Multi metallic nano alloys: understanding the structure and properties of nano alloys

Lehr, Alexander (2023) Multi metallic nano alloys: understanding the structure and properties of nano alloys. Doctoral thesis, Northern Arizona University.

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Abstract

Nanomaterials are this age’s defining material. Understanding how they are structured is key to controlling the formation of nanomaterials and obtain the desired properties. Nanoalloys are a key subset in that they have many applications in catalysis, medicine, energy, and informatics. In this dissertation, two, three, and four, metallic nanoparticles are studied under an electron beam to understand their structure and pull-out information about how they are formed. Looking at how size changed the structure, Pt and Cu were alloyed into small nanoparticles of size less than 20 nm. As size decreases, Cu becomes more likely to more to interstitial positions in the Pt-Cu lattice structure. This was studied by theoretical and experimental techniques. To more understand how three metals change the crystal structure, Au-Cu-Pt nanoalloys were synthesized to study the effects of adding a third metal (Pt) to a well-known system (Au-Cu). It was found that the structure is different from what is expected and the Cu forms bonds with Au and Pt forming core shell like structures. Another structure characteristic of nanoalloys is the prevalence of twin boundaries. Twins play an important role in the stabilization of multi metallic nanoparticles. To better explain the structure of nanoparticles, kinetic vs thermal equilibrium needs to be explored. The role of entropy in the stabilization of multimetallic nanoparticles is discussed along with the importance of the Gibbs free energy. The structure of multimetallic nanoparticles tends to form decahedra and icosahedra shapes. These shapes are full of twin boundaries where there is periodic strain throughout. Nanoalloys are of great interest and can find use in many fields, understanding the structure is the key.

Item Type:	Thesis (Doctoral)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	Alloys; Crystologrophy; Electron Microscopy; Hight Entropy Alloys; Quasicrystals; nanomaterials
Subjects:	Q Science > QC Physics
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > Physics and Astronomy
Date Deposited:	19 May 2025 17:09
Last Modified:	19 May 2025 17:09
URI:	https://openknowledge.nau.edu/id/eprint/6154

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