Complex Defect in Pyrite and Its Structure Model Derived from Geometric Phase Analysis

Németh, Péter and Dódony, István and Pósfai, Mihály (2013) Complex Defect in Pyrite and Its Structure Model Derived from Geometric Phase Analysis. MICROSCOPY AND MICROANALYSIS, Online. pp. 1-5. ISSN 1431-9276

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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= ½[100] edge dislocation as viewed in a [001] high-resolution TEM (HRTEM) image, but the measured ux and uy 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.

Item Type: Article
Uncontrolled Keywords: geometric phase analysis, pyrite defect, marcasite, asymmetric displacement, variations of elastic properties
Subjects: Q Science / természettudomány > QE Geology / földtudományok > QE02 Geochemistry / geokémia
Depositing User: MTMT SWORD
Date Deposited: 16 Jul 2013 08:31
Last Modified: 16 Jul 2013 08:31

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