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Transparent Colloidal Crystals With Structural Colours

Published version
Peer-reviewed

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Authors

Erdem, T 
O’Neill, T 
Zupkauskas, M 
Caciagli, A 
Xu, P 

Abstract

jats:pSpatially ordered arrangements of spherical colloids are known to exhibit structural colours. The intensity and brilliance of these structural colours typically improve with colloidal monodispersity, low concentrations of point and line defects and with increasing refractive index contrast between the colloids and the embedding medium. Here we show that suspensions of charge stabilised, fluorinated latex particles with low refractive-index contrast to their aqueous background form Wigner crystals with FCC symmetry for volume fractions between 13 and 40%. In reflection they exhibit both strong, almost angle-independent structural colours and sharp, more brilliant Bragg peaks despite the particle polydispersity and bimodal distribution. Simultaneously, these suspensions appear transparent in transmission. Furthermore, binary AB, Ajats:sub2</jats:sub>B and Ajats:sub13</jats:sub>B type mixtures of these fluorinated and similarly sized polystyrene particles appeared predominantly white but with clear Bragg peaks indicating a CsCl-like BCC structure and more complex crystals. We characterised the suspensions using a combination of reflectivity measurements and small-angle x-ray scattering, complemented by reflectivity modelling.</jats:p>

Description

Keywords

colloid, structural color, SAXS (small-angle X-ray scattering), latex particle, photonic crystals

Journal Title

Frontiers in Physics

Conference Name

Journal ISSN

2296-424X
2296-424X

Volume Title

10

Publisher

Frontiers Media SA