FINE GRAIN DENSE FERRITES.

Abstract

A number of Ni(1-x)CoxFe2)4 and Ni(1-x)MnxFe2O4 samples have been hot pressed using conventionally ball-milled powders. Densities in excess of 97% of theoretical values have been obtained together with X-band dielectric loss tangents below 0.001 and in most cases close to 0.0001. Low field magnetic losses at KU-band have been reduced almost an order of magnitude from previous levels, but are still two to four times greater than conventional nickel ferrite. There is some indication that these losses can be reduced by a heat treatment after hot pressing. Critical fields for subsidiary absorption as high as 95.0 Oe have been obtained at KU-band on 2-4 micron grain size materials, with values more typically lying between 60 and 80 Oe. This compares with a value of 16 Oe on a conventional nickel ferrite at this frequency. Cobalt increases h sub crit by an amount greater than would have been expected from previous measurements made at X-band on saturation of the main resonance. (Author)

Document Details

Document Type
Technical Report
Publication Date
Dec 31, 1964
Accession Number
AD0458873

Entities

People

  • A. E. Paladino
  • J. J. Green
  • J. S. Waugh

Organizations

  • RTX

Tags

DTIC Thesaurus Topics

  • Absorption
  • Frequency
  • Frequency Bands
  • Grain Size
  • Heat Treatment
  • Hot Pressing
  • Ku Band
  • Materials
  • Measurement
  • Radio Frequency
  • Resonance
  • Saturation
  • X Band

Fields of Study

  • Materials science

Readers

  • Materials Science and Engineering.
  • Metallurgy
  • Plasma Physics.