Influence of the Microstructure on Some Microwave Properties of Substituted Nickel Ferrites

Abstract

The influence of the substituents on the microstructure of nickel ferrites from the system Ni 1−italicx 1−italicx 2−italicx 3−italicx 4Ca italicx 1Cu italicx 2Co italicx 3Zn italicx 4Mn italicx 5Al italicx 6Fe italicx 7O4 + y SiO2 where 0 ≦ x1 ≦ 0.02; 0 ≦ x2 ≦ 0.3; 0 ≦ x3 ≦ 0.06; 0 ≦ x4 ≦ 0.5; 0 ≦ x5 ≦ 0.06; 0 ≦ x6 ≦ 0.2; 1.8 ≦ x7 ≦ 2; 0 ≦ y ≦ 0.3 wt%; x6 + x7 = 2; is investigated. Electrical resistance measurements are performed by a complex impedance method which permits the evaluation of the contributions due to the resistance of the bulk material and the grain boundaries. It is found that the dielectric and resonance magnetic losses can be improved to a certain degree by the average grain size.

Optimal prefiring conditions of substituted nickel ferrites for microwave applications

“…A good agreement between the results for composition (6) obtained by XRD and MS was observed ( Table 2). Similar values for the degree of ferrite formation for compositions (8) and (10) as well as for compositions (3) to (5) confirmed the assumption that the three components, Co, Mn, and Fe, used in the concentration intervals given with limitation (2), did not influence the prefiring conditions. -standard *) There was no spectrum corresponding to Fe203, but the intensity of the sextets for A-sites and B-sites of the spinel phase was weaker than that for the standard spinel sample.…”

“…The Mossbauer spectra of powder patterns from composition (6) prefired at different conditions ( Table 2) were recorded at room temperature using a standard Mossbauer constant acceleration spectrometer with "Co source in palladium matrix. The Mossbauer spectra could be resolved into three sextets corresponding to Fe203, A-site, and B-site Table 1 Prefiring conditions (PC) and degree of ferrite formation obtained by X-ray diffraction for compositions (4), (7), (8), and (9) PC degree of ferrite formation (%) comp. (4) WmP.…”

“…The degree of ferrite formation was determined by the ratio spinel phase/unreacted Fe203, which was calculated from the intensities of the corresponding sextets.The density and porosity of the double stage sintered samples were determined by methods described elsewhere[8]. Their electrophysical parameters, saturation magnetization M , resonance linewidth AH, relative dielectric constant E,, and dielectric loss angle tangent tg d,, were measured by a resonance method [9].…”

Structural, Magnetic and Electrical Properties of Cu Substituted Mn–Zn Soft Nanoferrites

“…[3]. Mn-Zn ferrites can be divided into two groups [4], high permeability materials that are used at low frequencies. The grain boundaries represent obstacles to domain movement, thus decreasing the permeability.…”

Magnetic properties and densification of Manganese–Zinc soft ferrites (Mn1-xZnxFe2O4) doped with low melting point oxides

“…The optimum microstructure for a Mn-Zn high frequency ferrite core is a fine, uniform microstructure with highly resistive grain boundaries and low porosity. The need to develop high permeability low loss materials for the telecommunication industry led to the use of various additives in Mn-Zn ferrites [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”