強誘電体の長年の論争を解明する新手法（New Technique Sheds Light on Longstanding Debates About Ferroelectric Materials）

2026-07-13 ノースカロライナ州立大学（NC State）

米国ノースカロライナ州立大学（NC State University）の研究チームは、強誘電体が電気的な性質を変化させる仕組みについて、新たな知見を明らかにした。強誘電体は、外部から電圧を加えると内部の電気分極の向きが反転する性質を持ち、不揮発性メモリーやセンサーなどに利用されている。しかし、分極がどのように切り替わるかは十分に理解されていなかった。研究チームは、高度な顕微鏡観察と理論解析を組み合わせ、分極反転の過程では原子レベルでの構造変化やドメイン境界の動きが重要な役割を果たすことを詳細に解明した。この成果により、分極の切り替えをより効率的に制御するための設計指針が得られ、消費電力が低く、高速で動作する次世代メモリーや電子デバイスの開発につながると期待されている。また、強誘電材料の基本的な物性理解を深める成果としても重要である。

＜関連情報＞

電気分極および脱分極中のリアルタイム強誘電体ドメイン壁ダイナミクス Real-Time Ferroelectric Domain Wall Dynamics During Electric Poling and Depoling

Ziqi Wang, Zhengze Xu, Anastasia Timofeeva, Hossam Elnaggar, Sipan Liu, Yusen Pei, Reece Henry, Brendan O’Connor, Eunkyoung Shim, Franky So, Kara Peters, Xiaoning Jiang, Jun Liu
Advanced Science Published: 09 July 2026
DOI:https://doi.org/10.1002/advs.76513

ABSTRACT

Electrical poling protocols, including alternating current poling (ACP), direct current poling (DCP), and electrical depoling (EDP), are widely used to optimize the electromechanical properties of relaxor-lead titanate (PT) ferroelectric single crystals. However, the microscopic mechanisms governing their distinct outcomes remain unresolved, largely due to the lack of direct, real-time, and in-situ experimental access to domain wall dynamics during poling. As a result, competing interpretations based on domain refinement, domain coarsening, or polarization switching have emerged from ex-situ imaging and bulk-averaged electromechanical measurements. Here, we track domain wall-related birefringence dynamics in [110]-oriented lead indium niobate-lead magnesium niobate-lead titanate single crystals during ACP, DCP, and EDP using instant polarized light microscopy π (IPOLπ). This single-shot, non-destructive technique enables continuous, real-time tracking of domain wall nucleation, motion, and reconfiguration throughout the poling/depoling process. We reveal distinct, field-dependent dynamic pathways for different electrical protocols, demonstrating pronounced path dependence and reversibility that are not evident from static domain configurations alone. These results identify domain wall dynamics as the dominant mechanism governing electrical poling and depoling in relaxor-PT ferroelectrics and provide a dynamic framework for rational domain wall engineering in high-performance electromechanical materials.

瞬間偏光顕微鏡による強誘電体単結晶中のドメイン壁のその場観察 In situ imaging of domain walls in ferroelectric single crystals by instant polarized light microscopy

Anastasia Timofeeva;Ziqi Wang;Zhengze Xu;Sipan Liu;Yusen Pei;Hossam Elnaggar;Franky So;Eunkyoung Shim;Xiaoning Jiang;Jun Liu;Kara Peters
Review of Scientific Instruments Published:March 02 2026
DOI:https://doi.org/10.1063/5.0299682

Ferroelectric domain walls separate regions of uniform polarization in ferroelectric materials, and their controlled manipulation, such as through electric poling, is essential for enhancing the electromechanical performance of advanced ferroelectric devices. While most existing imaging techniques only examine static domain structures at the pre- or post-poling state, real-time, in situ, and non-destructive visualization of internal domain wall dynamics during electric poling using a simple implementation remains a significant challenge. In this work, we present a simple and accessible optical technique, instant polarized light microscopy (IPOLπ), for through-volume, single-shot, and in situ observation of domain wall evolution during electric poling. Demonstrated on [110]-oriented Pb(In₁/₂Nb₁/₂)O₃–Pb(Mg₁/₃Nb₂/₃)O₃–PbTiO₃ single crystals, IPOLπ enables direct observation of polarization dynamics during alternating current poling and electrical depoling. The method reveals the formation of layered domain structures initiating at sample edges and progressing inward, as well as the correlation between optical birefringence changes and electrical current response. This low-cost, robust technique provides a powerful tool for studying real-time domain wall behavior, offering new insights into structure–property relationships in functional ferroelectric crystals.