Synthesis and characterization of novel lead free multiferroic structures

Hybrid ferromagnetic/piezoelectric nanoparticles and ceramics have potential for a wide range of applications due to their tunability, electronic and magnetic properties. Core-shell-type nanostructures of composition BNT-BT0.08 /CoFe2O4 (CF), where BNT-BT0.08 is the abbreviation of bismuth, sodium titanate (Bi0.5 Na0.5TiO3, BNT) doped with 8 mol% barium titanate (BaTiO3, BT) were prepared with different molar ratio of the two phases using the sol-gel synthesis technique. Scanning and transmission electron microscopy confirmed formation of a core- shell structure. XRD pattern of core-shell composites powder reveals only cubic CoFe2O4 and rhombohedral Bi0.5Na0.5TiO3 phases.The densification of the materials is a critical step as the ideal microstructure is nanosized CF grains well dispersed in a BNBT micrometric grains, fully dense matrix. The results of microstructure, dielectric, piezoelectric and magnetic investigations demonstrated that this heterostructures show simultaneously electrical and magnetic behavior, at room temperature.