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Ceramic samples of BaTi 0.95− x Hf 0.05 Co x O 3 (where, x =0.05, 0.1, and 0.15) were prepared through a solid state reaction route and structure, morphology, magnetic and ferroelectric properties have been investigated. Defects play a key role in influencing magnetic as well as the electric properties in the above compositions. Magnetism observed in doped compositions is significantly depended upon Co ion concentration and oxygen vacancies. With increasing of Co ion concentration, the concentration of oxygen vacancies is increased and as a result of which enhanced magnetic effect is observed. The presence of oxygen vacancy forms defect-dipoles with Co and Hf. These defect-dipoles prominently influenced the polarization and coercive field in doped compositions. Although remnant polarization is decreased noticeably in doped compositions, but the ferroelectricity is observed well above room temperature. These results clearly demonstrate the importance of the contribution of defects for observation of room temperature multiferroic properties in Co based BaTiO 3 ceramics. [ABSTRACT FROM AUTHOR]

Abstract: We report the observation of room temperature magnetism and ferroelectricity in polycrystalline BaTi0.95−x Hf0.05Co x O3 ceramics, where x=0.05, 0.1, and 0.15. Magnetic and ferroelectric hysteresis loops are strongly influenced by Co ion doping concentration. Magnetization of doped compositions is enhanced with increasing of Co ion concentration. Room temperature ferromagnetism is also observed in BaTi0.8Hf0.05Co0.15O3. Simultaneously, the saturation electric polarization value is decreased with the increasing of Co ion doping concentration. Our XPS results have revealed the presence of oxygen vacancies in doped samples. Oxygen vacancies have significant influence on magnetic and ferroelectric properties of doped BaTiO3. Observation of room temperature magnetism in our samples may be due to the exchange interactions of cobalt ions through oxygen vacancies. [Copyright &y& Elsevier]

Abstract: Our paper reports structural, magnetic and ferroelectric properties of Ni doped barium titanate. Ceramics samples of BaTi1−x Ni x O3 (here, x=0, 0.05, 0.1, and 0.15) were prepared through solid state sintering technique. It is revealed from structural studies that the phase transformation from tetragonal to hexagonal phase is strongly influenced by Ni doping concentration. Magnetism is induced in doped composition and the value of magnetism is dependent upon Ni ion concentration. This enhanced magnetic effect is likely to originate from carrier-mediated exchange interactions. Ferroelectricity was observed in all samples at room temperature, but it was decreased by Ni doping. [Copyright &y& Elsevier]