A Novel Percolative Ferromagnetic–Ferroelectric Composite with Significant Dielectric and Magnetic Properties

Abstract

In recent years, with increasing developments in the electronics industry, electronic components have been required with smaller size, higher performance, and multifunction capability. Therefore, composites, especially ferromagnetic-ferroelectric composites, have been attracting more and more attention. [1][2][3] When a ferromagnetic and ferroelectric phase coexist in one material, novel properties, such as magnetoelectric and magneto-optic properties, are expected due to the interaction between magnetization and electric polarization. [1,4] Therefore, much work on ferromagnetic-ferroelectric composites has been carried out. [1][2][3][4][5] However, many reports, including the authors' previous work, [3] indicate that the introduction of low-dielectric-constant (e) ferrite and the defect reaction between the ferrite and ferroelectric phases would result in a low dielectric constant for the composite, which is not compatible with the trend for higher capacitance and smaller size for electronic components. On the other hand, according to percolation theory, the dielectric constant depends strongly on the conductivity ratio of the ferroelectric and ferrite phases: [6][7][8] ). Thus, properties such as high permeability and a high dielectric constant are expected for this ferrite-ferroelectric composite. In this Communication, the magnetic and dielectric properties of the composite were investigated, and a considerable permeability and an unusually high dielectric constant were observed. In other words, we fabricated a composite system combining the merits of both the ferromagnetic-ferroelectric properties and percolative effect. We consider that this experiment could provide a new manufacturing method for ferromagnetic-ferroelectric composites with ultrahigh capacitance.The X-ray diffraction (XRD) patterns are shown in Figure 1. It can be seen that NZFO and BT phases coexisted in the composite. The NZFO had a typical spinel structure and the BT had a tetragonal perovskite structure in all the composites. All of the peaks can be identified and no intermediate phase was observed by using XRD, which indicates that no significant chemical interaction occurred between the BT and NZFO phases.The dielectric and magnetic properties of the ferroelectricferromagnetic composites depended strongly on their microstructure. Therefore, three typical microscopy images of the samples are shown in Figure 2. In the biphase-structured composites, the grain size of the NZFO phase (about 0.8 lm) was much smaller than that in an NZFO single-phase-structured ceramic (about 5 lm). From these observations, it seems that the perovskite phase inhibits the grain growth of NZFO in the composite system. Furthermore, compared to the compact structure of the plain NZFO ceramic (i.e., NZFO volume fraction, f NZFO = 1), large pores appear in the composite with

Multiferroic properties of Ni0.5Zn0.5Fe2O4–Pb(Zr0.53Ti0.47)O3 ceramic composites

“…Moreover, the relative permittivity decreases with increasing NZFO content in the measured temperature range. The observations differ greatly from the literature 13 and suggest the contribution of the dielectric properties of the composites by the PZT phase. The fact that the temperature dependence of relative permittivity is so similar to that of the PZT provides a further proof of the presence of ferroelectricity in the composites.…”

Crucial role of percolation transition on the formation and electromagnetic properties of BaTiO3/Ni0.5Zn0.47Fe2O4 ceramic composites

“…Perovskite/ferrite (ferroelectric/ferrimagnetic) composites are attractive due to their potential application as multiferroic and magneto-dielectric materials [1][2][3][4][5][6][7][8][9]. They can be utilized to fabricate integrated filters [5][6][7][8][9], microwave tunable devices [4,5], and novel magnetoelectric devices [1,2].…”

“…They can be utilized to fabricate integrated filters [5][6][7][8][9], microwave tunable devices [4,5], and novel magnetoelectric devices [1,2].…”

Multifunctional SrTiO3/NiZn ferrite/POE composites with eletromagnetic and flexible properties for RF applications

“…Some previous studies [20][21][22][23] have been carried out on this kind of composites. However, the composites obtained have a common deficiency of possessing very high loss and low cut-off frequency below 1GHz, which limits their practical high-frequency application.…”