Gravity enables self‐assembly
Abstract
Crystallization of granular assemblies has broad implications for rapid and scalable creation of architected materials with applications ranging from structural materials to microarchitected battery electrodes. While significant advances have been made in understanding colloidal self‐assembly at nano to micro scale, the governing mechanisms for organization of dry assemblies of hard spheres remain unclear. Here, we investigate crystallization of mono‐size hard spheres with and without imposed vibration. Using X‐ray computed tomographic analysis coupled with discrete‐element simulations, we unravel the roles of gravity and imposed vibration on the three‐dimensional self‐assembly of the dry spheres. We use these insights to introduce gravity‐mediated epitaxial crystal growth with slow pouring of balls on seeding templates. Contrary to vibration‐induced crystallization, this method can form large single crystals with both close‐packed and rather surprisingly, nonclose‐packed metastable particle arrangements. Our results provide insight for the scalable manufacture of defect‐free granular assemblies that can be used as space‐holding templates to manufacture cellular materials, such as inverse opals and other related topologies.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 31, 2022
- Source ID
- 10.1002/ntls.20220007
Entities
People
- Angkur Jyoti Dipanka Shaikeea
- H.N.G. Wadley
- Ivan Grega
- Vikram S Deshpande
Organizations
- Army Research Office
- University of Cambridge
- University of Virginia