Pang Jinglin,Duan Tianpeng,Liao Min,Jiang Limei,Zhou Yichun,Yang Qiong,Liao Jiajia,Jiang Jie
As the core component of ferroelectric memories, HfO 2 -based ferroelectric thin films play a crucial role in achieving their excellent storage performance. Here, we improved the ferroelectric properties and domain switching properties through in situ stress loading during annealing. The thin films are annealed under different bending states by applying different stress actions, and it is observed that, within a certain range of stress bending, the optimization of the ferroelectric properties of the annealed thin films can reach an extreme value. Specifically, under the influence of a small electric field, the 2 P r values of thin films annealed at +10 and −10 mm increased by 87.1% and 71.1%, respectively, compared with the unbent films. Additionally, these thin films exhibit extremely high domain wall mobility and excellent domain switching capabilities. Once the ferroelectric phase is formed through in situ stress modulation, it remains stable even under multiple service environments.
J. Sheng,W.P. Cao,W.L. Li,Q.R. Lin,M.L. Li,X. Hou,W.D. Fei
For applications involving high-precision displacement actuators, piezoceramics exhibiting extensive strain and minimal hysteresis are much sought-after. However, achieving extensive strain concurrent with low hysteresis remains a formidable challenge. We hereby propose an innovative design approach, synergistically harnessing compositional and defect engineering, to concurrently boost the strain response and mitigate hysteresis in (Na 0.5 Bi 0.5 )TiO 3 (NBT)-based ceramics. The defect dipoles are elaborately designed and introduced into the mixed rhombohedral ( R ) and tetragonal ( T ) phases system, which causing reversible domain switching, heightening recoverability of electric-field-induced phase transition and augmenting the electrostrictive effect. The synergy of defect dipoles leading to reversible domain switching and electric field-induced phase transitions is further validated via phase-field simulations. Ultimately, a giant strain of 0.62% with low hysteresis of 10.9% and correspondingly high d 33 * of 1033 pm V −1 were concurrently realized in the designed NBST(1- x )Mn x ( x = 0.3%) specimen. This study opens up a feasible and effective way to design piezoelectric materials with both a giant strain and a narrow hysteresis in lead-free actuator materials.
Over the past years, the application potential of ferroelectric nanomaterials with unique physical properties for modern electronics is highlighted to a large extent. However, it is relatively challenging to fabricate inorganic ferroelectric nanomaterials, which is a process depending on a vacuum atmosphere at high temperatures. As significant complements to inorganic ferroelectric nanomaterials, the nanomaterials of molecular ferroelectrics are rarely reported. Here a low-cost room-temperature antisolvent method is used to synthesize free-standing 2D organic–inorganic hybrid perovskite (OIHP) ferroelectric nanosheets (NSs), that is, (CHA) 2 PbBr 4 NSs (CHA = cyclohexylammonium), with an average lateral size of 357.59 nm and a thickness ranging from 10 to 70 nm. This method shows high repeatability and produces NSs with excellent crystallinity. Moreover, ferroelectric domains in single NSs can be clearly visualized and manipulated using piezoresponse force microscopy (PFM). The domain switching and PFM-switching spectroscopy indicate the robust in-plane ferroelectricity of the NSs. This work not only introduces a feasible, low-cost, and scalable method for preparing molecular ferroelectric NSs but also promotes the research on molecular ferroelectric nanomaterials.
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