Strain-induced lead-free morphotropic phase boundary

Ghanbari, Reza; KP, Harikrishnan; Patel, Kinnary; Zhou, Hua; Zhou, Tao; Liu, Rui; Wu, Liyan; Khandelwal, Aarushi; Crust, Kevin J.; Hazra, Sankalpa; Carroll, John; Meyers, Cedric J. G.; Wang, Jiayue; Prosandeev, Sergey; Qiao, Huimin; Kim, Young-Hoon; Nabei, Yoji; Chi, Miaofang; Sun, Dali; Balke, Nina; Holt, Martin; Gopalan, Venkatraman; Spanier, Jonathan E.; Muller, David A.; Bellaiche, Laurent; Hwang, Harold Y.; Xu, Ruijuan

doi:10.1038/s41467-025-63041-w

Title: Strain-induced lead-free morphotropic phase boundary

Journal Article · Wed Aug 20 00:00:00 UTC 2025 · Nature Communications

DOI: https://doi.org/10.1038/s41467-025-63041-w · OSTI ID:2587436

Ghanbari, Reza ^[1];

^[2];

^[3];

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^[4]; Wu, Liyan ^[5];

^[6]; Crust, Kevin J. ^[7]; Hazra, Sankalpa ^[8]; Carroll, John ^[9];

^[5];

^[6]; Prosandeev, Sergey ^[3];

^[1];

^[10];

^[1]; Chi, Miaofang ^[11];

^[1]; Balke, Nina ^[1] more »

North Carolina State University, Raleigh, NC (United States)
Cornell University, Ithaca, NY (United States)
University of Arkansas, Fayetteville, AR (United States)
Argonne National Laboratory (ANL), Argonne, IL (United States)
Drexel University, Philadelphia, PA (United States)
Stanford University, CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford University, CA (United States)
The Pennsylvania State University, University Park, PA (United States)
Drexel University, Philadelphia, PA (United States); DEVCOM C5ISR U.S. Army, Aberdeen Proving Grounds, MD (United States)
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Duke University, Durham, NC (United States)
Cornell University, Ithaca, NY (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY (United States)
University of Arkansas, Fayetteville, AR (United States); Tel Aviv University (Israel)

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)NbO₃ 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 NaNbO₃ 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.

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Research Organization:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: American Chemical Society Petroleum Research Fund; ETHOS MURI; National Science Foundation (NSF); U.S. Army Research Laboratory; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE); Vannevar Bush Faculty Fellowship (VBFF)

Grant/Contract Number:: AC02-76SF00515; SC0012375

OSTI ID:: 2587436

Journal Information:: Nature Communications, Journal Name: Nature Communications Journal Issue: 1 Vol. 16; ISSN 2041-1723

Publisher:: Springer Science and Business Media LLCCopyright Statement

Country of Publication:: United States

Language:: English

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