STUDY OF HIGHLY ANISOTROPIC HEXAGONAL FERRITE COMPOUNDS AS BROADBANDMICROWAVE ABSORBERS

FERRIMAGNETIC OXIDES WITH HEXAGONAL CRYSTAL STRUCTURE ARE CHARACTERIZED PRIMARILY BY THEIR FOLIATE (LEAF-LIKE OR PLATELET) STRUCTURE AND HIGH ANISOTROPY FIELDS. THESE HIGHLY ANISOTROPIC COMPOUNDS CAN BE PREPARED AS A COMPOSITE COMPOSED OF SINGLE DOMAIN GRAINS POSSESS ING A SPECTRUM OF CONTROLLED VALUES OF ANISOTROPY FIELDS AND ATTENDANT PREFERRED DIRECTION OF MAGNETIZATION. THESE HEXAGOAL SINGLE DOMAIN GRAINS WITH PREDICTABLE AND CONTROLLED PROPERTIES INCLUDING THE "BUILT IN" EFFECTIVE MAGNETIC FIELD (UP TO 50 KILO-OERSTEDS) IN BOTH UNIAXIAL AND PLANAR STRUCTURES, WILL THUS PROVIDE A COMPOSITE STRUCTURE IN WHICH THE COMPLEX PERMEABILITY AND DIELECTRIC PROPERTIES OF THE COMPOSITE CAN BE OPTIMIZED FOR BROADBAND MICROWAVE ABSORPTIVE CHARACTERISTICS THROUGH RESONANCE INTERACTIONS. ABSORPTIVE CHARACTE RISTICS WILL BE CONTROLLED THROUGH FERROMAGNETIC RESONANCE (DOMAIN ROTATION) INTERACTIONS WITH THE RANDOMLY ORIENTED MAGNETIC MOMENTS, BIASED GRAIN BY "BUILT-IN" INTERNAL ANISOTROPY FIELDS AND THROUGH CONDUCTIVE PROCESSES ASSOCIATED WITH OPTIMIZATION AND CONTROL OF THE COMPLEX DIELECTRIC PROPERTIES.