Growth and Piezoelectric Properties of Centimeter-Size BiFeO₃ Single Crystals Codoped with Sr and Ti Ions

Abstract

A BiFeO 3 crystal has both antiferromagnetism and piezoelectricity at room temperature. Unfortunately, it is difficult to grow a larger-size and high-quality BiFeO 3 single crystal. By a top-seeded solution growth method using Bi 2 O 3 as a solvent, centimeter-size Bi 1−x Sr x Fe 1−y Ti y O 3 crystals were successfully grown in this paper. Moreover, the lattice symmetry of the Bi 1−x Sr x Fe 1−y Ti y O 3 crystals changes from rhombohedra to cube with the increase in Sr 2+ and Ti 4+ doping concentration. The magnetization of a Bi 0.6 Sr 0.4 Fe 0.6 Ti 0.4 O 3 crystal reaches 0.25 emu/g at room temperature, which is about 3.1 times as large as that of a BiFeO 3 single crystal, in an applied magnetic field of 10,000 Oe. The piezoelectric effect is observed on all Bi 0.8 Sr 0.2 Fe 0.8 Ti 0.2 O 3 -2 wafers; especially, strong response was observed on the ⟨111⟩-oriented wafer. By optimizing the type and the concentration of doped ions, it is expected to obtain large-size doped BiFeO 3 single crystals with better magnetic and piezoelectric properties.