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Archive > Volume 38 Issue 1 > 2021,38(1):75-83. DOI:10.16356/j.1005-1120.2021.01.007 Prev Next

Large and Recoverable Electrostrain in Strained Ferroelectric Superlattices due to Domain Switching

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    Abstract:
    The ferroelectric superlattices have been widely studied due to their distinguished electromechanical coupling properties. Under different biaxial mismatch strains， ferroelectric superlattices exhibit different domain structures and electromechanical coupling properties. A three-dimensional phase field model is employed to investigate the detailed domain evolution and electromechanical properties of the PbTiO3/SrTiO3（PTO/STO） superlattices with different biaxial mismatch strains. The phase field simulations show that the ferroelectric superlattice exhibits large electrostrain in the stacking direction when an external field is applied. Under a large compressive mismatch strain， vortex domains appear in ferroelectric layers with the thickness of 4 nm. The vortex domains become stable c-domain under a large external electric field， which remains when the electric field is removed. When the initial compressive mismatch strain decreases gradually， the waved or a1/a2 domains replaces the initial vortex domains in the absence of electric field. The fully polarized c-domain by a large electric field switches to diagonal direction domain or a/c domain when the electric field is small. Furthermore， when a biaxial tensile strain is applied to the superlattice， ferroelectric domains switch back to the initial a1/a2 twin-like domain structure， resulting in the recoverable and large electrostrain. This provides an effective way to obtain the large and recoverable electrostrain for the engineering application.

    Keywords:
    large electrostrain ; ferroelectric superlattices ; domain switching ; recoverable domains

    Project Supported:
    This work was supported by the National Natural Science Foundation of China （Nos. 11672264， 11972320） and the Zhejiang Provincial Natural Science Foundation （No. LZ17A020001）.

    Clc Number:
    TB381

    图1 Schematic diagram of 3-D ferroelectric superlattices under given biaxial strains and vertical electric fieldFig.1
    图2 Polarization distributions of the superlattice with different statesFig.2
    图3 Hysteresis loops and typical domain structures of the superlattice under different biaxial compression strainsFig.3
    图4 Electrostrain curves of the superlattice under different biaxial compression strainsFig.4
    图5 Simulated a1/a2 domain in the superlattice and polarization distributions of its three incisionsFig.5
    图6 Polarization versus electric field and electrostrain versus electric field under different tensile misfit strainsFig.6

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