Six kinds of typical commercial Fe2O3 were sampled and divided into two groups A and B. according to the magnetic measurement results. The samples of group A are of susceptibility about 10-4 and the specific saturatio...Six kinds of typical commercial Fe2O3 were sampled and divided into two groups A and B. according to the magnetic measurement results. The samples of group A are of susceptibility about 10-4 and the specific saturation magnetization σs 0.2-0.3 A.M2/kg, being consistent with the feature of antiferromagnetic α-Fe2O3. While the samples of group B display strong magnetism with susceptibility 10-1-10-2 and σs 1.7-12 A.M2 /kg. Mossbauer spectra of the samples were investigated at room temperature in an external magnetic field. It is suggested there is the y - Fe2O3 phase in the group B according to the relative intensities of spectra I(2,5)/I(3,4). This was proved by the Mossbauer spectra for the mixed samples A with γ-Fe2O3 at various contents and by measuring the dependence of specific saturation magnetization on temperature for the samples of group B.展开更多
Fe/Al2O3 nanocomposites prepared by using the sol-gel technique were reduced in H： atmosphere at different temperatures, and the corresponding Fe/Al2O3 nanocomposites were obtained after the reduction of Fe/Al2O3 nan...Fe/Al2O3 nanocomposites prepared by using the sol-gel technique were reduced in H： atmosphere at different temperatures, and the corresponding Fe/Al2O3 nanocomposites were obtained after the reduction of Fe/Al2O3 nanocomposites at 1173 K. The structures and properties of the specimens were studied by X-ray diffraction （XRD）, Mossbauer spectroscopy（ MS）, and vibrating sample magnetometry（VSM）. The results show that the reduction temperature has a significant influence on the structure, the grain size, and the magnetic properties of the specimens.展开更多
文摘Six kinds of typical commercial Fe2O3 were sampled and divided into two groups A and B. according to the magnetic measurement results. The samples of group A are of susceptibility about 10-4 and the specific saturation magnetization σs 0.2-0.3 A.M2/kg, being consistent with the feature of antiferromagnetic α-Fe2O3. While the samples of group B display strong magnetism with susceptibility 10-1-10-2 and σs 1.7-12 A.M2 /kg. Mossbauer spectra of the samples were investigated at room temperature in an external magnetic field. It is suggested there is the y - Fe2O3 phase in the group B according to the relative intensities of spectra I(2,5)/I(3,4). This was proved by the Mossbauer spectra for the mixed samples A with γ-Fe2O3 at various contents and by measuring the dependence of specific saturation magnetization on temperature for the samples of group B.
基金Supported by the Jilin Distinguished Young Scholars'Program(No.20020118) and the National Key Laboratory of SuperhardMaterials, Jilin University(No. 2002006)
文摘Fe/Al2O3 nanocomposites prepared by using the sol-gel technique were reduced in H： atmosphere at different temperatures, and the corresponding Fe/Al2O3 nanocomposites were obtained after the reduction of Fe/Al2O3 nanocomposites at 1173 K. The structures and properties of the specimens were studied by X-ray diffraction （XRD）, Mossbauer spectroscopy（ MS）, and vibrating sample magnetometry（VSM）. The results show that the reduction temperature has a significant influence on the structure, the grain size, and the magnetic properties of the specimens.
