Accession Number : AD0714485

Title :   The High-Frequency Susceptibility of Certain Superparamagnetic Ferrites.

Descriptive Note : Final rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Pilon,R. O.

Report Date : 01 OCT 1970

Pagination or Media Count : 21

Abstract : The susceptibility of small crystallites of nickel and nickel-iron ferrite, precipitated in the manner of Schuele and Deetscreek, has been studied as a function of hydrothermal growth and frequency. The degree of superparamagnetism shown by nickel ferrite crystallites grown for various periods is correlated with the broadening of the microwave resonance, and the paramagnetic relaxation frequency is found to be approximately 6 GHz. An equation has been developed which describes the size and temperature dependence of the low-frequency susceptibility of single-domain ferrite particles. The effects of ferrous ion content and solution pH on the growth rate and the susceptibility after long growth periods are related. Efforts to reduce the internal fields in the particles and increase the susceptibilities to quasi ferrimagnetic levels are discussed. (Author)

Descriptors :   (*FERRITES, MAGNETIC PROPERTIES), MAGNETIC RESONANCE, NICKEL COMPOUNDS, FERRATES, PARAMAGNETIC MATERIALS, CRYSTAL GROWTH, MICROWAVE FREQUENCY

Subject Categories : Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE