New insights on ion track morphology in pyrochlores by aberration corrected scanning transmission electron microscopy
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New insights on ion track morphology in pyrochlores by aberration corrected scanning transmission electron microscopy Ritesh Sachana) Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
Yanwen Zhang Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831; and Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996
Xin Ou Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rassendorf, Dresden 01314, Germany
Christina Trautmann GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt 64291, Germany; and Materialwissenschaft, Technische Universität Darmstadt, Darmstadt 64287, Germany
Matthew F. Chisholm Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
William J. Weberb) Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831; and Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (Received 1 April 2016; accepted 24 October 2016)
Here, we demonstrate the enhanced imaging capabilities of an aberration corrected scanning transmission electron microscope to advance the understanding of ion track structure in pyrochlore structured materials (i.e., Gd2Ti2O7 and Gd2TiZrO7). Track formation occurs due to the inelastic transfer of energy from incident ions to electrons, and atomic-level details of track morphology as a function of energy-loss are revealed in the present work. A comparison of imaging details obtained by varying collection angles of detectors is discussed in the present work. A quantitative analysis of phase identification using high-angle annular dark field imaging is performed on the ion tracks. Finally, a novel 3-dimensional track reconstruction method is provided that is based on depth-dependent imaging of the ion tracks. The technique is used in extracting the atomic-level details of nanoscale features, such as the disordered ion tracks, which are embedded in relatively thicker matrix. Another relevance of the method is shown by measuring the tilt of the ion tracks relative to the electron beam incidence that helps in knowing the structure and geometry of ion tracks quantitatively.
I. INTRODUCTION
The study of atomic rearrangements and disordering due to the interaction of energetic ions with solids in extremely short time-scales is a critical issue for advancing the fundamental understanding of the radiation damage mechanisms in ceramics. One event of interest Contributing Editor: Thomas Walther a) Address all correspondence to this author. e-mail: [email protected] b) This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs. org/jmr-editor-manuscripts/. DOI: 10.1557/jmr.2016.418
occurs when the kinetic energy from incident ions is transferred to the electrons of the target material through inelastic interactions, and most
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