Novel Magnetic Nanoparticles and Nanoflakes

技术综述：本研究的重点是磁性硬质稀土-过渡金属(R-TM)纳米颗粒和尺寸小于100 nm的纳米薄片的合成和表征。最终的目标是将这些纳米颗粒与软磁性的Fe(Co)纳米颗粒结合起来，开发出具有非常高能量产物的各向异性纳米复合磁体。这种新型的表面活性剂辅助球磨技术将合成纳米粒子/片状纳米粒子以及RCo5、R2(Fe，Co)17和R2Fe14B晶体结构，该技术已被证明能够制备出分离的、磁各向异性的纳米粒子。拟议的实验将使人们更好地理解纳米颗粒/纳米片状粉末的形成机理(S)，这将使我们能够制备更多尺寸均匀且可控的纳米颗粒/纳米片状粉末，这是研究基本和技术性质所必需的。对颗粒尺寸在4-100 nm范围内的纳米颗粒的研究将使人们能够研究颗粒尺寸和表面效应对颗粒的晶体结构、磁性结构以及基本和硬磁性质的影响。新开发的具有定制性能的纳米颗粒/纳米片将通过自下而上的方法与软磁性Fe(Co)纳米颗粒组装在一起，形成定向纳米结构，这可能导致首次开发出具有非常高能量产品的高各向异性纳米复合永磁体。非技术摘要：拟议的研究旨在制备尺寸小于百万分之一英寸的稀土合金(SmCo5和Nd2Fe14B)粉末，并研究其磁性能随颗粒大小的变化。然后将性能最好的稀土合金纳米粉末与Fe(Co)纳米粉末一起自下而上地开发出高性能的复合磁体，其强度明显高于现有最好的Nd-Fe-B磁体。此外，这些复合磁体中的稀土含量将减少30%-40%，这将减少未来对这些稀有稀土金属的依赖。高性能的磁体将导致更低的成本，更有效的能源和电力密集型设备，这将导致我国对外国化石燃料来源的依赖大幅减少。该项目还将在对美国经济和国防至关重要的永磁体和纳米磁性的重要和关键领域为学生提供教育和培训。

TECHNICAL SUMMARY: The proposed research is focused on the synthesis and characterization of magnetically hard rare earth-transition metal (R-TM) nanoparticles and nanoflakes with a size below 100 nm. The ultimate goal is to use these nanoparticles together with magnetically soft Fe(Co) nanoparticles to develop anisotropic nanocomposite magnets with very high energy products. Nanoparticles /nanoflakes based and the RCo5, R2(Fe,Co)17 and R2Fe14B crystal structures will be synthesized by the novel surfactant-assisted ball milling technique which has been proven to be capable of producing separate and magnetically anisotropic nanoparticles. The proposed experiments will lead to a better understanding of the mechanism(s) of nanoparticle/nanoflake formation that would allow the preparation of larger amounts of nanoparticle/nanoflake powders with uniform and controlled size which are needed for the study of the fundamental and technological properties. The proposed studies on nanoparticles with particle sizes in the range of 4-100 nm, will enable investigations of particle size and surface effects on the crystal structure, the magnetic structure and the fundamental and hard magnetic properties of the particles. The newly developed nanoparticles/nanoflakes with tailored properties will then be assembled together with magnetically soft Fe(Co) nanoparticles via a "bottom-up" approach to form aligned nanostructures which may lead to the development for the first time of highly anisotropic nanocomposite permanent magnets with very high energy products.NON-TECHNICAL SUMMARY: The proposed study is aimed at the fabrication of rare-earth alloy (SmCo5 and Nd2Fe14B) powders with size below a few millionths of an inch, and the study of their magnetic properties as a function of particle size. The rare earth alloy nanopowders with the best properties will then be used together with Fe(Co) nanopowders in a bottom-up approach to develop high performance composite magnets with strength significantly higher than those of the best available Nd-Fe-B magnets. Furthermore, the amount of rare earth in these composite magnets will be lower by 30-40% and this will decrease the future dependency on these scarce rare earths metals. The high performance magnets will lead to lower-cost, more efficient energy and power-dense devices that will result in a substantial reduction in our nation's dependence upon foreign sources of fossil fuels. The project will also provide education and training of students in the important and critical areas of permanent magnets and nanoscale magnetism which are vital to the U.S. economy and defense.