Structure, Magnetic, and Ferroelectric Properties of Bi_1-<i>x</i>Gd_<i>x</i>FeO₃ Nanoparticles

Abstract

Bi1-xGdxFeO3 (x = 0, 0.1, 0.2, 0.3) nanoparticles were synthesized by polyol-mediated method. They show a compositional-driven phase transition from a rhombohedral phase (R3c) for x = 0 to an orthorhombic phase (Pn21a) for x = 0.2 and 0.3, and x = 0.1 is a mixture of both phases. Improved ferroelectric hysteresis loops are observed at room temperature for all samples with moderate polarization values. The substitution of Gd ions for Bi enhances the ferromagnetic properties of this system. A large saturated magnetization of 0.11 μB/f.u. is obtained at 300 K, which is mainly attributed to the antiferromagnetic core and ferromagnetic surface of the nanoparticles, together with the structural distortion. Temperature- and field-dependence of magnetization curves reveal the frustrated magnetic behavior of this system. The variation of magnetic behaviors at different reaction temperatures is also related to the competition between canted antiferromagnetic Fe sublattice and paramagnetic Gd sublattice.