Atomic Insight into the Successive Antiferroelectric–Ferroelectric Phase Transition in Antiferroelectric Oxides

Abstract

Antiferroelectrics characterized by voltage-driven reversible transitions between antiparallel and parallel polarity are promising for cutting-edge electronic and electrical power applications. Wide-ranging explorations revealing the macroscopic performances and microstructural characteristics of typical antiferroelectric systems have been conducted. However, the underlying mechanism has not yet been fully unraveled, which depends largely on the atomistic processes. Herein, based on atomic-resolution transmission electron microscopy, the deterministic phase transition pathway along with the underlying lattice-by-lattice details in lead zirconate thin films was elucidated. Specifically, we identified a new type of ferrielectric-like dipole configuration with both angular and amplitude modulations, which plays the role of a precursor for a subsequent antiferroelectric to ferroelectric transformation. With the participation of the ferrielectric-like phase, the phase transition pathways driven by the phase boundary have been revealed. We provide new insights into the consecutive phase transformation in low-dimensional lead zirconate, which thus would promote potential antiferroelectric-based multifunctional devices.

Research status and prospect of lead zirconate-based antiferroelectric films

“…8 该发现颠覆了长期以来对PZO相变过程的传统认知 [47] ；此外，Si上面生长的PZO 多晶薄膜研究中也观察到具有不相称的调制特性的FiE结构 [7] ，如图3(b)所示， 这是由于长程FE相和短程AFE相之间的竞争失败，在这种情况下，未补偿的不相 称调制转化为零电场下的净剩余极化；Lane W. Martin等通过改变脉冲激光沉积 过程中的氧压(从而改变原子动能和随后的轰击效应)，发现反铁电PZO薄膜的 极化行为可以受到点缺陷的强烈影响，沉积过程中氧压的降低导致了意想不到的 "类铁电"特性，并且通过电场调节可以观察到从AFE到"类铁电"的有趣演变 [48] ， 如图3(c)所示。到目前为止关于AFE薄膜中弱FE的结构和性能认识都没有达到 共识，由于薄膜易受到界面、应变、缺陷等因素影响，AFE薄膜中观察到的非中 心对称结构和弱FE行为是否为本征特性，尚待进一步考证。 2.2 电学特性 图4 (a) PZO块体的介电温谱图 [3] ；(b) PZO基反铁电薄膜的C-V特性曲线 [52] ；(c) PZO薄膜的P-E和I-E回线 [50] ； (d) PZO薄膜在直流电场E DC 和交流电场E AC 作用下的 电致应变和压电系数 [7] Fig. 4.…”

“…a) 改变电子束辐照时间同一区域PZO薄膜的电场驱动相变行为 [47] ；(b) 从 (001)和(042)取向PZO薄膜中铅离子位移提取的极化构型 [7] ；(c) 不同生长氧压 (120mTorr，80mTorr和45mTorr) PZO薄膜的极化行为 [48] Fig. 3.…”

“…3. (a) Phase-boundary-driven phase transition in PZO films under the irradiation of an electron beam [47] ; (b) Polarization configurations extracted from Pb ions displacements in (001) and (042) oriented PZO films [7] ; (c) Polarization-electric field loops of PZO grown at various oxygen pressures (120 mTorr, 80 mTorr and 45 mTorr) [48] .…”

Low voltage–driven high-performance thermal switching in antiferroelectric PbZrO 3 thin films

“…From the above discussion, to obtain the highest switching ratio in PZO films, two conditions should be satisfied, i.e., the lowest thermal conductivity k off at the “OFF” state and the highest thermal conductivity k on at the “ON” state. For the first condition, the AFE structure at zero field should be pure with small remnant polarization P r since the FE component might easily exist in PZO films ( 40 , 41 ) and thus increase k off . For the second condition, a wider-range modulation of n is beneficial since smaller n in the FE structure can lead to a higher k on .…”

A Polyvinylidene Fluoride‐Hexafluoropropylene (PVDF‐HFP)/Carboxylated g‐C3N4 Composite Separator for High‐Performance Lithium‐Ion Batteries

“…[14,15] PVDF-HFP has been widely studied in composite separators due to its high melting point, dielectric constant, and low glass transition temperature. The commonly used inorganic nanoparticles are SiO 2 , [16] TiO 2 , [17] Al 2 O 3 , [18] CaCO 3 , [19] and so on. PVDF/ TiO 2 nanoparticle composite separator was prepared with a high liquid absorption rate by phase inversion.…”