Transition Metal Pnictide Nanoparticles: Synthesis and Assembly of Novel Magnetic Materials

关于磁性纳米材料在器件中开发的基本问题，将探讨一系列具有自旋电子或磁性数据存储应用前景的过渡金属镍相。本文将利用常规和微波加热的阻滞沉淀策略，阐明支持砷化锰（MnAs）和磷化锰（MnP）成核和生长的基本因素。一旦制备完成，将研究粒径对MnP一级相变的作用，以及不同类型的各向异性对MnP矫顽力性能的影响。控制磷化铁（FexP, x=1、2或3）中产物化学计量的因素将通过对反应物化学计量、反应物活性、温度和时间的详细研究来识别。然后，单相纳米颗粒（FexP）样品将用于确定短物理长度尺度对复杂磁有序和矫顽力的影响。本研究还将探讨离散MnP纳米颗粒凝聚成凝胶结构以及聚集体和孔隙结构对离散颗粒之间偶极子-偶极子相互作用的影响。在进行这项研究的过程中，研究生和本科生的研究人员将培养批判性思维技能和熟练的科学写作和交流能力，以及学习尖端的研究技术，包括电子显微镜。由于纳米材料占地面积小，尺寸可调，因此有望彻底改变从计算机处理和数据存储到疾病状态的生物成像等一系列技术。然而，纳米材料在实际器件中的应用受到一些基本领域进展的限制。这些包括：制备具有形状和尺寸控制的单相、低多分散性颗粒样品的方法；将粒子组装成功能结构的方法；对所观察到的物理性质与材料的尺寸、形状和组成之间的关系进行量化；以及对三维结构中粒子-粒子相互作用影响的评估。该项目将在一系列具有自旋电子或磁性数据存储应用前景的过渡金属镍相的背景下解决这些基本问题，但尚未在纳米尺度上进行系统评估：MnAs， MnP和Fe-P （FeP, Fe2P, Fe3P）。在进行这项研究的过程中，研究生和本科生将培养批判性思维能力，熟练的科学写作和交流，以及学习前沿的研究技术和如何在一个跨学科的团队中工作。这些做好准备的学生将成为开发下一代先进技术的新研究人员的先锋。

Fundamental issues pertaining to the exploitation of magnetic nanomaterials in devices will be explored for a series of transition metal pnictide phases with promising attributes for spintronic or magnetic data storage applications. The fundamental factors that underpin the nucleation and growth of manganese arsenide (MnAs) and manganese phosphide (MnP) will be elucidated using arrested precipitation strategies with conventional and microwave heating. Once prepared, the role of particle size on the first-order phase transition in MnAs, and the effect of different kinds of anisotropy on the coercive properties of MnP, will be studied. The factors that control product stoichiometry in iron phosphides (FexP where x=1, 2, or 3) will be discerned by a detailed study of reactant stoichiometry, reactant activity, temperature and time. Single-phase nanoparticulate (FexP) samples will then be used to determine the effects of short physical length scales on complex magnetic ordering and coercivity. This work will also explore the condensation of discrete MnP nanoparticles into gel-structures and the influence of the aggregate and pore structure on dipole-dipole interactions between discrete particles. In the course of pursuing this research, graduate and undergraduate student researchers will develop critical thinking skills and proficiency in scientific writing and communication, as well as learn cutting-edge research techniques, including electron microscopy.%%%Due to their small footprint and size-tunable properties, nanomaterials promise to revolutionize a wide range of technologies from computer processing and data storage to biological imaging of disease states. However, the exploitation of nanomaterials in actual devices is limited by progress in a number of fundamental areas. These include: methods for preparing single-phase, low-polydispersity samples of particles with control of shape and size; methods for assembling particles into functional architectures; quantification of the relationship between the observed physical properties and the size, shape, and composition of the material; and evaluation of the influence of particle-particle interactions in 3 D architectures. This project will address these fundamental issues in the context of a series of transition metal pnictide phases with promising attributes for spintronic or magnetic data storage applications, but which have not been systematically evaluated on the nanoscale: MnAs, MnP, and Fe-P (FeP, Fe2P, Fe3P). In the course of pursuing this research, graduate and undergraduate students will develop critical thinking skills and proficiency in scientific writing and communication, as well as learning cutting-edge research techniques and how to work in an interdisciplinary team. So prepared, these students will be among the vanguard of new researchers employed in developing the next generation of advanced technologies.