Synthesis of Iron Oxide Nanostructures via Carbothermal Reaction of Fe Microspheres Generated by Infrared Pulsed Laser Ablation

Jeffrey De Vero,Alladin Jasmin,Roland Sarmago,Wilson Garcia,Lean Dasallas

doi:10.3390/coatings9030179

Jeffrey De Vero, Alladin Jasmin + Show 3 more

Open Access

https://doi.org/10.3390/coatings9030179

Copy DOI

Abstract

Iron oxide nanostructures were synthesized using the carbothermal reaction of Fe microspheres generated by infrared pulsed laser ablation. The Fe microspheres were successfully deposited on Si(100) substrates by laser ablation of the Fe metal target using Nd:YAG pulsed laser operating at λ = 1064 nm. By varying the deposition time (number of pulses), Fe microspheres can be prepared with sizes ranging from 400 nm to 10 µm. Carbothermal reaction of these microspheres at high temperatures results in the self-assembly of iron oxide nanostructures, which grow radially outward from the Fe surface. Nanoflakes appear to grow on small Fe microspheres, whereas nanowires with lengths up to 4.0 μm formed on the large Fe microspheres. Composition analyses indicate that the Fe microspheres were covered with an Fe3O4 thin layer, which converted into Fe2O3 nanowires under carbothermal reactions. The apparent radial or outward growth of Fe2O3 nanowires was attributed to the compressive stresses generated across the Fe/Fe3O4/Fe2O3 interfaces during the carbothermal heat treatment, which provides the chemical driving force for Fe diffusion. Based on these results, plausible thermodynamic and kinetic considerations of the driving force for the growth of Fe2O3 nanostructures were discussed.

Highlights

Nanomaterials offer a new way of designing structural, functional, and electronic devices on the nanometer scale
We extended the idea of using the Nd:YAG laser operating at λ = 1064 nm as the excitation source for the formation of nanoparticles on a Si(100) substrate coupled with the carbothermal reaction process to synthesize iron oxide nanostructures
The objective of this work is two-fold: (1) Synthesis of iron oxide nanostructures by carbothermal oxidation of Fe microspheres generated by infrared pulsed laser ablation, demonstrating the formation of iron oxide nanostructures without the need of catalysts; (2) discussion of the plausible mechanism for the self-assembly of iron oxide nanostructures in terms of thermodynamics and kinetic processes

Summary

Introduction

Nanomaterials offer a new way of designing structural, functional, and electronic devices on the nanometer scale. Fe2 O3 (iron oxide) nanostructures have been intensively studied because of their unique electrical and magnetic properties while maintaining their chemical compatibility with biological tissues for possible biological applications [1,2,3,4,5,6]. Their use extend to recording, ultrahigh density memory storage, and targeted drug delivery, including water splitting for energy applications [4,5,6]. Common to Coatings 2019, 9, 179; doi:10.3390/coatings9030179 www.mdpi.com/journal/coatings

Objectives

Methods

Results

Conclusion