Magnetoelectric perovskite (Bi0.5Pb0.5)(Fe0.5Zr0.5)O3: Preparation,structural and magnetic properties

The perovskite (Bi_0.5Pb_0.5)(Fe_0.5Zr_0.5)O₃ was synthesized by solid-state reaction in an attempt to find magnetoelectric materials, in which ferroelectricity and ferromagnetism coexist. This complex perovskite has been studied by X-ray and neutron powder diffraction in combination with magnetic measurements. The compound crystallizes in the orthorhombic space group Pbam with a ～ √2a_p, b ～ 2√2a_p and c ～ 2a_p (with a_p ～ 4.057 Å). The field and temperature dependence of the magnetization combined with neutron diffraction data showed antiferromagnetic behavior with the Neel temperature, T_N ～ 450 K. Rietveld refinements of neutron powder diffraction data collected at different temperatures, between 10 and 700 K, have been carried out in order to extract information about the thermal evolution of the nuclear and magnetic structures. A distorted orthorhombic perovskite structure was found within the whole temperature interval. The Bi/Pb and Fe/Zr ions were found to be partially ordered over the perovskite A-site and disordered over the B-site. The neutron diffraction patterns of the (Bi_0.5Pb_0.5)(Fe_0.5Zr_0.5)O₃ sample showed evidence of a long-range magnetic ordering below T_N with a propagation vector k = (0,0,0) and an antiferromagnetic arrangement of the magnetic moments of the Fe³⁺ cations in the B-site. This is consistent with an A_y-type magnetic structure. The factors governing the structural and magnetic properties of (1 ? x)BiFeO₃–xPbZrO₃ solid solutions are discussed and compared with those of pure BiFeO₃ and PbZrO₃. A solid solution strategy for developing magnetoelectric properties in BiFeO₃-based compounds is described, with the aim of realizing both a spontaneous polarization and magnetization at room temperature.