High temperature stable monodisperse superparamagnetic core-shell iron-oxide@SnO2 nanoparticles

Abstract

Monodisperse superparamagnetic SnO2-coated iron-oxide nanoparticles (∼16.4 nm) have been synthesized via thermal decomposition. The thickness of SnO2 shells can be controlled from 1–5 nm. As-prepared SnO2-coated iron-oxide nanoparticles with high saturation magnetization (18 A m2/kg), are stable up to 600 °C, which can be formed stable ferrofluid. It was suggested that the SnO2 shell acts as a barrier of preventing the growth of γ-Fe2O3 and consequently, avoiding the γ-Fe2O3-to-α-Fe2O3 phase transition at high temperatures.