In situ observation of reversible domain switching in aged Mn-doped BaTiO_3 single crystals

摘要

Very recently, a giant recoverable electrostrain effect has been found in aged Fe-doped BaTiO_3 single crystals; this effect is based on a defect-mediated reversible domain-switching mechanism. However, the reversible domain-switching process itself is yet to be directly verified. In the present study, we performed in situ domain observation during electric field cycling for an aged Mn-doped BaTiO_3 single crystal and simultaneously measured its polarization (P)-field (E) hysteresis loop. In addition, the electrostrain behavior of the sample was also characterized. Such experimentation made it possible to correlate the mesoscopic domain-switching behavior with the macroscopic properties. It was found that the aged sample shows a remarkable reversible domain switching during electric field cycling; it corresponds very well to a "double" hysteresis loop and a giant recoverable electrostrain effect (with a maximum strain of 0.4%). This provides direct mesoscopic evidence for our reversible domain-switching mechanism. By contrast, an unaged sample shows irreversible domain-switching behavior during electric field cycling; it corresponds to a normal hysteresis loop and a butterfly-type irrecoverable electrostrain behavior. This indicates that the reversible domain switching in the aged sample is related to point-defect migration during aging. We further found that the large recoverable strain is available over a wide frequency range. This is important for the application of this electrostrain effect.