Synthesis, Structure and Properties of Magnetic Nanocrystalsand Nanocrystalline Arrays

磁性纳米晶及纳米晶阵列的合成、结构与性能

• 批准号: 9803700
• 负责人: Michael McHenry
• 金额: $ 29.96万
• 依托单位: Carnegie-Mellon University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-01 至 2001-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9803700&HistoricalAwards=false
• 关键词: Synthesis; Structure; Properties; Magnetic; Nanocrystalsand

9803700 McHenry This research explores through synthesis and characterization the unique properties of magnetic nanocrystals. It continues a previous effort on varying alloy chemistry, nanocrystal morphology, and interfacial structure to influence the magnetic anisotropy in magnetic nanocrystals and nanocrystalline arrays. Magnetic anisotropy in nanocrystals and nanocrystalline arrays depends on magnetic crystalline anisotropy, shape anisotropy, interfacial anisotropy, and/or the anisotropy provided by magnetoelastic coupling. These issues are addressed in (1) C-coated nanoparticles; (2) filled C- nanotubes with carbide nanorods; and (3) infiltrated, periodically arranged pores in mesoporous silicates with ferromagnetic or ferrimagnetic species. Nanoparticles produced by plasma synthesis are usually spherical and do not benefit from shape anisotropy as a barrier to the thermally activated switching of the magnetization. The research examines the effects of shape anisotropy in detail in novel nanoparticles and nanoparticle arrays in which large aspect ratios in the magnetic particles can be used to exploit shape anisotropy. Issues of interfacial anisotropy are addressed by comparing the magnetic properties of nanoparticles having carbon and oxide coatings. %%% This research is aimed at understanding the magnetic reversal mechanisms in nanoparticles in order to determine fundamental limitations for a variety of magnetic applications. Nanosized clusters have demonstrated properties that differ from those of bulk crystalline solids. Examples of nanocrystalline forms include Buckyballs and Buckytubes, C-coated nanoparticles and nanorods, and other self-assembled structures. Understanding properties of these materials enables the development of novel materials with a host of applications. ***

小麦克亨利9803700 本研究通过合成和表征探索磁性纳米晶体的独特性质。 它继续了以前的努力，不同的合金化学，结晶形态，和界面结构的影响磁纳米晶体和纳米晶体阵列的磁各向异性。 纳米晶体和纳米晶体阵列中的磁各向异性取决于磁晶体各向异性、形状各向异性、界面各向异性和/或由磁弹性耦合提供的各向异性。 这些问题在（1）C-涂覆的纳米颗粒;（2）具有碳化物纳米棒的填充的C-纳米管;和（3）具有铁磁性或亚铁磁性物质的中孔硅酸盐中的渗透的、周期性排列的孔中得到解决。 通过等离子体合成产生的纳米颗粒通常是球形的，并且不受益于形状各向异性作为对磁化的热激活切换的障碍。 该研究详细研究了形状各向异性在新型纳米颗粒和纳米颗粒阵列中的影响，其中磁性颗粒中的大纵横比可用于利用形状各向异性。 通过比较具有碳和氧化物涂层的纳米颗粒的磁性来解决界面各向异性的问题。 这项研究旨在了解纳米颗粒中的磁性反转机制，以确定各种磁性应用的基本限制。 纳米尺寸的团簇已经显示出不同于块状结晶固体的性质。 纳米晶形式的实例包括巴基球和巴基管、C涂覆的纳米颗粒和纳米棒以及其他自组装结构。 了解这些材料的特性可以开发具有许多应用的新型材料。 ***