Defect stability in phase-field crystal models: Stacking faults and partial dislocations

TL;DR

This paper investigates defect stability in phase-field crystal models, demonstrating the stabilization of stacking faults and partial dislocations, and providing guidelines for constructing models with stable defect structures that align with experimental and theoretical results.

Contribution

It introduces a framework for stable defect modeling in PFC models, including the first stabilization of stacking faults and partial dislocations within this formalism.

Findings

Stable stacking faults and partial dislocations are achieved in PFC models.

Properties like dissociation width and Peierls strains are characterized.

Results agree with continuum elastic theories and experiments.

Abstract

The primary factors controlling defect stability in phase-field crystal (PFC) models are examined, with illustrative examples involving several existing variations of the model. Guidelines are presented for constructing models with stable defect structures that maintain high numerical efficiency. The general framework combines both long-range elastic fields and basic features of atomic-level core structures, with defect dynamics operable over diffusive time scales. Fundamental elements of the resulting defect physics are characterized for the case of fcc crystals. Stacking faults and split Shockley partial dislocations are stabilized for the first time within the PFC formalism, and various properties of associated defect structures are characterized. These include the dissociation width of perfect edge and screw dislocations, the effect of applied stresses on dissociation, Peierls strains for glide, and dynamic contraction of gliding pairs of partials. Our results in general are shown to compare favorably with continuum elastic theories and experimental findings.