Structural, Magnetic and Electronic Properties of Interstitially Modified Magnetic Systems

本课题是研究Sm2Fe17的气相-元素间质修饰效应及相关结构的更新课题。这种改性为开发一种新型磁性材料提供了希望，这种材料具有潜在的适合永磁体应用的性能。在拟进行的研究中，将解决关于间隙R2Fe17(N，C，H)x （R =稀土元素）和取代Sm2Fe17-yTy （T = Ga, Al, and Si）以及相关的R(Fe，T)12, R3(Fe，T)29和R2Fe14B稀土体系的一般问题。通过核磁共振、穆斯堡尔效应、x射线吸收精细结构、中子衍射和介子自旋等方法，探索其局部原子、电子和磁性结构以及相关的宏观磁性。目的是了解导致磁各向异性和单个亚晶格磁化变化的特定局部方面，以及确定特定位点矩对局部环境和晶格扩展的依赖。这是一个更新项目，研究Sm2Fe17的气相-元素间隙改性及其相关结构的影响。永磁体对国家安全和商业工业都至关重要。例如，一辆汽车包含100多个磁性部件。永磁体的总市场目前每年超过100亿美元，并且增长迅速。这种应用需要高性能、高工作温度、低成本的材料。自20世纪80年代以来，寻找永久磁性材料（取代钴）集中在铁基化合物上，因为铁储量丰富，价格低廉，并且具有相对较高的磁矩。最近，人们发现，当氮气等气态元素扩散到选定的铁化合物中时，磁性能大大增强。我们的研究项目利用微观实验技术，如磁共振，来研究这些插入元素在改善材料的磁性和一般物理性能方面所起的作用。＊＊＊

w:\awards\awards97\budnick05136.doc 9705136 Budnick This is a renewal project to study the effect of gas-phase- element interstitial modification of Sm2Fe17 and related structures. Such modification is showing promise for the development of in a new class of magnetic materials with properties potentially suitable for permanent magnet applications. In the proposed research, general questions concerning both interstitial R2Fe17(N,C,H)x (R = rare-earth element) and substitutional Sm2Fe17-yTy (T = Ga, Al, and Si), as well as the related R(Fe,T)12, R3(Fe,T)29, and R2Fe14B rare-earth systems, will be addressed. The local atomic, electronic, and magnetic structures, and the related macroscopic magnetic properties will be explored by nuclear magnetic resonance, Mssbauer effect, x-ray absorption fine structure, neutron diffraction, and muon spin rotation. The goals are to understand the specific local aspects leading to changes in magnetic anisotropy and individual sublattice magnetization as well as to determine the specific site moment dependence on local environment and lattice expansion. %%% This is a renewal project to study the effect of gas-phase- element interstitial modification of Sm2Fe17 and related structures Permanent magnetic magnets are vital for both national security as well as commercial industries. For example, an automobile contains more than 100 magnetic components. The total market for permanent magnets is currently more than $10 billion per year, and growing rapidly. This application requires materials with high performance, high working temperature, and low cost. Since the 1980s, the search for permanent magnetic materials (to replace cobalt) has concentrated on iron-based compounds because iron is abundant, inexpensive, and has relatively high magneti c moment. Recently, it has been discovered that when gaseous elements such as nitrogen are diffused into selected iron compounds, the magnetic properties are greatly enhanced. Our research program utilizes microscopic experimental techniques such as magnetic resonance to study the role that such inserted elements play in improving not only the magnetic properties, but the general physical properties of materials. ***