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Ferrite Powders (ferrite + powder)

Distribution by Scientific Domains

Physics and Astronomy	50%

Selected Abstracts

Aqueous Processing and Stabilization of Manganese Zinc Ferrite Powders via a Passivation,Dispersion Approach

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2002
Michael M. Mandanas
A dispersion scheme for aqueous processing of manganese zinc ferrite suspensions is presented. The addition of oxalic acid leads to the formation of a uniform negative charge on the surface such that a cationic polyelectrolyte, polyethyleneimine (PEI), adsorbs and provides electrosteric dispersion. At 0.5 w/w (weight percent with respect to the dry powder) oxalic acid addition, there is a relatively uniform negative surface charge (approximately ,30 mV) within the suspension pH range investigated (3,10), eliminating the isoelectric point (pH ,7.6) present for the as-received metal oxide powder. At the addition of 0.5 w/w PEI on an oxalate-treated surface, the surface charge is constant and positive (,20 mV) through a wide pH range, ,5,10. The resulting rheological data for passivation,dispersion of relatively high-solids manganese zinc ferrite suspensions (,80 wt%) demonstrate improved colloid stability with improved rheological properties. The resulting apparent viscosity and Bingham yield point is 0.01 Pa·s (12.0 cP) and 0.24 Pa (2.4 dynes/cm2), respectively. A sulfonated napthalene-based dispersant, typically used in industry, gives an apparent viscosity and Bingham yield point of 0.03 Pa·s (32 cP) and 3.1 Pa (31 dynes/cm2), respectively. [source]

Barium Ferrite Powders Prepared by Microwave-Induced Combustion Process and Some of Their Properties.

CHEMINFORM, Issue 13 2004
Yen-Pei Fu
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Influence of the starting powders on the synthesis of nickel ferrite

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2006
F. Kenfack
Abstract The thermal decomposition of freeze-dried nickel(II)-iron(III) formate was investigated by means of DTA, TG, mass spectrometry and X-ray powder diffractometry. For the preparation of homogeneous freeze-dried nickel(II)-iron(III) formate precursors, a rigorous control of nickel ion concentration in the precursor solution was required. The decomposition of the reactive nickel(II)-iron(III) formate does not only reflect aspects of single formates, but also an interaction between components which lowers the decomposition temperature. Crystalline nickel ferrite powders were obtained at 600-800°C. This temperature is quite lower than 1100°C employed for the ceramic method. In the presence of air, the regeneration of nickel ferrite from the taenite phase (,Ni,Fe) is accomplished at 800°C. This temperature is also 300°C below the temperature employed when the mixtures NiO:,-Fe2O3 or Ni:2Fe are the starting powders. The main reason for the high reactivity of the freeze-dried formates and the taenite alloy is the large homogeneity of these precursors. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Microwave absorption of ferrite powders in a polymer matrix

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2006
S. Kolev
Abstract The object of this work is to investigate the microwave absorbing properties of nanocomposite bulk samples. As filler we used magnetite with different particle size in a silicone rubber matrix and investigated the influence of the filler concentration and particle size in the polymer matrix on the microwave nonlinearity in a large frequency range (1 ÷ 13 GHz). We found that the intensity and the frequency at the reflection loss minimum depend on the particle size and particle concentration of magnetite in the samples. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]