Synthesis and characterization of Nd doped M-type hexagonal barium ferrite ultrafine powders

The hexagonal BaNd _x Fe_12−x O₁₉(x=0.1−1.0) fine powders with M-type structure were synthesized by sol-gel auto-combustion high-temperature synthesis method. The structure of powders, gels’ combustion and magnetic properties of powders were respectively studied by means of X-ray diffractometer (XRD), differential thermal analysis-thermogravimetric analysis (DTA-TG) and vibrating sample magnetometer (VSM). The powders before and after combustion and calcination at 450–850 °C with different mole ratio of Nd to Ba (0.1–1.0) were compared in terms of XRD. In addition, the effects of different synthesis conditions on magnetic properties of powders were also discussed. The results show that at pH 7.0 or so, mole ratio of citrate to nitrate (1–3) and calcination temperature of 850 °C for 1 h, M-type BaNd _x Fe_12−x O₁₉(x=0.1−1.0) fine powders can be obtained, and the coercive force reaches 436880 A·m⁻¹ at x=1, which is far greater than that of barium permanent ferrite (BaFe₁₂O₁₉). Biography of the first author: GUO Rui-qian, doctoral student, born in 1974, majoring in preparation and characterization of ultrafine powders.