Stress-modulated relaxor-to-ferroelectric transition in lead-free(Na1/2Bi1/2

Abstract

The effect of external mechanical fields on relaxor 0.94(Na 1/2 Bi 1/2 )TiO 3 -0.06BaTiO 3 was investigated by means of temperature-and stress-dependent dielectric constant measurements between 223 and 673 K. Analogous to previous investigations that showed an electric-field-induced ferroelectric long-range order in relaxor ferroelectrics, we show that compressive stress can also result in the transition to the long-range ferroelectric order, marked by the formation of an anomaly in the permittivity-temperature curves and a nonlinear, remanent change in permittivity during mechanical loading. In situ stress-dependent high-energy x-ray diffraction experiments were performed at room temperature and reveal an apparent phase transition during mechanical loading, consistent with previous macroscopic electrical measurements. The transition lines between the relaxor states and the stress-induced ferroelectric state were determined at constant temperatures with stress-dependent dielectric constant measurements, providing a stress-temperature phase diagram.

Phase‐Field Study of Electromechanical Coupling in Lead‐Free Relaxor/Ferroelectric‐Layered Composites

“…After removal of the poling field, the FE layer remains in the poled state, while the RE layers return to the nonpolar state. [47,48] In contrast, if a soft interphase layer is introduced, the FE and RE layers are mechanically uncoupled, which is confirmed by the finite element results shown in Figure 8c. Finite element simulations shown in Figure 8a demonstrate that the FE layer is in tension parallel to the interface, while the two RE layers experience compressive stress.…”

Domain‐scale imaging to dispel the clouds over the thermal depolarization of Bi0.5Na0.5TiO3‐based relaxor ferroelectrics

“…Intermediated by the transitional tilting system, domain reorientation or domain wall movement of these nano‐domains gave no negative effects on the piezoelectric strain, as the first cycle SS‐PFM results provided in Figure B. The external E ‐field will distort the local structure of these polar regions and their surrounding weak polar regions to the R 3 c ( a − a − a − anti‐phase tilting) preferably, leading to a mechanical mismatch among polar entities with different polarization orientations . To minimize the elastic energy, this mechanical mismatch stress can be relieved by self‐organization of nano‐domains into ordered large‐sized bulk domain shown in Figure C (extracted from Figure A), resulting in the suppressed permittivity ( ε r = 849 @ 100 Hz) and the macroscopically observed RE‐FE state transition .…”

“…The external E-field will distort the local structure of these polar regions and their surrounding weak polar regions to the R3c (a − a − a − anti-phase tilting) preferably, leading to a mechanical mismatch among polar entities with different polarization orientations. [24][25][26] To minimize the elastic energy, this mechanical mismatch stress can be relieved by self-organization of nano-domains into ordered large-sized bulk domain shown in Figure 6C (extracted from Figure 3A), resulting in the suppressed permittivity (ε r = 849 @ 100 Hz) and the macroscopically observed RE-FE state transition. 13,24,[26][27][28][29][30][31] Because of the thermal activation, those areas sharing the different orientation potential in the bulk domain start to fluctuate (extracted from Figure 3C,D).…”

“…[24][25][26] To minimize the elastic energy, this mechanical mismatch stress can be relieved by self-organization of nano-domains into ordered large-sized bulk domain shown in Figure 6C (extracted from Figure 3A), resulting in the suppressed permittivity (ε r = 849 @ 100 Hz) and the macroscopically observed RE-FE state transition. 13,24,[26][27][28][29][30][31] Because of the thermal activation, those areas sharing the different orientation potential in the bulk domain start to fluctuate (extracted from Figure 3C,D). 13,26 When the material is heated to T d region and above, the oriented bulk domain breaks up into smaller sized polar clusters with different orientations, leading to the loss of macroscopic polarization.…”

Revealing the core-shell interactions of a giant strain relaxor ferroelectric 0.75Bi1/2Na1/2TiO3-0.25SrTiO3

“…In addition to these advancements, it has been shown that the strain mechanisms behind large electrostrain materials can be highly complex, and not only piezoelectricity but also rotostriction might play a crucial role19. Recent studies highlighted that the strain state20 and intergranular constraints could greatly influence the phase transitions leading to a giant strain, thus paving the way to new potential developmental routes1921.…”