ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Colloidally precipitated powders were investigated for the synthesis of chemically homogeneous, uniformly fine-grained Mn-Zn ferrites. The process consists of the atomized dispersion of an aqueous solution of Mn, Zn, and Fe nitrates in an agitated solution of 1M ammonium hydroxide. This results in the coprecipitation of a fine colloidal mixture of Mn, Zn, and Fe hydroxides. The mixture is filtered, washed, dried, and heat treated to form agglomerated powders. The agglomerated powders are reduced in size and sintered after cold compaction. Sintering was performed at temperatures of 1100–1250 °C with oxygen partial pressures from 0 to 500 ppm in argon. Magnetic permeability and disaccommodation were measured on selected samples after an initial 0.5–5.0 Oe decaying sinusoidal field was applied to the specimens to excite time varying permeability. The permeability variation depended strongly on the magnitude of this excitation; both disaccommodation and accommodation were observed. The duplex structure typically associated with severe discontinuous grain growth was not observed for either of the two compositions examined over the range of sintering temperatures studied. Low levels of porosity were seen in samples sintered at 1150 and 1250 °C.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.342521
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