Concurrent multi-peak Bragg coherent x-ray diffraction imaging of 3D nanocrystal lattice displacement via global optimization

Maddali, Siddharth; Frazer, Travis; Delegan, Nazar; Harmon, Katherine; Sullivan, Sean; Allain, Marc; Cha, Wonsuk; Dibos, Alan; Poudyal, Ishwor; Kandel, Saugat; Nashed, Youssef S. G.; Heremans, F. Joseph; You, Hoydoo; Cao, Yue; Hruszkewycz, S. O.

doi:10.1038/s41524-023-01022-7

Cited by 3 publications

(1 citation statement)

References 36 publications

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“…However, advancements in the field have facilitated the development of Multi-BCDI. This innovative approach allows for the concurrent analysis of multiple Bragg peaks from a single nanoparticle, thereby enabling the effective reconstruction of vector-valued lattice distortion fields within nanoscale crystals 33 – 36 .…”

Section: Resultsmentioning

confidence: 99%

Three-dimensional domain identification in a single hexagonal manganite nanocrystal

Mokhtar,

Serban,

Porter

et al. 2024

Nat Commun

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The three-dimensional domain structure of ferroelectric materials significantly influences their properties. The ferroelectric domain structure of improper multiferroics, such as YMnO3, is driven by a non-ferroelectric order parameter, leading to unique hexagonal vortex patterns and topologically protected domain walls. Characterizing the three-dimensional structure of these domains and domain walls has been elusive, however, due to a lack of suitable imaging techniques. Here, we present a multi-peak Bragg coherent x-ray diffraction imaging determination of the domain structure in single YMnO3 nanocrystals. We resolve two ferroelectric domains separated by a domain wall and confirm that the primary atomic displacements occur along the crystallographic c-axis. Correlation with atomistic simulations confirms the Mexican hat symmetry model of domain formation, identifying two domains with opposite ferroelectric polarization and adjacent trimerization, manifesting in a clockwise arrangement around the hat’s brim.

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Section: Resultsmentioning

confidence: 99%

Three-dimensional domain identification in a single hexagonal manganite nanocrystal

Mokhtar,

Serban,

Porter

et al. 2024

Nat Commun

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Atomic resolution coherent x-ray imaging with physics-based phase retrieval

Meziere,

Carpenter,

Pateras

et al. 2024

npj Comput Mater

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Coherent x-ray imaging and scattering from accelerator based sources such as synchrotrons continue to impact biology, medicine, technology, and materials science. Many synchrotrons around the world are currently undergoing major upgrades to increase their available coherent x-ray flux by approximately two orders of magnitude. The improvement of synchrotrons may enable imaging of materials in operando at the atomic scale which may revolutionize battery and catalysis technologies. Current algorithms used for phase retrieval in coherent x-ray imaging are based on the projection onto sets method. These traditional iterative phase retrieval methods will become more computationally expensive as they push towards atomic resolution and may struggle to converge. Additionally, these methods do not incorporate physical information that may additionally constrain the solution. In this work, we present an algorithm which incorporates molecular dynamics into Bragg coherent diffraction imaging (BCDI). This algorithm, which we call PRAMMol (Phase Retrieval with Atomic Modeling and Molecular Dynamics) combines statistical techniques with molecular dynamics to solve the phase retrieval problem. We present several examples where our algorithm is applied to simulated coherent diffraction from 3D crystals and show convergence to the correct solution at the atomic scale.

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Imaging extended single crystal lattice distortion fields with multi-peak Bragg ptychography

Kandel,

Maddali,

Huang

et al. 2024

Opt. Express

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Recent advances in phase-retrieval-based x-ray imaging methods have demonstrated the ability to reconstruct 3D distortion vector fields within a nanocrystal by using coherent diffraction information from multiple crystal Bragg reflections. However, these works do not provide a solution to the challenges encountered in imaging lattice distortions in crystals with significant defect content that result in phase wrapping. Moreover, these methods only apply to isolated crystals smaller than the x-ray illumination, and therefore cannot be used for imaging of distortions in extended crystals. We introduce multi-peak Bragg ptychography which addresses both challenges via an optimization framework that combines stochastic gradient descent and phase unwrapping methods for robust image reconstruction of lattice distortions and defects in extended crystals. Our work uses modern automatic differentiation toolsets so that the method is easy to extend to other settings and easy to implement in high-performance computers. This work is particularly timely given the broad interest in using the increased coherent flux in fourth-generation synchrotrons for innovative material research.

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Concurrent multi-peak Bragg coherent x-ray diffraction imaging of 3D nanocrystal lattice displacement via global optimization

Cited by 3 publications

References 36 publications

Three-dimensional domain identification in a single hexagonal manganite nanocrystal

Three-dimensional domain identification in a single hexagonal manganite nanocrystal

Atomic resolution coherent x-ray imaging with physics-based phase retrieval

Imaging extended single crystal lattice distortion fields with multi-peak Bragg ptychography

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