Spatially resolved mapping of phase transitions in liquid-crystalline materials by X-ray birefringence imaging

Zhou, Yating; Patterson, Rhian; Palmer, Benjamin A.; Edwards-Gau, Gregory R.; Kariuki, Benson M.; Kumar, N. S. Saleesh; Bruce, Duncan W.; Dolbnya, Igor P.; Collins, Stephen P.; Malandain, Andrew; Harris, Kenneth D. M.

doi:10.1039/c8sc05285a

Cited by 4 publications

(1 citation statement)

References 23 publications

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“…spatially resolved X-ray birefringence imaging. 52,53 If MOF skyrmion crystals with emergent periodicities commensurate with those of visible light prove accessible, one should observe optical Bragg scattering from the lattice-as in many liquid crystalline phases. 54 In such cases a colour change is direct experimental evidence of skyrmion crystal formation and may form the basis for efficient chemical, temperature, or pressure sensors.…”

Section: Discussionmentioning

confidence: 99%

Skyrmion Lattices in Chiral Metal–organic Frameworks

Wolpert¹,

Coudert²,

Goodwin

2020

Preprint

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<p>Skyrmions are knot-like topologically-protected objects of use in data storage and low-energy smart devices. They can be generated by applying a magnetic field to certain chiral ferromagnets, with the knotted state involving a curling of the underlying magnetisation to give a nonzero winding number. Here we explore the possibility that chiral metal–organic frameworks (MOFs) might in principle host skyrmionic phases—realised not through the winding of magnetic spins but through that of guest molecule orientations. We propose a simple model for the interactions governing guest orientational order in chiral MOFs, with uniaxial strain acting as conjugate field. Using Monte Carlo simulations we show that this model gives a rich phase behaviour that includes molecular skyrmion crystals. <i>Ab initio</i> molecular dynamics simulations carried out for a candidate chiral MOF of tractable complexity demonstrate that our simple model effectively captures its underlying energetics. Our results suggest that skyrmionic states may indeed be realisable in MOFs and related porous media and may even arise spontaneously in thin-film samples.</p>

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Section: Discussionmentioning

confidence: 99%

Skyrmion Lattices in Chiral Metal–organic Frameworks

Wolpert¹,

Coudert²,

Goodwin

2020

Preprint

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X-Ray Birefringence Imaging (XBI): A New Technique for Spatially Resolved Mapping of Molecular Orientations in Materials

Harris

Patterson

Zhou

et al. 2020

Advances in Organic Crystal Chemistry

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X-ray linear dichroic tomography of crystallographic and topological defects

Apseros,

Scagnoli,

Holler

et al. 2024

Nature

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The functionality of materials is determined by their composition1–4 and microstructure, that is, the distribution and orientation of crystalline grains, grain boundaries and the defects within them5,6. Until now, characterization techniques that map the distribution of grains, their orientation and the presence of defects have been limited to surface investigations, to spatial resolutions of a few hundred nanometres or to systems of thickness around 100 nm, thus requiring destructive sample preparation for measurements and preventing the study of system-representative volumes or the investigation of materials under operational conditions7–15. Here we present X-ray linear dichroic orientation tomography (XL-DOT), a quantitative, non-invasive technique that allows for an intragranular and intergranular characterization of extended polycrystalline and non-crystalline16 materials in three dimensions. We present the detailed characterization of a polycrystalline sample of vanadium pentoxide (V2O5), a key catalyst in the production of sulfuric acid17. We determine the nanoscale composition, microstructure and crystal orientation throughout the polycrystalline sample with 73 nm spatial resolution. We identify and characterize grains, as well as twist, tilt and twin grain boundaries. We further observe the creation and annihilation of topological defects promoted by the presence of volume crystallographic defects. The non-destructive and spectroscopic nature of our method opens the door to operando combined chemical and microstructural investigations11,18 of functional materials, including energy, mechanical and quantum materials.

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Spatially resolved mapping of phase transitions in liquid-crystalline materials by X-ray birefringence imaging

Abstract: X-ray Birefringence Imaging is shown to be a sensitive method for spatially resolved mapping of molecular orientations in liquid-crystalline materials.

Cited by 4 publications

References 23 publications

Skyrmion Lattices in Chiral Metal–organic Frameworks

Skyrmion Lattices in Chiral Metal–organic Frameworks

X-Ray Birefringence Imaging (XBI): A New Technique for Spatially Resolved Mapping of Molecular Orientations in Materials

X-ray linear dichroic tomography of crystallographic and topological defects

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