Influence of PbZrO3 doping on the structural and magnetic properties of BiFeO3

Solid solutions of the perovskites (1 − x)BiFeO3–xPbZrO3 with x ranging from 0 to 0.2 were synthesized by solid-state reaction in an attempt to find magnetoelectric materials, in which ferroelectricity and ferromagnetism coexist. These complex perovskites have been studied by X-ray and neutron powder diffractions, magnetic and Mössbauer spectroscopic measurements. All samples are single phase with rhombohedrally distorted perovskite structure. The field and temperature dependences of the magnetization of (1 − x)BiFeO3–xPbZrO3 samples showed antiferromagnetic behavior with Neel temperatures, TN = 635 K (x = 0.1) and 500 K (x = 0.2); a weak ferromagnetic moment appeared at TN in both samples reaching about 0.01 μB/Fe at low temperature for the x = 0.1 sample. Mössbauer spectra also support the existence of the magnetic order and are consistent with the presence of high-spin Fe3+ cations located in the octahedral B-site position. Rietveld refinements of neutron powder diffraction data collected at different temperatures, between 10 and 700 K, have been carried out. The structure of these compounds is a rhombohedrally distorted perovskite (space group R3c) within the whole temperature interval. The Bi/Pb and Fe/Zr ions were found to be disordered over the perovskite A- and B-sites, respectively. Neutron diffraction patterns showed evidence of a long-range magnetic ordering below TN with a G-type antiferromagnetic arrangement of the magnetic moments of Fe3+ cations in the B-site. The effect of PbZrO3 doping on BiFeO3 results in a noticeable lattice expansion and a significant decrease of TN. The factors governing the observed structural and magnetic properties of (1 − x)BiFeO3–xPbZrO3 are discussed and compared with those of pure BiFeO3.

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