Title

Lattice Instability during Solid-Solid Structural Transformations under a General Applied Stress Tensor: Example of Si I → Si II with Metallization

Publication Date

10-17-2018

Department

Ames Laboratory; Aerospace Engineering; Materials Science and Engineering; Mechanical Engineering

Campus Units

Ames Laboratory, Aerospace Engineering, Materials Science and Engineering, Mechanical Engineering

OSTI ID+

1481876

Report Number

IS-J 9756

DOI

10.1103/PhysRevLett.121.165701

Journal Title

Physical Review Letters

Volume Number

121

Issue Number

16

First Page

165701

Abstract

The density functional theory was employed to study the stress-strain behavior and elastic instabilities during the solid-solid phase transformation (PT) when subjected to a general stress tensor, as exemplified for semiconducting Si I and metallic Si II, where metallization precedes the PT, so stressed Si I can be a metal. The hydrostatic PT occurs at 76 GPa, while under uniaxial loading it is 11 GPa (3.7 GPa mean pressure), 21 times lower. The Si  I→Si  II PT is described by a critical value of the phase-field’s modified transformation work, and the PT criterion has only two parameters given six independent stress elements. Our findings reveal novel, more practical synthesis routes for new or known high-pressure phases under predictable nonhydrostatic loading, where competition of instabilities can serve for phase selection rather than free energy minima used for equilibrium processing.

DOE Contract Number(s)

AC02-07CH11358; CMMI-1536925; DMR-1434613; W911NF-17-1-0225; N00014-16-1-2079; TG-MSS140033; MSS170015

Language

en

Department of Energy Subject Categories

42 ENGINEERING

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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