Hydrothermal synthesis of pure BaFe12O19 hexaferrite nanoplatelets under high alkaline system

► Single-phase BaFe12O19 hexaferrite was synthesized by the single hydrothermal method. ► The only Fe/Ba mole ratio is identified as 8:1. ► The optimum amount of KOH was 4.0 g. ► Formation mechanism of disk-like shape for BaFe12O19 hexaferrite was discussed.