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

Abstract

The hexagonal BaNd_xFe_12−xO₁₉(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_xFe_12−xO₁₉(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).

Keywords

sol-gel method / rare earth element / permanent ferrite / citate / ultrafine powder

References

[1] TianYu-lin. Preparation and magnetic properties of oriented barium ferrite ultrafine powders[J]. Bulletin of the Chinese Ceramic Society, 1989, 8(1): 21-29

[2] DouYou-weiFerrite[M], 1996, Nanjing, Jiangsu Science and Technology Press

[3] PankovV V, PernetM, GermiP, et al.. Fine hexaferrite particles for perpendicular recording prepared by the coprecipitation method in the presence of an inert component[J]. J Magn Magn Mat, 1993, 120: 69-72

[4] RoosW. Formation of chemically coprecipitated barium ferrite[J]. J Am Ceram Soc, 1980, 63(11–12): 601-603

[5] HanedaK, KojimaH. Magnetization reversal process in chemically precipitated and ordinary prepared BaFe₁₂O₁₉[J]. J Appl Phys, 1973, 44: 3760-3762

[6] AtaieA, HarrisR, PontonC B, et al.. Magnetic properties of hydrothermally synthesized strontium hexaferrite as a function of synthesis conditions[J]. J Mater Sci, 1995, 30(6): 1429-1433

[7] LinC H, ShihZ W, ChinT S, et al.. Hydrothermal processing to produce magnetic particulates[J]. IEEE Transactions on Magnetics, 1990, 26(1): 15-17

[8] HanedaK, MiyakawaC, GotoK. Preparation small particles of SrFe₁₂O₁₉ with high coercivity by hydrolysis of metal-organic complexes[J]. IEEE Transactions on Magnetics, 1987, 23(5): 3134-3136

[9] OdaK, YoshioT, O-OkaK. Magnetic properties of SrFe₁₂O₁₉ particles prepared by the glass-ceramic method[J]. J Mater Sci Let, 1984, 3(11): 1007-1010

[10] PillaiV, KumarP, ShahD O. Magnetic properties of barium ferrite synthesized using a microemulsion mediated process[J]. J Magn Magn Mat, 1992, 116(3): L299-L304