CAREER: Magnetic-Nanocrystal Self-Assembled Superlattices

本基金主要研究磁性纳米晶超晶格材料的合成与表征。为了利用纳米团簇的尺寸特异性和选择性所提供的技术优势，必须了解制备宏观数量和具有高尺寸，结构形态和形状均匀性标准的团簇组装材料的基本方法。这些是系统探索由这些建筑单元组装而成的有图案的上层建筑的本质，以及制定设计和控制这种新型组装材料的方法的至关重要的步骤。主要研究目标为：Co、y-Fe2O3和Fe3O4自组装钝化磁性纳米晶超晶格的合成、表征和性能测定；测定纳米粒子和超晶格的体积和表面微观结构，以了解纳米晶体之间的磁耦合/解耦与粒子间距离的关系；研究纳米颗粒、表面活性剂和超晶格的原位结构演变和相变，以预测器件应用系统的稳定性、可靠性和耐久性，并模拟纳米晶体及其组装的结构和行为。教育工作集中在开发研究生合作论文项目、扩展外展项目、开发面向高中生和公众的互动显微镜显示器以及开发与材料科学相关的跨学科教学实验等领域。纳米晶簇及其所具有的物理和化学功能特异性和选择性表明，它们是二维和三维团簇自组装超晶格结构的理想构建块。自组装阵列可以包括自组织成单层、薄膜和尺寸选择的纳米团簇的超晶格，并封装在保护性紧密的有机涂层中。由于其在信息存储、彩色成像、生物处理、磁制冷和铁磁流体等方面的潜在应用，图案磁性纳米晶体在科学和技术上都具有重要的意义。＊＊＊

9733160 Wang This grant explores synthesis and characterization of magnetic nanocrystal superlattice materials. To utilize the technological advantages offered by the size specificity and selectivity of nanoclusters, it is imperative to understand the fundamental methodologies for preparation of cluster assembled materials in macroscopic quantities and with high standards of size, structural morphological and shape uniformity. These are vitally important steps toward a systematic exploration of the nature of patterned superstructures assembled from such building units, as well as the formulation of methods for designing and controlling such novel assembled materials. The major research objectives are: to synthesize, characterize, and determine the properties of self-assembly passivated magnetic nanocrystal superlattices of Co, y-Fe2O3 and Fe3O4; to determine the bulk and surface microstructures of the nanoparticles and the superlattices for understanding the magnetic coupling/decoupling among nanocrystals as a function of the interparticle distance; to examine the in- situ structure evolution and phase transformation of the nanoparticles, the surfactant and the superlattices for predicting the stability, reliability and durability of the system for device applications, and to model the structure and behavior of nanocrystals and their assemblies. Education efforts are concentrated in the areas of development of collaborative graduate student thesis projects, expansion of outreach programs, development of interactive microscopy displays for high school students and the public, and development of interdisciplinary teaching experiments related to materials science. %%% Nanocusters, and the physical and chemical functional specificity and selectivity they possess, suggest that they are ideal building blocks for two-and three-dimensional cluster self-assembled superlattice structures. Self- assembled arrays can involve self-organization into monolayers, thi n films, and superlattices of size-selected nanoclusters with encapsulated in protective compact organic coatings. Patterned magnetic nanocrystals are of vital interest both scientifically and technologically because of their potential applications in information storage, color imaging, bioprocessing, magnetic refrigeration, and ferrofluids. ***