Work

On the relationship and distinction between atomic density and coordination number in describing crystal defects

Year: 2026

Type: article

Abstract: Crystal defects are often described through broken atomic bonds, through counting the nearest neighbor coordination number. In this work, we highlight that the intrinsic heterogeneities in interatomic spacing due to a crystal defect, which is overlooked in broken-bond models, can decisively shape defect properties. We analyze excess free volume, energy, and entropy for a large set of BCC-Fe grain boundaries relaxed by molecular statics, and demonstrate that an atomic-density field, as a systematically coarse-grained field variable, shows much better correlations with the grain boundary properties. The atomic density field is shown to simultaneously capture bond depletion and spacing variations, thereby covering and unifying both structural and volumetric information. Our results establish the coarse-grained atomic density field as a principled surrogate for describing grain boundary thermodynamics, motivating the augmentation of broken-bond rules in predictive theories of interfacial energetics, excess properties, segregation, and phase behavior, and providing a direct bridge from atomistic to mesoscale models, with potential applications extending to other microstructural defects.

Source: RSC Advances

DOI: 10.1039/d6ra05403j

Authors: Reza Darvishi Kamachali, Theophilus Wallis

Institutions: Federal Institute For Materials Research and Testing, University of Münster

Language: English

Topic: Microstructure and mechanical properties

Subfield: Metals and Alloys

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,042

Funders: European Commission, Deutsche Forschungsgemeinschaft, HORIZON EUROPE Framework Programme, European Research Council