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Title: Pathways to exotic metastable silicon allotropes

The Group 14 element silicon possesses a complex free-energy landscape with many (local) minima, allowing for the formation of a variety of unusual structures, some of which may be stabilized at ambient conditions. Such exotic silicon allotropes represent a significant opportunity to address the ever-increasing demand for novel materials with tailored functionality since these exotic forms are expected to exhibit superlative properties including optimized band gaps for solar power conversion. The application of pressure is a well-recognized and uniquely powerful method to access exotic states of silicon since it promotes large changes to atomic bonding. Conventional high-pressure syntheses, however, lack the capability to access many of these local minima and only four forms of exotic silicon allotropes have been recovered over the last 50 years. However, more recently, signifi- cant advances in high pressure methodologies and the use of novel precursor materials have yielded at least three more recoverable exotic Si structures. This review aims to give an overview of these innovative methods of high-pressure application and precursor selection and the recent discoveries of new Si allotropes. The background context of the conventional pressure methods and multitude of predicted new phases are also provided. Furthermore, this review also offers amore » perspective for possible access to many further exotic functional allotropes not only of silicon but also of other materials, in a technologically feasible manner« less
ORCiD logo [1] ;  [2] ;  [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Carnegie Institution of Washington, Washington, D.C. (United States)
  3. The Australian National Univ., Canberra (Australia)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; SC0001057
Accepted Manuscript
Journal Name:
Applied Physics Reviews
Additional Journal Information:
Journal Volume: 3; Journal Issue: 4; Journal ID: ISSN 1931-9401
American Institute of Physics
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; silicon; high pressure; crystal structure; band gap; clathrates
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1349134