Breaking the icosahedra in boron carbide
Abstract
The extraordinary hardness of boron compounds is related to their internal structure, which is comprised of 12-atom icosahedra arranged in crystalline lattices. In these hierarchical materials, the icosahedra are easy to image with EM, but individual atoms are not. Here, we show that laser-assisted atom probe tomography can be used to deduce the atomic structure and relative interatomic bond strengths of atoms in boron carbide. To our surprise, the icosahedra disintegrated during the field evaporation process. Statistical analyses of event multiplicity and stoichiometry in the atom probe dataset substantiate that the icosahedra are less tightly bound than their interconnecting chains. Comparisons with quantum mechanics simulations further suggest that this instability plays a role in the amorphization of boron carbide.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 06, 2016
- Source ID
- 10.1073/pnas.1607980113
Entities
People
- Andrew J. Breen
- Julie Cairney
- Kelvin Y. Xie
- Kevin J. Hemker
- Qi An
- Simon P. Ringer
- Takanori Sato
- William Andrew Goddard III
Organizations
- California Institute of Technology
- Johns Hopkins University
- National Science Foundation
- United States Army Research Laboratory
- University of Sydney