The structure of nanoscale materials is difficult to study because crystallography, the gold-standard for structure studies, no longer works at the nanoscale. New tools are needed to study nanostructure. Furthermore, it is important to study the evolution of nanostructure of complex nanostructured materials as a function of various parameters such as temperature or other environmental variables. These are calledparametric studies because an environmental parameter is being varied. This means that the new tools for studying nanostructure also need to be extended to work quickly and on large numbers of datasets. This thesis describes the development of new tools for high throughput studies of complex and nanostructured materials, and their application to study the structural evolution of bulk, and nanoparticles of, MnAs as a function of temperature. The tool for high throughput analysis of the bulk material was developed as part of this PhD thesis work and is called SrRietveld. A large part of making a new tool is to validate it and we did this for SrRietveld by carrying out a high-throughput study of uncertainties coming from the program using different ways of estimating theuncertainty. This tool was applied to study structural changes in MnAs as a function of temperature. We were also interested in studying different MnAs nanoparticles fabricated through different methods because of their applications in information storage. PDFgui, an existing tool for analyzing nanoparticles using Pair distribution function (PDF) refinement, was used in these cases. Comparing the results from theanalysis by SrRietveld and PDFgui, we got more comprehensive structure information about MnAs. The layout of the thesis is as follows. First, the background knowledge about material structures is given. The conventional crystallographic analysis is introduced in both theoretical and practical ways. For high throughput study, the next-generation Rietveld analysis program: SrRietveld, is coded in Python. The details of SrRietveldare provided in the thesis. More importantly, two real applications of SrRietveld are demonstrated to show its use cases. For the error analysis on Rietveld refinement, it is found that the results from two popular Rietveld programs are very sensitive to the input errors and the subset sampling method is particularly useful when the errorson diffraction pattern are unknown. In order to show the power of SrRietveld, I did the parametric study on MnAs bulk and nanoparticles. It is found that the magnetostructural property exists in bulk and one type of MnAs nanoparticles. However, when I want to probe the other type of MnAs nanoparticles that has smaller size, the conventional Rietveld method doesn't work and I turn to PDF for help. Using PDF approach, the structures of bulk and nanoparticle MnAs have been explored.Finally the conclusion is that I can either retain or modify the bulk properties by using different synthesis methods.
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