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Stimulus-responsive shape memory materials have attracted tremendous research interests recently, with much effort focused on improving their mechanical actuation. Driven by the needs of nanoelectromechnical devices, materials with large mechanical strain particularly at nanoscale are therefore desired. Here we report on the discovery of a large shape memory effect in BiFeO3 at the nanoscale. A maximum strain of up to ~14% and a large volumetric work density can be achieved in association with a martensitic-like phase transformation. With a single step, control of the phase transformation by thermal activation or electric field has been reversibly achieved without the assistance of external recovery stress. Although aspects such as hysteresis, micro-cracking etc. have to be taken into consideration for real devices, the large shape memory effect in this oxide surpasses most alloys and therefore demonstrates itself as an extraordinary material for potential use in state-of-art nano-systems., Comment: Accepted by Nature Communications

The polarization fatigue in (Pb0.97La0.02)(Zr0.95Ti0.05)O3 (PLZT) antiferroelectric thin films deposited onto silicon wafers is studied by investigating the effect of the peak/average/effective cycling voltage through varying the waveform of the electrical excitation. Interestingly, it is found that the fatigue endurance of the film is determined by the effective voltage of the external driving excitation rather than by the peak or average voltages. Our results can be well explained in the framework of the local phase decomposition model and indicate that the effective voltage should be considered as the genuine driving voltage determining the polarization fatigue in PLZT antiferroelectric films., Comment: 17 pages, 3 figures, 1 table