Influence of IrO2 addition on magnetoelectric properties of Ni0.5Zn0.5Fe2O4/Ba0.8Sr0.2TiO3 composite ceramics

Abstract

Ni0.5Zn0.5Fe2O4/Ba0.8Sr0.2TiO3 (NZFO/BST) magnetoelectric composites were synthesized through traditional solid-phase method, and effects of IrO2 addition on the microstructure, surface appearance and magnetoelectric properties were comparatively investigated. XRD patterns demonstrate a spinel structure of NZFO and tetragonal perovskite structure of BST, and the addition of IrO2 is conducive to improving the crystallinity of materials. SEM presents that a certain amount of IrO2 is beneficial to the growth of ceramic grains and the densification of ceramics. Through SEM and EDS analysis, it is found that the smaller grain size is BST, and its size is about 100 nm. Sample NZFO/BST-5% has the largest average grain size (~ 277.51), while sample NZFO/BST-1% has a relative density of 91.23%. The relaxation behavior is more obvious with the addition of a certain content of IrO2, which leads to the increase of dielectric constants. In the high temperature region (> 200 ℃), the sample exhibits a large dielectric loss, particularly, the more the content of IrO2, the more obvious this phenomenon is. The addition of IrO2 causes the larger leakage current of NZFO/BST composites so that samples NZFO/BST-3% and NZFO/BST-5% exhibit poor ferroelectricity, in addition, the magnetic properties of the sample are also weakened, and the NZFO/BST composites exhibited a soft ferromagnetic behavior.