scholarly journals Atomic Scale Structure and Chemistry of Interfaces by Z-Contrast Imaging and Electron Energy Loss Spectroscopy in the Stem

1993 ◽  
Vol 319 ◽  
Author(s):  
M.M. Mcgibbon ◽  
N.D. Browning ◽  
M.F. Chisholm ◽  
S.J. Pennycook ◽  
V. Ravikumar ◽  
...  
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Structural Information ◽  
Atomic Scale ◽  
Boundary Structure ◽  
Structure Property ◽  
Contrast Imaging ◽  
Z Contrast ◽  
Electron Energy Loss

AbstractThe macroscopic properties of many materials are controlled by the structure and chemistry at grain boundaries. A basic understanding of the structure-property relationship requires a technique which probes both composition and chemical bonding on an atomic scale. The high-resolution Z-contrast imaging technique in the scanning transmission electron microscope (STEM) forms an incoherent image in which changes in atomic structure and composition can be interpreted intuitively. This direct image allows the electron probe to be positioned over individual atomic columns for parallel detection electron energy loss spectroscopy (EELS) at a spatial resolution approaching 0.22nm. In this paper we have combined the structural information available in the Z-contrast images with the bonding information obtained from the fine structure within the EELS edges to determine the grain boundary structure in a SrTiO3 bicrystal.

Investigating Ca Segregated to a Grain Boundaries in MgO Using Multiple Scattering Analysis of Electron Energy Loss Spectra

1998 ◽  
Vol 4 (S2) ◽  
pp. 776-777
Author(s):  
J. P. Buban ◽  
J. Zaborac ◽  
H. Moltaji ◽  
G. Duscher ◽  
N. D. Browning
Keyword(s):  
Energy Loss ◽  
Grain Boundaries ◽  
Electron Energy ◽  
Structural Model ◽  
Boundary Structure ◽  
Structure Property ◽  
Contrast Imaging ◽  
Scale Properties ◽  
Z Contrast ◽  
Electron Energy Loss

Although grain boundaries typically account for only a small fraction of a material, they can have far reaching effects on the overall bulk scale properties. These effects are usually simply linked to the boundary having a different atomic arrangement to the bulk. A necessary first step in understanding the structure-property relationships is therefore a detailed determination of the boundary structure.One means of obtaining detailed information on the structure of grain boundaries is through correlated Z-contrast imaging and electron energy loss spectroscopy (EELS). The Z-contrast image generates a map of the grain boundary which can be used to position the probe in defined locations for spectroscopy. In the case of oxides, a structural model of the metal atom positions can be determined directly from the image. Furthermore, using a simple bond-valence sum minimization routine, the oxygen atoms can be placed so that the structure contains atoms that have valences consistent with their expected formal valence state.

scholarly journals Atomic Scale Structure and Chemistry of Interfaces by Z-Contrast Imaging and Electron Energy Loss Spectroscopy in the Stem

1994 ◽  
Vol 341 ◽  
Author(s):  
M. M. McGibbon ◽  
N. D. Browning ◽  
M. F. Chisholm ◽  
A. J. McGibbon ◽  
S. J. Pennycook ◽  
...  
Keyword(s):  
High Resolution ◽  
Energy Loss ◽  
Electron Energy ◽  
Atomic Structure ◽  
Electron Energy Loss Spectroscopy ◽  
Atomic Scale ◽  
Chemical Information ◽  
Contrast Imaging ◽  
Z Contrast ◽  
Electron Energy Loss

AbstractThe macroscopic properties of many materials are controlled by the structure and chemistry at grain boundaries. A basic understanding of the structure-property relationship requires a technique which probes both composition and chemical bonding on an atomic scale. High-resolution Z-contrast imaging in the scanning transmission electron microscope (STEM) forms an incoherent image in which changes in atomic structure and composition across an interface can be interpreted directly without the need for preconceived atomic structure models (1). Since the Z-contrast image is formed by electrons scattered through high angles, parallel detection electron energy loss spectroscopy (PEELS) can be used simultaneously to provide complementary chemical information on an atomic scale (2). The fine structure in the PEEL spectra can be used to investigate the local electronic structure and the nature of the bonding across the interface (3). In this paper we use the complimentary techniques of high resolution Zcontrast imaging and PEELS to investigate the atomic structure and chemistry of a 25° symmetric tilt boundary in a bicrystal of the electroceramic SrTiO3.

Analysis of the Atomic-Scale Defect Chemistry at Interfaces in Fluorite Structured Oxides by Electron Energy Loss Spectroscopy

2001 ◽  
Vol 703 ◽  
Author(s):  
Y. Ito ◽  
Y Lei ◽  
N.D. Browning ◽  
T.J. Mazanec
Keyword(s):  
Energy Loss ◽  
Grain Boundaries ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Contrast Imaging ◽  
Ceramic Electrolyte ◽  
Scanning Transmission ◽  
Electron Energy Loss

ABSTRACTGd3+ doped Ce oxides are a major candidate for use as the electrolyte in solid oxide fuel cells operating at ∼500 °C. Here, the effect of the atomic structure on the local electronic properties, i.e. oxygen coordination and cation valence, at grain boundaries in the fluorite structured Gd0.2Ce0.8O2-x ceramic electrolyte is investigated by a combination of atomic resolution Z-contrast imaging and electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). In particular, EELS analyses from grain boundaries reveals a complex interaction between segregation of the dopant (Gd3+), oxygen vacancies and the valence state of Ce. These results are similar to observations from fluorite-structured Yttria-Stabilized Zirconium (YSZ) bicrystal grain boundaries.

scholarly journals Study of Chromium-Doped Diamond-Like Carbon by Z-Contrast Imaging and Electron Energy Loss Spectroscopy

1999 ◽  
Vol 593 ◽  
Author(s):  
X. Fan ◽  
E. C. Dickey ◽  
S. J. Pennycook
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Metal Cluster ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Contrast Imaging ◽  
White Line ◽  
Z Contrast ◽  
Electron Energy Loss

ABSTRACTMetal-doped diamond-like carbon films were produced for the purpose of an electrochemical nano-electrode. In this study we use Z-contrast scanning transmission electron microscopy to directly observe metal cluster formation and distributions within the chromium-doped carbon films. At low doping (∼6at%Cr), Cr is uniformly distributed; at high doping (∼12at%Cr), Cr-rich clusters are formed. Using electron energy loss spectroscopy, we find that the Cr clusters tend to be metallic-like at low doping levels and carbide-like at high doping levels according to the Cr L2.3 white line ratios. The carbon is more diamond-like at low doping and more graphite/carbide like at high doping according to the sp2/sp3 electron percentage measurements.

Characterization of Ultra-Thin Hf-based Alternative Dielectric Layers for Si CMOS by Z-contrast Imaging and Electron Energy-Loss Spectroscopy in STEM

2004 ◽  
Vol 10 (S02) ◽  
pp. 322-323
Author(s):  
Melody P Agustin ◽  
Brendan Foran ◽  
Gennadi Bersuker ◽  
Joel Barnett ◽  
Susanne Stemmer
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Contrast Imaging ◽  
Dielectric Layers ◽  
Z Contrast ◽  
Electron Energy Loss

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Atomic resolution characterisation of interface structures by Electron Energy Loss Spectroscopy

1993 ◽  
Vol 51 ◽  
pp. 576-577
Author(s):  
N. D. Browning ◽  
M. M. McGibbon ◽  
M. F. Chisholm ◽  
S. J. Pennycook
Keyword(s):  
High Resolution ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Imaging Technique ◽  
Atomic Scale ◽  
Atomic Resolution ◽  
Reference Image ◽  
The Impact ◽  
Electron Energy Loss

The recent development of the Z-contrast imaging technique for the VG HB501 UX dedicated STEM, has added a high-resolution imaging facility to a microscope used mainly for microanalysis. This imaging technique not only provides a high-resolution reference image, but as it can be performed simultaneously with electron energy loss spectroscopy (EELS), can be used to position the electron probe at the atomic scale. The spatial resolution of both the image and the energy loss spectrum can be identical, and in principle limited only by the 2.2 Å probe size of the microscope. There now exists, therefore, the possibility to perform chemical analysis of materials on the scale of single atomic columns or planes.In order to achieve atomic resolution energy loss spectroscopy, the range over which a fast electron can cause a particular excitation event, must be less than the interatomic spacing. This range is described classically by the impact parameter, b, which ranges from ~10 Å for the low loss region of the spectrum to <1Å for the core losses.

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