One pot, scalable synthesis of hydroxide derived ferrite magnetic nanoparticles

Abstract

Herein we describe a new, quite simple, highly scalable, one-pot protocol for the synthesis of ferrite nanoparticles, NPs. We immerse water insoluble iron boride, FeB, powders – in plastic bottles at temperatures between 50 °C and 80 °C and ambient pressures – for tens of hours in high pH aqueous solutions of potassium-, sodium-, tetramethylammonium-, or tetrabutylammonium-hydroxides. The resulting powder is comprised of iron oxide, Fe3O4, NPs with, in one case, a saturation magnetization of 75 Am2kg−1, that exhibit ferrimagnetic behavior, with a critical temperature of 820 K. The same protocol was used to convert water soluble iron sulphate, FeSO4, to the same NPs. The average size of the NPs depends on reaction time; after 24 h, they are in the 15 nm range; after 48 h, they are closer to 25 nm. While our approach may appear to be similar to the co-precipitation method for making such NPs, we make a strong case that our approach is significantly simpler, nonetheless reaching high magnetization of NPs.