Nickel Copper Ferrites for Microwave Applications

Abstract

Ferrites having both high relative density (∼98%) and high dc resistivity (>109 ohm-centimeters) can be prepared by properly sintering nickel copper ferrites which have both an iron deficiency and a small amount of manganese or cobalt present. Magnetic saturation at room temperature shows a linear dependence upon copper content in this system varying from 3150 gauss for NiFe1.9Mn0.02O4± to 2400 gauss for furnace cooled CuFe1.9Mn0.02O4±. Direct current resistivity remains high for mixtures of these two ferrites if 2Cu<Ni. An anomalous break in the curve relating dc resistivity with copper content occurs when the copper to nickel ratio exceeds this 1:2 value.