RUI: Synthesis, Structure, and Magnetic Studies of High Anisotropy Magnetic Nanocrystals

技术：这是圣何塞州立大学三个研究小组（物理系、化学工程系和生物系）的合作成果，专注于控制组装的单分散纳米晶体的合成、结构和磁性研究。该小组最近通过自组装方法合成了铁磁材料的单元素颗粒。这项资助将研究扩展到包括二元磁性材料（FePd, FePt， CoPt和MnAl）和这些化合物的三元纳米颗粒，添加Cu， Ag或Au以促进L10结构的生长。通过化学自组装可以控制两种元素的比例、纳米晶粒度和晶格结构，使磁性材料具有广泛的性能和应用。Ag、Au或Cu的加入降低了将纳米颗粒fcc相转变为具有高各向异性常数的L10相所需的加热温度。此外，由于这些纳米晶体的有序相形成在10 - 500nm的尺度上，因此研究了这些纳米晶体在光刻生长的衬底的图案孔内的生长。这提供了与新晶格结构相关的参数变化，以及垂直于衬底表面方向上填充的单个孔的高度和直径的变化。实验工作包括TEM和XRD等结构研究。磁性表征包括利用VSM和SQUID的磁强计，交流磁化率，磁力显微镜和穆斯堡尔效应光谱在广泛的温度和磁场范围内。非技术：该活动产生的更广泛的影响包括磁性纳米晶体材料在药物输送、MRI造影剂、铁磁流体和存储技术等领域的广泛应用。合成具有控制尺寸和晶格结构的单分散纳米晶体的能力为具有所需性能的材料的生长提供了灵活性。参与研究的PI及其同事在科学和工程教育、研究培训和推广活动方面取得了长期的成功。硕士水平的研究生和本科生已经参与了过去活动的各个阶段，并将继续为研究的进步做出贡献，同时增强他们的实践教育经验。在科学和工程领域，女性和少数民族等代表性不足的群体占SJSU学生总数的58%。在学生选拔过程中，将努力使这个小组的成员参与研究活动。

TECHNICAL: This is a collaborative effort of three research groups at San Jose State University (physics, chemical engineering, and biology departments) focused on the synthesis, structure and magnetic studies of monodispersed nanocrystals with controlled assembly. This group has recently synthesized single element particles of ferromagnetic materials by a self-assembly method. This grant extends the research to include binary magnetic materials (FePd, FePt, CoPt, and MnAl) and ternary nanoparticles of these compounds with added Cu, Ag or Au to enhance the growth of L10 structure. Through chemical self-assembly one can control the ratio of two elements, nanocrystalline particle size, and lattice structure rendering magnetic materials with broad range of properties and applications. Addition of Ag, Au or Cu decreases the heating temperature required to transform the nanoparticle fcc phase to L10 phase with high anisotropy constant. Additionally, since the ordered phase of these nanocrystals form over a dimension of 10 - 500 nm, the growth of these nanocrystals inside patterned holes of a substrate grown by photolithography is explored. This provides variation of parameters associated with a new lattice structure as well as variation of the height and diameter of individual holes filled in the direction perpendicular to the substrate surface. Experimental work to be carried out includes structural studies such as TEM and XRD. Magnetic characterizations include magnetometry utilizing VSM and SQUID, AC susceptibility, magnetic force microscopy, and Mossbauer effect spectroscopy over a wide range of temperature and magnetic field. NONTECHNICAL: Broader Impacts resulting from the activity include a wide range of application of magnetic nanocrystalline materials in areas such as drug delivery, MRI contrast agents, ferrofluids, and storage technology. The capability to synthesize monodispersed nanocrystals with controlled size and lattice structure provides flexibility in growth of materials with desired properties. The PI and colleagues involved in the research have a long record of success in science and engineering education, research training, and outreach activities. MS level graduate and undergraduate students have been involved in all stages of past activities and will continue to contribute to the progress of research while enhancing their hands-on educational experience. Underrepresented groups in science and engineering such as women and minorities constitute 58% of student body at SJSU. In the student selection process effort will be made to involve the members of this group in the research activities.