One pot, scalable synthesis of hydroxide derived ferrite magnetic nanoparticles

Herein we describe a new, quite simple, highly scalable, one-pot protocol for the synthesis of ferrite nano-particles, NPs. We immerse water insoluble iron boride, FeB, powders - in plastic bottles at temperatures be-tween 50 degrees C and 80 degrees 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 sul-phate, 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.