【摘要】 利用透射电子显微镜和X射线衍射研究了溶胶法制备的分散在SiO₂母体内的纯Fe微粉（Fe-SiO₂）和化学共沉法制得的含Coγ-Fe₂O₃微粉的晶形和结构。用振动样品磁强计测量这些微粉的磁性。发现粒度为50—300（?）的Fe-SiO₂微粉,当温度由300K降至80K时,矫顽力变化很少,但1000（?）的含Coγ-Fe₂O₃微粉的矫顽力则上升了10倍以上。利用趋近饱和定律求出这些样品的各向异性常数随温度的变化,并讨论了它们的矫顽力随温度变化的原因。更多还原

【Abstract】 The pure iron ultrafine particles dispersed in the SiO2 matrix (Fe-SiO2 granu-lar solid) were prepared using a sol-gel method and the ultrafine Co-r-Fe2O3 parti-cles were prepared using a chemical coprecipitation method. The morphology and structure of these particles were studied by means of TEM and X-ray diffraction. The magnetic characteristics was measured using the VSM with the 2T maximum field. It is found that the coercivity varies a little for the Fe-SiO2 granular solid with the 50-300 A average size for the iron particles and the coercivity increases about 10 times for the Co-*T’*-Fe2O3 particles with 1000A average size as tempera-cure decreases from 300 to 80K. The effective magnetic anisotropy constants were obtained using the law of approach to saturation for these ultrafine particles. The coercivity versus the temperature for them is discussed.更多还原