NiFe2O4纳米晶的制备及表面效应对其比饱和磁化强度的影响

以FeSO4*7H2O和NiSO4*7H2O为原料，首先制备出颗粒细小的碱式碳酸盐前驱体，在300～700℃焙烧1h后，制备出铁酸镍纳米晶，粒径为8～54nm，粒度均匀。通过测量它的比饱和磁化强度σs与比表面积Sa，得出经验公式σs(Sa)=σs(∞)(1-aSa)，运用非共线磁结构理论很好地解释了上述经验公式，并得到纳米晶的非共线表面层的厚度。，A basic carbonate precursor with very fine particles was synthesied by using FeSO4*7H2O and NiSO4*7H2O, and NiFe2O4 nanocrystallites were then obtained by calcining the precursor. The results of XRD and TEM analysis show the NiFe2O4 nanocrystallites with spherical shape are even, and their average diameters increase from 8nm to 54nm when the precursor is calcined at 300—700℃ for 1h. Their specific saturation magnetization σs and specific surface area Sa were measured. A empirical formula σs(Sa)=σs(∞)(1-aSa)was obtained which can be interpreted very well by a noncollinear magnetic structure model, and the value of the canted-layer thickness was deduced.

Preparation and Surface Effects on Specific Saturation Magnetization of NiFe2O4 Nanocrystallites

A basic carbonate precursor with very fine particles was synthesied by using FeSO4*7H2O and NiSO4*7H2O, and NiFe2O4 nanocrystallites were then obtained by calcining the precursor. The results of XRD and TEM analysis show the NiFe2O4 nanocrystallites with spherical shape are even, and their average diameters increase from 8nm to 54nm when the precursor is calcined at 300—700℃ for 1h. Their specific saturation magnetization σs and specific surface area Sa were measured. A empirical formula σs(Sa)=σs(∞)(1-aSa)was obtained which can be interpreted very well by a noncollinear magnetic structure model, and the value of the canted-layer thickness was deduced.