Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 149243

149243 - Multi-Principal Element Nanostructures via Nanosecond Laser-Induced Dewetting 

The multi-principal element alloy nanoparticles, a new class of nanomaterials, present a highly rewarding opportunity to explore new or vastly different functional properties than the traditional mono/bi/multimetallic nanostructures due to their unique characteristics of atomic-level homogeneous mixing of constituent elements in the nanoconfinements. The idea of downscaling the bulk MPEAs into nanostructures has enthralled the scientific community in view of creating enormous possibilities both in structural and functional applications. Yet, designing the synthesis processes that can control the phase segregation within the nanoparticles due to the elemental immiscibility of constituents and maintaining the atomic structure are the prime challenges towards succeeding in this direction. A few efforts have been made to overcome these challenges and demonstrate the synthesis of MPEA NPs following the ultrafast non-equilibrium pathways. Such routes limit the elemental diffusion and phase segregation, which could be more likely in equilibrium conditions and have enabled achieving a variety of MPEA NPs. Here, we report the successful creation of NiCoCr nanoparticles, a well-known MPEA system, using ultrafast nanosecond laser-induced dewetting of alloy thin films. Nanoparticle formation occurs by spontaneously breaking the energetically unstable thin films in a melt state under laser-induced hydrodynamic instability and subsequently accumulating in a droplet shape via surface energy minimization. While NiCoCr alloy shows a stark contrast in physical properties compared to individual metallic constituents, i.e., Ni, Co and Cr, yet the transient nature of the laser-driven process facilitates a homogeneous distribution of the constituents (Ni, Co and Cr) in the nanoparticles. The utilization of conventional and advanced data science driven characterization methods, such as 4D scanning transmission electron microscopy, will resolve the compositional and microstructural complexities to fill the knowledge gaps in understanding laser-material interactions for creating NPs. Using high-resolution chemical analysis and scanning nanodiffraction, we further investigate the environmental stability and grain arrangement in the nanoparticles. Thermal transport simulations reveal that the ultrashort (~100 ns) melt-state lifetime of NiCoCr during the dewetting event helps retain the constituent elements in a single-phase solid solution with homogenous distribution and opens the pathway to create the unique MPEA nanoparticles with laser-induced dewetting process. Altogether, the efficiency of NLiD in fabricating complex nanoscale structures is evaluated, along with the enormous possibility of modifying their performance for prospective applications in catalysis and energy storage. This will further help in investigating several functional properties of MPEA NPs beyond the current primary focus of electrocatalysis and in the directions of magnetism, plasmonics, photothermal conversion and photocatalysis, chemical and biomolecular detection etc.

 

 

Presenting Author: Ritesh Sachan Oklahoma State University

Presenting Author Biography: Dr. Ritesh Sachan is an assistant professor in the Department of Mechanical and Aerospace Engineering at Oklahoma State University. His research interests primarily lie in developing a quantitative understanding of structure-property correlations in high entropy materials using combinatorial thin film approaches and advanced electron microscopy. His current research interest is developing nanosecond laser-based processes to create high entropy alloy nanoparticles and understanding the evolution mechanism for nanoparticle formation. Previously, Dr. Sachan worked at the Army Research Office as an NRC researcher and at Oak Ridge National Laboratory as a postdoctoral researcher. He has received NSF-CAREER, ASM-IIM lectureship, National Science, NRC fellowship from the National Academy of Sciences, and the TMS Young Leader Award.

Authors:

Ritesh Sachan Oklahoma State University