The rhombohedral phase of Si (r8-Si), a promising semiconducting material, is formed by indentation together with the body-centered cubic phase (bc8-Si). Using a novel sample preparation method, x-ray diffraction is used to determine the relative volume of these phases in indented Si and allow observation of a distorted unit cell along the direction of indentation loading. Theoretical calculations together with these observations suggest the indent contains an intrinsic compression of ∼4 GPa that stabilizes the r8 phase.We would like to acknowledge and thank Beamline
Scientist Ruqing Xu for his help in obtaining the X-ray
data. J. E. B. would like to acknowledge the Australian
Research Council (ARC) (FT130101355). B. H. gratefully
acknowledges funding through a Weinberg Fellowship
sponsored by the Laboratory Directed Research and
Development Program of Oak Ridge National
Laboratory, managed by UT-Battelle, LLC, for the U.S.
Department of Energy and ORNL’s Neutron Facilities, a
DOE Office of Science User Facility operated by the Oak
Ridge National Laboratory. A. M. acknowledges support
from MINECO Project No. MAT2016-75586-C4-3-P
(Spain)
