Polaris-SMC in-situ microwave reactor: a new technique for real time neutron diffraction of rapid microwave-induced syntheses

McFadzean, Ross George Bell (2023) Polaris-SMC in-situ microwave reactor: a new technique for real time neutron diffraction of rapid microwave-induced syntheses. PhD thesis, University of Glasgow.

Abstract

Direct microwave heating holds much promise in revolutionising the synthesis of solid state materials due to the clear benefits from greatly reduced reaction times and lower energy requirements compared to conventional methods. For the modern laboratory the principles of green chemistry to reduce energy usage and actions with a detrimental impact to the environment are increasingly taking prominence, and microwave reactors work well within this framework. The rapidity of microwave heating however, makes following a reaction progression and identification of unusual synthesis pathways a difficult process. The bespoke single mode cavity reactor designed to operate within the Polaris neutron diffractometer allows for neutron data to be collected over the short time scale of a microwave reaction. The neutron data is recorded with respect to time which can then be split into smaller sections to investigate the reaction pathways in increasingly granular detail.

Throughout this project, several binary metal chalcogenide chemical systems known to be thermoelectric materials of interest were investigated. Thermoelectric generators make use of the Seebeck effect to generate useable currents from an applied temperature gradient, allowing waste heat to be converted back into valuable electricity. For each system a range of samples were prepared in which the selenium component was partially substituted with a either tellurium or sulfur in order to hopefully tune the thermoelectric properties. The substitution subprojects enabled a large list of samples to be prepared for synthesis in the Polaris-SMC microwave reactor under well understood reaction conditions. Many of these materials have not been produced previously using a direct microwave heating method in the solid state, and so the insights gained from the in-situ neutron data should help optimisation their synthesis conditions in the future.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering > School of Chemistry
• Supervisor's Name: Gregory, Professor Duncan
• Date of Award: 2023
• Depositing User: Theses Team
• Unique ID: glathesis:2023-83705
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 05 Jul 2023 11:35
• Last Modified: 05 Jul 2023 11:35
• Thesis DOI: 10.5525/gla.thesis.83705
• URI: https://theses.gla.ac.uk/id/eprint/83705