Review of Micro‐/Nanoscale Single Crystals: Synthesis, Size‐Dependent Key Properties Versus Deformation Instabilities, and Mitigation Strategies

ABSTRACT

Micro‐/nanoscale single‐crystal materials have garnered significant attention due to their unique size‐dependent mechanical and functional properties, with applications spanning diverse cutting‐edge fields. This review provides a state‐of‐the‐art overview of these materials, encompassing their synthesis methods, advanced mechanical and functional properties, as well as practical and emerging applications. A particular focus is placed on the fundamentally different deformation traits observed at such confined scales, specifically localized shear/slip banding, surface relief, and serrated stress‐strain response. Such deformation instabilities are ubiquitous yet often detrimental to the integrity, lifespan, and reliability of micro‐/nanodevices. We critically analyze the physical origins of these deformation phenomena, which are rooted in crystallographic constraints, thermodynamic considerations, size effects, and dislocation mechanics. Furthermore, we summarize recent research efforts aimed at mitigating these adverse effects through strategies such as optimizing crystal qualities and edge geometries, controlling deformation conditions, utilizing specific loading geometries and crystal orientations, alloying and precipitation, surface engineering, and employing in situ observation with feedback control. This review underscores the challenges and potential solutions in leveraging the exceptional properties and attributes of micro‐/nanoscale single crystals toward the development of robust next‐generation single‐crystal‐based miniature devices.