Mossbauer Diffraction From Polycrystalline Ordered Alloys

小行星9415331 本研究将穆斯堡尔衍射应用于粉末结构表征。 超精细相互作用导致57铁原子的散射因子强烈改变稍微不同的伽马射线能量。 这可能为衍射实验中独特的化学选择性提供了基础。 这种化学选择性可以用来将伽马射线调谐到铁57原子的特定化学环境，并单独从该化学环境中确定特定的衍射图案。 实验测量了DO_3 ~（57）铁铝化物中两个铁位的面心立方和简立方衍射花样。 初步的实验结果是令人鼓舞的，并为这项工作提供了实用的参数。 如果这些第一个实验是成功的，测量反位原子在部分有序的57铁铝化物和在B2 57铁铑的安排。 同时，还将测试位置敏感探测器的计时能力。 如果探测器可以同时具有时间和正电子分辨率，以后的实验可能会在同步辐射装置上进行。到目前为止，材料科学在很大程度上依赖于X射线，电子和中子衍射来表征粉末的结构。 穆斯堡尔衍射，它发生的γ射线从核散射，探索作为一个额外的有用的技术粉末衍射。 ***

9415331 Fultz In this research, Mossbauer diffraction is applied to powder structure characterization. Hyperfine interactions cause the scattering factor of an 57iron atom to change strongly for slightly different gamma ray energies. This could provide a basis for unique chemical selectivity in diffraction experiments. The chemical selectivity could be used to tune a gamma ray to the specific chemical environment of an 57iron atom and determine a specific diffraction pattern from that chemical environment alone. The experimental work attempts to measure the face-centered cubic and simple cubic diffraction patterns from two iron sites in DO3-ordered 57iron aluminide. Preliminary experimental results have been encouraging and have provided practical parameters for the this work. If these first experiments are successful, measurement will be made on the arrangements of antisite atoms in partially-ordered 57iron aluminide and in a B2 57iron - rhodium. In a parallel effort, the timing capabilities of the position-sensitive detector will be tested. If the detector can be operated with both time and positron resolution, later experiments may be performed at a synchrotron radiation facility. %%% To date, materials science has relied heavily on x-ray, electron, and neutron diffraction to characterize the structure of powders. Mossbauer diffraction, which occurs by scattering of gamma rays from nuclei, is explored as an additional useful technique for powder diffractometry. ***