High Anisotropy Magnetic Nanoparticles and Nanocomposites

该基金的一个主要目标是制造用于高磁矩高矫顽力铁磁体的纳米颗粒，重点是CoPT、FePT和稀土金属间化合物。这些纳米粒子将用于制造具有定制性能的特殊纳米复合结构，用于高性能永久磁体和高密度记录。利用各种实验技术，如透射电子显微镜、SQUID磁测量、穆斯堡尔谱、洛伦兹显微镜、同步辐射和中子衍射，研究了颗粒尺寸、颗粒间距和基质材料对磁性和磁滞性质的影响。我们将通过实验和模拟相结合的方法来研究复合纳米粒子在光吸收原位退火过程中的成核、生长及其相变。颗粒的原位热处理有望在它们沉积到衬底之前将其结构转变为所需的相，从而避免合金化和氧化的不良影响。所提出的纳米复合结构及其技术重要性将作为测试和改进现有磁滞模型的模型结构，这将有助于开发新的先进磁体。纳米颗粒的粒度-化学组成-结构-性能关系的研究将有助于纳米复合材料的技术发展。所提出的合金/化合物体系的高各向异性将使制备尺寸在1-4 nm范围内的热稳定纳米粒子成为可能。学生的培训包括纳米粒子的合成，X射线衍射和电子显微镜的结构和微结构表征，以及磁性测量技术。学生们通过参加由国际和平协会组织的关于纳米结构材料的特别国际研讨会来进一步丰富他们的教育。拟议工作的跨学科性质将建立与其他部门、行业和国家实验室的合作，并将帮助学生拓宽和丰富他们的知识基础。拟议的计划将加强与特拉华州教育部、学区、商业和工业以及整个大学社区建立的合作伙伴关系，以帮助K-12数学和科学教师在课堂上实施新的内容和基于成绩的标准。我们将鼓励和支持学生参加工作坊和会议，向社会传播他们的研究成果。

A major objective of the grant is to fabricate nanoparticles for high moment high coercivity ferromagnets with emphasis on CoPt, FePt and rare earth intermetallic compounds. The nanoparticles will be used to fabricate special nanocomposite structures with tailored properties for high performance permanent magnets and high-density recording. The influence of particle size, particle separation, and matrix material on magnetic and hysteresis properties will be studied using various experimental techniques such as transmission electron microscopy, SQUID magnetometry, Mossbauer spectroscopy, Lorentz microscopy, synchrotron radiation and neutron diffraction. The nucleation and growth of compound nanoparticles and their phase transformations will be studied by both experiment and modeling during in-situ annealing through light absorption. The in-situ heat treatment of the particles is expected to transform their structure into the desired phase before they are deposited onto the substrate, avoiding the undesirable effects of alloying and oxidation. The proposed nanocomposite structures, along with their technological importance, will serve as model structures for the testing and refinement of existing hysteresis models that will help the development of new advanced magnets. The proposed work on the particle size-chemical composition-structure-properties relationship in nanoparticles will benefit the technological development of these nanocomposite materials. The high anisotropy of the proposed alloy/compound systems will make it possible to fabricate thermally stable nanoparticles with a size in the range of 1-4 nm.The training of students includes nanoparticle synthesis, structural and microstructural characterization by x-ray diffraction and electron microscopy and magnetic measurement techniques. The students further enrich their education through participation in special international workshops on nanostructured materials organized by the PI. The interdisciplinary nature of the proposed work will establish collaborations with other departments, industry, and national labs, and would help the students broaden and enrich their knowledge base. The proposed program will strengthen the established partnership with the Delaware Department of Education, school districts, business and industry, and the university community at large to help K-12 math and science teachers implement new content and performance-based standards in their classrooms. The students will be encouraged and supported to attend workshops and meetings to disseminate their research findings to the community.