◽  
pp. 136-141 ◽  
Author(s):  
Anna Pantze ◽  
Olov Karlsson ◽  
Ulla Westermark
Keyword(s):  
Solid State ◽  
Carboxylic Acids ◽  
Reaction Times ◽  
Solid State Reactions ◽  
Hydroxyl Groups ◽  
Hydroxybutyric Acid ◽  
Monocarboxylic Acids ◽  
Ester Formation ◽  
Suitable Structure ◽  
Reactive Compound

Abstract In the present work, the formation of ester linkages in cellulosic materials during drying and heating was addressed. The results indicated that direct ester formation, without anhydride intermediate, occurs between carboxylic acids of suitable structure and cellulosic hydroxyls at 180°C, even after reaction times as short as 5 min. The 2(R)-hydroxybutyric acid is most effective in ester formation, followed by 2-ketobutyric acid and 3-hydroxybutyric acid. Hexanoic acid is less effective and veratric acid produces no esters at all. At lower temperatures, 2-ketobutyric acid is the most reactive compound. One conclusion is that a hydroxyl or keto group in α position of the carboxylic acids favours ester formation. Another finding is that three pyrrolidine structures are produced after esterification and aminolysis of 2-ketobutyric acid. One of the structures indicates that 2-ketobutyric acid is reactive in two positions and could therefore be a potential cross-linker. A critical parameter for ester formation is pH, and the results indicate that pH <2 strongly favours esterification, whereas almost no esters are produced at pH >5–6. All experiments were performed in a solid-state model system (on cellulosic filter paper) with low moisture content. Esterification of five carboxylic acids was studied. Samples were heated constantly at 180°C for 5 min or gradually from 22°C to 180°C over periods ranging from 5 to 45 min. Quantitative analysis of ester formation between the monocarboxylic acids and the hydroxyl groups of cellulose was performed by means of aminolysis and gas chromatography.

Microstructural Variations in Melt-Spun Rapidly Solidified Ribbons

1985 ◽  
Vol 43 ◽  
pp. 54-55
Author(s):  
L. A. Bendersky ◽  
W. J. Boettinger
Keyword(s):  
Solid State ◽  
Processing Parameters ◽  
Heat Extraction ◽  
Solid State Reactions ◽  
Careful Examination ◽  
Ion Milling ◽  
Melt Spun ◽  
Wheel Side ◽  
Rapidly Solidified ◽  
Heat Extraction Rate

Rapid solidification produces a wide variety of sub-micron scale microstructure. Generally, the microstructure depends on the imposed melt undercooling and heat extraction rate. The microstructure can vary strongly not only due to processing parameters changes but also during the process itself, as a result of recalescence. Hence, careful examination of different locations in rapidly solidified products should be performed. Additionally, post-solidification solid-state reactions can alter the microstructure.The objective of the present work is to demonstrate the strong microstructural changes in different regions of melt-spun ribbon for three different alloys. The locations of the analyzed structures were near the wheel side (W) and near the center (C) of the ribbons. The TEM specimens were prepared by selective electropolishing or ion milling.

The wustite-spinel interface

1987 ◽  
Vol 45 ◽  
pp. 268-269
Author(s):  
S.R. Summerfelt ◽  
C.B. Carter
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Strain Energy ◽  
Matrix Material ◽  
Lattice Misfit ◽  
Solid State Reactions ◽  
Oxygen Sublattice ◽  
Large Particles ◽  
Small Lattice ◽  
Coherent Interfaces

The wustite-spinel interface can be viewed as a model interface because the wustite and spinel can share a common f.c.c. oxygen sublattice such that only the cations distribution changes on crossing the interface. In this study, the interface has been formed by a solid state reaction involving either external or internal oxidation. In systems with very small lattice misfit, very large particles (>lμm) with coherent interfaces have been observed. Previously, the wustite-spinel interface had been observed to facet on {111} planes for MgFe2C4 and along {100} planes for MgAl2C4 and MgCr2O4, the spinel then grows preferentially in the <001> direction. Reasons for these experimental observations have been discussed by Henriksen and Kingery by considering the strain energy. The point-defect chemistry of such solid state reactions has been examined by Schmalzried. Although MgO has been the principal matrix material examined, others such as NiO have also been studied.

TEM study of amorphization of Cu and Ti foils by cold-rolling

1990 ◽  
Vol 48 (4) ◽  
pp. 146-147
Author(s):  
W. A. Chiou ◽  
N. L. Jeon ◽  
Genbao Xu ◽  
M. Meshii
Keyword(s):  
Solid State ◽  
Cold Rolling ◽  
High Energy ◽  
Rapid Quenching ◽  
Vapor Condensation ◽  
Metallic Alloys ◽  
Solid State Reactions ◽  
High Energy Particle ◽  
Amorphous Metallic Alloys ◽  
Thin Foils

For many years amorphous metallic alloys have been prepared by rapid quenching techniques such as vapor condensation or melt quenching. Recently, solid-state reactions have shown to be an alternative for synthesizing amorphous metallic alloys. While solid-state amorphization by ball milling and high energy particle irradiation have been investigated extensively, the growth of amorphous phase by cold-rolling has been limited. This paper presents a morphological and structural study of amorphization of Cu and Ti foils by rolling.Samples of high purity Cu (99.999%) and Ti (99.99%) foils with a thickness of 0.025 mm were used as starting materials. These thin foils were cut to 5 cm (w) × 10 cm (1), and the surface was cleaned with acetone. A total of twenty alternatively stacked Cu and Ti foils were then rolled. Composite layers following each rolling pass were cleaned with acetone, cut into half and stacked together, and then rolled again.

The use of high-resolution FESEM to study solid-state phase transformations and reactions

1994 ◽  
Vol 52 ◽  
pp. 1028-1029
Author(s):  
P. G. Kotula ◽  
D. D. Erickson ◽  
C. B. Carter
Keyword(s):  
Solid State ◽  
High Resolution ◽  
Phase Transformations ◽  
High Efficiency ◽  
Sol Gel ◽  
Quantitative Information ◽  
Solid State Reactions ◽  
Critical Dimensions ◽  
Backscattered Electrons ◽  
Backscattered Electron

High-resolution field-emission-gun scanning electron microscopy (FESEM) has recently emerged as an extremely powerful method for characterizing the micro- or nanostructure of materials. The development of high efficiency backscattered-electron detectors has increased the resolution attainable with backscattered-electrons to almost that attainable with secondary-electrons. This increased resolution allows backscattered-electron imaging to be utilized to study materials once possible only by TEM. In addition to providing quantitative information, such as critical dimensions, SEM is more statistically representative. That is, the amount of material that can be sampled with SEM for a given measurement is many orders of magnitude greater than that with TEM.In the present work, a Hitachi S-900 FESEM (operating at 5kV) equipped with a high-resolution backscattered electron detector, has been used to study the α-Fe2O3 enhanced or seeded solid-state phase transformations of sol-gel alumina and solid-state reactions in the NiO/α-Al2O3 system. In both cases, a thin-film cross-section approach has been developed to facilitate the investigation. Specifically, the FESEM allows transformed- or reaction-layer thicknesses along interfaces that are millimeters in length to be measured with a resolution of better than 10nm.

TEM studies of solid-state reactions in sputter-deposited Nb/Al multilayer thin films

1996 ◽  
Vol 54 ◽  
pp. 1020-1021
Author(s):  
F. Ma ◽  
S. Vivekanand ◽  
K. Barmak ◽  
C. Michaelsen
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Stoichiometric Composition ◽  
Analytical Electron Microscopy ◽  
Grain Structure ◽  
Solid State Reactions ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sputter Deposited

Solid state reactions in sputter-deposited Nb/Al multilayer thin films have been studied by transmission and analytical electron microscopy (TEM/AEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The Nb/Al multilayer thin films for TEM studies were sputter-deposited on (1102)sapphire substrates. The periodicity of the films is in the range 10-500 nm. The overall composition of the films are 1/3, 2/1, and 3/1 Nb/Al, corresponding to the stoichiometric composition of the three intermetallic phases in this system.Figure 1 is a TEM micrograph of an as-deposited film with periodicity A = dA1 + dNb = 72 nm, where d's are layer thicknesses. The polycrystalline nature of the Al and Nb layers with their columnar grain structure is evident in the figure. Both Nb and Al layers exhibit crystallographic texture, with the electron diffraction pattern for this film showing stronger diffraction spots in the direction normal to the multilayer. The X-ray diffraction patterns of all films are dominated by the Al(l 11) and Nb(l 10) peaks and show a merging of these two peaks with decreasing periodicity.

TEM STUDIES OF THE MICROMECHANISMS OF SOLID STATE REACTIONS IN Ni-Zr BULK DIFFUSION COUPLES

1990 ◽  
Vol 51 (C4) ◽  
pp. C4-121-C4-130
Author(s):  
U. KÖSTER ◽  
R. PRIES ◽  
G. BEWERNICK ◽  
B. SCHUHMACHER ◽  
M. BLANK-BEWERSDORFF
Keyword(s):  
Solid State ◽  
Bulk Diffusion ◽  
Solid State Reactions ◽  
Diffusion Couples

Electric-Field Effects on Reactions Between Oxides

1997 ◽  
Vol 481 ◽  
Author(s):  
Matthew T. Johnson ◽  
Shelley R. Gilliss ◽  
C. Barry Carter
Keyword(s):  
Solid State ◽  
Electric Field ◽  
Elevated Temperatures ◽  
Ionic Current ◽  
Reaction Rates ◽  
Solid State Reactions ◽  
Interfacial Stability ◽  
Electric Field Effects ◽  
Thin Film Diffusion ◽  
Microscopy Techniques

ABSTRACTThin films of In2O3 and Fe2O3 have been deposited on (001) MgO using pulsed-laser deposition (PLD). These thin-film diffusion couples were then reacted in an applied electric field at elevated temperatures. In this type of solid-state reaction, both the reaction rate and the interfacial stability are affected by the transport properties of the reacting ions. The electric field provides a very large external driving force that influences the diffusion of the cations in the constitutive layers. This induced ionic current causes changes in the reaction rates, interfacial stability and distribution of the phases. Through the use of electron microscopy techniques the reaction kinetics and interface morphology have been investigated in these spinel-forming systems, to gain a better understanding of the influence of an electric field on solid-state reactions.

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