Date of Graduation

Summer 2020

Degree

Master of Science in Chemistry

Department

Chemistry

Committee Chair

Fei Wang

Keywords

solid-state chemistry, computational chemistry, thermoelectric materials, crystallography, physical chemistry, materials science

Subject Categories

Chemistry | Inorganic Chemistry | Materials Chemistry | Physical Chemistry

Abstract

Re1Si1Al1 and its related compounds are potential thermoelectric materials. Previously, it was reported to adopt a MoSi2-type structure with Si and Al atoms statistically sharing the same crystallographic sites. This recent study indicates otherwise – Si and Al are segregated and occupy different sites when mixed with a 1:1:1 stoichiometry. To confirm and rationalize the segregation between Si and Al, this research studied this compound with first-principle calculations. Several model structures have been constructed for Re1Si1Al1 including a number of different super-cell models. Energy analysis confirmed that the model with Si/Al segregation has the lowest energy. The chemical bonding in Re1Si1Al1 was investigated by computing Crystal Overlap Hamilton Populations (COHPs) and comparing the band structures of the models. It was found that low energy models typically possess a bandgap. The valence electron density maps were calculated to investigate the origin of the bandgaps. Bonding appears to play the largest factor in the 1:1 structures. These computations should provide more insight into the nature of Re1Si1Al1 and its related compounds.

Copyright

© Alec George Neeson

Open Access

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