Structural, morphological and piezoresponse studies of Pr and Sc co-substituted BiFeO ₃ ceramics

Pristine (BiFeO ₃), Pr and Sc co-substituted Bi _0.9Pr _0.1Fe _1xSc _xO ₃ (0.01x0.07) ceramics have been investigated for their structural (including x-ray diffraction and Raman), morphological and piezoresponse behaviour. Secondary phases observed in pristine BiFeO ₃ (BFO) ceramic were significantly suppressed in the co-substituted samples. Grain size decreased in the co-substituted samples. Raman study revealed ten active phonon modes which remained almost invariant with co-substitution. Out-of-plane piezoresponse (OPP-PFM) exhibited negative self-polarization effect in the virgin state (without any poling) which has been explained in terms of built-in electric field. The self-polarization effect is largest in 3% Sc co-substituted sample. Poling with 30V dc voltage demonstrated both positive and negative domains. Maximum difference in the peak values (from histograms) of such opposite domains was observed in the Bi _0.9Pr _0.1Fe _0.99Sc _0.01O ₃ sample. Information from local measurements (such as PFM) should be useful in deciding such multiferroic materials for device application.