Enhanced dielectric, ferroelectric, and ferromagnetic responses of BaZr0.2Ti0.8O3–Ni0.5Zn0.5Fe2O4 multiferroic ceramic composite

Abstract

Pure BaZr0.2Ti0.8O3, pure Ni0.5Zn0.5Fe2O4, and 80BaZr0.2Ti0.8O3–20Ni0.5Zn0.5Fe2O4, 70BaZr0.2Ti0.8O3–30Ni0.5Zn0.5Fe2O4, and 60BaZr0.2Ti0.8O3–40Ni0.5Zn0.5Fe2O4 multiferroic composites were prepared by a solid-state sintering method, and their structural, morphological, electrical (dielectric and ferroelectric), and magnetic properties were analyzed. A perovskite tetragonal phase (BaZr0.2Ti0.8O3) and a cubic spinel phase (Ni0.5Zn0.5Fe2O4) were simultaneously present in each composite. Peak shifting toward higher angles was observed for the 80BaZr0.2Ti0.8O3–20Ni0.5Zn0.5Fe2O4 and 70BaZr0.2Ti0.8O3–30Ni0.5Zn0.5Fe2O4 composites. BaZr0.2Ti0.8O3 part of all the composites demonstrated tensile strain value, while Ni0.5Zn0.5Fe2O4 part exhibited compressive strain values. A grain growth reduction phenomenon was observed with increasing Ni0.5Zn0.5Fe2O4 content in the composites. The largest average grain size was obtained for 80BaZr0.2Ti0.8O3–20Ni0.5Zn0.5Fe2O4 (933.23 ​nm), while the values for 70BaZr0.2Ti0.8O3–30Ni0.5Zn0.5Fe2O4 and 60BaZr0.2Ti0.8O3–40Ni0.5Zn0.5Fe2O4 composites were 843.07 ​nm, 718.35 ​nm, respectively. All composites exhibited giant dielectric constants because of the electron hopping phenomenon between ​Fe2+and ​Fe3+. The 60BaZr0.2Ti0.8O3–40Ni0.5Zn0.5Fe2O4 composite exhibited the highest dielectric constant of 88217.31 ​at 100 ​Hz. Similarly, it showed an enhanced dielectric loss of 2.77 (at 100 ​Hz). The 80BaZr0.2Ti0.8O3–20Ni0.5Zn0.5Fe2O4 composite exhibited the highest remnant polarization (13.58 ​μC ​cm−2), charge density (0.28 ​J ​cm−3), and discharge density (0.20 ​J ​cm−3) among the synthesized composites. However, 70BaZr0.2Ti0.8O3–30Ni0.5Zn0.5Fe2O4 exhibited the largest energy storage efficiency of 75%. Although pure BaZr0.2Ti0.8O3 did not show any response to an applied magnetic field, meaningful hysteresis loops were obtained for pure Ni0.5Zn0.5Fe2O4 and the (1-x)BaZr0.2Ti0.8O3-xNi0.5Zn0.5Fe2O4 composites. In addition, 60BaZr0.2Ti0.8O3–40Ni0.5Zn0.5Fe2O4 showed the highest saturation magnetization (17.52 emu/g) and remnant magnetization (0.92 emu/g) among the synthesized composites. Eventually, (1-x)BaZr0.2Ti0.8O3-xNi0.5Zn0.5Fe2O4 composites showed better performance compared to pure BaZr0.2Ti0.8O3 and Ni0.5Zn0.5Fe2O4 ceramics.