Strain engineering in lead zirconate titanate thin films: Reversible ferroelastic domain switching and giant electromechanical response

Piezoelectric thin films are essential building blocks for next-generation microelectromechanical systems (MEMS).However, their functional performance has historically been limited by substrate mechanical constraints-a phenomenon known as the "clamping effect."This phenomenon typically suppresses ferroelectric-and ferroelastic-domain mobilities.This review summarizes a paradigm shift in thin-film design: it redefines substrate clamping as a vital "restoring force" that ensures reversible domain switching rather than viewing it as purely degradative.By implementing a "hybrid strain engineering" approach that precisely tunes epitaxial and thermal strains in lead zirconate titanate thin films, our group demonstrate the feasibility of maximizing extrinsic contributions from non-180° (ferroelastic) domain-wall motion.Employing in situ synchrotron X-ray diffraction (XRD) at SPring-8, our group provide direct evidence of ultrafast, reversible 90°-domain switching at megahertz frequencies.This design guideline enables the giant piezoelectric responses in MEMS cantilevers, outperforming conventional clamped films and providing a scalable path for Beyond 5G/6G communication technologies and high-efficiency actuators.