Accession Number:

AD0257388

Title:

FINE-GRAINED FERRITES. I. NICKEL FERRITE

Descriptive Note:

Corporate Author:

ARMY ELECTRONICS LABS FORT MONMOUTH NJ

Personal Author(s):

Report Date:

1961-03-09

Pagination or Media Count:

1.0

Abstract:

A process was developed for preparing dense nickel ferrite bodies composed of grains small enough to remain single domain, and their magnetic and crystallographic properties were determined This process was accomplished by combining two techniques, flame-spraying and hot-pressing,AND INVESTIGATING THE EFFECT OF VARYING THE PARAMETERS IN EACH OF THESE. Powder as fine as 0.02 micron was prepared of single-phase nickel ferrite, and was subsequently densified by hotpressing while maintaining the crystallite size as small as 0.06 micron below the critical size for multi-domains. The effect on the dispersion of the complex permeability as the ferrite is annealed through the critcal size is shown. Of practical interest were an improvement in the temperature coefficient of initial permeability over conventionally prepared ferrite and good linearity in main resonance loss at high-power levels at X-band. X-ray diffraction determinations of crystalline phases and crystallite sizes are given, along with measurements of apparent density. Theoretical considerations indicate domain rotation to be the mechanism responsible for the resonances observed at high frequencies. Author

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Distribution Statement:

APPROVED FOR PUBLIC RELEASE