Synthesis Of Nanoparticle Networks By Femtosecond Laser Ablation Of Microparticles

Paineet S Waraich

doi:10.32920/ryerson.14661432.v1

Abstract

The process of laser ablation has been adapted to generate nonoparticles from microparticles of the material, referred to as laser ablation of microparticles (LAM). The LAM process has been shown to generate finer nanoparticles than were previously possible through laser ablation of solid targets. In this thesis, a method of generating a 3D nanoparticle network using the LAM process has been proposed using a femtosecond laser. 3D naoparticles were successfully generated through ablation of microparticle samples of lead oxide, nickel oxide and zinc oxide. The size of the nanoparticles in the generated network was significantly reduced in comparison with similar networks generated through laser ablation of solid targets. The method has been further extended to generate a unique alloy nanomaterial through the ablation of the microparticle containing powders of two metals (Aluminum and Nickel Oxide).

Highlights

Earlier research conducted at the Laser Micro and Nano Fabrication Research Facility at Ryerson University showed that the use of megahertz laser ablation can generate fibrous nanoparticle networks from metals, dielectrics and a wide range of other material [31-33]
The analysis of the results indicated that nanoparticle formation did not occur through condensation process in a dilute atomic vapour, rather the nanoparticles were formed near the target surface as a result of ultrashort non-thermal melting and the consequent expansion into the vacuum of the material through extremely high temperatures and pressure created by the intense femtosecond laser pulse [23, 24]
This study has shown that femtosecond laser ablation in an ambient environment can be used for generating a 3D nanoparticle network from microparticles without the use of external stimulants or catalysts

Summary

Introduction

Earlier research conducted at the Laser Micro and Nano Fabrication Research Facility at Ryerson University showed that the use of megahertz laser ablation can generate fibrous nanoparticle networks from metals, dielectrics and a wide range of other material [31-33]. The study on the generation of very fine nanoparticle networks by the process of laser ablation of microparticles will be discussed. Nanoparticles generated from individual precursor materials (metals, polymers, semiconductors, dielectrics) have been shown to be useful for a lot of applications [25, 36-38]. Non-conventional methods have been used for the synthesis of nanocrystalline alloys from immiscible metals Methods such as ion beam mixing, sputtering, vapor deposition, thermal evaporation and laser ionization have been used for the synthesis of such alloys [39-43]. All these non-conventional methods take advantage of the theoretical predictions of lowered or suppressed phase separation at the nano scale [44, 45]. One theory has suggested the lack of nucleation barrier for the formation of segregated species at the nanoparticle size regime [46]

Methods

Results

Discussion

Conclusion