Abstract
Symmetry changes during phase transformations fundamentally determine the behavior of thermodynamic systems, governing phenomena as diverse as water evaporation, fermion condensation, and epidemic spreading. Phase transitions are conventionally divided into two classes, and this classification is typically assumed to remain invariant upon reversing the transition. Here, an asymmetric phase transformation is uncovered in the ferroelectric–paraelectric transition of single-crystal BaTiO3, a model system for first-order transitions. Under slow temperature variation (≤0.1 °C min−1), thermodynamic, dielectric, and domain-structure measurements reveal that the ferroelectric-to-paraelectric transition exhibits latent heat, phase coexistence, and a discontinuous order parameter, while these signatures are absent upon cooling. Complementary phase-field simulations demonstrate similar behavior, attributing it to distinct elastic strain energy accumulation and release during heating and cooling. These findings reveal a first-order character upon heating but a second-order-like behavior upon cooling, challenging the conventional paradigm of symmetric phase-transition classification and suggesting new possibilities for ferroelectric-based energy storage.
| Original language | English |
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| Journal | Advanced Materials |
| DOIs | |
| State | Accepted/In press - 2025 |
Funding
The Technion team acknowledges support from the Zuckerman STEM Leadership Program, Grand Technion Energy Program, Technion's Hellen Diller Quantum Center, and Pazy Research Foundation Grant No. 732‐2025. The authors also thank Dr. Inna Zeltser, Dr. Cecile Saguy, Dr. Yaron Kauffman, and Mr. Michael Kalina for technical support. S.G. acknowledges the following funding: Israel Science Foundation (grant Nos. 1561/18, 3455/21, 1365/23 and 2089/25); United States–Israel Bi‐national Science Foundation (grant No. 2018161). N.D. acknowledges the support from the Spanish Ministerio de Ciencia e Innovacion (MICINN) under project PID2019‐109931GB‐I00. The ICN2 is funded by the CERCA programme / Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa Centres of Excellence Programme, funded by the Spanish Research Agency, and a Severo Ochoa Grant No. CEX2021‐001214‐S. The authors thank the support of ALBA staff for the successful performance of the measurements at the CIRCE beamline from the ALBA Synchrotron Light Source. Research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. B.W. and L.Q.C. acknowledge the support from the National Science Foundation (NSF) through Grant No. DMR‐2133373. Part of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE‐AC52‐07NA27344. P.K. acknowledges support of the Intel Corp. as part of the COFEEE program and Army Research Office under the ETHOS MURI via cooperative agreement W911NF‐21‐2‐0162. C.‐.C.L. acknowledges the support of the Army Research Office under W911NF‐21‐1‐0118 and the Taiwan Major Fields Scholarship from the Ministry of Education in Taiwan. L.W.M. acknowledges the support of the National Science Foundation under Grant DMR‐2329111.
Keywords
- origin of ferroelectricity
- phase-change materials
- phase-transition asymmetry
- thermo-elastic energy storage