Investigation of double-gyroid grain boundaries beyond twinning

TL;DR

This study numerically investigates four double-gyroid grain boundaries, analyzing their topological and geometric features, and identifies the network switching boundary as the most stable with the lowest energy and width.

Contribution

It provides a detailed numerical analysis of various double-gyroid grain boundaries beyond twinning, highlighting their topological and energetic differences.

Findings

Network switching GB has the lowest energy.

Deviations in strut lengths and dihedral angles are significant.

The contact plane spectra help evaluate GB widths.

Abstract

We study four double-gyroid (DG) grain boundaries (GBs) with different orientations numerically using the Landau--Brazovskii free energy, including the (422) twin boundary studied recently, a network switching GB, and two tilt GBs. Topological variations and geometric deformations are investigated. It is found that deviations in strut lengths and dihedral angles from the bulk DG substantially exceed changes in strut angles and nodal coplanarity. We also examine the spectra along the contact plane of two grains and utilize them to evaluate the GB widths. Of the four GBs we study, the network switching GB changes to the least extent topologically and geometrically, meanwhile has the lowest energy and the smallest GB width.