The size-dependent magnetic properties of Co3O4 nanoparticles
The size-dependent magnetic properties of Co3O4 nanoparticles
复制标题
DOI：
10.1016/j.poly.2005.03.158
复制
发表时间：
2005-11-17
期刊：
影响因子：
2.6
通讯作者：
Yamada, S
中科院分区：
文献类型：
--
作者：
Ichiyanagi, Y;Yamada, S
将氯化钴（CoCl2中心点6H(2)O）水溶液与偏硅酸钠（Na2SiO3中心点9H(2)O）水溶液混合制备纳米Co3O4。根据x射线衍射图估计这些粒子的直径在3到30纳米之间。通过退火条件和溶液中硅的浓度来控制颗粒的大小。对不同尺寸的Co3O4纳米颗粒进行了磁化测量。阻滞温度T-b在4 ~ 28 K之间，而Co3O4体晶的Neel温度T-N = 33 K。在阻挡温度下，粒子中的超顺磁自旋被热涨落能量阻挡。当粒径小于10 nm时，饱和磁化强度M-s显著增加。计算得到的3圈Co3O4粒子的有效磁矩mu（eff）是体晶的两倍。这些磁异常取决于颗粒大小，可能是由于极小的Co3O4颗粒的表面自旋。(c) 2005 Elsevier Ltd版权所有。
Co3O4 nanoparticles were prepared by mixing cobalt chloride (CoCl2 center dot 6H(2)O) aqueous solutions with sodium metasilicate nonahydrate (Na2SiO3 center dot 9H(2)O) aqueous solutions. The diameters of these particles were estimated from the X-ray diffraction patterns as ranging from 3 to 30 nm. The particle sizes were controlled through the annealing conditions and by the Si concentration of the solutions.Magnetization measurements were performed on the various Sizes Of Co3O4 nanoparticles. The blocking temperatures T-b were observed to be between 4 and 28 K, while the Neel temperature Of Co3O4 bulk crystal is known to be T-N = 33 K. At the blocking temperature, the superparamagnetic spins in the particle are supposed to be blocked against the thermal fluctuation energy. The saturation magnetization M-s increased dramatically for particle sizes below about 10 nm. The calculated effective magnetic moment mu(eff) for a Co3O4 particle of 3 rim was twice as large as that of bulk crystal. These magnetic anomalies, which are dependent on particle size, could be due to the surface spins of the extremely small Co3O4 particles. (c) 2005 Elsevier Ltd. All rights reserved.