Magnetic spectra analysis of dielectrics

Method of magnetic spectroscopy is used to analyze and to interpret the experimental data obtained by magnetic measurement of the complex permeability spectra of Mg ferrite and NiZn ferritepolymers. Ferritepolymers were prepared from various concentration of NiZn ferrite particles as a soft magnetic fillers dispersed in PVC polymer matrix. Effect of the filler content on the permeability spectra of NiZn ferritepolymers was examined and compared with presented sintered ferrite samples. The variations of permeability and relaxation frequency due to ferrite filler concentration in composite are presented and discussed from point of view the magnetization processes in samples

Optimization of Magnetic and Structural Properties of Sr Ferrite Prepared by Low-Temperature Combustion

Fine strontium hexaferrite particles were prepared by the low temperature auto-combustion method. Aqueous solution of the corresponding metal salts and a combustible co-reactant compound -glycine were used as initial precursor. The resulting powders were calcined at various temperatures from 750 • C up to 1100 • C. The microstructure and magnetic properties were investigated by the Mössbauer spectroscopy, thermomagnetic analysis, scanning electron microscopy, and vibrating magnetometer

Characteristics of magnetic properties of substituted hexagonal ferrites

The samples of barium hexaferrite BaFe12-2x(Me1Me2)xO19 with x from 0.0 to 0.6 were prepared by various methods. The cationic preference of mainly divalent Me1 = Zn, Co, Ni, Sn ions and tetravalent Me2 = Ti, Zr, Ir, Sn, Ru ions and their combinations in substituted Ba ferrites was investigated. The substitutions were performed to reduce the grain size and high magnetic uniaxial anisotropy field of the M-type Ba ferrite without affecting the magnetic polarisation. The goal is to reach the properties of ferrite proper for high-density magnetic recording and microwave absorption devices. Magnetic properties were determined as a function of the substitution level x. The specific saturation magnetic polarisation Js–m and remanence Js–r increased with small x due to the substitution of non-magnetic and less magnetic ions in 4f1 and 4f2 sites. The steep decrease of coercivity Hc with increasing x may be caused by the Co2+ preference of 4f2 site and Ti4+or Zr4+ ions preference of 2b and slightly in 4f1 sites. The temperature coefficient of the coercivity TKHc was very low (0.01kA.m–1.oC–1) for the Co-Zr substitutions and positive for the rest of samples

Electromagnetic properties of selected hexaferrites

Ba(Sr)(Me12+Me24+)xFe12-xO19 hexagonal ferrites preparation with substitution ratio of 0.0 x 0.6. The iron ionswere substituted by selected cation combinations (divalent Me12+= Ni, Zn, Sn, Co and tetravalent Me24+= Ti, Zr, Ru ions).The samples were synthesised by high energy milling and metallorganic precursor method. A special attention was focused toresults obtained for (ZnTi)x substitutions.. The changes of coercivity HC were chosen as a evaluation criterion of anisotropyvariation. Simultaneously with the magnetic properties, the dielectric parameters were also tested. Two dielectric relaxationprocesses were detected in Ba - Sr ferrite. Our results showed probably a ferroelectric behaviour of some ferrite samples

The influence of particle size and substituent contents on the magnetic properties of Be or Cu substituted NiZn ferrites

Polycrystalline NiZn ferrites with the chemical formula (Ni0.3Zn0.7)1−xMexFe2O4 where Me being Be or Cu and x=0.05, 0.1 and 0.25 have been prepared by a ceramic method. Certain magnetic properties such as the coercivity Hc, initial permeability m i, real part of the complex permeability m’ and saturation magnetization Ms of the ferrites have been measured and discussed from the point of view of the substituting element type and contents as well as the average particle size

Optimization of Magnetic and Structural Properties of Sr Ferrite Prepared by Low-Temperature Combustion

Fine strontium hexaferrite particles were prepared by the low temperature auto-combustion method. Aqueous solution of the corresponding metal salts and a combustible co-reactant compound - glycine were used as initial precursor. The resulting powders were calcined at various temperatures from 750°C up to 1100°C. The microstructure and magnetic properties were investigated by the Mössbauer spectroscopy, thermomagnetic analysis, scanning electron microscopy, and vibrating magnetometer. The particles of sizes less than 1 μm have monophasic hexagonal structure. Coercivity $H_c$≈400 kA/m, specific saturation polarization $J_{s-m} ≈ 72×10^{-6} Tm^3 kg^{-1}$ and remanence polarization $J_{s-r} ≈ 43×10^{-6} T m^3 kg^{-1}$ were achieved for the Sr ferrite annealed at 850°C for 6 h

Effect of Filler Mixture Ratio on Permeability of Multicomponent Soft Magnetic Composites

Composites with hybrid LiZnTi ferrite/FeSiAl alloy filler and PVC polymer matrix were synthesized by thermal pressing process. The influence of the mixture ratio of hybrid filler on the frequency dispersion of complex permeability of the composites has been studied. The dispersion of permeability varied from resonance type to relaxation one with the configuration change from LiZnTi/PVC composite to FeSiAl/PVC one and was mainly due to the magnetic resonance phenomena such as domain wall and spin precession resonance and due to the eddy current effect

Frequency Variation of Complex Permeability in Dual Ferrite Filler - Single Polymeric Matrix Composites

The frequency dependences of complex initial permeability for triple-component composite materials based on two different types of ferrite filler (MnZn and NiZn ferrite) and a nonmagnetic polymeric matrix (PVC) were studied in the frequency range of 10 kHz-1 GHz. The frequency dispersion of permeability is discussed by means of a dynamic model based on the superposition of the two types of magnetic resonance, the resonance of vibrating domain walls and the resonance of precessing magnetic moments in domains

Complex Permeability of LiZn/MnZn/PVC Composite Materials

The effect of particle content, size, and the fraction ratio of the double LiZn/MnZn ferrite filler in hybrid LiZn/MnZn/PVC composites on the frequency dispersion of complex permeability has been studied in the 1 MHz-3 GHz frequency range. The obtained relaxation type of permeability dispersion is due to the domain wall resonance, the natural ferromagnetic resonance, and the relaxation of magnetization rotation. The permeability and resonance/relaxation frequency of composites seem to be strongly affected by the change of particle content and fraction ratio of the double ferrite filler rather than by particle size

Magnetic Properties of Divalent (Ni,Sn,Zn)- Tetravalent (Ru,Sn) Ionic Mixtures of Substituted Ba Ferrite

The drop of coercivity, while preserving the saturation magnetic polarisation $J_{S}$ of substituted M-type Ba hexaferrites with composition $BaFe_{12-2x}(Me_{1}Me_{2})_{x}O_{19}$, was studied. Divalent $Me_{1}$=Ni, Zn, Sn and tetravalent $Me_{2}$=Ru, Sn ionic combinations were used in various compounds. Mössbauer spectroscopy was used to reveal sites of replacement of the $Fe^{3+}$ ions by $Ru^{4+}$ and $Sn^{4+}$. The $Ni^{2+}$, $Zn^{2+}$ and $Sn^{2+}$ occupation sites were identified as well. Strong drop of coercivity difference Δ $H_{c}(x)$ near x=0.1 and slight decrease of Δ $H_{c}(x)$ close to x=0.3 was obtained for suitable coupling of $Me_{1}^{2+}$ and $Me_{2}^{4+}$ ions