The complex nature of the structural disorder in the lead-free ferroelectric $\mathrm{N}{\mathrm{a}}_{1/2}\mathrm{B}{\mathrm{i}}_{1/2}\mathrm{Ti}{\mathrm{O}}_3$ has a profound impact on the perceived global structure and polar properties. In this paper, we have investigated the effect of electric field and temperature on the local structure around the Bi and Ti atoms using extended x-ray absorption fine structure. Detailed analysis revealed that poling brings about a noticeable change in the bond distances associated with the Bi-coordination sphere, whereas the Ti coordination remains unaffected. We also observed discontinuity in the Bi-O bond lengths across the depolarization temperature of the poled specimen. These results establish that the disappearance of the monoclinic-like ($Cc$) global distortion, along with the drastic suppression of the short-ranged in-phase octahedral tilt after poling [B. N. Rao et al., Phys. Rev. B 88, 224103 (2013)] is a result of the readjustment of the A-O bonds by the electric field, so as to be in conformity with the rhombohedral $R3c$ structure.

• Received 6 November 2015

DOI:https://doi.org/10.1103/PhysRevB.93.024106