Noise‐Assisted Crystallization of Opal Films

Abstract

An improvement of the crystal quality of opal films self‐assembled from polymer spheres in a moving meniscus using the agitation by white noise acoustic vibrations is demonstrated. A tenfold higher ordering of a hexagonal sphere packing in the (111) plane is achieved. This crystallization method, the mechanism of which is described in terms of the stochastic resonance, is a contrast to the widely used approach based on maintaining equilibrium conditions during the crystallization process. The precise quantification of the incremental lattice order improvement as a function of acoustic noise intensity is achieved by calculating the probability of finding an opposite partner for each sphere in the lattice. This method is examined against conventional and established techniques such as Fourier transforms and translational and bond‐orientational correlation functions, and its advantages are demonstrated. Rotational symmetry analysis of diffraction resonances in measured and calculated optical transmission spectra as a function of the azimuth lattice orientation are carried out to confirm that the surface ordering translates into the bulk ordering of high index crystal planes, which are most sensitive to disorder.

New Routes towards Formation of Tin Oxide Inverted Opals for Charge Storage Applications

“…The order of the spheres is clearly visible, with the (111) face of the effectively cubic arrangement parallel to the substrate. Usually, in the preparation of opal templates, the (111) plane forms preferentially to other planes due to lowest energy (maximum packing) for the spheres in this arrangement (20)(21)(22). Increasing temperature or changing deposition conditions can also allow for other planes to crystallize (for instance {110} or {100}).…”

Light Scattering Investigation of 2D and 3D Opal Template Formation on Hydrophilized Surfaces

“…Contact angle measurements were taken for both sample cleaning methods on a Kruss Easy Drop measurement system. After cleaning by these methods, both samples were settled vertically in a 2.5 wt% aqueous solution of PMMA spheres and withdrawn at a constant rate of ~1.5 mm/hr using a home-made dipping apparatus while subjected to acoustic vibrations through a loudspeaker beneath the solution, this setup is described elsewhere (23,30).…”

“…Improvement in the coverage and long-range order of deposits can be achieved through the control and/or the addition of other variables such as temperature (21), management of the ionic strength of the solution via the use of charged colloids (22), or noise-induced stochastic resonance effects (23). We briefly investigate the formation of 3D PhCs on glass substrates by dip-coating of 500 nm PS spheres with noise induced stochastic resonance.…”

2D and 3D photonic crystal materials for photocatalysis and electrochemical energy storage and conversion

“…(c) Galvanostatic discharge-charge profile experimentally determined for a V 2 O 5 IO cathode in a lithium battery. The schematic depicts the reduction in periodic, ordered structure that occurs during discharge, reproduced from [144] with permission from the American Chemical Society, 2015. (d) Example of the variation in p ( y ) as a function of the reduced y radius parameter, showing how the order reduction is measured from imagines of the IO top surface.…”