Synthesis and size-dependent magnetic properties of single-crystalline hematite nanodiscs

Single-crystalline α-Fe₂O₃ nanodiscs with diameters of 132150 nm were synthesized by a facile and efficient hydrothermal reaction of FeCl₃ with NaH₂PO₄ and H ₂O at 200 °C for 12 h. The diameters of the nanodiscs can be decreased to 91112 and 7892 nm by adding ethanol glycol into the hydrothermal system. The α-Fe₂O₃ nanodiscs are formed by the cooperative action of selective adsorption and etching of the phosphate ions. The as-synthesized α-Fe₂O₃ nanodiscs exhibit weak ferromagnetic behaviours. The remanent magnetization and coercivity of the nanodiscs with the diameters of 132150 nm are 0.01743 emu g^-1 and 214.8 Oe, respectively, and the remanent magnetization and coercivity decrease with deceasing the nanodisc size.