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Nanosecond Pulsed Laser-Driven Formation of Novel Multimetallic Nanostructures.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Nanosecond Pulsed Laser-Driven Formation of Novel Multimetallic Nanostructures./
Author:	Mandal, Soumya.
Description:	1 online resource (149 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-10, Section: B.
Contained By:	Dissertations Abstracts International85-10B.
Subject:	Mechanical engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9798382176307

Nanosecond Pulsed Laser-Driven Formation of Novel Multimetallic Nanostructures.
Mandal, Soumya.

Nanosecond Pulsed Laser-Driven Formation of Novel Multimetallic Nanostructures. - 1 online resource (149 pages)

Source: Dissertations Abstracts International, Volume: 85-10, Section: B.

Thesis (Ph.D.)--Oklahoma State University, 2023.

Includes bibliographical references

Multi-principal element alloys (MPEAs) nanostructures have attracted significant attention because of their unique characteristics of homogeneous mixing of constituent elements in the nanoconfinements. However, a fundamental challenge is to devise efficient methods for fabricating such novel nanostructures of MPEAs by restricting the segregation of elements that have varying miscibility with each other. In this study, a non-equilibrium approach of nanosecond pulsed laser-induced dewetting (PLiD) has been used to successfully fabricate the MPEA nanostructures. Ni-based MPEA constituting Ni, Co, Cr, Fe, Mn, Cu, and Ag is selected as the model system, where the NiCoCr system is studied first. Here, the non-stochiometric MPEA thin film formation behavior from an equiatomic ablation target of NiCoCr using pulsed laser deposition has been investigated. It is observed that average atomic percentages of Ni and Cr are twice as high as Co in the as-deposited thin films, which is explained by considering the vapor pressures and optical properties of Ni, Co, and Cr. The next study demonstrates the successful formation of NiCoCr nanoparticles via PLiD of ultrathin alloy films. Interestingly, the fabricated nanoparticles maintain a homogenous distribution of the constituent elements (Ni, Co, and Cr) without any trace of segregation. This study also reveals the environmental stability and grain arrangement of the nanoparticles using high-resolution chemical analysis and 4D-STEM. In the third study, self-assembled AgNiCoCr nanoparticles are successfully fabricated using the PLiD approach from different co-organized films of NiCoCr and Ag having various thicknesses by overcoming the immiscible characteristics of Ag. Results show the uniform distribution of constituent elements throughout the nanoparticles fabricated from thinner film (~5 nm) and NiCoCr segregates towards the shell region as the film thickness increases. This phenomenon is explained by leveraging the differences in the thermal conductivity, solidification rate, and cohesive energy of NiCoCr and Ag. The fourth study presents the successful fabrication of self-assembled Cr2O3-Fe2O3 core-shell nanoparticles using the PLiD of an alloy oxide thin film. Due to the differences in cooling rates, surface energies, and enthalpies of mixing, thermodynamically miscible Cr2O3 and Fe2O3 phase-segregate in the core and shell areas within the nanoparticle, respectively. These studies provide the fundamental understanding of fabricating unique MPEA nanoparticles via PLiD that could be useful for catalysis and energy related applications.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798382176307Subjects--Topical Terms:

557493
Mechanical engineering.
Subjects--Index Terms:

Atom probe tomographyIndex Terms--Genre/Form:

554714
Electronic books.

Nanosecond Pulsed Laser-Driven Formation of Novel Multimetallic Nanostructures.
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504 $a Includes bibliographical references
520 $a Multi-principal element alloys (MPEAs) nanostructures have attracted significant attention because of their unique characteristics of homogeneous mixing of constituent elements in the nanoconfinements. However, a fundamental challenge is to devise efficient methods for fabricating such novel nanostructures of MPEAs by restricting the segregation of elements that have varying miscibility with each other. In this study, a non-equilibrium approach of nanosecond pulsed laser-induced dewetting (PLiD) has been used to successfully fabricate the MPEA nanostructures. Ni-based MPEA constituting Ni, Co, Cr, Fe, Mn, Cu, and Ag is selected as the model system, where the NiCoCr system is studied first. Here, the non-stochiometric MPEA thin film formation behavior from an equiatomic ablation target of NiCoCr using pulsed laser deposition has been investigated. It is observed that average atomic percentages of Ni and Cr are twice as high as Co in the as-deposited thin films, which is explained by considering the vapor pressures and optical properties of Ni, Co, and Cr. The next study demonstrates the successful formation of NiCoCr nanoparticles via PLiD of ultrathin alloy films. Interestingly, the fabricated nanoparticles maintain a homogenous distribution of the constituent elements (Ni, Co, and Cr) without any trace of segregation. This study also reveals the environmental stability and grain arrangement of the nanoparticles using high-resolution chemical analysis and 4D-STEM. In the third study, self-assembled AgNiCoCr nanoparticles are successfully fabricated using the PLiD approach from different co-organized films of NiCoCr and Ag having various thicknesses by overcoming the immiscible characteristics of Ag. Results show the uniform distribution of constituent elements throughout the nanoparticles fabricated from thinner film (~5 nm) and NiCoCr segregates towards the shell region as the film thickness increases. This phenomenon is explained by leveraging the differences in the thermal conductivity, solidification rate, and cohesive energy of NiCoCr and Ag. The fourth study presents the successful fabrication of self-assembled Cr2O3-Fe2O3 core-shell nanoparticles using the PLiD of an alloy oxide thin film. Due to the differences in cooling rates, surface energies, and enthalpies of mixing, thermodynamically miscible Cr2O3 and Fe2O3 phase-segregate in the core and shell areas within the nanoparticle, respectively. These studies provide the fundamental understanding of fabricating unique MPEA nanoparticles via PLiD that could be useful for catalysis and energy related applications.
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