Atomically engineered interfaces yield extraordinary electrostriction

Gd and O O atomically interfaces on NdGaO 3 substrates. We find that the electrostriction coefficient 25 reaches 2.38×10 -14 m 2 /V 2 , exceeding the best-known relaxor ferroelectrics by three 26 orders of magnitude. Our atomic-scale calculations show that the extraordinary electrostriction coefficient is driven by the coherent strain imparted by the interfacial lattice mismatches. Thus, artificial heterostructures open a new avenue to design and manipulate electrostrictive materials and devices for nano/micro actuation and cutting-edge sensor applications.


Gd2O3-doped CeO2 and Er2O3-stabilized δ-Bi2O3 with atomically controlled 24
interfaces on NdGaO3 substrates. We find that the electrostriction coefficient 25 reaches 2.38×10 -14 m 2 /V 2 , exceeding the best-known relaxor ferroelectrics by three Materials developing strain in response to an electric field have attracted significant 32 attention over the previous several decades due to their wide applications, ranging from 33 non-resonant actuators, high-end transducers, artificial muscles, energy harvesting, and 34 various sensors. 3-4 While piezoelectricity is limited to materials with a non-35 centrosymmetric crystal structure, electrostriction is a general property of all dielectrics, 36 which produces a high displacement accuracy with the absence of strain-field hysteresis 37 and remnant polarization. However, the electrostriction coefficient (Mxx) is usually low, 38 attaining a value less than 10 -19 m 2 /V 2 for simple oxides such as MgO, TiO2 and Y:ZrO2. 5 39 Owing to their very high electromechanical responses, the two archetypes of 40 electrostrictive materials are relaxor ferroelectrics and ferroelectric polymers. The electrostrictive response of the 17 nm thick multilayer deposited on an NGO 96 cantilever is proportional to the square of the electric field strength (Extended Data Fig.  97 2). The maximum stress generated in this configuration was 9.7 GPa. Fig. 1c   The minimum in the out-of-plane lattice parameters at 1/Λ = 0.8 nm -1 correlates well with 172 the measured modulation length-dependent electrostriction coefficient (Fig. 1c). heterostructures with different modulation lengths and biaxial strain (ε*). Fig. 4a shows 202 the calculated Helmholtz free energy (F) as a function of the biaxial strain for the 203 heterostructure with Λ = 1.55 nm (12 cationic layers), which is close to the maximum 204 electrostrictive effect (Fig. 1c). The system has the lowest total energy (F) in the absence 205 of strain and increasing free energy when compressive or tensile strains are applied. The 206 free energy increases at a specific strain value and exhibits a maximum function of 1/Λ 207 (Fig. 4b). This effect is attributed to the enhanced interlayer interactions, as CGO and 208 ESB couple at the interfaces. µ (1/Λ) 1.3 (see Fig. 1c). Similarly, a tensile strain would drive the system away from its 221 ground state to a higher energy state (see Fig. 4a). Therefore, a larger field-induced lattice change could be generated, allowing the heterostructure to contract when E is applied 223 parallel to the (100) direction (Extended Data Fig. 5).

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Correspondence and requests for materials should be addressed to H. Z, V.E and N. P.

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