Johnson, DavidLemon, Mellie2024-01-092024-01-092024-01-09https://hdl.handle.net/1794/29135This dissertation focuses on the use of the modulated elemental reactants synthesis method to target previously unknown, metastable compounds. The nucleation and growth of the compounds discovered were monitored via x-ray characterization techniques, leading to insights on the reaction pathways and parameters for trapping kinetic products. The insights about the growth technique contribute to the goal of materials discovery by design. The exploration of the physics behind Laue oscillations and the incorporation of Laue oscillation fitting into GSAS-II is an advance in x-ray characterization techniques, and enabled a deeper, fundamental understanding of the growth of layered compounds.This thesis begins with background and motivation for thin film synthesis before delving into an in-depth description of the modulated elemental reactants synthesis method. An exploration of the reaction pathways of MER precursors as they crystallize into metastable products is described, with three novel materials presented as experimental examples. For Fe0.8V0.2Se2, nucleation of VSe2 grains during the deposition kinetically favor the growth of highly Fe-substituted VSe2. For (PbSe)1+δ(FeSe2)2, interlayer interactions with PbSe stabilize the formation of a novel, hexagonal FeSe2 phase. For (Pb3Mn2Se5)0.6(VSe2), finite size effects and interlayer stabilization promote the formation of a novel, quintuple layer Pb3Mn2Se5 unit cell. In each example, nucleation during the deposition controls the formation of the targeted metastable phases. The second section describes how to extract the maximum amount of structural information from Laue oscillations in thin film samples. Laue oscillations are theoretically explored to understand how to distribution of domains sizes impact their intensities. Laue oscillation fitting is incorporated into the crystallography data analysis software GSAS-II. Laue oscillations are key in the development of an approach to determine the distribution and extent of substitution and/or intercalation of dopant atoms, which is demonstrated for FexV1-ySe2 samples. The remainder of this thesis focuses on the experimental synthesis and characterization of novel Fe-containing phases from MER precursors. This includes the synthesis of a Pb1-xFexSe phase, a range of FexV1-ySe2 compounds with more Fe incorporation than had previously been achieved, and a family of (PbSe)1+δ(FeSe2)n heterostructures.en-USAll Rights Reserved.Laue OscillationsMaterials DiscoveryThin Film SyntheisX-ray DiffractionElectronic Thesis or Dissertation