Rare Earth Based Nanoparticles and Nanocomposites

9972035 hadjipanayis本项目由凝聚态物理项目和金属项目共同支持。研究重点是小磁性粒子，重点是稀土纳米粒子和纳米复合材料。这项工作依赖于一种新的溅射技术，该技术可以产生具有控制尺寸的纯纳米颗粒，同时将它们嵌入惰性基质中。目标是：(1)制备稀土金属纳米颗粒和稀土金属间化合物，并研究其基本和技术性质，包括尺寸和表面/界面效应；(2)制备由嵌入软（硬）基质的硬（软）纳米颗粒组成的简单纳米复合结构，并研究磁化反转机制。纳米颗粒的大表面积，加上远程RKKY交换相互作用的性质，有望导致各种磁性结构和磁性现象，与磁性材料的块状形式完全不同。纳米复合材料将允许研究磁滞，包括畴壁钉钉和反畴结构的成核。本项目由凝聚态物理项目和金属项目共同支持。这项工作涉及稀土纳米粒子和纳米复合材料的基本和技术性质。这些颗粒的尺寸只有百万分之一英寸，它们的特性使它们在超高密度磁记录和永磁体应用中都具有吸引力。这项研究为研究生和博士后提供了极好的培训和教育机会，在一个专注于磁性材料的跨学科项目中。学生们将接受最先进的方法的培训，如纳米颗粒的制造、透射电子显微镜成像、x射线衍射的结构表征以及现代磁强计技术的磁测量。

9972035HadjipanayisThis project is co-supported by the Condensed Matter Physics Program and the Metals Program. The research is focused on small magnetic particles, with emphasis on rare-earth nanoparticles and nanocomposites. The work relies on a new sputtering technique which produces pure nanoparticles with controlled size while simultaneously embeding them in an inert matrix. The objectives are (1) to prepare nanoparticles of rare earth metals and rare earth intermetallic compounds and to study their fundamental and technological properties including size and surface/interface effects, and (2) to fabricate simple nanocomposite structures consisting of hard (soft) nanoparticles embedded in soft (hard) matrices and to study magnetization reversal mechanisms. The large surface area in nanoparticles, together with properties of the long range RKKY exchange interaction is expected to lead to a variety of magnetic structures and magnetic phenomena quite different from those found in the bulk forms of the magnetic materials. The nanocomposite materials will allow the study of magnetic hysteresis, including the domain wall pinning and nucleation of reverse domain structures.%%%This project is co-supported by the Condensed Matter Physics Program and the Metals Program. The work deals with the fundamental and technological properties of rare earth nanoparticles and nanocomposites. These particles, with a size of a fraction of a millionth of an inch, have properties which make them attractive for both ultrahigh density magnetic recording, and permanent magnet applications. This research offers excellent training and educational opportunity for graduate students and post-docs within a divers interdisciplinary program focused on magnetic materials. The students will be trained in state-of-the art methods, such as fabrication of nanoparticles, imaging with transmission electron microscopy, structural characterization with x-ray diffraction, and magnetic measurements with modern magnetometry techniques.