Accession Number : AD0458873


Title :   FINE GRAIN DENSE FERRITES.


Descriptive Note : Quarterly rept. no. 2, 1 Oct-31 Dec 64,


Corporate Author : RAYTHEON CO WALTHAM MA RESEARCH DIV


Personal Author(s) : Paladino, A E ; Waugh, J S ; Green, J J


Report Date : 31 Dec 1964


Pagination or Media Count : 23


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)


Descriptors :   *FERRITES , MATERIAL FORMING , NICKEL COMPOUNDS , COBALT COMPOUNDS , IRON COMPOUNDS , MANGANESE COMPOUNDS , OXIDES , DENSITY , GRAIN STRUCTURES(METALLURGY) , MICROSTRUCTURE , DIELECTRIC PROPERTIES , MAGNETIC PROPERTIES , MICROWAVES , HEAT TREATMENT , X BAND , MAGNETIC MATERIALS , POWDER METALLURGY , PREPARATION


Distribution Statement : APPROVED FOR PUBLIC RELEASE