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Research on nanoscopic magnet including 3d transition metals

含3d过渡金属的纳米磁体研究

基本信息

批准号：
15510089
负责人：
ICHIYANAGI Yuko
金额：
$ 1.73万
依托单位：
Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Magnetic properties of nanoparticles including 3d transition metals were investigated. Prepared samples were Co3O4, Mn3O4,Mn2O3, Ni-ferrite, NiZn-ferrite, Mn-ferrite, Mg-ferrite surrounded by amorphous SiO2.1.Co3O4 nanoaprticles with 3 nm in size showed ferromagnetic behavior below blocking temperature Tb, though bulk crystal has antiferromagnetic below TN=33 K.2.Magnetization of Mn3O4 nanoparticles showed drastic change depending on particle sizes. For 2.5 nm- sample was considered to be ordered periodically than other samples though the size was extremely small. This phenomenon could be confirmed by the results of XAFS measurements.3.NiO nanoparticles were produced by annealing Ni(OH)2 monolayer-nanoclusters above 973 K in air. In the magnetization measurements superparamagnetic or ferromagnetic behaviors were observed and characteristic properties of NiO nanoparticles were confirmed.4.Nil-xZnFe2O4(2<x<1) mixed ferrite nanoparticles encapsulated with amorphous SiO2 were prepared. Particle sizes were controlled to range from 2.6 nm to 33.7 nm by heat treatment, and the particle size dependence of saturation magnetization Ms was investigated for the x=0.5 region. The Ms value decreased abruptly for particle sizes. The relationship between saturation magnetizations Ms and the Zn concentration was almost similar to that between the saturation magnetization and Ni-Zn ferrite bulk crystal, however, the absolute values of Ms of the nanoparticles were about 30 % smaller than those of bulk crystal5.XAFS measurements and thermal analysis were also performed for all the samples. Functionalizing of medical application was newly considerd.

研究了包含 3d 过渡金属的纳米颗粒的磁性。制备的样品为Co3O4、Mn3O4、Mn2O3、Ni-铁氧体、NiZn-铁氧体、Mn-铁氧体、Mg-铁氧体，周围环绕着非晶SiO2.1。尺寸为3 nm的Co3O4纳米颗粒在截止温度Tb以下表现出铁磁行为，尽管块状晶体在TN=33以下具有反铁磁性。 K.2.Mn3O4 纳米颗粒的磁化强度随颗粒尺寸的不同而发生剧烈变化。对于 2.5 nm，尽管尺寸极小，但样品被认为比其他样品定期订购。 XAFS测量结果证实了这一现象。3.Ni(OH)2单层纳米团簇在空气中973K以上退火制备得到NiO纳米颗粒。在磁化强度测量中观察到了超顺磁或铁磁行为，证实了NiO纳米颗粒的特性。4.制备了非晶SiO2包裹的Nil-xZnFe2O4(2<x<1)混合铁氧体纳米颗粒。通过热处理将粒径控制在2.6 nm至33.7 nm范围内，并在x=0.5区域研究饱和磁化强度Ms的粒径依赖性。对于粒径，Ms 值突然下降。饱和磁化强度Ms与Zn浓度之间的关系几乎类似于饱和磁化强度与Ni-Zn铁氧体晶体之间的关系，然而，纳米颗粒的Ms绝对值比块体晶体小约30%。还对所有样品进行了XAFS测量和热分析。医疗应用的功能化被重新考虑。