Quenching-induced enhancement of ferroelectricity via electron density redistribution and Bi off-centering

Le résumé fourni par la source

The structural origin of quenching-induced enhancement in the ferroelectricity of 0.95(0.33BaTiO 3 –0.67BiFeO 3 )–0.05Bi(Mg 0.5 Ti 0.5 )O 3 ceramics was investigated using synchrotron radiation X-ray diffraction and electron density analysis. Rietveld refinement revealed that both as-sintered and quenched ceramics possessed a rhombohedral structure ( R 3 m ), and Bi ions were off-centered in the (100) directions at 300 K. Electron density analysis indicated that the quenching-induced enhancement in ferroelectricity originated from an enhanced asymmetry in the electron density distribution between the upper ([100], [010], and [001]) and lower ([ 1 ― 00 ] , [0 1 ― 0 ] , and [00 1 ― ] ) sites and a larger off-centering displacement of Bi ions. These cooperative mechanisms enhanced the local dipole moment associated with the off-centered Bi ions while suppressing polarization cancellation between the upper and lower sites, yielding enhanced spontaneous polarization along the [111] direction. These findings provide novel insights into the mechanisms underlying the quenching-induced enhancement in the functional properties of Bi-based, lead-free piezoelectric ceramics.

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