Abstract
This paper surveys the variables controlling the lattice structure and charge in macroscopic Coulombic crystals made from electrically charged, millimeter-sized polymer objects (spheres, cubes, and cylinders). Mechanical agitation of these objects inside planar, bounded containers caused them to charge electrically through contact electrification, and to self-assemble. The processes of electrification and self-assembly, and the characteristics of the assemblies, depended on the type of motion used for agitation, on the type of materials used for the objects and the dish, on the size and shape of the objects and the dish, and on the number of objects. Each of the three different materials in the system (of the dish and of the two types of spheres) influenced the electrification. Three classes of structures formed by self-assembly, depending on the experimental conditions: two-dimensional lattices, one-dimensional chains, and zero-dimensional ‘rosettes’. The lattices were characterized by their structure (disordered, square, rhombic, or hexagonal) and by the electrical charges of individual objects; the whole lattices were approximately electrically neutral. The lattices observed in this study were qualitatively different from ionic crystals; the charge of objects had practically continuous values which changed during agitation and self-assembly, and depended on experimental conditions which included the lattice structure itself. The relationship between charge and structure led to the coexistence of regions with different lattice structures within the same assembly, and to transformations between different lattice structures during agitation.
Highlights
Crystallization and glass formation are the two microscopic processes that generate solids from liquids and gases
This paper reports the development of a model system for studying self-assembly processes important in crystallization, and in the formation of forms of condensed matter in which charge-charge interactions dominate the interactions between the particles
The charges of the spheres are neither quantized, nor constant during self-assembly; this characteristic limits the possibility of modeling ionic crystallization with our system but it offers the possibility of studying types of electrostatic self-assembly that are impossible in systems with fixed electrical charges
Summary
Crystallization and glass formation are the two microscopic processes that generate solids from liquids and gases. Understanding and controlling the formation of crystalline matter is a process of great theoretical and technological importance, and a considerable amount of work has been invested in the study of crystallization.[1,2,3,4] Beyond its practical importance, crystallization is a fascinating phenomenon that occurs in many systems which are not common materials, such as stacked macroscopic spheres,[5,6] bubbles on a surface of a liquid,[7] electrons in plasmas,[8,9] and vortices in quantum fluids.[10] The study of these exotic cases of crystallization is in part motivated by the hopes of drawing analogies with, and of generating insights about, the crystallization of materials. In studies of systems of crystallizing colloids,[11,12,13,14] more information can be extracted about individual objects, but again these systems are often too complicated to follow all relevant particles, and events involving small particle numbers usually are not detectable
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
