Refining single-crystalline epsilon iron oxide nanorods via low-temperature aging

Refinement of epsilon-Fe2O3 phase in epsilon-Fe2O3/SiO2 composite powder is an urgent need in terms of its practical applications in high-density magnetic storage media. In this work, two types of refinement routes were employed for this purpose. It was found that short-time tempering treatment was not an ideal route for the refinement, because epsilon-Fe2O3 nanorods were ruptured to nanoparticles with an extremely wide size distribution, and their low coercivity of merely 1.0 kOe was not desirable for expected applications. By contrast, low-temperature aging route facilitated the formation of uniform epsilon-Fe2O3 nanorods with a length of about 200 nm and a width of about 40 nm. Because of their narrow size distribution and high crystallinity, these nanorods possessed large coercivity around 19 kOe, pronounced remanent squareness and prominent thermomagnetic behaviors, making them fairly desirable for further applications in magnetically-relevant field. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.