Grain Boundary Segregation in Titanium Dioxide: Evaluation of Relative Driving Forces for Segregation

2002 ◽  
Vol 751 ◽  
Author(s):  
Qinglei Wang ◽  
Guoda D. Lian ◽  
Elizabeth C. Dickey
Keyword(s):  
Titanium Dioxide ◽  
Driving Forces ◽  
Boundary Segregation ◽  
Solute Segregation ◽  
Dielectric Behavior ◽  
Relative Role ◽  
Transmission Electron ◽  
Fundamental Phenomenon ◽  
Versus Strain

ABSTRACTSolute segregation to grain boundaries is a fundamental phenomenon in polycrystalline metal-oxide electroceramics that has enormous implications for the macroscopic dielectric behavior of the materials. This paper presents a systematic study of solute segregation in a model dielectric, titanium dioxide. We investigate the relative role of the electrostatic versus strain energy driving forces for segregation by studying yttrium-doped specimens. Through analytical transmission electron microscopy studies, we quantitatively determine the segregation behavior of the material. The measured Gibbsian interfacial excesses are compared to thermodynamic predictions.

Interfacial Segregation in Ionic Conductors: Ceria

1996 ◽  
Vol 458 ◽  
Author(s):  
D. A. Blom ◽  
Y.-M. Chiang
Keyword(s):  
Driving Forces ◽  
Boundary Segregation ◽  
Scanning Transmission Electron Microscope ◽  
Solute Segregation ◽  
Ionic Conductors ◽  
X Ray ◽  
Surface Sites ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Interfacial Segregation

ABSTRACTGrain boundary segregation in cerium dioxide doped with varying amounts of gadolinium oxide and tantalum oxide has been measured with x-ray energy dispersive spectroscopy using a Vacuum Generators HB603 Scanning Transmission Electron Microscope (STEM). The data has been analyzed in the framework of both elastic relaxation and space charge segregation forces with a limited number of surface sites. Results show that multiple driving forces must be taken into account to explain aliovalent solute segregation.

scholarly journals The role of grain boundary character in solute segregation and thermal stability of nanocrystalline Pt–Au

Nanoscale ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 3552-3563
Author(s):  
Christopher M. Barr ◽  
Stephen M. Foiles ◽  
Malek Alkayyali ◽  
Yasir Mahmood ◽  
Patrick M. Price ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Grain Boundary ◽  
Boundary Segregation ◽  
Solute Drag ◽  
Solute Segregation ◽  
Grain Boundary Segregation ◽  
Grain Boundary Character ◽  
Service Conditions ◽  
Thermal Stability Of

In nanocrystalline alloys, the anisotropy in grain boundary segregation and its impact on dynamic solute drag plays a key role in the thermal stability of these systems during processing treatments or under service conditions.

Tailoring Grain-Boundary Segregation to Control Mechanical Properties

1999 ◽  
Vol 586 ◽  
Author(s):  
D. B. Williams ◽  
V. J. Keast
Keyword(s):  
Mechanical Properties ◽  
Grain Boundary ◽  
Boundary Segregation ◽  
X Ray ◽  
Transmission Electron ◽  
Intergranular Brittle Fracture ◽  
Properties Of Materials ◽  
Boundary Chemistry ◽  
First Time

ABSTRACTRecent advances in our understanding of the role of the chemistry of grain boundaries in controlling the mechanical properties of materials (in particular intergranular brittle fracture) are reviewed. It is now possible in a modem field-emission gun (FEG) analytical transmission electron microscope (AEM) to measure the chemistry of sub-nanometer films of GB segregants while at the same time observing the effect (if any) on the bonding of the atoms within a nanometer of the boundary plane. This has been accomplished by the development of X-ray mapping (XRM) a powerful new tool for the study of segregation. For the first time, in the same instrument, on the same grain boundary, any changes in the boundary chemistry can be correlated with the occurrence or absence of brittle failure, which is often associated with boundary segregation. There is strong evidence that boundary segregation is extremely nonuniform, even in some strongly embrittling systems (e.g. Cu-Bi) and in these same systems, embrittling segregants introduce subtle but consistent changes in the bonding. Non-embrittling segregants (e.g. Ag in Cu) do not introduce detectable bonding changes.

scholarly journals Grain boundary segregation and precipitation in an Al-Zn-Mg-Cu alloy

2020 ◽  
Vol 326 ◽  
pp. 01004
Author(s):  
Huan Zhao ◽  
Baptiste Gault ◽  
Frédéric De Geuser ◽  
Dirk Ponge ◽  
Dierk Raabe
Keyword(s):  
Local Structure ◽  
Boundary Segregation ◽  
High Strength ◽  
Solute Segregation ◽  
Al Alloys ◽  
Grain Boundary Segregation ◽  
Precipitation Behavior ◽  
Cu Alloy ◽  
Intergranular Embrittlement

High strength Al-alloys are highly susceptible to intergranular embrittlement, which severely limits their lifetime. This article summarizes our recent work on the effect of solute segregation in the precipitation behavior at grain boundaries (GBs) compared to the grain interiors. Solute segregation could accelerate the precipitation behavior at GBs, which causes the formation of coarse precipitates and precipitate free zones along GBs. Furthermore, the interplay of solute segregation and the local structure at GBs has been considered. We show that the distinct segregation and precipitation behavior occurs within the same GB, which makes the GB excess of solutes at one facet significantly higher than the other facet. This paper enriches the current understanding on the role of chemistry and structure at GBs related to intergranular fracture and corrosion resistance in high strength Al-alloys.

On Future Directions in Pathology

1982 ◽  
Vol 40 ◽  
pp. 274-277
Author(s):  
Benjamin F. Trump ◽  
Irene K. Berezesky ◽  
Raymond T. Jones
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Clinical Pathology ◽  
Future Directions ◽  
Diagnostic Pathology ◽  
The Past ◽  
Transmission Electron ◽  
Organ Systems ◽  
The Many

The role of electron microscopy and associated techniques is assured in diagnostic pathology. At the present time, most of the progress has been made on tissues examined by transmission electron microscopy (TEM) and correlated with light microscopy (LM) and by cytochemistry using both plastic and paraffin-embedded materials. As mentioned elsewhere in this symposium, this has revolutionized many fields of pathology including diagnostic, anatomic and clinical pathology. It began with the kidney; however, it has now been extended to most other organ systems and to tumor diagnosis in general. The results of the past few years tend to indicate the future directions and needs of this expanding field. Now, in addition to routine EM, pathologists have access to the many newly developed methods and instruments mentioned below which should aid considerably not only in diagnostic pathology but in investigative pathology as well.

Transmission Electron Microscopy studies of texture of Cr underlayer of magnetic recording hard disk

1991 ◽  
Vol 49 ◽  
pp. 580-581
Author(s):  
L. Tang ◽  
G. Thomas ◽  
M. R. Khan ◽  
S. L. Duan
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Magnetic Recording ◽  
Magnetic Thin Films ◽  
Magnetic Films ◽  
Substrate Bias ◽  
Epitaxial Relationship ◽  
Transmission Electron

Cr thin films are often used as underlayers for Co alloy magnetic thin films, such as Co1, CoNi2, and CoNiCr3, for high density longitudinal magnetic recording. It is belived that the role of the Cr underlayer is to control the growth and texture of the Co alloy magnetic thin films, and, then, to increase the in plane coercivity of the films. Although many epitaxial relationship between the Cr underlayer and the magnetic films, such as ﹛1010﹜Co/ {110﹜Cr4, ﹛2110﹜Co/ ﹛001﹜Cr5, ﹛0002﹜Co/﹛110﹜Cr6, have been suggested and appear to be related to the Cr thickness, the texture of the Cr underlayer itself is still not understood very well. In this study, the texture of a 2000 Å thick Cr underlayer on Nip/Al substrate for thin films of (Co75Ni25)1-xTix dc-sputtered with - 200 V substrate bias is investigated by electron microscopy.

Transmission Electron Microscopy of Evaporated Perylene Thin Films

1990 ◽  
Vol 48 (2) ◽  
pp. 336-337
Author(s):  
C. Ewins ◽  
J.R. Fryer
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Molecular Electronics ◽  
High Vacuum ◽  
Amorphous Layer ◽  
Electric Heater ◽  
Transmission Electron ◽  
Polycyclic Aromatic

The preparation of thin films of organic molecules is currently receiving much attention because of the need to produce good quality thin films for molecular electronics. We have produced thin films of the polycyclic aromatic, perylene C10H12 by evaporation under high vacuum onto a potassium chloride (KCl) substrate. The role of substrate temperature in determining the morphology and crystallography of the films was then investigated by transmission electron microscopy (TEM).The substrate studied was the (001) face of a freshly cleaved crystal of KCl. The temperature of the KCl was controlled by an electric heater or a cold finger. The KCl was heated to 200°C under a vacuum of 10-6 torr and allowed to cool to the desired temperature. The perylene was then evaporated over a period of one minute from a molybdenum boat at a distance of 10cm from the KCl. The perylene thin film was then backed with an amorphous layer of carbon and floated onto copper microscope grids.

Fine structure and possible functions of the hermaphrodite duct of some pulmonate snails (Mollusca: Gastropoda)

1990 ◽  
Vol 48 (3) ◽  
pp. 68-69
Author(s):  
Alan N. Hodgson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Seminal Vesicle ◽  
Reproductive Biology ◽  
Light Microscope ◽  
Light Microscope Level ◽  
Transmission Electron ◽  
Standard Techniques

The hermaphrodite duct of pulmonate snails connects the ovotestis to the fertilization pouch. The duct is typically divided into three zones; aproximal duct which leaves the ovotestis, the middle duct (seminal vesicle) and the distal ovotestis duct. The seminal vesicle forms the major portion of the duct and is thought to store sperm prior to copulation. In addition the duct may also play a role in sperm maturation and degredation. Although the structure of the seminal vesicle has been described for a number of snails at the light microscope level there appear to be only two descriptions of the ultrastructure of this tissue. Clearly if the role of the hermaphrodite duct in the reproductive biology of pulmonatesis to be understood, knowledge of its fine structure is required.Hermaphrodite ducts, both containing and lacking sperm, of species of the terrestrial pulmonate genera Sphincterochila, Levantina, and Helix and the marine pulmonate genus Siphonaria were prepared for transmission electron microscopy by standard techniques.

Chronic Pain: Fundamental Scientific Considerations, Specifically for Legal Claims

2013 ◽  
Vol 18 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Robert J. Barth
Keyword(s):  
Health Outcomes ◽  
Pain Perception ◽  
Driving Forces ◽  
Psychological Treatment ◽  
Dominant Role ◽  
Meta Analysis ◽  
General Medicine ◽  
Pain Syndrome ◽  
Problematic Relationship

Abstract Scientific findings have indicated that psychological and social factors are the driving forces behind most chronic benign pain presentations, especially in a claim context, and are relevant to at least three of the AMA Guides publications: AMA Guides to Evaluation of Disease and Injury Causation, AMA Guides to Work Ability and Return to Work, and AMA Guides to the Evaluation of Permanent Impairment. The author reviews and summarizes studies that have identified the dominant role of financial, psychological, and other non–general medicine factors in patients who report low back pain. For example, one meta-analysis found that compensation results in an increase in pain perception and a reduction in the ability to benefit from medical and psychological treatment. Other studies have found a correlation between the level of compensation and health outcomes (greater compensation is associated with worse outcomes), and legal systems that discourage compensation for pain produce better health outcomes. One study found that, among persons with carpal tunnel syndrome, claimants had worse outcomes than nonclaimants despite receiving more treatment; another examined the problematic relationship between complex regional pain syndrome (CRPS) and compensation and found that cases of CRPS are dominated by legal claims, a disparity that highlights the dominant role of compensation. Workers’ compensation claimants are almost never evaluated for personality disorders or mental illness. The article concludes with recommendations that evaluators can consider in individual cases.

Convergence of Corporate Governance Models

2004 ◽  
pp. 129-140 ◽  
Author(s):  
M. Tretyakov
Keyword(s):  
Corporate Governance ◽  
Institutional Environment ◽  
Driving Forces ◽  
Commodity Markets ◽  
Legal Systems ◽  
National Institutions ◽  
Governance Models ◽  
Changing Role

The article focuses on the analysis of the process of convergence of outsider and insider models of corporate governance. Chief characteristics of basic and intermediate systems of corporate governance as well as the changing role of its main agents are under examination. Globalization of financial and commodity markets, convergence of legal systems, an open exchange of ideas and information are the driving forces of the convergence of basic systems of corporate governance. However the convergence does not imply the unification of institutional environment and national institutions of corporate governance.

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