This paper presents a study of the relationship between the magnetic properties and microstructure of nanocomposite Ni/MnO, Ni/CoO, Co/MnO, Co/CoO. The objective is to understand how the coupling interface FM/AFM （fe...This paper presents a study of the relationship between the magnetic properties and microstructure of nanocomposite Ni/MnO, Ni/CoO, Co/MnO, Co/CoO. The objective is to understand how the coupling interface FM/AFM （ferromagnetic/anti-ferromagnetic） manifests itself in magnetic response of these materials to an applied field. Sample preparation was performed using mechanochemical synthesis by means of a ball mill planetary type high power at normal atmosphere. The characterization was done by XRD （X-ray diffraction）, SEM （scanning electron microscopy） and VSM （vibrating sample magnetometry）. Analyzing the XRD peaks of the samples studied, there was a decrease in the average particle diameter with increasing milling time, which is important in the magnetic interactions of the atoms of the surface. In addition, the diffraction pattern showed formation of new phases by oxidation interfering with the magnetic measurements. Analyses by SEM show chipboard multiform nano- and micrometer-sized grains on the surface of the clusters being responsible for the interaction. The magnetic measurements show a strong coupling between the phases present in nanocomposites showing once again that the MS （mechanosynthesis） is a powerful technique for this kind of purpose. The effect of the decrease in crystallite size leads to large variations of magnetic properties of the material which have been specifically observed changes in HC （coercive field） in the RM （remanent magnetization） and SM （saturation magnetization）. The decrease in crystallite size in the course of grinding intensifies the effects that depend on the surface-to-volume ratio of the material. M vs. T measures were taken for different values of applied field and found a jump in the moment of the sample near the N6el temperature of the antiferromagnetic.展开更多
文摘This paper presents a study of the relationship between the magnetic properties and microstructure of nanocomposite Ni/MnO, Ni/CoO, Co/MnO, Co/CoO. The objective is to understand how the coupling interface FM/AFM （ferromagnetic/anti-ferromagnetic） manifests itself in magnetic response of these materials to an applied field. Sample preparation was performed using mechanochemical synthesis by means of a ball mill planetary type high power at normal atmosphere. The characterization was done by XRD （X-ray diffraction）, SEM （scanning electron microscopy） and VSM （vibrating sample magnetometry）. Analyzing the XRD peaks of the samples studied, there was a decrease in the average particle diameter with increasing milling time, which is important in the magnetic interactions of the atoms of the surface. In addition, the diffraction pattern showed formation of new phases by oxidation interfering with the magnetic measurements. Analyses by SEM show chipboard multiform nano- and micrometer-sized grains on the surface of the clusters being responsible for the interaction. The magnetic measurements show a strong coupling between the phases present in nanocomposites showing once again that the MS （mechanosynthesis） is a powerful technique for this kind of purpose. The effect of the decrease in crystallite size leads to large variations of magnetic properties of the material which have been specifically observed changes in HC （coercive field） in the RM （remanent magnetization） and SM （saturation magnetization）. The decrease in crystallite size in the course of grinding intensifies the effects that depend on the surface-to-volume ratio of the material. M vs. T measures were taken for different values of applied field and found a jump in the moment of the sample near the N6el temperature of the antiferromagnetic.
