Complex defect in pyrite and its structure model derived from geometric phase analysis

Péter Németh, István Dódony, Mihály Pósfai, P R Buseck

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1303-1307
Number of pages5
JournalMicroscopy and Microanalysis
Issue number5
StatePublished - Oct 2013


  • asymmetric displacement
  • geometric phase analysis
  • marcasite
  • pyrite defect
  • variations of elastic properties

ASJC Scopus subject areas

  • Instrumentation


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