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Orientational ordering and assembly of silica–nickel Janus particles in a magnetic field

Authors :
Gouranga Manna
Thomas Zinn
Lewis Sharpnack
Theyencheri Narayanan
Source :
IUCrJ, Vol 11, Iss 1, Pp 109-119 (2024)
Publication Year :
2024
Publisher :
International Union of Crystallography, 2024.

Abstract

The orientation ordering and assembly behavior of silica–nickel Janus particles in a static external magnetic field were probed by ultra small-angle X-ray scattering (USAXS). Even in a weak applied field, the net magnetic moments of the individual particles aligned in the direction of the field, as indicated by the anisotropy in the recorded USAXS patterns. X-ray photon correlation spectroscopy (XPCS) measurements on these suspensions revealed that the corresponding particle dynamics are primarily Brownian diffusion [Zinn, Sharpnack & Narayanan (2023). Soft Matter, 19, 2311–2318]. At higher fields, the magnetic forces led to chain-like configurations of particles, as indicated by an additional feature in the USAXS pattern. A theoretical framework is provided for the quantitative interpretation of the observed anisotropic scattering diagrams and the corresponding degree of orientation. No anisotropy was detected when the magnetic field was applied along the beam direction, which is also replicated by the model. The method presented here could be useful for the interpretation of oriented scattering patterns from a wide variety of particulate systems. The combination of USAXS and XPCS is a powerful approach for investigating asymmetric colloidal particles in external fields.

Details

Language :
English
ISSN :
20522525
Volume :
11
Issue :
1
Database :
Directory of Open Access Journals
Journal :
IUCrJ
Publication Type :
Academic Journal
Accession number :
edsdoj.2c1800a22b5a461489e3b987daf2fde2
Document Type :
article
Full Text :
https://doi.org/10.1107/S205225252301000X