Ultrafine particles of Fe, Co, and Ni ferromagnetic metals

Journal of Applied Physics - Tập 69 Số 8 - Trang 5119-5121 - 1991
Wenjie Gong1, Hua Li1, Zhongren Zhao1, Jinchang Chen1
1Magnetism Laboratory, Physics Institute, Chinese Academy of Sciences, Beijing 100080, China

Tóm tắt

Fe, Co, and Ni ultrafine particles (UFP) were prepared by a gas evaporation method in an inert atmosphere. The different preparing conditions of the Fe, Co, and Ni UFP included inert gas pressures and kinds were investigated by means of x-ray diffraction, transmission electron microscopy (TEM), and magnetic measurements with low or high temperatures. The experimental results show that coercivities Hc of the Fe, Co, and Ni UFP, depending on particle sizes, obey a single-domain theory. The maximum Hc was 450, 1000, and 1500 Oe, respectively, for Ni (310 Å), Fe (210 Å), and Co (200 Å) at room temperature. The coercivities came up to high in the low temperatures. The saturation magnetizations Ms of the Fe, Co, and Ni UFP decreased with small particle sizes. A face-centered structure of Co UFP (200–300 Å) was confirmed by x-ray diffraction. Some Fe UFP in the shape of balls (200–400 Å) observed in the TEM may be an amorphous structure.

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Thông tin xuất bản

Journal of Applied Physics

Tập 69 Số 8

5119-5121

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