Organic fluxes as a tool for solid-state synthesis

Fallon, M. Jewels, author
Neilson, James R., advisor
Finke, Richard G., committee member
Menoni, Carmen S., committee member
Buchanan, Kristen S., committee member
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Colorado State University. Libraries
Solid-state materials allow us to charge our phones, store information on a computer, and harvest energy from the sun, among many other applications. They are the backbone of many modern technologies. However, making solid-state materials remains challenging. Traditional solid-state synthesis involves heating materials up to high temperatures to promote reactivity. These high temperatures make controlling the reactions and directing product formation difficult, as they generally form products that are stable at those high temperatures. There are limited techniques to make solid-materials, especially those that are not stable at high temperatures. In order to advance modern technologies based on solid-state materials, more well-understood, controllable synthetic techniques are necessary. This thesis describes a new technique for making solid-state materials. This technique is based on using molten organic materials, called organic fluxes, to enable selective reactivity between solids at lower temperatures. Owing to the lower reaction temperatures, this synthesis can form materials that are traditionally more difficult to make. The concept of an organic flux is introduced through a case study where triphenylphosphine, the organic flux, is used to make the low-temperature phase of iron selenide. This study demonstrates the efficacy of organic fluxes and provides insight to their mechanism of reactivity. Then, triphenylphosphine fluxes are further explored through reactions involving other metal chalcogenide binaries. By analyzing a variety of systems, the guiding principles behind the reactivity of triphenylphosphine fluxes are determined. Next, the ability of organic fluxes to aid materials discovery is shown through the formation of a new cobalt-selenium-triphenylphosphine complex. Finally, preliminary work exploring other organic fluxes and the future prospects for this synthetic scheme are discussed. This research introduces a new technique to target low-temperature materials. The tunability of organic fluxes enables the design of synthesis for selective reactivity in the solid-state. Adding to the library of synthetic tools available to solid-state chemists is a step towards materials discovery and the advancement of technologies based on solid-state materials.
2022 Summer.
Includes bibliographical references.