Ievlev Anton V, Kc Santosh, Vasudevan Rama K, Kim Yunseok, Lu Xiaoli, Alexe Marin, Cooper Valentino R, Kalinin Sergei V, Ovchinnikova Olga S
The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Nat Commun. 2019 Jul 11;10(1):3064. doi: 10.1038/s41467-019-11089-w.
The unique properties of ferroelectric materials enable a plethora of applications, which are hindered by the phenomenon known as ferroelectric fatigue that leads to the degradation of ferroelectric properties with polarization cycling. Multiple microscopic models explaining fatigue have been suggested; however, the chemical origins remain poorly understood. Here, we utilize multimodal chemical imaging that combines atomic force microscopy with time-of-flight secondary mass spectrometry to explore the chemical phenomena associated with fatigue in PbZrTiO (PZT) thin films. Investigations reveal that the degradation of ferroelectric properties is correlated with a local chemical change and migration of electrode ions into the PZT structure. Density functional theory simulations support the experimental results and demonstrate stable doping of the thin surface PZT layer with copper ions, leading to a decrease in the spontaneous polarization. Overall, the performed research allows for the observation and understanding of the chemical phenomena associated with polarization cycling and their effects on ferroelectric functionality.
铁电材料的独特性能使其具有众多应用，但一种名为铁电疲劳的现象阻碍了这些应用，铁电疲劳会导致铁电性能随极化循环而退化。人们已经提出了多种解释疲劳的微观模型；然而，其化学根源仍知之甚少。在此，我们利用将原子力显微镜与飞行时间二次质谱相结合的多模态化学成像技术，来探究与PbZrTiO（PZT）薄膜疲劳相关的化学现象。研究表明，铁电性能的退化与局部化学变化以及电极离子向PZT结构中的迁移有关。密度泛函理论模拟支持了实验结果，并证明了铜离子对PZT薄膜表面层的稳定掺杂，导致自发极化降低。总体而言，所开展的研究使得人们能够观察和理解与极化循环相关的化学现象及其对铁电功能的影响。
