Strain-induced lead-free morphotropic phase boundary
Enhanced susceptibilities in ferroelectrics often arise near phase boundaries between competing ground states. While chemically-induced phase boundaries have enabled ultrahigh electrical and electromechanical responses in lead-based ferroelectrics, precise chemical tuning in lead-free alternatives, such as (K,Na)NbO<sub>3</sub> thin films, remains challenging due to the high volatility of alkali metals. Here, we demonstrate strain-induced morphotropic phase boundary-like polymorphic nanodomain structures in chemically simple, lead-free, epitaxial NaNbO<sub>3</sub> thin films. Combining ab initio simulations, thin-film epitaxy, scanning probe microscopy, synchrotron X-ray diffraction, and electron ptychography, we reveal a labyrinthine structure comprising coexisting monoclinic and bridging triclinic phases near a strain-induced phase boundary. The coexistence of energetically competing phases facilitates field-driven polarization rotation and phase transitions, giving rise to a multi-state polarization switching pathway and large enhancements in dielectric susceptibility and tunability across a broad frequency range. Our results open new possibilities for engineering lead-free thin films with enhanced functionalities for next-generation applications.
Authors
- Tao Zhou (ORCID: https://orcid.org/0000-0002-8093-7666)
- Sankalpa Hazra (ORCID: https://orcid.org/0000-0002-9126-8058)
- Reza Namdar Ghanbari (ORCID: https://orcid.org/0000-0002-7935-0489)
- Venkatraman Gopalan (ORCID: https://orcid.org/0000-0001-6866-3677)
- Hua Zhou (ORCID: https://orcid.org/0000-0001-9642-8674)
- Kevin J. Crust
- Harold Y. Hwang (ORCID: https://orcid.org/0000-0002-9230-3214)
- Kinnary Patel (ORCID: https://orcid.org/0000-0002-1380-5858)
- Nina Balke (ORCID: https://orcid.org/0000-0001-5865-5892)
- David Anthony Muller (ORCID: https://orcid.org/0000-0003-4129-0473)
- Miaofang Chi (ORCID: https://orcid.org/0000-0003-0764-1567)
- Martin Victor Holt (ORCID: https://orcid.org/0000-0003-2640-7100)
- Aarushi Khandelwal (ORCID: https://orcid.org/0000-0001-5747-482X)
- Huimin Qiao (ORCID: https://orcid.org/0000-0001-9556-7832)
- John M. Carroll (ORCID: https://orcid.org/0000-0001-5189-337X)
- Cedric J. G. Meyers (ORCID: https://orcid.org/0009-0004-0263-2834)
- Jonathan E. Spanier (ORCID: https://orcid.org/0000-0002-3096-2644)
- L. Bellaïche (ORCID: https://orcid.org/0000-0002-6181-2024)
- Jiayue Wang (ORCID: https://orcid.org/0000-0002-2027-3634)
- Ruijuan Xu (ORCID: https://orcid.org/0000-0001-5046-0599)
- Rui Liu (ORCID: https://orcid.org/0000-0002-5039-7419)
- Yoji Nabei (ORCID: https://orcid.org/0000-0001-5107-7540)
- Dali Sun (ORCID: https://orcid.org/0000-0003-4662-3265)
- Young‐Hoon Kim (ORCID: https://orcid.org/0000-0001-7343-1512)
- Liyan Wu (ORCID: https://orcid.org/0000-0002-9448-4370)
- Sergey Prosandeev (ORCID: https://orcid.org/0000-0002-0511-8310)
- Harikrishnan KP
Institutions
- Argonne National Laboratory (US)
- Oak Ridge National Laboratory (US)
- Pennsylvania State University (US)
- North Carolina State University (US)
- Tel Aviv University (IL)
- DEVCOM Army Research Laboratory (US)
- Duke University (US)
- Cornell University (US)
- CECOM Software Engineering Center (US)
- SLAC National Accelerator Laboratory (US)
- United States Army Combat Capabilities Development Command (US)
- Drexel University (US)
- University of Arkansas at Fayetteville (US)
- Stanford University (US)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-08-20
- DOI
- https://doi.org/10.1038/s41467-025-63041-w
- Citations
- 5
- Primary Topic
- Ferroelectric and Piezoelectric Materials
- Type
- article
- Field-Weighted Citation Impact
- 2.59
Funders
- National Science Foundation
- U.S. Department of Defense
- U.S. Department of Energy
- North Carolina State University
- Arkansas Economic Development Commission
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Office of Science
- American Chemical Society Petroleum Research Fund
- Cornell Center for Materials Research
- Multidisciplinary University Research Initiative
- Division of Materials Research
- Division of Electrical, Communications and Cyber Systems
- Basic Energy Sciences
- Army Research Office
- Oak Ridge National Laboratory
- Army Research Laboratory
- Division of Materials Sciences and Engineering