PROPERTIES OF BaTiO3 -NiZnFe2O4 MULTIFERROIC COMPOSITES OBTAINED BY AUTO-COMBUSTION SYNTHESIS

Abstract

Nickel zinc ferrite (NZF(70-30)) and barium titanate (BT) nanosized powders were synthesised by auto-combustion method. Multiferroic composites with the general formula xNi0.7Zn0.3Fe2O4–(1-x)BaTiO3 (x = 0.1, 0.3, 0.5, 0.7, 0.9) were prepared from nickel zinc ferrite and barium titanate powders by mixing in planetary ball mill for 24 h. Pellets were sintered at different temperatures in order to get dense, two phased composites. XRD characterization showed the formation of nickel zinc ferrite spinel structure and perovskite barium titanate structure, without presence of secondary phases. SEM images at the free surface indicated the formation of two types of grain morphology: polygonal grains typical for NZF phase and rounded grains typical for BT phase, both nanosized . Magnetic measurements of all sintered composites were carried out and presented in Figure 1. Saturation magnetization moment decreases in comparison with pure NZF, because of non-magnetic barium titanate phase. Coercive field was higher for composites with regard to pure NZF, which can be explained with fact that the composite possesses a higher anisotropy field than the NZF at the same applied field. The fields at which saturation occur was almost the same for all materials.