Structural transformations of growing thin colloidal crystals in confined space via convective assembly

Sumeng Hu; Jun Nozawa; Kejia Kang; Suxia Guo; Haruhiko Koizumi; Zon-Han Wei; Satoshi Uda

doi:10.1016/j.jcis.2021.02.016

Structural transformations of growing thin colloidal crystals in confined space via convective assembly

J Colloid Interface Sci. 2021 Jun:591:300-306. doi: 10.1016/j.jcis.2021.02.016. Epub 2021 Feb 8.

Authors

Sumeng Hu¹, Jun Nozawa², Kejia Kang³, Suxia Guo⁴, Haruhiko Koizumi⁵, Zon-Han Wei⁶, Satoshi Uda⁵

Affiliations

¹ School of Mechanical Engineering, North China University of Water Resources and Electric Power (NCWU), Zhengzhou 450045, China; School of Mechanics and Engineering Science, Zhengzhou University, Zhengzhou 450001, China; Zhengzhou New Dafang Heavy Industry Technology Co., Ltd., Zhengzhou 450005, China.
² Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577, Japan. Electronic address: nozawa@imr.tohoku.ac.jp.
³ School of Electromechanical Engineering, Henan University of Technology, Zhengzhou 450001, China; School of Mechanics and Engineering Science, Zhengzhou University, Zhengzhou 450001, China.
⁴ Department of Materials Processing, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan.
⁵ Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577, Japan.
⁶ School of Mechanics and Engineering Science, Zhengzhou University, Zhengzhou 450001, China.

PMID: 33611048
DOI: 10.1016/j.jcis.2021.02.016

Abstract

The structural evolution of growing thin colloidal crystals in a confined space via the convective assembly technique has been investigated. The thin colloidal crystals were grown in a wedge-shaped cell, where the height of the cell increased with increased crystal growth. Triangle and square patterns, denoted as [111]- and [100]-oriented grains, respectively, were formed alternately as the height of the cell increased. The structural transformation was associated with an increase in the number of layers when the n-layer [100]-oriented grains changed to n + 1-layer [111]-oriented grains. Between the different grain structures, a stripe pattern was observed, which was a transitional region, where particle configuration gradually changed. The structural transformation occurred through the continuous change of particle configuration rather than through the abrupt formation of a grain boundary. The interval of the strip pattern lengthened as the number of layers increased, which is understood to be the structure with the highest packing density. The findings of the study give a better insight into convective assembly in a confined space, and also contribute to the greater structural control of colloidal crystals, useful for a number of applications.

Keywords: Colloidal crystals; Convective assembly; Growth in a confined space.