Development of Multi-Cation-Doped M-Type Hexaferrite Permanent Magnets

We report enhanced permanent magnet performance for multi-cation-substituted M-type Sr-hexaferrites (SrM) prepared using conventional ceramic processes. The final cation composition, Sr0.4Ca0.3La0.3Fe10.2Co0.1Mn0.1Si0.05Mg0.05O19, could be derived through stepwise and systematic cation composition designs, processing, and characterization. The hexaferrites sample sintered in the temperature range of 1200-1220 degrees C showed an enhanced coercivity (H-C) of approximately 4.0 kOe and a residual magnetic flux density (B-r) of 2.5-2.6 kG. When samples of the same composition were fabricated into anisotropic magnets through a magnetic-field molding process, performance parameters of B-r = 4.42 kG, H-C = 3.57 kOe, and BHmax = 4.70 M center dot G center dot Oe were achieved, a significant improvement over B-r = 4.21 kG, H-C = 3.18 kOe, and BHmax = 4.24 M center dot G center dot Oe for the non-substituted SrFe12O19 magnet processed under optimized conditions.

Automated summary

Enhanced permanent magnet performance was reported for multi-cation-substituted M-type Sr-hexaferrites prepared using conventional ceramic processes. A cation composition of Sr0.4Ca0.3La0.3Fe10.2Co0.1Mn0.1Si0.05Mg0.05O19 was obtained through stepwise and systematic cation composition designs, processing, and characterization. The magnet demonstrated improved coercivity and residual magnetic flux density compared to the non-substituted SrFe12O19 magnet.