Magneto-dielectric properties of ferrites and ferrite/ferroelectric multiferroic composites

Abstract

Ni-Zn ferrites, with the general formula Ni 1-x Zn x Fe 2 O 4 (x = 0.0, 0.3, 0.5, 0.7, 1.0), CoFe 2 O 4 , BaTiO 3 and PbZr 0.52 Ti 0.48 O 3 powders were synthesized by auto-combustion method. The composites were prepared by mixing the appropriate amounts of individual phases, pressing and conventional sintering. X-ray analysis, for individual phase and composites, indicated the formation of crystallized structure of NiZnFe 2 O 4 , BaTiO 3 and PbZr 0.52 Ti 0.48 O 3 without the presence of secondary phases or any impurities. SEM analyses indicated a formation of uniform grain distribution for ferromagnetic and ferroelectric phases and formation of two types of grains, polygonal and rounded, respectively. Magneto-dielectric effect was exhibited in all samples because of the applied stress occurring due to the piezomagnetic effect and the magnetic field induced the variation of the dielectric constant. For all samples the dielectric constant was higher in applied magnetic field. At the low frequency, the dispersion of dielectric losses appeared, while at the higher frequency the value of tan δ become constant (Maxwell-Wagner relaxation). Investigation of J-E relation between leakage and electric field revealed that both nickel zinc ferrite and composites have three different regions of conduction: region with ohmic conduction mechanism, region with the trap-controlled space charge limited current mechanism and region with space charge limited current mechanism.

Nonlinear Matrix Ferroelectric Composites on Construction Quality and Safety Measures

“…In the formula, ε 0 is the strain vector on the middle plane (z � 0), and ω { } is the curvature change vector on the middle plane [24].…”

The Structural, Impedance and Dielectric a Ferrite Core of Iron Manganite and Its Composite

“…The microstructure density is greatly influenced by the heating temperature [13]. The denser microstructure will have better electrical properties [6]. From Figures 2 (b) and (c) From Figures 2(b) and (c), it appears agglomeration occurs.…”

“…Ferrite is a ceramic compound of transition metals with oxygen, which is ferrimagnetic but not conductive. The ferrite used in transformer or electromagnetic cores contains iron oxide combined with manganese [1][2][3][4], zinc, and / or nickel compounds [5][6][7][8]. These materials have high resistivity or low electrical conductivity which prevents eddy currents in the core from causing energy loss.…”

“…Iron manganite (MnFeO3) has its impedance and dielectric constant which decreases with increasing frequency [1,4]. The electrical resistivity of nickel zinc nano ferrites is highly dependent on the size of the crystallinity and with increasing frequency, the dielectric constant decreases [5,6], and the value of tan 𝜕 also decreases [7,8]. The perovskite LaMnO3 compound, with increasing frequency will also experience a decrease in impedance, dielectric and tan 𝜕 constants [9], and also their electrical conductivity [10].…”

“…Several methods have been used for the sample preparation process, for example solid reaction [1,10], sono-chemical [2], sol-gel auto-combustion [4,6], coprecipitation [5], the polymerizable complex [9]. Of the several methods, the solid reaction is the easiest and cheapest method.…”