Exchange-coupled Fe3O4/CoFe2O4 nanoparticles for advanced magnetic hyperthermia

J Robles,H Srikanth,M H Phan,M Glassell,R Das

doi:10.1063/1.5007249

Abstract

We report a systematic study of the effects of core and shell size on the magnetic properties and heating efficiency of exchange-coupled Fe3O4/CoFe2O4 core/shell nanoparticles. The nanoparticles were synthesized using thermal decomposition of organometallic precursors. Transmission electron microscopy (TEM) confirmed the formation of spherical Fe3O4 and Fe3O4/CoFe2O4 nanoparticles. Magnetic measurements showed high saturation magnetization for the nanoparticles at room temperature. Increasing core diameter (6.4±0.7, 7.8±0.1, 9.6±1.2 nm) and/or shell thickness (∼1, 2, 4 nm) increased the coercive field (HC), while an optimal value of saturation magnetization (MS) was achieved for the Fe3O4 (7.8±0.1nm)/CoFe2O4 (2.1±0.1nm) nanoparticles. Magnetic hyperthermia measurements indicated a large increase in specific absorption rate (SAR) for 8.2±1.1 nm Fe3O4/CoFe2O4 compared to Fe3O4 nanoparticles of same size. The SAR of the Fe3O4/CoFe2O4 nanoparticles increased from 199 to 461 W/g for 800 Oe as the thickness of the CoFe2O4 shell was increased from 0.9±0.5 to 2.1±0.1 nm. The SAR enhancement is attributed to a combination of the large MS and the large HC. Therefore, these Fe3O4/CoFe2O4 core/shell nanoparticles can be a good candidate for advanced hyperthermia application.

Highlights

INTRODUCTIONWe report how the variations in the core diameter and shell thickness affect the magnetic response and heating efficiency of exchange-coupled Fe3O4/CoFe2O4 core/shell nanoparticles
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We observed an increment in the nanoparticle size by ∼2 nm, excluding the case for Figure 1(f) where we saw an increment of ∼4 nm (Table I)

Summary

INTRODUCTION

We report how the variations in the core diameter and shell thickness affect the magnetic response and heating efficiency of exchange-coupled Fe3O4/CoFe2O4 core/shell nanoparticles

EXPERIMENT

RESULTS AND DISCUSSION

CONCLUSIONS