Structure-Property Relationships in Transition-Metal Pnictides Confined to Nanoscale Dimensions

纳米尺度过渡金属磷族化合物的结构-性能关系

• 批准号: 1064159
• 负责人: Stephanie Brock
• 金额: $ 40.5万
• 依托单位: Wayne State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-02-01 至 2014-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1064159&HistoricalAwards=false
• 关键词: Structure; Property; Relationships; Transition; Metal

TECHNICAL SUMMARYIn this NSF Solid State and Materials Chemistry funded project, key steps towards establishing how confinement of dimensions to the nanometer scale impacts structure-property relationships in transition metal pnictides of increased complexity (ternary formulations) will be undertaken. Three systems will be studied, chosen based on the prior experience of the Brock group with related binary phases, and the expectation of unique size-dependent physical properties: (MM')2P (M, M' = Mn, Fe, Co, Ni), Mn1-xFexAs, and Na1-xFeAs. The (MM')2P phases are ternary derivatives of binary phases for which syntheses have been established. The motivation for targeting these phases is based on the expectation that they will have ferromagnetic transitions at elevated temperatures, relative to the binaries, making them potentially suitable for room-temperature applications (magnetic refrigeration, data storage). Mn1-xFexAs phases were chosen because they represent Fe-doped analogs of MnAs nanoparticles, a system wherein thermodynamic phase transitions, characteristic of bulk MnAs phases, are suppressed on the nanoscale. It is expected that phase transformation phenomena can be controlled through incorporation of chemical defects, such as Fe, and this will be explicitly tested. Finally, Na1-xFeAs will be pursued because these phases will enable a new range of synthesis space to be charted, enabling nanomaterials combining ionic and covalent/metallic bonding to be prepared. Moreover, the preparation of nanoscale Na1-xFeAs will enable the effect of size confinement on the superconducting transition to be probed in this novel class of materials. In the course of the project, graduate and undergraduate researchers will develop critical thinking and communication skills, and will learn cutting-edge research techniques, including electron microscopy. The project will also introduce Detroit-area middle and high school girls, many of which are minorities, to nano- and materials science through the GO-GIRL (Gaining Options-Girls Investigate Real Life) outreach project. NON-TECHNICAL SUMMARYThe unique properties attained when solids are prepared with dimensions of just 10-1000 times the diameter of an individual atom (nanomaterials) promise to revolutionize a wide range of technologies from data storage to energy conversion. However, the exploitation of nanomaterials in actual devices is limited by progress in a number of fundamental areas, including established methods for making functional nanomaterials and a developed understanding of how properties change when the size is varied in this critical regime. This NSF Solid State and Materials Chemistry funded project will establish how size, structure, and chemical composition affect the magnetic or superconducting properties of a series of phases called transition metal pnictides. In the course of the research, key factors that underpin material preparation on this lengthscale will be discovered. The development of a rationale for the synthesis of transition metal pnictides on the nanoscale has potential to impact fields such as catalysis, energy conversion, and energy storage (batteries). Moreover, insight gained from the study of materials proposed here is expected to impact use of these phases in magnetic recording, refrigeration, and so-called "spintronic" devices. In the course of the project, graduate and undergraduate students will develop the necessary critical thinking and technical skills, as well as hands-on experience with cutting-edge techniques, for developing the next generation of advanced technologies. The project will also introduce Detroit-area middle and high school girls, many of which are minorities, to nano- and materials science through the GO-GIRL (Gaining Options-Girls Investigate Real Life) outreach project. This program addresses perennially underrepresented groups in Science, Technology, Education, and Math (STEM) fields and seeks to develop these untapped assets by empowering them with positive STEM experiences and by providing them (and their parents) with the resources and information needed to ensure they get the most out of the educational system.

技术摘要 在这个 NSF 固态和材料化学资助的项目中，将采取关键步骤来确定纳米尺度的尺寸限制如何影响复杂性增加的过渡金属磷化物（三元配方）的结构-性能关系。 将根据 Brock 小组在相关二元相方面的先前经验以及对独特的尺寸相关物理性质的期望来研究三个系统：(MM')2P（M、M' = Mn、Fe、Co、Ni）、Mn1-xFexAs 和 Na1-xFeAs。 (MM')2P相是已建立合成的二元相的三元衍生物。 针对这些相的动机是基于这样的预期：相对于二元星，它们将在高温下发生铁磁转变，从而使它们可能适合室温应用（磁制冷、数据存储）。选择 Mn1-xFexAs 相是因为它们代表了 MnAs 纳米颗粒的 Fe 掺杂类似物，这是一种系统，其中热力学相变（块体 MnAs 相的特征）在纳米尺度上受到抑制。预计相变现象可以通过掺入化学缺陷（例如铁）来控制，这将得到明确的测试。 最后，Na1-xFeAs 将得到发展，因为这些相将能够绘制新的合成空间范围，从而能够制备结合离子键和共价/金属键的纳米材料。 此外，纳米级Na1-xFeAs的制备将能够在此类新型材料中探讨尺寸限制对超导转变的影响。 在该项目过程中，研究生和本科生研究人员将培养批判性思维和沟通技巧，并将学习包括电子显微镜在内的尖端研究技术。 该项目还将通过 GO-GIRL（获得选择——女孩调查现实生活）外展项目向底特律地区的初中和高中女生（其中许多是少数民族）介绍纳米和材料科学。 非技术摘要当固体的尺寸仅为单个原子直径的 10-1000 倍（纳米材料）时，所获得的独特性能有望彻底改变从数据存储到能量转换的各种技术。然而，纳米材料在实际设备中的利用受到许多基本领域进展的限制，包括制造功能性纳米材料的既定方法以及对在这种关键状态下尺寸变化时性能如何变化的深入理解。 这个由 NSF 固态和材料化学资助的项目将确定尺寸、结构和化学成分如何影响一系列称为过渡金属磷氮化物的相的磁性或超导特性。在研究过程中，将发现支持这种长度尺度材料制备的关键因素。纳米级过渡金属磷化物合成原理的发展有可能影响催化、能量转换和能量存储（电池）等领域。 此外，从本文提出的材料研究中获得的见解预计将影响这些相在磁记录、制冷和所谓的“自旋电子”设备中的使用。在该项目过程中，研究生和本科生将培养必要的批判性思维和技术技能，以及尖端技术的实践经验，以开发下一代先进技术。 该项目还将通过 GO-GIRL（获得选择——女孩调查现实生活）外展项目向底特律地区的初中和高中女生（其中许多是少数民族）介绍纳米和材料科学。 该计划针对的是科学、技术、教育和数学 (STEM) 领域中长期代表性不足的群体，并寻求通过赋予他们积极的 STEM 体验并为他们（及其父母）提供所需的资源和信息来开发这些未开发的资产，以确保他们从教育系统中获得最大收益。