Author ORCID Identifier

https://orcid.org/0000-0002-3599-408X

Year of Publication

2021

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Engineering

Department/School/Program

Chemical and Materials Engineering

First Advisor

Dr. T. John Balk

Abstract

The study of nanoporous materials has become a key aspect of nanotechnology due to their high surface-area-to-volume ratio, arising from the small size ligaments and pores that form the structure. Sensing, catalysis, micro-electromechanical systems (MEMS), medical applications, and materials for radiation environments are some of the applications for which nanoporous materials are considered great candidates. This work, performed at the Ion Beam Laboratory (IBL) at Sandia National Laboratories (SNL), examines the effect of heavy and light ion irradiation exposure on nanoporous Au. Radiation damage accumulation is observed with real-time recording of the creation, migration, and removal of the radiation-induced defects within the nanoporous framework. Promising results of nanoporous gold to radiation tolerance have emerged, underscoring the need to explore the synthesis of nanoporous refractory metals. For this purpose, niobium was selected as one such element, primarily due to its low neutron absorption cross-section and high-temperature stability that renders it a candidate structural material in fusion energy systems. A novel technique, named Vacuum Thermal Dealloying (VTD), is introduced for refractory metals since conventional dealloying is problematic for highly chemically active elements that are prone to oxidation. An analytical investigation of this unique dealloying technique has occurred with real-time recording through in-situ TEM annealing experiments under various heating conditions in order to optimize the final nanoporous structure. Finally, elemental and morphological characterization of the nanoscale volume were performed using 3D electron tomography, providing essential information about the interconnected porosity of two nanostructured samples: 1. Nanoporous Niobium and 2. Multilayered Nanoporous Tantalum / Dense Tantalum.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2021.239

Available for download on Sunday, July 09, 2023

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