Partition of Solute Atoms among Sublattices in Intermetallic Compounds

非技术摘要：许多技术材料是具有有序晶体结构的化合物。 机械强度和其他性能经常通过将溶质原子溶解到化合物中来改善。 本计画将探讨溶质原子如何在主元素的次晶格间分配。 溶质分配的方式可能对材料性质有重要的和未被认识的影响。 然而，分配，即溶质原子在两个子晶格上的分布，一直难以测量。 将采用与磁共振成像中使用的方法类似的实验性超精细相互作用方法，该方法可以准确地测量分布。 主要目标是确定主体化合物的精确组成、溶解溶质的量和温度如何影响分配。 所获得的知识应有助于预测溶质如何分配为其他组合的主体化合物和溶质，从而推进固体溶液的一般领域。 其他影响包括本科生和研究生的教育和培训，以及所有研究参与者通过参加科学会议、研讨会和出版物向更广泛的公众传播研究成果。 技术摘要：该项目的目标是确定溶质原子如何在化合物中的不同位置之间分配。 考虑有序二元化合物AB 2，溶质原子分布在一个或两个亚晶格上？ 将进行调查以确定分配如何随着化学计量A：B组成比的偏差、溶质摩尔分数和温度而变化。 一个待探讨的主题假设是溶质和反位原子的摩尔分数之和受相界和溶解度的约束。 溶质原子的分配在此之前一直难以测量。 用核方法扰动角关联法（PAC）求解In探针原子的晶格位置。 研究将集中在GdAl 2。 将精确测量相边界和溶解度极限。 溶质分配也将研究在主机相场延伸到两侧的化学计量组成，导致不同类型的结构点缺陷。添加1原子%（质量分数，下同）的稀土，可以改善许多功能材料和结构材料的性能溶质。 溶质的分配方式可能对物质性质有重要影响，但迄今为止尚未认识到这一点。 预计该项目将全面推进溶质分配的理解。 更广泛的影响包括固体物理学、核实验室方法和数据分析方面的高等教育和学生培训。 研究成果将由所有研究参与者通过参加地方和国家科学会议、研讨会和出版物向更广泛的公众传播。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Abstract:Many technological materials are compounds with ordered crystal structures. Mechanical strength and other properties have frequently been improved by dissolving solute atoms into the compound. This project will explore how solute atoms partition between sublattices of the host elements. The ways in which solutes partition may have important and unrecognized influences over materials properties. However, the partition, that is, the distribution of solute atoms on the two sublattices, has been difficult to measure. An experimental hyperfine interaction method similar to that used in magnetic resonance imaging will be employed that can measure the distribution accurately. The principal goal is to determine how the precise composition of the host compound, the amount of dissolved solute, and temperature all affect the partition. Knowledge gained should help predict how solutes partition for other combinations of host compounds and solutes and thereby advance the general field of solutions in solids. Other impacts include education and training of undergraduate and graduate students and dissemination of research findings by all research participants to the broader public through participation in scientific meetings, seminars, and publications. Technical Abstract:The goal of this project is to determine how solute atoms partition among different sites in a compound. Considering an ordered binary compound AB2, do solute atoms distribute on one or both sublattices? Investigations will be carried out to determine how the partition varies with deviation from a stoichiometric A:B composition ratio, with the mole fraction of solute, and with temperature. A thematic hypothesis to be explored is that the sum of mole fractions of solutes and antisite atoms is constrained by phase boundaries and the solubility. The partition of solute atoms has heretofore been difficult to measure. Lattice locations of In-probe atoms will be resolved using the nuclear method perturbed angular correlation of gamma rays (PAC). Studies will focus on GdAl2. Phase boundaries and solubility limits will be precisely measured. Solute partition will also be studied in hosts for which the phase field extends to both sides of the stoichiometric composition, leading to differing types of structural point defects. Properties of many functional and structural materials are improved by addition of 1 at.% of solute. The ways in which solutes are partitioned may have important influences over material properties that have not been recognized up until now. The project is expected to comprehensively advance understanding of solute partition. Broader impacts include advanced education and training of students in solid-state physics, nuclear laboratory methods, and data analysis. Research findings are to be disseminated by all research participants to the broader public through participation in local and national scientific meetings, seminars, and publications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.