Highly Oriented SrM Tape Hexaferrite

This paper reports on preparation of a magnetically anisotropic polycrystalline hexaferrite, Sr0.95Ca0.05Fe12O19, whose orientation degree is as high as 100%. The preparation uses standard ceramic techniques, including wet pressing and flowing-oxygen sintering. In this process, Ca+2 ions are substituted for Sr+2 ions in SrFe12O19 by adding minimum impurities (Bi2O3 and MnCO3). Such a hexaferrite has a dielectric loss lower than 2.3 X10-3 at 9.5 GHz, which is important for microwave applications and possibly for millimeter-wave applications. The paper describes the variation of specific saturation magnetization and magnetic crystal anisotropy field (HQ) with temperature (T), and compares the magnetic properties of the sintered hexaferrite with those of the strontium hexaferrite SrFe12O19.