Shape-memory effect in twisted ferroic nanocomposites.

Kim, Donghoon; Kim, Minsoo; Reidt, Steffen; Han, Hyeon; Baghizadeh, Ali; Zeng, Peng; Choi, Hongsoo; Puigmartí-Luis, Josep et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

The shape recovery ability of shape-memory alloys vanishes below a critical size (~50 nm), which prevents their practical applications at the nanoscale. In contrast, ferroic materials, even when scaled down to dimensions of a few nanometers, exhibit actuation strain through domain switching, though the generated strain is modest (~1%). Here, we develop freestanding twisted architectures of nanoscale ferroic oxides showing shape-memory effect with a giant recoverable strain (>8%). The twisted geometrical design amplifies the strain generated during ferroelectric domain switching, which cannot be achieved in bulk ceramics or substrate-bonded thin films. The twisted ferroic nanocomposites allow us to overcome the size limitations in traditional shape-memory alloys and open new avenues in engineering large-stroke shape-memory materials for small-scale actuating devices such as nanorobots and artificial muscle fibrils.