Effect of composition on coupled electric, magnetic, and dielectric properties of two phase particulate magnetoelectric composite

Abstract

The particulate composite materials of ferrite-ferroelectric ceramics viz. nickel-cobalt-copper ferrite (i.e., Ni0.94Co0.01Cu0.05Fe2O4) and barium titanate were synthesized by the double sintering ceramic technique. The presence of constituent phases in the composites was confirmed by x-ray diffraction studies. The average grain size was calculated by using a scanning electron micrograph. The electrical properties such as dc resistivity and thermo-emf were measured as a function of temperature and volume fraction of constituent phases. The ac conductivity was calculated from dielectric data in the frequency range from 100Hzto1MHz. It is concluded that the conduction in the present composites is due to small polarons. The relative dielectric constant measured as a function of applied frequency varies with the variation in the dc resistivity and molar fraction of constituent phases. It shows dispersion in the lower frequency range. The hysteresis behavior was studied to understand the magnetic properties such as saturation magnetization (Ms) and magnetic moment (μB). The static magnetoelectric (ME) voltage coefficient was measured as a function of applied dc magnetic field. It increases first and then falls down with increasing magnetic field. The variation in ME response has been explained in terms of content of ferrite phase, resistivity of composites, and intensity of magnetic field. The maximum ME conversion factor of 637μV∕cmOe was observed for the composite with 30% Ni0.94Co0.01Cu0.05Fe2O4+70% BaTiO3. These composites may be useful as phase shifters, magnetic sensors, cables, etc.

Influence of Cr<sup>3+</sup> Ion on the Dielectric Properties of Nano Crystalline Mg-Ferrites Synthesized by Citrate-Gel Method

“…In the high frequency region, which corresponds to a low resistivity (due to the grains), small energy is required for electron transfer between the two Fe ions at the octahedral site. Moreover, the dielectric loss factor also depends on a number of factors such as stoichiometry, Fe 2+ content, and structural homogeneity which in turn depend upon the composition and sintering temperature of the samples [21].…”

Effect of cobalt substitution on structural, magnetic and electric properties of nickel ferrite

“…It is well known that the cobalt, copper, lithium and zinc-doped Ni ferrite have also been studied in order to improve the resistivity, permeability, magnetization and coercive field, etc. [3][4][5][6]. The investigation of ferromagnetic resonance properties in Ni (1−x) Co x Fe 2 O 4 with low cobalt concentration (X < 0.1) were performed by many workers [7][8][9][10].…”

Effect of Gd3+ substitution on the structural and electrical properties of Mg0.75Zn0.25Fe2O4 nanoparticles

“…The conductivity is found to decrease with gadolinium ion concentration. The conductivity plots are almost linear, which points to small polaron hopping in Mg-Zn-Gd mixed ferrite [33]. Figure 6 shows typical curves that correlate AC conductivity and absolute temperature at selected frequencies for the sample with x = 0.1.…”