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

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

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

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

Magnetic Properties of Yttrium-Substituted NiZn Ferrites

Polycrystalline NiZn ferrite doped with a small amount of $Y^{3+}$ ions and having the composition of $Ni_{0.42}Zn_{0.58}Y_{x}Fe_{2-x}O_{4}$, where x=0.00, 0.01, 0.02, 0.04, 0.06, 0.08 and 0.10, was analyzed. Specimens were prepared by the ceramic method. Thermo-magnetic analysis and evaluation of hysteresis loops parameters were chosen as main examination methods in this study. Various parameters, such as Curie temperature $T_{C}$, coercive field $H_{c}$, remanent magnetic flux density $B_{r}$, hysteresis loop area and amplitude/initial permeability were studied at low frequencies

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

Nickel/Zinc ratio and lanthanum substitution effect on structural and magnetic properties of nickel zinc ferrites

Improvement of NiZn ferrites properties by means on Ni/Zn content ratio modification and by partial substitution of Fe³⁺ ions by La³⁺ ions is presented. Ni_{x}Zn_{1-x}Fe₂O₄ and Ni_{x}Zn_{1-x}La_{0.02}Fe_{1.98}O₄ samples of small particles were prepared by self-propagated combustion method. X-ray spectroscopy was used for structural analysis, temperature dependence of magnetic susceptibility was used for evaluation of chemical and phase composition. Analysis showed that pure spinel structure without secondary phase caused by La ions for all values of Ni/Zn content was present. Noticeable growth of the magnetic susceptibility at room temperature was observed with rising of Zn²⁺ ions content

Electromagnetic Properties of Substituted Barium Hexaferrites

Substituted M-type ferrite $BaFe_{12-2x}(Me_1Me_2)_xO_{19}$, 0≤x≤0.6 was prepared by both mechanical alloying and precursor method, where $Me_1$ = Co, Ni, Zn, Sn and $Me_2$ =Ru, Ti, Zr, Sn. Magnetic phase purity, change of saturation polarization, Curie temperature, coercivity and magnetic susceptibility was studied as function of x. Attention was focused to results obtained for $(NiRu)_x,$ $(ZnRu)_x,$ and $(SnRu)_x$ mixtures with low doping ratio x

Hopkinson effect in soft and hard magnetic ferrites

The dependences of the susceptibility of selected spinel and hexagonal ferrites on temperature are analyzed. The susceptibility shows a peak just below the Curie temperature T_{C} due to the Hopkinson effect during the heating. The appearance of this effect is associated with a transition from the region of stable magnetization state to superparamagnetic relaxations of the magnetic particles. It is in contrast to other explanations of the Hopkinson effect. These results are compared with measured particles size and with scanning electron microscope micrographs of both types of ferrites