TY - JOUR
T1 - Complex defect in pyrite and its structure model derived from geometric phase analysis
AU - Németh, Péter
AU - Dódony, István
AU - Pósfai, Mihály
AU - Buseck, P R
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/10
Y1 - 2013/10
N2 - New methods for defect analysis can lead to improved interpretation of experimental data and thus better understanding of material properties. Although transmission electron microscopy (TEM) has been used to study defects for many decades, interpretive ambiguities can arise for cases that seem simple or even trivial. Using geometric phase analysis (GPA), an image processing procedure, we show that an apparent simple line defect in pyrite has an entirely different character. It appears to be a b = [100] edge dislocation as viewed in a [001] high-resolution TEM (HRTEM) image, but the measured u x and u y displacements are asymmetric, which is inconsistent with a simple line dislocation. Instead, the defect is best understood as a terminating {101} marcasite slab in pyrite. The simulated HRTEM image based on this model reproduces the defect contrast and illustrates the power of GPA analysis for (1) avoiding potential pitfalls of misinterpreting apparently simple defects in HRTEM images, (2) detecting differences in elastic properties at the atomic scale, and (3) providing data for the positions of atom columns, thereby facilitating the construction of structure models for complex defects.
AB - New methods for defect analysis can lead to improved interpretation of experimental data and thus better understanding of material properties. Although transmission electron microscopy (TEM) has been used to study defects for many decades, interpretive ambiguities can arise for cases that seem simple or even trivial. Using geometric phase analysis (GPA), an image processing procedure, we show that an apparent simple line defect in pyrite has an entirely different character. It appears to be a b = [100] edge dislocation as viewed in a [001] high-resolution TEM (HRTEM) image, but the measured u x and u y displacements are asymmetric, which is inconsistent with a simple line dislocation. Instead, the defect is best understood as a terminating {101} marcasite slab in pyrite. The simulated HRTEM image based on this model reproduces the defect contrast and illustrates the power of GPA analysis for (1) avoiding potential pitfalls of misinterpreting apparently simple defects in HRTEM images, (2) detecting differences in elastic properties at the atomic scale, and (3) providing data for the positions of atom columns, thereby facilitating the construction of structure models for complex defects.
KW - asymmetric displacement
KW - geometric phase analysis
KW - marcasite
KW - pyrite defect
KW - variations of elastic properties
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U2 - 10.1017/S1431927613001839
DO - 10.1017/S1431927613001839
M3 - Article
C2 - 23773546
AN - SCOPUS:84884552685
SN - 1431-9276
VL - 19
SP - 1303
EP - 1307
JO - Microscopy and Microanalysis
JF - Microscopy and Microanalysis
IS - 5
ER -