Defect phases offer a unifying framework for describing chemically and structurally distinct states of lattice defects, including surfaces, interfaces, grain and phase boundaries, stacking faults, dislocations, and point-defect ensembles. Rather than treating defects only as deviations from an ideal crystal, the concept of defect phases considers their atomic-scale structure, chemistry, stability, transitions, and properties in analogy to phases confined to a defect geometry. Recent advances in microscopy, spectroscopy, atom probe tomography, atomistic simulation, and thermodynamic modelling now make it possible to identify such states and map their dependence on chemical potential, temperature, stress, environment, and processing history. This opens a route towards defect phase diagrams as a basis for predicting, selecting, and controlling defect phases. Such defect phase diagrams can also serve as anchor points for connecting the physical mechanisms associated with defect phases with the macroscopic properties they give rise to, thereby enabling their use in materials design. The Collection therefore invites work that advances defect phases to pave the way from intriguing local observations towards a predictive basis for materials understanding and design.
This Collection highlights recent advances in theoretical and experimental methods that deepen fundamental understanding and enable predictive modeling or targeted synthesis of defect phases across diverse classes of materials. We welcome contributions spanning: the development of new methodologies, pathways, and processing techniques for creating defect phases; advances in characterizing or modeling thermodynamic stability and kinetics in the context of defect phase diagrams; and high-throughput or data-driven approaches to identifying ordered arrangements at lattice defects and their relevance to defect states. The Collection also encompasses computational and empirical studies that deliver new mechanistic insight into defect phase behavior and thereby the properties of materials that may be manipulated and controlled by means of defect phase design This Collection aims to reflect the breadth and ambition of modern defect phase research, and to highlight its growing role in accelerating both fundamental understanding and the rational design of materials.
