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.

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.

Experimental Determination Of Relaxation Of Interphase Interfaces In Oxide Eutectics

1991 ◽  
Vol 238 ◽  
Author(s):  
Vinayak P. Dravid ◽  
V. Ravikumar ◽  
G. Dhalenne ◽  
A. Revcolevschi
Keyword(s):  
Experimental Determination ◽  
Interface Structure ◽  
Low Energy ◽  
Three Dimensions ◽  
Directionally Solidified ◽  
Lamellar Morphology ◽  
Analytical Tem ◽  
Directionally Solidified Eutectics

ABSTRACTInterphase interfaces in the directionally solidified eutectics.(DSEs) of NiO-ZrO2(CaO), NiO-Y2O3 and MnO-ZrO2 have been investigated using a variety of TEM techniques. The unique lamellar morphology of the DSEs allows characterization of interfaces and identification of relaxations along multiple directions, aiding visualization of interface structure in three dimensions. Possible low energy interface orientations were identified through examination of facets. The low energy interface planes almost invariably correspond to polar surfaces of adjacent crystals. An attempt has been made to experimentally identify the variety of interfacial relaxation mechanisms using a variety of analytical TEM techniques and only HRTEM results are summarized in this paper. It was found that most of the DSE systems exhibit very little relaxation and possess tight interface cores.

Mimicking the Real World and Exploring New Ones with In-Situ Electron Microscopy

1995 ◽  
Vol 404 ◽  
Author(s):  
A. Howie
Keyword(s):  
Electron Microscopy ◽  
Recent Progress ◽  
Low Energy ◽  
Metallic Materials ◽  
Transmission Imaging ◽  
In Situ Electron Microscopy ◽  
Low Energy Electron ◽  
Imaging And Spectroscopy ◽  
Electron Imaging

AbstractRecent progress with in-situ observations by electron microscopy is briefly surveyed by referring to developments in instrumentation for reflection and low energy electron imaging as well as for high resolution transmission imaging and spectroscopy. New opportunities have been opened up by environmental microscopy. With increased levels of illumination intensity, the ever present question of beam-induced effects is of mounting concern particularly in studies of non-metallic materials.

The coprecipitation of Cr3P and Cr in Cu

1988 ◽  
Vol 46 ◽  
pp. 764-765
Author(s):  
M.J. Witcomb ◽  
U. Dahmen ◽  
K.H. Westmacott
Keyword(s):  
Orientation Relationship ◽  
Interface Structure ◽  
Model System ◽  
Relative Orientation ◽  
Age Hardening ◽  
Precipitation Behavior ◽  
Solution Treated ◽  
Small Needle ◽  
Diffraction Patterns ◽  
Interface Structures

Cu-Cr age-hardening alloys are of interest as a model system for the investigation of fcc/bcc interface structures. Several past studies have investigated the morphology and interface structure of Cr precipitates in a Cu matrix (1-3) and good success has been achieved in understanding the crystallography and strain contrast of small needle-shaped precipitates. The present study investigates the effect of small amounts of phosphorous on the precipitation behavior of Cu-Cr alloys.The same Cu-0.3% Cr alloy as was used in earlier work was rolled to a thickness of 150 μm, solution treated in vacuum at 1050°C for 1h followed by quenching and annealing for various times at 820 and 863°C.Two laths and their corresponding diffraction patterns in an alloy aged 2h at 820°C are shown in correct relative orientation in Fig. 1. To within the limit of accuracy of the diffraction patterns the orientation relationship was that of Kurdjumov-Sachs (KS), i.e. parallel close-packed planes and directions.

Determination of interface width using EELS fine structure changes

1991 ◽  
Vol 49 ◽  
pp. 730-731
Author(s):  
Vinayak P. Dravid ◽  
M.R. Notis ◽  
C.E. Lyman
Keyword(s):  
Fine Structure ◽  
Materials Science ◽  
Input Parameter ◽  
Core Loss ◽  
Directionally Solidified ◽  
Interface Width ◽  
Structure Changes ◽  
Important Input ◽  
Directionally Solidified Eutectics

The concept of interfacial width is often invoked in many materials science phenomena which relate to the structure and properties of internal interfaces. The numerical value of interface width is an important input parameter in diffusion equations, sintering theories as well as in many electronic devices/processes. Most often, however, this value is guessed rather than determined or even estimated. In this paper we present a method of determining the effective structural and electronic- structural width of interphase interfaces using low- and core loss fine structure effects in EELS spectra.The specimens used in the study were directionally solidified eutectics (DSEs) in the system; NiO-ZrO2(CaO), NiO-Y2O3 and MnO-ZrO2(ss). EELS experiments were carried out using a VG HB-501 FE STEM and a Hitachi HF-2000 FE TEM.

Interpretation of Alumina/Yttrium-Aluminum Garnet Orientation Relationships by Geometric Criteria

1990 ◽  
Vol 209 ◽  
Author(s):  
R.S. Hay ◽  
L.E. Matson
Keyword(s):  
Structural Unit ◽  
Yttrium Aluminum Garnet ◽  
Sol Gel ◽  
Interface Energy ◽  
Interface Structure ◽  
Invariant Line ◽  
Directionally Solidified ◽  
Orientation Relationships ◽  
Yttrium Aluminum

ABSTRACTGeometric criteria for low interface energy and interface structure were tested for the cubic-rhombohedral system YAG/alumina. Orientation relationships near (111){110}a // (112){110}y and facets on (111)a(112)y were observed in both sol-gel derived composites and directionally solidified eutectic composites. The ΣYAG=12 near-CSL of 2{111}, {110}, {112} was inferred to be the preferred structural unit. Dislocations with b=1/3{111}a and b=1/2{110}a were observed and inferred to accomodate deviation from the structural unit, respectively. The {110}a,y direction met some of the criteria for an invariant line. Although the OR was explained by geometric criteria it would have been difficult to predict it with such criteria

Magmatic and metasomatic processes during formation of the Nb-Zr-REE deposits Khaldzan Buregte and Tsakhir (Mongolian Altai): Indications from a combined CL-SEM Study

1999 ◽  
Vol 63 (2) ◽  
pp. 165-177 ◽  
Author(s):  
U. Kempe ◽  
J. Götze ◽  
S. Dandar ◽  
D. Habermann
Keyword(s):  
Metasomatic Rock ◽  
Metasomatic Alteration ◽  
Small Bodies ◽  
Mongolian Altai ◽  
Mineral Phases ◽  
Internal Structures ◽  
Sem Study ◽  
Backscattered Electron ◽  
Imaging And Spectroscopy ◽  
Electron Imaging

AbstractCathodoluminescence (CL) imaging and spectroscopy, as well as backscattered electron imaging, were used to assign the occurrence of several mineral phases and rock structures in altered nordmarkites and calcite-bearing granites from the Nb-Zr-REE deposits from Khaldzan Buregte and Tsakhir (Mongolian Altai) to three events: (1) intrusion of barren nordmarkites; (2) intrusion of small bodies of calcite-bearing granites with metasomatic alteration of the wall-rocks; and (3) alteration by F-rich fluids.Unusual red and yellow CL caused by Fe3+ and Mn2+ emission centres were detected in microcline and albite. Fe3+ centres were also established (along with others) in quartz, zircon, and possibly in fluorite.Magmatic and metasomatic rock structures and internal structures of the minerals coexist in the samples. The primary magmatic features were in part preserved during alteration. In contrast, the internal and the centre structures may be changed during alteration even in non-replaced mineral phases. Euhedral minerals may be formed by secondary processes as shown for lath-shaped albite. The occurrence of pseudomorphs, the inheritance of elements during replacement, and the mechanical effects of secondary minerals on earlier mineral phases during metasomatic growth are proposed as criteria for the reconstruction of the mineral succession in altered rocks. Snowball structures may be formed as a result of metasomatic alteration rather than as a magmatic intergrowth.

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