Electron Microscopy Study of Binary Nanocolloidal Crystals with ico-AB₁₃ Structure Made of Monodisperse Silica Nanoparticles

Abstract

Binary nanocolloidal crystals (BNCCs) made of two different nanoparticles are a promising new class of advanced functional materials with synergetic and collective properties. These materials have been shown to exhibit excellent structural diversity and a wide range of different stoichiometries. In this study, BNCCs with an ico-AB13 structure were prepared as inorganic bulk materials by simple solvent evaporation of silica nanocolloidal aqueous solutions. Systematic analysis of Fourier diffractograms of high-resolution transmission electron microscopy (HRTEM) images shows the reflection conditions of the space group Fm3̅c without any ambiguities, which is indicative of the ico-AB13 structure. Simulated HRTEM images based on the ideal ico-AB13 structure were also calculated under the kinematical scattering approximation. These images showed the characteristic fine structure of the ico-AB13 structure along the high-symmetry axes. The agreement between the observed and simulated HRTEM images indicates the validity of the ideal ico-AB13 model structure. This result shows that HRTEM together with a quantitative image simulation is a versatile method for the characterization of the BNCCs at the nanoscale and can be routinely applied for any nanocolloidal crystals, even for complex structures.

A Mesoporous Superlattice Consisting of Alternately Stacking Interstitial Nanospace within Binary Silica Colloidal Crystals

“…In unary systems, monodispersed silica nanospheres are usually assembled into face‐centered cubic (fcc) and/or hexagonal close‐packed (hcp) structures. We as well as Snyder and co‐workers have successfully prepared binary colloidal crystals (i.e. AlB 2 ‐, NaZn 13 ‐, and NaCl‐type structures; see Figure S1 in the Supporting Information) by combining different‐sized nanospheres with strictly controlled particle number ratios.…”

“…We as well as Snyder and co‐workers have successfully prepared binary colloidal crystals (i.e. AlB 2 ‐, NaZn 13 ‐, and NaCl‐type structures; see Figure S1 in the Supporting Information) by combining different‐sized nanospheres with strictly controlled particle number ratios. The coexistance of nanostructures with different geometries is difficult to observe in the surfactant system because surfactant micelles readily reorganize into a single phase .…”

An Artificial Neural Network Reveals the Nucleation Mechanism of a Binary Colloidal AB13 Crystal

“…The colloidal analogue of the NaZn 13 was for the first time observed by Sanders et al . in natural gem opals consisting of two sizes of silica spheres in 1987. , The same AB 13 structure was later observed in systems of charged-stabilized colloids or PMMA particles − and in various nanoparticle systems, e.g ., mixtures of semiconductor, metal oxide, magnetic, silica, and polymer-grafted nanoparticles, as well as polyoxometalate clusters. ,,− …”

Binary Colloidal Crystal Films Grown by Vertical Evaporation of Silica Nanoparticle Suspensions

“…Optimal unary and binary colloidal deposition conditions vary necessarily according to solvent and colloid size/ratio composition. − A systematic study of conditions for each system is necessary for reproducibility and for a better understanding of binary colloidal assembly. Intensive efforts have gone into binary crystal phase modeling, microparticle assembly, and bulk growth, − but the field of binary nanoparticle film deposition is still in the early stages of development. Colloidal crystal film growth, in contrast to bulk growth, yields a supported material for device applications or physical property measurements that utilize the support.…”