Influences of annealing temperature on dielectric, magnetic and magnetoelectric coupling properties of 0.7Bi0.5Na0.5TiO3-0.3NiFe2O4 ceramics

•Increased dielectric constant with low loss is observed in studied samples.•Ferromagnetic properties are dependent on the annealing temperature.•Magnetoelectric coupling effect are strongly dependent on annealing temperature. Multiferroic 0.7Bi0.5Na0.5TiO3-0.3NiFe2O4 ceramics were prepared by sol-gel method with various temperatures ranging from 950 to 1100 °C. The influence of annealing temperature on structure, morphology, dielectric, magnetic and magnetoelectric coupling effect was investigated. The refinement of x-ray diffraction data and the thermogravimetric-differential thermal analysis indicated the coexistence of perovskite and spinel phases with annealing temperature above 950 °C. Increasing grain size in surface morphology measurement was closely related to the increasing annealing temperature. Enhancement in dielectric properties was observed with increasing annealing temperature. The room-temperature ferromagnetic properties were also detected with saturated magnetic hysteresis loops under different annealing temperatures. Finally, magnetoelectric coupling effect was confirmed in the samples. The possible factors for room-temperature multiferroic properties were discussed with increasing annealing temperature. This study showed that annealing temperature could evidently affect the multiferroic properties in 0.7Bi0.5Na0.5TiO3-0.3NiFe2O4 solid solution.