Characterization of plate-shaped strontium ferrite particles synthesized via co-precipitate and heat treatment in molten potassium bromide flux

Plate-shaped hexagonal strontium ferrite particles were synthesized using potassium bromide as the molten salt flux. The co-precipitate of strontium and iron hydroxides was heated in the temperature range of 670–870 °C in the flux. Clear peaks based on hexagonal ferrite and weak peaks based on α-Fe ₂O ₃ were observed after the heat treatment at 670 °C. The peaks based on α-Fe ₂O ₃ almost disappeared after the heat treatment at 730 °C, and the peaks observed in the particles heated at temperatures higher than 730 °C were consistent with the standard data for SrFe ₁₂O ₁₉. The particle shape tended to change from a hexagonal plate shape to a rounded plate shape with increasing temperature while maintaining a particle diameter of approximately 100–200 nm. The coercive force was approximately 420–440 kA/m, while the magnetization at the applied field of 1353 kA/m was approximately 62 Am2/kg at heating temperatures higher than 750 °C.