Profound Interfacial Effects in CoFe2O4/Fe3O4 and Fe3O4/CoFe2O4 Core/Shell Nanoparticles

Dmytro Polishchuk,Anatolii Belous,Vladyslav Zamorskyi,Alexandr Tovstolytkin,Anna Ślawska-Waniewska,Natalia Nedelko,Sergii Solopan

doi:10.1186/s11671-018-2481-x

Dmytro Polishchuk, Anatolii Belous + Show 5 more

Open Access

https://doi.org/10.1186/s11671-018-2481-x

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Abstract

Two sets of core/shell magnetic nanoparticles, CoFe2O4/Fe3O4 and Fe3O4/CoFe2O4, with a fixed diameter of the core (~ 4.1 and ~ 6.3 nm for the former and latter sets, respectively) and thickness of shells up to 2.5 nm were synthesized from metal chlorides in a diethylene glycol solution. The nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, and magnetic measurements. The analysis of the results of magnetic measurements shows that coating of magnetic nanoparticles with the shells results in two simultaneous effects: first, it modifies the parameters of the core-shell interface, and second, it makes the particles acquire combined features of the core and the shell. The first effect becomes especially prominent when the parameters of core and shell strongly differ from each other. The results obtained are useful for optimizing and tailoring the parameters of core/shell spinel ferrite magnetic nanoparticles for their use in various technological and biomedical applications.

Highlights

Core/shell architecture has acquired increasing interest due to the possibility of combining different materials and fabricating nanostructures with improved characteristics [1, 2]
X-ray diffraction (XRD) and Transmission electron microscopy (TEM) Investigations XRD patterns for the nanoparticles under study indicate that all synthesized samples have a cubic spinel structure (JCPDS card number 19-0629 [20])
To confirm the formation of core/shell structure, we used a comparative analysis of XRD patterns collected from separate CoFe2O4 and Fe3O4 Magnetic nanoparticles (MNP), mechanical mixture composed of these compounds taken in 1:1 ratio, and supposed core/shell structures

Summary

Introduction

Core/shell architecture has acquired increasing interest due to the possibility of combining different materials and fabricating nanostructures with improved characteristics [1, 2]. Cobalt ferrite (CoFe2O4) is magnetically hard with a large magnetocrystalline anisotropy constant K > 106 erg/cm3 [5, 6]. Due to the same crystallographic structure and almost negligible lattice mismatch among these spinel ferrites, it should be markedly controllable to epitaxially grow a uniformed shell over a core. Among other things, such kind of the well-defined bimagnetic spinel ferrite nanocrystals with core/shell architecture can provide a better platform for the fundamental understanding of magnetism and the relationship between the crystalline structure, the morphology, and the physical properties

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