Co_9S_8 hexagonal aggregations were synthesized in hydrazine hydrate(N_2H_4 centre dot H_2O)solvent at 150 deg C for 12 h using cobalt(II)sulfate hydrate(CoSO_4 centre dot 7H_2O)and sodium sulfite(Na_2SO_3)as starting materials through a hydrothermal con-trolled-reduction method.The as-prepared samples were characterized by X-ray diffraction(XRD),field-emission scanning electron microscopy(FE-SEM),and transmission electron microscopy(TEM),and their magnetic properties were evaluated on a vibrating sample magnetometer(VSM).The results showed the samples were mainly composed of Co_9S_8 hexagonal aggregations with an average diameter of 2.2 |im and a thickness of 200 nm.About 3 nm Co_9S_8 nanocrys-tallites deposited on its single-crystal flakes.The products exhibited ferromagnetism;the saturation magnetization(M_s)and coercivity(H_c)values of the samples were 80 emu/g and 320 Oe,respectively.The possible formation mechanism of Co_9S_8 hexagonal aggregations is discussed.
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