Protonation‐Driven Polarization Retention Failure in Nano‐Columnar Lead‐Free Ferroelectric Thin Films
Understanding microscopic mechanisms of polarization retention characteristics in ferroelectric thin films is of great significance for exploring unusual physical phenomena inaccessible in the bulk counterparts and for realizing thin-film-based functional electronic devices. Perovskite (K,Na)NbO<sub>3</sub> is an excellent class of lead-free ferroelectric oxides attracting tremendous interest thanks to its potential applications to nonvolatile memory and eco-friendly energy harvester/storage. Nonetheless, in-depth investigation of ferroelectric properties of (K,Na)NbO<sub>3</sub> films and the following developments of nano-devices are limited due to challenging thin-film fabrication associated with nonstoichiometry by volatile K and Na atoms. Herein, ferroelectric (K,Na)NbO<sub>3</sub> films of which the atomic-level geometrical structures strongly depend on thickness-dependent strain relaxation are epitaxially grown. Nanopillar crystal structures are identified in fully relaxed (K,Na)NbO<sub>3</sub> films to the bulk states representing a continuous reduction of switchable polarization under air environments, that is, polarization retention failures. Protonation by water dissociation is responsible for the humidity-induced retention loss in nano-columnar (K,Na)NbO<sub>3</sub> films. The protonation-driven polarization retention failure originates from domain wall pinning by the accumulation of mobile hydrogen ions at charged domain walls for effective screening of polarization-bound charges. Conceptually, the results will be utilized for rational design to advanced energy materials such as photo-catalysts enabling ferroelectric tuning of water splitting.
Authors
- Hyoung‐Su Han (ORCID: https://orcid.org/0000-0002-7423-2862)
- Si‐Young Choi (ORCID: https://orcid.org/0000-0003-1648-142X)
- Shinuk Cho (ORCID: https://orcid.org/0000-0002-6855-833X)
- Yoon Ki Kim (ORCID: https://orcid.org/0000-0003-1303-072X)
- Myang Hwan Lee
- Ji‐Soo Jang (ORCID: https://orcid.org/0000-0001-6018-7231)
- Tae Kwon Song (ORCID: https://orcid.org/0000-0002-6787-8681)
- Muhammad Sheeraz (ORCID: https://orcid.org/0000-0003-3447-8179)
- Sung Woo Hwang (ORCID: https://orcid.org/0000-0002-0628-2649)
- Tae Heon Kim (ORCID: https://orcid.org/0000-0003-4835-0707)
- Jong Sung Jin (ORCID: https://orcid.org/0000-0003-4507-7450)
- Gi‐Yeop Kim (ORCID: https://orcid.org/0000-0002-3557-5387)
- Sang Don Bu (ORCID: https://orcid.org/0000-0003-4883-1308)
- Seung‐Hyub Baek (ORCID: https://orcid.org/0000-0002-3187-6596)
- Chang Won Ahn (ORCID: https://orcid.org/0000-0003-0613-9823)
- Sang Mo Yang (ORCID: https://orcid.org/0000-0002-4553-137X)
- Eun‐Young Kim (ORCID: https://orcid.org/0000-0001-5885-9473)
- Jong‐Seong Bae (ORCID: https://orcid.org/0000-0003-0039-4030)
- Jae-Yeong Lee (ORCID: https://orcid.org/0000-0002-7827-9836)
- Nguyen Xuan Duong
- Ill Won Kim
Institutions
- Pohang University of Science and Technology (KR)
- Sogang University (KR)
- Changwon National University (KR)
- University of Ulsan (KR)
- Institute for Basic Science (KR)
- Korea Basic Science Institute (KR)
- Korea Institute of Science and Technology (KR)
- Jeonbuk National University (KR)
- Korea University of Science and Technology (KR)
Publication Details
- Journal
- Advanced Science
- Published
- 2024-11-03
- DOI
- https://doi.org/10.1002/advs.202408784
- Citations
- 6
- Primary Topic
- Ferroelectric and Piezoelectric Materials
- Type
- article
- Field-Weighted Citation Impact
- 0.70
Funders
- National Research Foundation
- Pohang University of Science and Technology
- Korea Institute of Science and Technology
- Korea Basic Science Institute
- National Research Foundation of Korea
- Ministry of Science and ICT, South Korea