Solid-state sintering method was used to prepare ceramic materials based on bismuth ferrite, i.e., (BiFeO3)1 − x–(BaTiO3)x and Bi1 − xNdxFeO3 solid solutions and the Aurivillius Bi5Ti3FeO15 compound. The structure of the materials was examined using X-ray diffraction, and the Rietveld method was applied to phase analysis and structure refinement. Magnetoelectric coupling was registered in all the materials using dynamic lock-in technique. The highest value of magnetoelectric coupling coefficient αME was obtained for the Bi5Ti3FeO15 compound (αME ~ 10 mVcm−1 Oe−1). In the case of (BiFeO3)1 − x–(BaTiO3)x and Bi1 − xNdxFeO3 solid solutions, the maximum αME is of the order of 1 and 2.7 mVcm−1 Oe−1, respectively. The magnitude of magnetoelectric coupling is accompanied with structural transformation in the studied solid solutions. The relatively high magnetoelectric effect in the Aurivillius Bi5Ti3FeO15 compound is surprising, especially since the material is paramagnetic at room temperature. When the materials were subjected to a preliminary electrical poling, the magnitude of the magnetoelectric coupling increased 2–3 times.

The aim of the present work was to study magnetoelectric effect (ME) in (BiFeO 3 ) x -(BaTiO 3 ) 1−x solid solutions in terms of technological conditions applied in the samples fabrication process. The rapidly growing interest in these materials is caused by their multiferroic behaviour, i.e. coexistence of both electric and magnetic ordering. It creates possibility for many innovative applications, e.g. in steering the magnetic memory by electric field and vice versa. The investigated samples of various chemical compositions (i.e. x = 0.7, 0.8 and 0.9) were prepared by the solid-state sintering method under three sets of technological conditions differing in the applied temperature and soaking time. Measurements of the magnetoelectric voltage coefficient α ME were performed using a dynamic lock-in technique. The highest value of α ME was observed for 0.7BiFeO 3 -0.3BaTiO 3 solid solution sintered at the highest temperature (T = 1153 K) after initial electrical poling despite that the soaking time was reduced 10 times in this case.

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In this work the results of investigations for (BiFeO3)x(BaTiO3)1-xand Bi1-xNdxFeO3solid solutions are described. Samples were prepared by the conventional solid-state sintering method. X-ray diffraction,57Fe Mössbauer spectroscopy, and magnetoelectric effect measurements were applied as complementary methods to determine the structure and magnetic properties of materials. For (BiFeO3)x(BaTiO3)1-xsolid solutions Mössbauer spectroscopy revealed the relationship between the content of BiFeO3and the magnetic properties of the samples. Moreover, the presence of magnetoelectric coupling in (BiFeO3)x(BaTiO3)1-xsolid solutions was registered at room temperature for the materials sintered at various temperatures. The maximum value of magnetoelectric voltage coefficient was achieved for 0.7(BiFeO3)0.3(BaTiO3) sintered at 1153K. Structure of Bi1-xNdxFeO3solid solutions was investigated in the whole range of concentration. Hyperfine interactions parameters were determined for the first time for these solid solutions.