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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]

We have optimized Gd ion substitution in BiFeO 3 (BFO) and observed prominently change in structural, electrical and magnetic behavior of Bi 1+2x Gd 2x/2 Fe 1−2x O 3 ceramics synthesized through slow step sintering schedule. It is observed that with the increase in concentration of Gd (x=0.1), original structure of BFO is transformed from rhombohedral R 3 c space group to orthorhombic Pn 21 a space group. Surprisingly, unit cell volume is drastically contracted (35% for x=0.2) and the sintered specimen showed enhanced room temperature ferromagnetic behavior although the original BFO is normally G-type antiferromagnetic in nature at 643 K. It is expected that intrinsic chemical pressure within the bulk body built by the substitution of Gd in presence of excess bismuth greatly supported through unidirectional movement of electrical dipole moment with in each individual domain as a result of which suppression of leakage current with enhanced dielectric and ferroelectric hysteresis is observed. [ABSTRACT FROM AUTHOR]