Title: Consequences of Lattice Mismatch for Phase Equilibrium in Heterostructured Solids

Abstract

Lattice mismatch - the difference in natural bond length between two species comprising a solid is a common occurrence in modern materials. Spatial patterns in certain nanocrystal heterostructures, for instance, are thought to be a result of elastic forces arising from lattice mismatch. However, the role of lattice mismatch in mediating the arrangement of atoms in such materials is incompletely understood. Here we consider a simple microscopic model for lattice mismatch, in which the difference in natural lengths between bonded atoms produces interactions mediated by elastic strain. Computer simulations reveal that the model exhibits rich phase behavior, including structures with periodic order and unusual coexistence scenarios. To explain this phase behavior, we derive an effective pairwise interaction potential between atoms, revealing preferred spatial arrangements of atoms driven by spatial variations in the interaction potential. We then develop a mean field theory based on this effective interaction which qualitatively captures observed transition to phases with modulated order. Finally, we explain the observed scenarios of coexistence between using a graphical construction, based on the realization that the free energy cost of phase separation in elastic systems grows with system size. Here, these results clarify the equilibrium effects of lattice mismatch in macroscopicmore » solids and suggest a role for lattice mismatch in creating spatially heterogeneous compositions in nanoscale materials.« less

Authors:

Frechette, Layne B.  ^[1];

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Dellago, Christoph ^[2]; Geissler, Phillip L. ^[1]

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+ Show Author Affiliations

1. Univ. of California, Berkeley, CA (United States)
2. Univ. of Vienna (Austria)

Publication Date:

2019-09-24

Research Org.:

Univ. of California, Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1572233

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review Letters

Additional Journal Information:

Journal Volume: 123; Journal Issue: 13; Journal ID: ISSN 0031-9007

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Lattice mismatch, strain, phase transition