X-ray powder diffraction, resistivity and magnetization studies have been performed on polycrystalline Nd（FexMn1-x）2Si2 （0≤x 〈 1） compounds which crystallize in a ThCr2Si2-type structure with the space group 14/...X-ray powder diffraction, resistivity and magnetization studies have been performed on polycrystalline Nd（FexMn1-x）2Si2 （0≤x 〈 1） compounds which crystallize in a ThCr2Si2-type structure with the space group 14/mmm. The field-cooled temperature dependence of the magnetization curves shows that, at low temperatures, NdFe2Si2 is antiferromagnetic, while the other compounds show ferromagnetic behaviour. The substitution of Fe for Mn leads to a decrease in lattice parameters a, c and unit-cell volume V. The Curie temperature of the compounds first increases, reaches a maximum around x=0.7, then decreases with Fe content. However, the saturation magnetization decreases monotonically with increasing Fe content. This Fe concentration dependent magnetization of Nd（FexMn1-x）2Si2 compounds can be well explained by taking into account the complex effect on magnetic properties due to the substitution of Mn by Fe. The temperature＇s square dependence on electrical resistivity indicates that the curve of Nd（Fe0.6Mn0.4）2Si2 has a quasi-linear character above its Curie temperature, which is typical of simple metals.展开更多
研究了强磁场对共晶铝硅合金变质效果的影响.对共晶A l-12.6%S i合金进行N a盐变质处理,发现施加强磁场的条件下,在变质剂反应温度下保温20 m in,共晶硅细化,并呈现一定程度的粒状化,其变质效果明显优于不施加强磁场.760℃下延长保温时...研究了强磁场对共晶铝硅合金变质效果的影响.对共晶A l-12.6%S i合金进行N a盐变质处理,发现施加强磁场的条件下,在变质剂反应温度下保温20 m in,共晶硅细化,并呈现一定程度的粒状化,其变质效果明显优于不施加强磁场.760℃下延长保温时间至40 m in,未施加强磁场条件下的试样出现严重的变质衰退现象,施加强磁场的试样变质衰退现象相对较轻.在施加强磁场条件下,即使保温40 m in,其变质效果也优于不施加强磁场时保温20m in时的,即强磁场具有一定的延长变质有效时间的作用.分析认为强磁场抑制对流是其中的原因之一.展开更多
基金Project supported by the National Basic Research Program of China (Grant No 2006CB601101)
文摘X-ray powder diffraction, resistivity and magnetization studies have been performed on polycrystalline Nd（FexMn1-x）2Si2 （0≤x 〈 1） compounds which crystallize in a ThCr2Si2-type structure with the space group 14/mmm. The field-cooled temperature dependence of the magnetization curves shows that, at low temperatures, NdFe2Si2 is antiferromagnetic, while the other compounds show ferromagnetic behaviour. The substitution of Fe for Mn leads to a decrease in lattice parameters a, c and unit-cell volume V. The Curie temperature of the compounds first increases, reaches a maximum around x=0.7, then decreases with Fe content. However, the saturation magnetization decreases monotonically with increasing Fe content. This Fe concentration dependent magnetization of Nd（FexMn1-x）2Si2 compounds can be well explained by taking into account the complex effect on magnetic properties due to the substitution of Mn by Fe. The temperature＇s square dependence on electrical resistivity indicates that the curve of Nd（Fe0.6Mn0.4）2Si2 has a quasi-linear character above its Curie temperature, which is typical of simple metals.
文摘研究了强磁场对共晶铝硅合金变质效果的影响.对共晶A l-12.6%S i合金进行N a盐变质处理,发现施加强磁场的条件下,在变质剂反应温度下保温20 m in,共晶硅细化,并呈现一定程度的粒状化,其变质效果明显优于不施加强磁场.760℃下延长保温时间至40 m in,未施加强磁场条件下的试样出现严重的变质衰退现象,施加强磁场的试样变质衰退现象相对较轻.在施加强磁场条件下,即使保温40 m in,其变质效果也优于不施加强磁场时保温20m in时的,即强磁场具有一定的延长变质有效时间的作用.分析认为强磁场抑制对流是其中的原因之一.
