Fine Particle Li-Ferrite for APS Millimeter-Wave Phase Shifter,

Powders composed of spheroidal particles 0.5–0.6 μm average size have been synthesized by rapidly quenching melts in the system Li2CO3‐B2O3‐Fe2O3. The flow characteristics of the powders are adequate to fabricate Li‐ferrite ceramic bodies by arc‐plasma‐spraying (APS) the powders. Post annealing leads to densification and grain growth with concomitant decrease in Hc and increase in 4πMs and Br. Inversions in x‐ray diffraction line intensity disappears with APS and annealing, yielding expected cation distribution. The inadvertent introduction of Zn accounts for the observed inverse relationship between magnetic moment and Curie temperature. The synthetic powder process requires further refinement to improve powder flow characteristics.