%0 Journal Article %T In situ 3D observations of a core–shell volume transition in an Ni 3 Fe nanocrystal using Bragg coherent X-ray diffraction imaging %+ Nanostructures et Rayons X (NRX) %+ CRG & Grands instruments (NEEL - CRG) %+ European Synchroton Radiation Facility [Grenoble] (ESRF) %+ Technion - Israel Institute of Technology [Haifa] %+ Institut des Matériaux, de Microélectronique et des Nanosciences de Provence (IM2NP) %A Chatelier, C. %A Atlan, C. %A Dupraz, M. %A Li, Ni %A Rabkin, E. %A Labat, S. %A Eymery, J. %A Richard, M.I. %Z Abstracts of the 33rd European Crystallography Meeting, 23-27 August 2022 %< avec comité de lecture %@ 2053-2733 %J Acta Crystallographica Section A : Foundations and Advances [2014-...] %I International Union of Crystallography %V 78 %N a2 %P e766-e766 %8 2022-08 %D 2022 %R 10.1107/S2053273322090192 %Z Physics [physics]/Condensed Matter [cond-mat] %Z Engineering Sciences [physics]/MaterialsJournal articles %X Coherent X-ray Diffraction Imaging (CDI) [1] allows for the in situ 3D mapping of the structural changes during phase transitions and chemical reactions, with a fair spatial resolution of the order of magnitude of 10 nm [2]. Using this technique in multi-Bragg conditions (Bragg CDI on multiple reflections), it was possible to follow the structural evolution (change in morphology, variation of the displacement and strain fields) as a function of temperature in a 300 nm Ni3Fe nanocrystal. During this volume transition, which happens between 500°C and 600°C, a core-shell structure is progressively observed with two distinct lattice parameters (difference of 0.39%, corresponding to two different Ni:Fe ratios), leading to highly strained and coherent domains. A rounding of the particle is also observed, with a disappearing of the initial facets. Static molecular calculations (LAMMPS) of different systems, such as faceted and core-shellnanoparticles, complete this work and allow for the confirmation of a core-shell structure. This study shows the perfect ability of modern phase retrieval methods to reconstruct highly strained systems such as core-shell nanoparticles. %G English %2 https://cea.hal.science/cea-04066341/document %2 https://cea.hal.science/cea-04066341/file/a61830.pdf %L cea-04066341 %U https://cea.hal.science/cea-04066341 %~ CEA %~ UGA %~ UNIV-TLN %~ CNRS %~ UNIV-AMU %~ INPG %~ NEEL %~ IM2NP %~ NEEL-CRG %~ IRIG %~ CEA-GRE %~ UGA-EPE %~ NEEL-TECHNO