A Combined-Techniques Approach to Elucidating Crystalline Interface Atomic Structure

1996 ◽  
Vol 466 ◽  
Author(s):  
E. C. Dickey ◽  
V. P. Dra Vid ◽  
S. J. Pennycook ◽  
P. D. Nellist ◽  
D. J. Wallis
Keyword(s):  
Atomic Structure ◽  
Three Dimensional ◽  
Interface Structure ◽  
Contrast Imaging ◽  
Imaging And Spectroscopy ◽  
Complementary Techniques ◽  
Electron Imaging ◽  
Z Contrast ◽  
Interface Structures

ABSTRACTA case study is presented in which HREM, Z-Contrast Imaging and EELS are used as complementary techniques for elucidating interface structure. The NiO-ZrO2(cubic) interface is investigated along two orthogonal directions by these electron imaging and spectroscopy techniques to reveal the three-dimensional interface structure. Based on findings from this study, a protocol is suggested for using all three experimental techniques to gain a thorough understanding of interface structures.

Atomic Structure Determination of Nio-Y2O3 Interfaces by HRTEM

1997 ◽  
Vol 3 (S2) ◽  
pp. 649-650
Author(s):  
E.C. Dickey ◽  
V.P. Dravid
Keyword(s):  
Three Dimensional ◽  
Interface Structure ◽  
Low Energy ◽  
Directionally Solidified ◽  
Research Initiative ◽  
Imaging And Spectroscopy ◽  
Electron Imaging ◽  
Directionally Solidified Eutectics ◽  
Interface Structures ◽  
Oxide Composites

The investigation of interfaces between NiO and Y2O3 is part of a research initiative to understand low-energy heterophase interface structures between different oxide materials. In-situ oxide composites formed by the directional solidification of pseudo-binary eutectics are used as model materials in this study because they are amenable to chemical and structural characterization at the atomic length-scale. Previously, interfaces in NiO-ZrO2(cubic) directionally solidified eutectics (DSEs) were examined by various electron imaging and spectroscopy techniques to reveal the three-dimensional interface structure.[l] The second DSE system studied, NiO-Y2O3,[2] was chosen because it is very similar in crystallography to NiO-ZrO2(cubic). The goal of this second, analogous study is not only to understand the NiO-Y2O3 interface structure but, by comparing the results to NiO-ZrO2, is to draw more general conclusions about low energy oxide-oxide interfaces. Table one compares the crystallography of the NiO-ZrO2 and the NiO-Y2O3 DSEs.

Z-contrast imaging of an ordered interface structure in the Si/CoSi2/Si system

1993 ◽  
Vol 51 ◽  
pp. 802-803
Author(s):  
M. F. Chisholm ◽  
D. E. Jesson ◽  
S. J. Pennycook ◽  
S. Mantl
Keyword(s):  
Atomic Structure ◽  
Substrate Surface ◽  
Interface Structure ◽  
Unit Cell ◽  
Contrast Imaging ◽  
Treatment Results ◽  
Semiconductor Interfaces ◽  
Contrast Technique ◽  
Z Contrast ◽  
Insight Into

We show the atomic structure of buried CoSi2/Si(001) boundaries involves a 2×1 ordering of the interfacial Co atoms. The ability to directly image and interpret this unforeseen structure is possible through the Z-contrast technique, and presents a new level of insight into the important and controversial relationship between the atomic structure and electronic properties, such as the energy barrier for electron transport across metal-semiconductor interfaces.The buried CoSi2 layer was produced by implanting Co+ ions (200 keV, 2 × 1017 ions/cm2) in a Si(001) substrate heated to 350°C. The substrate was capped with 200 nm of SiO2 and then given a two-step anneal in high purity argon (750°C for 30 s + 1150°C for 10 s). This treatment results in a continuous buried CoSi2 layer ~70 nm thick, ~90 nm below the substrate surface. The layer and the substrate are oriented such that the cubic CaF2 unit cell of CoSi2 is aligned parallel to the cubic unit cell of Si.

Atomic structure determination of NIO-ZRO2(CaO) and NI-ZRO2(CaO) interfaces using Z-contrast imaging and EELS

1996 ◽  
Vol 54 ◽  
pp. 106-107
Author(s):  
E.C. Dickey ◽  
V.P. Dravid ◽  
P. Nellist ◽  
D.J. Wallis ◽  
N. D. Browning ◽  
...  
Keyword(s):  
Atomic Structure ◽  
Bulk Material ◽  
Interface Structure ◽  
Structure Property ◽  
Contrast Imaging ◽  
Spatially Resolved ◽  
Structure Property Relationships ◽  
Powerful Approach ◽  
Resolution Imaging ◽  
Z Contrast

Combining atomic-resolution imaging with spatially resolved electron energy loss spectroscopy (EELS) is a powerful approach to probing the geometric, chemical and electronic aspects of internal interfaces. By elucidating these interrelated constituents of interface structure, one can begin to understand the influence of the interface atomic structure on relevant bulk material properties, deducing atomic structure/property relationships. The combined Z-contrast and EELS approach was applied to two types of heterophase interfaces: oxide-oxide (NiO-ZrO2) and metal-oxide (Ni-ZrO2). The interface structure will be discussed in light of these experiments and compared to previous HREM results.

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.

scholarly journals Influence of a Cu-Zirconia Interface Structure on CO2 Adsorption and Activation

2021 ◽  
Author(s):  
Lars Gell ◽  
Aku Lempelto ◽  
toni Kiljunen ◽  
Karoliina Honkala
Keyword(s):  
Density Functional Theory ◽  
Chemical Composition ◽  
Atomic Structure ◽  
Density Functional ◽  
Co2 Adsorption ◽  
Density Functional Theory Calculations ◽  
Interface Structure ◽  
Functional Theory ◽  
Binding Strength ◽  
Interface Structures

We have screened different Cu-ZrO<sub>2</sub> interface structures and analysed the influence of the interface structure on CO<sub>2</sub> binding strength using density functional theory calculations. Our results demonstrate that a Cu nanorod favours one position on both tetragonal and monoclinic ZrO<sub>2</sub> surfaces, where the bottom Cu atoms are placed close the lattice oxygens. CO<sub>2</sub> prefers a bent bidentate configuration at the interface and the molecule is clearly activated being negatively charged. Altogether, our results highlight that CO<sub>2</sub> adsorption and activation depend sensitively on the chemical composition and atomic structure of the interface used in the calculations. <div><br></div>

scholarly journals Influence of a Cu-Zirconia Interface Structure on CO2 Adsorption and Activation

2021 ◽  
Author(s):  
Lars Gell ◽  
Aku Lempelto ◽  
toni Kiljunen ◽  
Karoliina Honkala
Keyword(s):  
Density Functional Theory ◽  
Chemical Composition ◽  
Atomic Structure ◽  
Density Functional ◽  
Co2 Adsorption ◽  
Density Functional Theory Calculations ◽  
Interface Structure ◽  
Functional Theory ◽  
Binding Strength ◽  
Interface Structures

We have screened different Cu-ZrO<sub>2</sub> interface structures and analysed the influence of the interface structure on CO<sub>2</sub> binding strength using density functional theory calculations. Our results demonstrate that a Cu nanorod favours one position on both tetragonal and monoclinic ZrO<sub>2</sub> surfaces, where the bottom Cu atoms are placed close the lattice oxygens. CO<sub>2</sub> prefers a bent bidentate configuration at the interface and the molecule is clearly activated being negatively charged. Altogether, our results highlight that CO<sub>2</sub> adsorption and activation depend sensitively on the chemical composition and atomic structure of the interface used in the calculations. <div><br></div>

Microscopic and Theoretical Investigations of the Si-SiO2 Interface

1999 ◽  
Vol 592 ◽  
Author(s):  
G. Duscher ◽  
R. Buzcko ◽  
S. J. Pennycook ◽  
S. T. Pantelides ◽  
H. Müllejans ◽  
...  
Keyword(s):  
Energy Loss ◽  
Local Density ◽  
Interface Layer ◽  
Atomic Scale ◽  
Contrast Imaging ◽  
Edge Structure ◽  
Crystalline Oxide ◽  
Theoretical Investigations ◽  
Z Contrast ◽  
Interface Structures

ABSTRACTZ-contrast imaging and electron energy-loss spectroscopy with a spatial resolution at the atomic scale provide evidence of an atomically abrupt Si-SiO2, interface. Th micrographs revealed no indication for an interface layer of crystalline oxide at this thermally grown interface. Theoretical ab-initio calculations of two different interface structures showed that even in the most ideal interface the local density of states extends into the region of the oxide band gap. The O-K energy-loss near-edge structure was simulated for both interface models. The comparison of theoretical and experimental results of the O-K near-edge structure agreed and showed that states below the conduction band of the oxide are caused by the dimer-like SiO-Si bridges present in all structural models.

Atomic Structure of Si-SiO2 Interface

1997 ◽  
Vol 3 (S2) ◽  
pp. 459-460
Author(s):  
G. Duscher ◽  
F. Banhart ◽  
H. Müllejans ◽  
S.J. Pennycook ◽  
M. Rühle
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Structure ◽  
Phase Contrast ◽  
Thermally Grown Oxide ◽  
Interface Roughness ◽  
Spatial Difference ◽  
Contrast Imaging ◽  
Transmission Electron ◽  
Z Contrast

Investigations of the atomic structure of Si-SiO2 interfaces have mostly been performed with high resolution transmission electron microscopy. However, the interpretation of the phase contrast in the amorphous phase at the interface is not unique. While Ourmazd et al. concluded on a crystalline phase at the Si-SiO2 interface, Akatsu and Ohdomari attributed the same contrast to an interface roughness parallel to the incident electrons.We investigated the Si-SiO2 interface by studying the ELNES of the O-K edge with the spatial difference technique with a dedicated STEM with l00kV (VG HB501 UX). Also the interface was studied by Z-contrast imaging with a 300 kV dedicated STEM (VG HB603 U). Silicon wafers (110) were first thermally oxidised to produce a SiO2 layer. The thermally grown oxide was used as a substrate for liquid phase epitaxy of silicon, given two {111} Si-SiO2 interfaces in the sample grown by two different techniques (see fig. 1).

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