Crystallization is a fundamental natural phenomenon and the ubiquitous physical process in materials science for the design of new materials. So far, experimental observations of the structural dynamics in crystallization have been mostly restricted to slow dynamics. We present here, for the first time, an exclusive way to explore the dynamics of crystallization in highly controlled conditions, i.e. in the absence of impurities acting as seeds of the crystallites, as it occurs in vacuum. We have measured the early formation stage of solid Xe nanoparticles nucleated in an expanding supercooled Xe jet by means of an X-ray diffraction experiment with 10-fs X-ray free-electron laser (XFEL) pulses. We found that the structure of Xe nanoparticles is not pure face-centered cubic (fcc), the expected stable phase, but a mixture of fcc and randomly-stacked hexagonal close-packed (rhcp) structures. Furthermore, we identified the instantaneous coexistence of the comparably sized fcc and rhcp domains in single Xe nanoparticles. The observations are explained by the scenario of structural aging, in which the nanoparticles initially crystallize in the highly stacking-disordered rhcp phase, and the structure later forms the stable fcc phase. The results are reminiscent of analogous observations in hard-sphere systems, indicating the universal role of the stacking-disordered phase in nucleation.

Crystallization kinetics of atomic crystals revealed by a single-shot and single-particle X-ray diffraction experiment / A. Niozua, Y. Kumagaid, T. Nishiyama Hiraki, H. Fukuzawa, K. Motomurad, M. Buchere, K. Asaa, Y. Satoa, Y. Itod, D. Youd, T. Onod, Y. Lid, E. Kukkf, C. Miron, L. Neagu, C. Callegari, M. Di Fraia, G. Rossi, D.E. Galli, T. Pincelli, A. Colombo, S. Owadal, K. Tonol, T. Kameshimal, Y. Jotil, T. Katayamal, T. Togashil, M. Yabashib, K. Matsudaa, C. Bostedt, K. Ueda, K. Nagaya. - In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. - ISSN 1091-6490. - 118:51(2021 Dec 21), pp. e2111747118.1-e2111747118.8. [10.1073/pnas.2111747118]

Crystallization kinetics of atomic crystals revealed by a single-shot and single-particle X-ray diffraction experiment

G. Rossi;D.E. Galli;T. Pincelli;A. Colombo;
2021

Abstract

Crystallization is a fundamental natural phenomenon and the ubiquitous physical process in materials science for the design of new materials. So far, experimental observations of the structural dynamics in crystallization have been mostly restricted to slow dynamics. We present here, for the first time, an exclusive way to explore the dynamics of crystallization in highly controlled conditions, i.e. in the absence of impurities acting as seeds of the crystallites, as it occurs in vacuum. We have measured the early formation stage of solid Xe nanoparticles nucleated in an expanding supercooled Xe jet by means of an X-ray diffraction experiment with 10-fs X-ray free-electron laser (XFEL) pulses. We found that the structure of Xe nanoparticles is not pure face-centered cubic (fcc), the expected stable phase, but a mixture of fcc and randomly-stacked hexagonal close-packed (rhcp) structures. Furthermore, we identified the instantaneous coexistence of the comparably sized fcc and rhcp domains in single Xe nanoparticles. The observations are explained by the scenario of structural aging, in which the nanoparticles initially crystallize in the highly stacking-disordered rhcp phase, and the structure later forms the stable fcc phase. The results are reminiscent of analogous observations in hard-sphere systems, indicating the universal role of the stacking-disordered phase in nucleation.
Crystallization kinetics; XFEL; X-ray diffraction
Settore FIS/03 - Fisica della Materia
Settore FIS/01 - Fisica Sperimentale
PRIN201214GROSS_M - NOXSS (X-ray Single Shots of Nano Objects) un approccio sperimentale e teorico integrato per la caratterizzazione strutturale di nano e micro oggetti (clusters, nanocristalli, biomolecole, virus, liposomi) utilizzando gli impulsi X ultrabrevi ed ultrabrillanti delle sorgenti free electron laser europee - ROSSI, GIORGIO - PRIN2012 - PRIN bando 2012 - 2014
21-ott-2021
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/890378
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