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.

High-resolution x-ray imaging of small copper-rich precipitates in steels

1988 ◽  
Vol 46 ◽  
pp. 528-529
Author(s):  
J. R. Michael ◽  
K. A. Taylor
Keyword(s):  
Electron Microscopy ◽  
Thermomechanical Processing ◽  
Atom Probe ◽  
Ferrite Matrix ◽  
Scanning Transmission Electron Microscope ◽  
Probe Field ◽  
X Ray ◽  
Subsequent Transformation ◽  
Transmission Electron ◽  
Scanning Transmission

Although copper is considered an incidental or trace element in many commercial steels, some grades contain up to 1-2 wt.% Cu for precipitation strengthening. Previous electron microscopy and atom-probe/field-ion microscopy (AP/FIM) studies indicate that the precipitation of copper from ferrite proceeds with the formation of Cu-rich bcc zones and the subsequent transformation of these zones to fcc copper particles. However, the similarity between the atomic scattering amplitudes for iron and copper and the small misfit between between Cu-rich particles and the ferrite matrix preclude the detection of small (<5 nm) Cu-rich particles by conventional transmission electron microscopy; such particles have been imaged directly only by FIM. Here results are presented whereby the Cu Kα x-ray signal was used in a dedicated scanning transmission electron microscope (STEM) to image small Cu-rich particles in a steel. The capability to detect these small particles is expected to be helpful in understanding the behavior of copper in steels during thermomechanical processing and heat treatment.

The effect of small additions of Cu on precipitation in Al-Mg-Si alloys

1990 ◽  
Vol 48 (2) ◽  
pp. 442-443
Author(s):  
M. Tamizifar ◽  
G. Cliff ◽  
R.W. Devenish ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Argon Atmosphere ◽  
Age Hardening ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Analytical Electron ◽  
Scanning Transmission

Small additions of copper, <1 wt%, have a pronounced effect on the ageing response of Al-Mg-Si alloys. The object of the present investigation was to study the effect of additions of copper up to 0.5 wt% on the ageing response of a series of Al-Mg-Si alloys and to use high resolution analytical electron microscopy to determine the composition of the age hardening precipitates.The composition of the alloys investigated is given in Table 1. The alloys were heat treated in an argon atmosphere for 30m, water quenched and immediately aged either at 180°C for 15 h or given a duplex treatment of 180°C for 15 h followed by 350°C for 2 h2. The double-ageing treatment was similar to that carried out by Dumolt et al. Analyses of the precipitation were carried out with a HB 501 Scanning Transmission Electron Microscope. X-ray peak integrals were converted into weight fractions using the ratio technique of Cliff and Lorimer.

High Spatial Resolution Compositional Analysis at Interfaces

1980 ◽  
Vol 38 ◽  
pp. 356-359
Author(s):  
John B. Vander Sande ◽  
Thomas F. Kelly ◽  
Douglas Imeson
Keyword(s):  
Electron Microscope ◽  
High Spatial Resolution ◽  
Compositional Analysis ◽  
Scanning Transmission Electron Microscope ◽  
Thin Specimen ◽  
X Ray ◽  
Volume Of Interest ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Energy Loss

In the scanning transmission electron microscope (STEM) a fine probe of electrons is scanned across the thin specimen, or the probe is stationarily placed on a volume of interest, and various products of the electron-specimen interaction are then collected and used for image formation or microanalysis. The microanalysis modes usually employed in STEM include, but are not restricted to, energy dispersive X-ray analysis, electron energy loss spectroscopy, and microdiffraction.

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.

Phase Transformation of Powdered Material by Using Metal Jet

2012 ◽  
Vol 706-709 ◽  
pp. 741-744 ◽  
Author(s):  
Akio Kira ◽  
Ryuichi Tomoshige ◽  
Kazuyuki Hokamoto ◽  
Masahiro Fujita
Keyword(s):  
Phase Transformation ◽  
Powdered Material ◽  
Scanning Transmission Electron Microscope ◽  
Ultrahigh Pressure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Metal Jet ◽  
Very High

The various techniques of phase transformation of the material have been proposed by many researchers. We have developed several devices to generate the ultrahigh pressure by using high explosive. One of them uses metal jets. It is expected that the ultrahigh pressure occurs by the head-on collision between metal jets, because the velocity of the metal jet is very high. By mixing a powdered material with metal jets, the pressure of the material becomes high. The purpose of this study is to transform the phase of the powdered material by using this high pressure. The powders of the graphite and hBN were applied. The synthesis to the diamond and cBN was confirmed by X-ray diffraction (XRD). In this paper, the mechanism of the generation of the ultrahigh pressure is explained and the results of the observation of the powder by using scanning transmission electron microscope (STEM) are reported.

Quantification Of Segregation Levels Using Xeds In The Stem

1999 ◽  
Vol 5 (S2) ◽  
pp. 146-147
Author(s):  
V. J. Keast ◽  
D. B. Williams
Keyword(s):  
Grain Boundary ◽  
Boundary Segregation ◽  
Scanning Transmission Electron Microscope ◽  
Factor V ◽  
X Ray ◽  
Interaction Volume ◽  
Probe Size ◽  
Scanning Transmission ◽  
The Matrix ◽  
Image Position

The quantification of grain boundary segregation levels, as measured with X-ray energy dispersive spectroscopy (XEDS) in a scanning transmission electron microscope (STEM), is dependent on the size and shape of the interaction volume. The segregation level T (in atoms/nm2) is related to the intensities of the characteristic peaks in the X-ray spectrum, Is and Im, bywhere ρ is the density of the matrix in atoms/nm3, Am and As are the atomic masses of the matrix and segregant respectively and ksm is the usual k-factor. The geometric factor, V/A, is the ratio of the volume of interaction to the area of the grain boundary inside in the interaction volume. Different models have been used to describe the interaction volume and these are illustrated in Fig. 1 and the appropriate expression for V/A is given in each case. In the simplest case, beam broadening is neglected and the interaction volume can be described as a cylinder with diameter equal to the probe size, d.

A Study of Grain Boundaries in High TC Superconducting Yba2Cu3O7-x Thin Films Using High Resolution Analytical Stem

1989 ◽  
Vol 169 ◽  
Author(s):  
D. H. Shin ◽  
J. Silcox ◽  
S. E. Russek ◽  
D. K. Lathrop ◽  
R. A. Buhrman
Keyword(s):  
Thin Films ◽  
High Resolution ◽  
Grain Boundaries ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Resolution ◽  
High Tc ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Edx Microanalysis

AbstractGrain boundaries in thin films of high Tc YBa2Cu3O7-x superconductors have been investigated with high resolution scanning transmission electron microscope (STEM) imaging and nanoprobe energy dispersive x-ray (EDX) analysis. Atomic resolution images indicate that the grain boundaries are mostly clean, i.e., free of a boundary layer of different phase or of segregation, and are often coherent. EDX microanalysis with a 10 Å spatial resolution also indicates no composition deviation at the grain boundaries.

X-Ray Microanalysis Combined with Monte Carlo Simulation for the Analysis of Layered Thin Films: The Case of Carbon Contamination

2009 ◽  
Vol 15 (2) ◽  
pp. 99-105 ◽  
Author(s):  
Aldo Armigliato ◽  
Rodolfo Rosa
Keyword(s):  
Monte Carlo ◽  
Carbon Film ◽  
Sample Surface ◽  
Scanning Transmission Electron Microscope ◽  
Carbon Layer ◽  
Monte Carlo Code ◽  
X Ray ◽  
Transmission Electron ◽  
The Monte Carlo Method ◽  
Scanning Transmission

AbstractA previously developed Monte Carlo code has been extended to the X-ray microanalysis in a (scanning) transmission electron microscope of plan sections, consisting of bilayers and triple layers. To test the validity of this method for quantification purposes, a commercially available NiOx (x ∼ 1) thin film, deposited on a carbon layer, has been chosen. The composition and thickness of the NiO film and the thickness of the C support layer are obtained by fitting to the three X-ray intensity ratios I(NiK)/I(OK), I(NiK)/I(CK), and I(OK)/I(CK). Moreover, it has been investigated to what extent the resulting film composition is affected by the presence of a contaminating carbon film at the sample surface. To this end, the sample has been analyzed both in the (recommended) “grid downward” geometry and in the upside/down (“grid upward”) situation. It is found that a carbon contaminating film of few tens of nanometers must be assumed in both cases, in addition to the C support film. Consequently, assuming the proper C/NiOx/C stack in the simulations, the Monte Carlo method yields the correct oxygen concentration and thickness of the NiOx film.

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