Determination of core and hydrodynamic size distributions of CoFe2O4 nanoparticle suspensions using ac susceptibility measurements
Determination of core and hydrodynamic size distributions of CoFe2O4 nanoparticle suspensions using ac susceptibility measurements
复制标题
DOI：
10.1063/1.3463350
复制
发表时间：
2010-08-01
影响因子：
3.2
通讯作者：
Schmidt, A. M.
中科院分区：
文献类型：
--
作者：
Ludwig, F.;Guillaume, A.;Schmidt, A. M.
在1 kHz和1 MHz之间的频率范围内的叠加的静态磁场的不同值的CoFe 2 O 4纳米粒子悬浮液的复杂的磁化率进行了测量。交流磁化率虚部的最大值随静磁场的增加向高频移动。利用磁场的布朗弛豫时间常数的依赖性，并假设流体动力学颗粒尺寸的分布，在理论上模拟的移位。从零场的最大chi“确定的平均流体动力学尺寸和从chi "峰随静场的移动获得的平均核尺寸分别与透射电子显微镜和动态光散射测量的数据非常一致。结果表明，核心和流体动力学的尺寸分布可以确定从测量的纳米粒子悬浮液提出的磁偶极-偶极相互作用是可以忽略不计的。(C)2010年美国物理学会。[doi：10.1063/1.3463350]
The complex susceptibility was measured on CoFe2O4 nanoparticle suspensions in the frequency range between 1 kHz and 1 MHz for different values of a superimposed static magnetic field. The maximum in the imaginary part chi '' of the ac susceptibility shifts to higher frequencies with increasing static magnetic field. The shift is theoretically modeled utilizing the magnetic field dependence of the Brownian relaxation time constant and assuming a distribution of hydrodynamic particle sizes. The mean hydrodynamic size as determined from the maximum of chi '' in zero field and the mean core size as obtained from the shift of the chi '' peak with static field agree very well with the data from transmission electron microscopy and dynamic light scattering measurements, respectively. The results indicate that both core and hydrodynamic size distributions can be determined from measurements on nanoparticle suspensions proposed that magnetic dipole-dipole interactions are negligible. (C) 2010 American Institute of Physics. [doi:10.1063/1.3463350]