Vertsioti G, Zhang S J, Stamopoulos D
Department of Solid State Physics, National and Kapodistrian University of Athens, Zografou Panepistimioupolis, Athens, Greece.
Institute of Nanoscience and Nanotechnology, National Center for Scientific Research 'Demokritos', Aghia Paraskevi, Athens, Greece.
Sci Rep. 2019 Feb 18;9(1):2178. doi: 10.1038/s41598-019-38675-8.
Composite magnetoelectric compounds that combine ferroelectricity/piezoelectricity and ferromagnetism/magnetostriction are investigated intensively for room-temperature applications. Here, we studied bulk composites of a magnetostrictive constituent, ferromagnetic FeO nanoparticles, homogeneously embedded in a ferroelectric/piezoelectric matrix, Pb(ZrTi)O (PZT). Specifically, we focused on PZT-5%FeO samples which are strongly insulating and thus sustain a relatively high out-of-plane external electric field, E. The in-plane strain-electric field curve (S(E)) was carefully recorded upon successive application and removal of an out-of-plane external magnetic field, H. The obtained S(E) data exhibited two main features. First, the respective in-plane piezoelectric coefficients, d(E) = 200-250 pm/V, show a dramatic decrease, 50-60%, upon application of a relatively low H = 1 kOe. Second, the process is completely reversible since the initial value of d(E) is recovered upon removal of H. Polarization data, P(E), evidenced that the FeO nanoparticles introduced static structural disorder that made PZT harder. Taken together, these results prove that the FeO nanoparticles, except for static structural disorder, introduce reconfigurable magnetic disorder that modifies the in-plane S(E) curve and the accompanying d(E) of PZT when an external magnetic field is applied at will. The room-temperature feasibility of these findings renders the PZT-x%FeO system a solid basis for the development of magnetic-field-controlled PE devices.
结合铁电性/压电性与铁磁性/磁致伸缩性的复合磁电化合物因其室温应用而受到深入研究。在此，我们研究了一种磁致伸缩成分——铁磁性FeO纳米颗粒均匀嵌入铁电/压电基体Pb(ZrTi)O（PZT）中的块状复合材料。具体而言，我们重点关注PZT - 5%FeO样品，该样品具有强绝缘性，因此能够承受相对较高的面外外部电场E。在连续施加和去除面外外部磁场H时，仔细记录了面内应变 - 电场曲线（S(E)）。所获得的S(E)数据呈现出两个主要特征。首先，各自的面内压电系数d(E) = 200 - 250 pm/V，在施加相对较低的H = 1 kOe时，显示出急剧下降，下降幅度为50 - 60%。其次，该过程是完全可逆的，因为去除H后面内压电系数d(E)会恢复到初始值。极化数据P(E)表明，FeO纳米颗粒引入了静态结构无序，使PZT变硬。综合来看，这些结果证明，除了静态结构无序外，FeO纳米颗粒还引入了可重构的磁无序，当随意施加外部磁场时，这种磁无序会改变PZT的面内S(E)曲线以及伴随的d(E)。这些研究结果在室温下的可行性使PZT - x%FeO系统成为开发磁场控制压电电子器件的坚实基础。
