Analytical Electron Microscopy of Surface-Modified Ceramics

1985 ◽  
Vol 43 ◽  
pp. 276-279
Author(s):  
P. S. Sklad
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Theoretical Models ◽  
Ceramic Materials ◽  
Solute Concentration ◽  
Second Phase ◽  
Analytical Electron ◽  
Implantation Techniques ◽  
Lattice Damage ◽  
Surface Modified

Over the past several years, it has become increasingly evident that materials for proposed advanced energy systems will be required to operate at high temperatures and in aggressive environments. These constraints make structural ceramics attractive materials for these systems. However it is well known that the condition of the specimen surface of ceramic materials is often critical in controlling properties such as fracture toughness, oxidation resistance, and wear resistance. Ion implantation techniques offer the potential of overcoming some of the surface related limitations.While the effects of implantation on surface sensitive properties may be measured indpendently, it is important to understand the microstructural evolution leading to these changes. Analytical electron microscopy provides a useful tool for characterizing the microstructures produced in terms of solute concentration profiles, second phase formation, lattice damage, crystallinity of the implanted layer, and annealing behavior. Such analyses allow correlations to be made with theoretical models, property measurements, and results of complimentary techniques.

Application of Analytical Electron Microscopy to Ion Implantation and Near Surface Microstructures

1985 ◽  
Vol 62 ◽  
Author(s):  
P. S. Sklad
Keyword(s):  
Electron Microscopy ◽  
Ion Implantation ◽  
Ion Beam ◽  
Analytical Electron Microscopy ◽  
Theoretical Models ◽  
Solute Concentration ◽  
Specimen Preparation ◽  
Second Phase ◽  
Near Surface ◽  
Analytical Electron

ABSTRACTSurface modification using ion beam techniques is recognized as an important method for improving surface controlled properties of metallic, ceramic, and semiconductor materials. Determination of the microstructure and composition in regions located within a few hundred nanometers of the surface is essential to gaining an understanding of the mechanisms responsible for the improved properties. Analytical electron microscopy (AEM), high resolution microscopy, and microdiffraction are ideally suited for this purpose. These techniques are powerful tools for characterizing microstructure in terms of solute concentration profiles, second phase formation, lattice damage, crystallinity of the implanted layer and annealing behavior. Such analyses allow correlations with theoretical models, property measurements and results of complementary techniques. The proximity of the regions of interest to the surface also places stringent requirements on specimen preparation techniques. The power of AEM in examining the effects of ion implantation will be illustrated by reviewing the results of several investigations. A brief discussion of some important aspects of specimen preparation will also be included.

Analytical Electron Microscopy Studies of Bi-Substituted Garnet Films

1991 ◽  
Vol 232 ◽  
Author(s):  
P. A. Crozier ◽  
P. A. Labun ◽  
T Suzuki
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Second Phase ◽  
Processing Conditions ◽  
Transformation Kinetics ◽  
Heating Rates ◽  
Garnet Films ◽  
Analytical Electron ◽  
In Situ Heating

ABSTRACTIn-situ heating in an electron microscope, together with EDX and EELS analysis, was used to characterize as-deposited amorphous and transformed garnet films. It was found that upon initial crystallization, a non-uniform precipitation of a second phase occurred, altering the local chemistry and microstructure of the transformed film. In addition, to study the transformation kinetics in more detail some experiments were conducted at slower heating rates and lower temperatures. It is hoped that the data obtained can be correlated to magnetic property measurements and contribute to the development of improved processing conditions.

Grain Boundary Chemistry in Al-Cu Metallizations as Determined by Analytical Electron Microscopy

1991 ◽  
Vol 229 ◽  
Author(s):  
J. R. Michael ◽  
A. D. Romig ◽  
D. R. Frear
Keyword(s):  
Electron Microscopy ◽  
Integrated Circuits ◽  
Grain Boundary ◽  
Analytical Electron Microscopy ◽  
Second Phase ◽  
Collector Plate ◽  
Analytical Electron ◽  
Cu Thin Film ◽  
Boundary Chemistry ◽  
Interconnect Lines

AbstractAl with additions of Cu is commonly used as the conductor metallizations for integrated circuits (ICs). As the packing density of ICs increases, interconnect lines are required to carry ever higher current densities. Consequently, reliability due to electromigration failure becomes an increasing concern. Cu has been found to increase the lifetimes of these conductors, but the mechanism by which electromigration is improved is not yet fully understood. In order to evaluate certain theories of electromigration it is necessary to have a detailed description of the Cu distribution in the Al microstructure, with emphasis on the distribution of Cu at the grain boundaries. In this study analytical electron microscopy (AEM) has been used to characterize grain boundary regions in an Al-2 wt.% Cu thin film metallization on Si after a variety of thermal treatments. The results of this study indicate that the Cu distribution is dependent on the thermal annealing conditions. At temperatures near the θ phase (CuAl2) solvus, the Cu distribution may be modelled by the collector plate mechanism, in which the grain boundary is depleted in Cu relative to the matrix. At lower temperatures, Cu enrichment of the boundaries occurs, perhaps as a precursor to second phase formation. Natural cooling from the single phase field produces only grain boundary depletion of Cu consistent with the collector-plate mechanism. The kinetic details of the elemental segregation behavior derived from this study can be used to describe microstructural evolution in actual interconnect alloys.

Phase Identification in TiB2-Ni Composites by Analytical Electron Microscopy

1981 ◽  
Vol 39 ◽  
pp. 138-139
Author(s):  
P. S. Sklad ◽  
J. Bentley ◽  
A. T. Fisher ◽  
G. L. Lehman
Keyword(s):  
Electron Microscopy ◽  
Cutting Tools ◽  
Analytical Electron Microscopy ◽  
High Hardness ◽  
Phase Identification ◽  
Second Phase ◽  
Binder Phase ◽  
Ion Milling ◽  
X Ray ◽  
Analytical Electron

The transition metal diboride TiB2 is characterized by high hardness and high melting point (3253 K) . These properties make this material attractive for applications such as valve components in coal liquefaction plants and cutting tools. Liquid phase hot pressing using nickel as the fluidizing medium allows densification at lower temperatures than when using TiB2 powders alone, but the nickel and TiB2 react to form a complex multiphase microstructure. The purpose of this investigation was to identify the nickel-rich binder phase. The material examined was taken from a cylindrical compact hot pressed at ∼1720 K. During pressing most of the original 15 mol % Ni exuded from the initial mixtures. Specimens 3 mm dia were prepared for analytical electron microscopy (AEM) examination by mechanical lapping followed by ion milling.A typical microstructure of the TiB2-Ni composite examined at 120 kv by conventional transmission electron microscopy (TEM) is shown in Fig. 1. The microstructure is characterized by TiB2 grains bonded by a second phase which was observed at multiple grain intersections. X-ray energy dispersive spectroscopy (EDS) measurements were made using a Philips EM400T/FEG. probe sizes of ∼10 nm dia and probe currents of ∼5 nA were used so that measurements could be made in thin regions of the binder phase, where beam broadening was small. Typical x-ray spectra from an intergranular region and an adjacent TiB2 grain are shown in Fig. 2. The results of standardless quantitative analyses of binder phase spectra indicated a composition (for Z > 11) of at least 95% Ni.

Second Phase Formation in Aluminum annealed after Ion Implantation with Molybdenum.

1983 ◽  
Vol 27 ◽  
Author(s):  
J. Bentley ◽  
L. D. Stephenson ◽  
R. B. Benson ◽  
P. A. Parrish ◽  
J. K. Hirvonen
Keyword(s):  
Electron Microscopy ◽  
Ion Implantation ◽  
Phase Transformations ◽  
Phase Formation ◽  
Analytical Electron Microscopy ◽  
Second Phase ◽  
Continuous Film ◽  
Video Recordings ◽  
Analytical Electron ◽  
Annealing Experiments

ABSTRACTThe microstructure of aluminum annealed after implantation to peak concentrations of approximately 4.4 and 11 at. % Mo was investigated by analytical electron microscopy. Al12Mo precipitates formed with pseudo-lamellar and continuous film microstructures. Video recordings of insitu annealing experiments revealed the details of the phase transformations.

Analytical ELectron Microscopy Characterization of Basalt Glass Ceramics

1982 ◽  
Vol 40 ◽  
pp. 616-617
Author(s):  
L. E. Thomas ◽  
L. A. Chick ◽  
R. O. Lokken
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Glass Ceramics ◽  
Ceramic Materials ◽  
Basalt Glass ◽  
Glass Ceramic Materials ◽  
Analytical Electron ◽  
Microscopy Characterization

Radioactive waste produced by nuclear reactors poses long term environmental hazards if not adequately immobilized and stored. As part of a program for developing basalt-based waste forms with high leach durability, analytical electron microscopy has been used to identify and chemically analyze the phases in several basalt glass/ceramic materials.

Application of Analytical Electron Microscopy to glass-bonded aluminas

1986 ◽  
Vol 44 ◽  
pp. 436-439
Author(s):  
B.J. Hockey
Keyword(s):  
Electron Microscopy ◽  
Volume Fraction ◽  
Sintered Material ◽  
Analytical Electron Microscopy ◽  
Microstructural Characterization ◽  
Ceramic Materials ◽  
Liquid Phase Sintering ◽  
Binder Phase ◽  
Analytical Electron ◽  
Polycrystalline Body

Liquid phase sintering represents one of the most common methods of producing aluminas and other ceramic materials. Regardless of the specific processing details, this sintering procedure invariably results in a polycrystalline body containing a certain volume fraction of an intergranular binder phase. This phase is typically a glass, which can control many important properties of the sintered material. Clearly, microstructural characterization - describing not only the physical distribution of the binder phase but also its chemical composition - represents its an important part in the study of these materials.

Electron Beam Damage of Biomolecules Assessed by Energy Loss Spectroscopy

1978 ◽  
Vol 36 (3) ◽  
pp. 61-69
Author(s):  
M. Isaacson ◽  
M.L. Collins ◽  
M. Listvan
Keyword(s):  
Electron Microscopy ◽  
Radiation Damage ◽  
Structural Integrity ◽  
Analytical Electron Microscopy ◽  
High Dose ◽  
Dose Rates ◽  
Special Cases ◽  
Analytical Electron ◽  
Atom Migration ◽  
Beam Damage

Over the past five years it has become evident that radiation damage provides the fundamental limit to the study of blomolecular structure by electron microscopy. In some special cases structural determinations at very low doses can be achieved through superposition techniques to study periodic (Unwin & Henderson, 1975) and nonperiodic (Saxton & Frank, 1977) specimens. In addition, protection methods such as glucose embedding (Unwin & Henderson, 1975) and maintenance of specimen hydration at low temperatures (Taylor & Glaeser, 1976) have also shown promise. Despite these successes, the basic nature of radiation damage in the electron microscope is far from clear. In general we cannot predict exactly how different structures will behave during electron Irradiation at high dose rates. Moreover, with the rapid rise of analytical electron microscopy over the last few years, nvicroscopists are becoming concerned with questions of compositional as well as structural integrity. It is important to measure changes in elemental composition arising from atom migration in or loss from the specimen as a result of electron bombardment.

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