Antiferroelectric (AFE) materials are electronic materials actively studied for their potential applications such as in high energy storage capacitors and power generators, high-strain transducers and actuators, pyroelectric and electrocaloric devices [1]. A microscopic picture for the AFE behavior proposed by Kittel [2] involves an antiparallel dipole alignment in adjacent subcells, which yields zero net polarization in the absence of an applied electric field E and no piezoelectric activity. Transition to the ferroelectric (FE) phase under E field application is a result of dipoles aligning in one direction. The AFE/FE phase transition, when E exceeds a critical magnitude EC, is accompanied by a sharp change in polarization, volume, electro-optic coefficients, dielectric constant, and strain [3], providing these materials with rich functional properties. Moreover, the FE phase can turn back to AFE phase when E drops below a critical point EA, with EA < EC due to the hysteresis of the phase transition.
The properties of thin films can be distinctly different from their bulk counterparts because of the enormous strains generated by a lattice misfit to the substrate, thus affecting the crystalline structure and polarization ordering. Functional characterization of AFE materials typically involves macroscopic testing of their electric properties like polarization hysteresis loops or capacitance without having access to the structural information.
Here, we present in situ synchrotron X-ray diffraction of the structural evolution and induced strain of the electric-field-driven AFE/FE phase transition in PbZrO3 (PZO) thin films with a thickness of 100 nm. They were epitaxially grown on SrTiO3 substrates with SrRuO3 bottom electrode and Pt top electrode. Three-dimensional reciprocal space maps (RSMs) were recorded in the vicinity of the PZO 480 and 008 Bragg reflections during the application of E to up to 700 kV/cm in steps of 20 kV/cm. Elastic strain values of up to 0.3% were determined at highest E. A hysteretic behaviour of the transformation process was evidenced with the onset of the AFE/FE phase transformation at 200 kV/cm while the back transformation was completed only at 160 kV/cm. While the antiferroelectric phase is not supposed to be actuated by an applied electric field, the corresponding Bragg reflections also showed a hysteretic behaviour.

[1] C.A. Randall et al., J. Am. Ceram. Soc. 104 (2021) 3775-3810
[2] C. Kittel, Phys. Rev. 82 (1951) 729
[3] X. Hao et al., Prog. Mater. Sci. 63 (2014) 1