Ferroelectric and magnetic properties of magnetoelectric (Na0.5Bi0.5)TiO3–BiFeO3 synthesized by acetic acid assisted sol–gel method

The perovskite solid solution system resulting from the combination of Na0.5Bi0.5TiO3 (NBT) and BiFeO3 (BFO) has been studied for its magnetoelectric properties in BFO-rich phases of the series, using magnetometry and piezoresponse force microscopy (PFM). Raman spectroscopy results confirmed the successful formation of solid solutions having spectral features that are combination of two parent compounds. The solid solutions displayed a variable bandgap in the range 2.12–2.39 eV with composition. The results of PFM suggest an improved spontaneous polarization with the progressive replacement of (Na,Bi)2+ and Ti4+ ions at A- and B-sites of BFO lattice. At the same time room temperature weak ferromagnetic response was seen in mixed compositions. A systematic shift in magnetic transition temperatures from 650 K to 410 K was observed with the increase of NBT content. Magnetoelectric (ME) coefficient of 9 mV/cm-Oe was obtained for 40NBT–60BFO composition. Our studies indicate that NBT–BFO solid solution system is a potentially useful candidate for lead-free single phase ME applications.