Giant negative electrostriction and dielectric tunability in a van der Waals layered ferroelectric
Sabine M. Neumayer, Eugene A. Eliseev, Michael A. Susner, Alexander Tselev, Brian J. Rodriguez, John A. Brehm, Sokrates T. Pantelides, Ganesh Panchapakesan, Ste… 展开作者
Sabine M. Neumayer, Eugene A. Eliseev, Michael A. Susner, Alexander Tselev, Brian J. Rodriguez, John A. Brehm, Sokrates T. Pantelides, Ganesh Panchapakesan, Stephen Jesse, Sergei V. Kalinin, Michael A. McGuire, Anna N. Morozovska, Petro Maksymovych, Nina Balke
The interest in ferroelectric van der Waals crystals arises from the potential to realize ultrathin ferroic systems owing to the reduced surface energy of these materials and the layered structure that allows for exfoliation. Here, we quantitatively unravel giant negative electrostriction of van der Waals layered copper indium thiophosphate (CIPS), which exhibits an electrostrictive coefficient Q33 as high as -3.2 m4/C2 and a resulting bulk piezoelectric coefficient d33 up to -85 pm/V. As a result, the electromechanical response of CIPS is comparable in magnitude to established perovskite ferroelectrics despite possessing a much smaller spontaneous polarization of only a few uC/cm2. In the paraelectric state, readily accessible owing to low transition temperatures, CIPS exhibits large dielectric tunability, similar to widely-used barium strontium titanate, and as a result both giant and continuously tunable electromechanical response. The persistence of electrostrictive and tunable responses in the paraelectric state indicates that even few layer films or nanoparticles will sustain significant electromechanical functionality, offsetting the inevitable suppression of ferroelectric properties in the nanoscale limit. These findings can likely be extended to other ferroelectric transition metal thiophosphates and (quasi-) two-dimensional materials and might facilitate the quest towards novel ultrathin functional devices incorporating electromechanical response.
Finite temperature dielectric properties of KTaO$_3$ from first principles and machine learning: Phonon spectra, Barrett law, strain engineering and electrostriction
Stability, Evolution and Switching of Ferroelectric Domain Structures in Lead-free BaZr$_{0.2}$Ti$_{0.8}$O$_3$-Ba$_{0.7}$Ca$_{0.3}$TiO$_3$ System: Thermodynamic Analysis and Phase-field Simulations
无铅铁电体系$(1-x)$ BaZr $_{0.2}$ Ti $_{0.8}$ O $_{3}$ - $x$ Ba $_{0.7}$ Ca $_{0.3}$ TiO $_{3}$中增强的室温机电耦合在$x=0.5$处的BZCT（缩写为BZCT）归因于在末端菱面体（$R$）BZT和四面体（$T$）BCT相之间存在含有中间正交（$O$）相的准同型相区（MPR）。然而，关于BZCT在室温下的形态相变存在模糊性-虽然一些实验表明MPR内存在单个$O$相，但其他实验表明三个极性相（$T+R+O$）共存。因此，为了理解极性相的热力学稳定性及其与BZCT中准同型相变过程中机电开关的关系，我们基于极性各向异性理论建立了一个朗道势。由于固有的电致伸缩各向异性的机电加工的功能的变化，我们建立了我们的潜在的参数和电致伸缩系数之间的相关性。我们还进行了相场模拟的基础上，这种潜力，以证明从单相$O$到三相$T+R+O$在等摩尔组成的电致伸缩各向异性的增加的域配置的变化。无扩散相图和相应的压电系数从我们的模型比较好的实验结果。电致伸缩各向异性的增加增加了在环境温度和压力下的自由能的简并性，导致极性各向异性降低，尽管存在伴随的机电各向异性的增加，其表现为有效纵向和横向压电系数$d_{33}$和$d_{31}$之间的差异的增加。
The Influence of Chemical Strains on the Electrocaloric Response, Polarization Morphology, Tetragonality and Negative Capacitance Effect of Ferroelectric Core-Shell Nanorods and Nanowires
