Alfred University Research and Archive (AURA)

Total Scattering Analysis of Disordered Nanosheet Materials

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dc.contributor.advisor Misture, Scott
dc.contributor.advisor Pilgrim, Steven
dc.contributor.advisor Edwards, Doreen
dc.contributor.advisor Liu, Dawei Metz, Peter C. 2021-07-23T13:28:14Z 2021-07-23T13:28:14Z 2017-04
dc.description Thesis completed in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Ceramic Engineering at the Inamori School of Engineering, New York State College of Ceramics at Alfred University en_US
dc.description.abstract Two dimensional materials are of increasing interest as building blocks for functional coatings, catalysts, and electrochemical devices. While increasingly sophisticated processing routes have been designed to obtain high-quality exfoliated nanosheets and controlled, self-assembled mesostructures, structural characterization of these materials remains challenging. This work presents a novel method of analyzing pair distribution function (PDF) data for disordered nanosheet ensembles, where supercell stacking models are used to infer atom correlations over as much as 50 Å. Hierarchical models are used to reduce the parameter space of the refined model and help eliminate strongly correlated parameters. Three data sets for restacked nanosheet assemblies with stacking disorder are analyzed using these methods: simulated data for graphene-like layers, experimental data for ~1 nm thick perovskite layers, and and experimental data for highly defective δ-MnO2 layers. In each case, the sensitivity of the PDF to the real-space distribution of layer positions is demonstrated by exploring the fit residual as a function of stacking vectors. The refined models demonstrate that nanosheets tend towards local interlayer ordering, which is hypothesized to be driven by the electrostatic potential of the layer surfaces. Correctly accounting for interlayer atom correlations permits more accurate refinement of local structural details including local structure perturbations and defect site occupancies. In the δ-MnO2 nanosheet material, the new modeling approach identified 14% Mn vacancies while application of 3D periodic crystalline models to the <7 Å PDF region suggests a 25% vacancy concentration. In contrast, the perovskite nanosheet material is demonstrated to exhibit almost negligible structural relaxation in contrast with the bulk crystalline material from which it is derived. en_US
dc.format.extent 135 pages en_US
dc.language en_US en_US
dc.language.iso en_US en_US
dc.publisher New York State College of Ceramics at Alfred University. Inamori School of Engineering. en_US
dc.relation.ispartof Scholes Library en_US
dc.rights.uri en_US
dc.subject Nanostructured materials en_US
dc.subject Materials--Analysis en_US
dc.title Total Scattering Analysis of Disordered Nanosheet Materials en_US
dc.type Thesis en_US

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