Ponente
Descripción
Partial ion substitution was used to reduce the required electric field that reorients the polarization state of of BiFeO3 films. Ions of Ba, Ta, and Cr were introduced in the BiFeO3 structure through the solid-state reaction method to produce a ceramic Bi0.9Ba0.1Fe0.94Ta0.05Cr0.01O3 (BBFTCO) target, which was ablated with a pulsed laser to produce thin films. The BBFTCO films presented a rhombohedral crystal structure of space group R3c like BiFeO3 films. Ferroelectric switching experiments were performed using an atomic force microscope and a conductive probe. The coercive field is ~50% lower for BBFTCO films than BiFeO3 films, which was attributed to a weakening of Asites-O bonds caused for the Ba incorporation. Ferroelectric switching under different mechanical loadings on a BBFTCO film was performed. As the mechanical loading increased, it was observed that the piezoresponse improved and the coercive field shifted, which can be due to the flexoelectric effect caused by the small radius of curvature of the probe. Conductive maps reveal no distinction between conductivity per grain and conductivity per grain boundary on the BBFTCO film, whereas in BiFeO3 films the grain conducts more than the grain boundary. Finally, charge injection during the electrical writing on the BBFTCO film resulted in ferroelectric hysteresis loops with imprint effect, which moves the coercive field location.
Keywords: ferroelectrics; hysteresis loops; imprint effect; ferroelectric domain switching; bismuth ferrite; flexoelectricity.
