Issue 24, 2015

The transformation of α-Fe nanoparticles into multi-domain FeNi–M3O4 (M = Fe, Ni) heterostructures by galvanic exchange

Abstract

In this work we describe a novel method to prepare multi-domain metal–metal oxide heterostructured nanoparticles (NPs). We investigated the ability of Ni(acac)2 to undergo galvanic exchange with pre-synthesized metallic α-Fe NPs. Findings indicate that an asymmetric heterostructure emerges from the exchange, which is followed by rapid oxidation to form a NiFe–M3O4 (M = Fe, Ni) alloy-oxide microstructure. Nucleation and growth was monitored using UV-vis and TEM, and crystal evolution, composition change, and oxidation states were measured by XRD and XPS respectively. Galvanic exchange and growth was studied by varying Ni : Fe molar feed ratios during synthesis. The findings indicate that at low Ni : Fe ratios, the NP forms multiple domains of oxides, whereas at higher ratios form regions with novel Ni–NiFe–M3O4 interfaces. These new heterostructures were highly magnetic, and the extent of magnetization was proportional to composition and morphology, where NPs prepared at high Ni : Fe feed ratios resulted in decreased saturation magnetization and increased magnetic hysteresis. The nickel deposition and NP growth mechanism was considered as a combination of both galvanic exchange and reduction, and the observed rapid oxidation of the remaining α-Fe core was considered in light of electron density change at the heterostructures interfaces. Nanomaterials like these may find use as components in magnetic storage and spintronic devices, probes in biomedicine, additives in corrosion resistant coatings, and even as 3D printing inks.

Graphical abstract: The transformation of α-Fe nanoparticles into multi-domain FeNi–M3O4 (M = Fe, Ni) heterostructures by galvanic exchange

Supplementary files

Article information

Article type
Paper
Submitted
02 Apr 2015
Accepted
27 May 2015
First published
27 May 2015

J. Mater. Chem. C, 2015,3, 6367-6375

The transformation of α-Fe nanoparticles into multi-domain FeNi–M3O4 (M = Fe, Ni) heterostructures by galvanic exchange

R. D. Slaton, I. Bae, P. S. Lutz, L. Pathade and M. M. Maye, J. Mater. Chem. C, 2015, 3, 6367 DOI: 10.1039/C5TC00929D

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements