Room-temperature multiferroic properties of Ba2+ doped 0.7Bi0.5Na0.5TiO3-0.3NiFe2O4 ceramics

Abstract The 0.7(Bi 0.5 Na 0.5 ) 1- x Ba x TiO 3 -0.3NiFe 2 O 4 samples ( x  = 0.02–0.12) have been synthesized through sol-gel method. Structure, micromorphology and the room-temperature multiferroic properties have been investigated, respectively. The characterization of structure and micromorphology reveals the coexistence of two different phases. In addition, lattice deformation and morphology variation can be clearly confirmed with doping Ba ions. Dielectric properties are improved evidently from x  = 0.02–0.08 and then weakened from x  = 0.08–0.12 with enough low values of dielectric loss for all the samples. The ferroelectric polarization demonstrates that room-temperature ferroelectric properties are monotonously enhanced with increasing content of Ba. The change tendency of magnetic properties is firstly decreasing and then increasing with the special content value of x  = 0.08. Room-temperature magnetoelectric coupling effect is verified by the measurement of magnetoelectric coupling coefficient. The variation trend of magnetoelectric coupling coefficient with doping of Ba is similar to that of magnetic properties. The room-temperature multiferroic properties of 0.7(Bi 0.5 Na 0.5 ) 1- x Ba x TiO 3 -0.3NiFe 2 O 4 samples are related to the larger ionic radius of Ba. Furthermore, the special multiferroic behavior with x  = 0.08 can be attributed to the morphotropic phase boundary effect with doping Ba.