Self-Assembly Behavior of Modulated Elemental Reactants
| dc.contributor.advisor | Johnson, David | |
| dc.contributor.author | Cordova, Dmitri Leo | |
| dc.date.accessioned | 2020-09-24T17:13:05Z | |
| dc.date.available | 2020-09-24T17:13:05Z | |
| dc.date.issued | 2020-09-24 | |
| dc.description.abstract | Diverse bulk-derived layered structures have been made via Modulated Elemental Reactants (MER) synthesis despite only superficial understanding of its mechanism. The premise behind this approach is that an elemental multilayer precursor self-assembles in an almost diffusionless process if it has the correct number of atoms per layer and its nanoarchitecture closely resembles the target product. The work presented here is concentrated on developing a deeper understanding of the reaction mechanism of Modulated Elemental Reactants, prompted by developments in analysis methods for thin films. A new method for analyzing X-ray Florescence (XRF) data was developed to measure the number of atoms per square Angstrom (areal density) in a thin film with sub-monolayer accuracy. With this advancement, precursors can be made so that the two conditions set by the simple MER mechanism are satisfied. The crystallographic alignment of thick PbSe layers on VSe2 demonstrated a strong non-epitaxial relationship between the two constituents, suggesting that compatibility of two layered constituents in a heterostructure can be determined by testing for preferred alignment. A new class of charge density wave containing heterostructures, [(PbSe)1+]m(VSe2)1, where m = 1-4 and the number of PbSe bilayers, was synthesized by precisely controlling the element areal density and nanoarchitecture of the precursor. Alternate reaction pathways were explored when the areal density of the precursor was modified. Next, a similar class of heterostructures, [(PbSe)1+]1(VSe2)1, where q = 1-11 and the number of PbSe monolayers, was investigated. When a small odd number of PbSe monolayers (q = 1, 3, and 5) was targeted for synthesis, the precursors exhibited unexpected long range lateral surface diffusion during the deposition process, uncovering a new aspect of MER synthesis. Computational studies confirmed that the low temperature rearrangement is driven by the stability of PbSe bilayers compared to monolayers. Lastly, the growth mechanism of a new heterostructure, [(SnSe2)1+d]1(VSe2)1 was elucidated from Laue oscillations in x-ray reflectivity data and in-plane x-ray diffraction and precursor nanoarchitecture, and was used as a guide to direct reaction pathways toward the synthesis of a new alloy, SnxV1-xSe2. This dissertation contains previously published and unpublished coauthored material. | en_US |
| dc.identifier.uri | https://hdl.handle.net/1794/25616 | |
| dc.language.iso | en_US | |
| dc.publisher | University of Oregon | |
| dc.rights | All Rights Reserved. | |
| dc.subject | metastable solids | en_US |
| dc.subject | nanoarchitecture | en_US |
| dc.subject | reaction mechanisms | en_US |
| dc.subject | solid state synthesis | en_US |
| dc.title | Self-Assembly Behavior of Modulated Elemental Reactants | |
| dc.type | Electronic Thesis or Dissertation | |
| thesis.degree.discipline | Department of Chemistry and Biochemistry | |
| thesis.degree.grantor | University of Oregon | |
| thesis.degree.level | doctoral | |
| thesis.degree.name | Ph.D. |
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