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应用科学学报 ›› 1998, Vol. 16 ›› Issue (4): 434-442.

• 论文 • 上一篇    下一篇

γ-Fe2O3微粉的磁各向异性和磁粘滞性的研究

侯登录1, 聂向富1, 唐贵德1, 罗河烈2   

  1. 1. 河北师范大学;
    2. 中国科学院物理研究所
  • 收稿日期:1997-01-09 修回日期:1997-04-17 出版日期:1998-12-31 发布日期:1998-12-31
  • 作者简介:侯登录:讲师,河北师范大学物理系,石家庄 050016

Study on the Magnetic Anisotropy and Magnetic Viscosity of γ-Fe2O3 Powders

HOU DENGLU1, NIE XIANGFU1, TANG GUIDE1, LUO HELIE2   

  1. 1. Department of Physics, Hebei Normal University, Shijiazhuang 050016;
    2. Institute of Physics, Academia Sinica, Beijing 100080
  • Received:1997-01-09 Revised:1997-04-17 Online:1998-12-31 Published:1998-12-31

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摘要： 制备了粒状γ-Fe2O3微粉和针状γ-Fe2O3以及CoFe-γ-Fe2O3磁片样品.利用透射电子显微镜观察了样品颗粒的形貌,并用X射线衍射确定了样品的相组成.利用振动样品磁强计测量了样品在不同温度下的磁化曲线和磁滞回线,用"趋近饱和定律"方法求出了在不同温度下粒状γ-Fe2O3微粉的有效磁各向异性常数,而用磁转矩方法测量针状γ-Fe2O3和CoFe-γ-Fe2O3样品的有效磁各向异性常数,结果首次显示粒状γ-Fe2O3微粉的有效磁各向异性常数KE随温度的变化趋势与其形状各向异性常数随温度的变化趋势相同.还测量了不同温度下样品的涨落场和有效激活体积,推导了有效激活体积的理论表达式,并和实验结果进行了比较.粒状样品在不同温度下的实验结果皆与理论计算基本符合,但针状样品的实验结果与理论计算则有明显差别.首次得出粒状γ-Fe2O3微粉在不同温度下的反磁化机制与均匀反磁化较为符合的结果.

关键词: 磁各向异性, 磁粘滞性, 磁记录微粉

Abstract: The granular γ-Fe2O3 powders, the acicular γ-Fe2O3 and CoFe γ-Fe2O3 powders are prepared. The particle shapes and mean particle sizes of the samples are determined by transmission electron microscopy. The phases are determined by X ray diffraction. By using vibrating sample magnetometer, the magnetic parameters are measured at different temperatures. By the law of approach to saturation, the effective magnetic anisotropy constants of granular γ-Fe2O3 powders at different temperatures are obtained. By using magnetotorquemeter, the effective magnetic anisotropy constants of acicular γ-Fe2O3 and CoFe γ-Fe2O3 powders are measured. It is found for the first time that variation tendency of effective magnetic anisotropy of granular γ-Fe2O3 with the temperature is about the same as that of the magnetic anisotropy with the temperature. The fluctuation field Hf and the activation volume of the samples at different temperatures are measured. The theoretical expression of activation volume is derived, For the granular γ-Fe2O3 powders, the calculated activation volumes at different temperatures are consistent with the experimental ones. But for acicular γ-Fe2O3 powders, the calculated activation volumes at different tempera tures is different from the experimental ones. It is found experimentally, for the first time, that magnetization reversal of granular γ-Fe2O3 at different temperatures is close to the uniform rotation.

Key words: mganetic recording powders, magnetic anisotropy, magnetic viscosity