Understanding the formation of ultrafine spinel CoFe₂O₄ nanoplatelets and their magnetic properties

Abstract

Cobalt ferrite (CoFe₂O₄, CFO) nanoplatelets with a rhomboidal shape were synthesized through a facile hydrothermal route using a very low concentration precursor at low temperatures. The effects of reaction temperature and time on the morphologies as well as the sizes of the products were systemically investigated. The as-synthesized CFO nanocrystals showed a special rhomboidal shape with crystal growth along the (111) direction. The very low concentration precursor plays an important role in forming CFO nanocrystals with such special shape and ultrafine size. The single-phase CFO nanoplatelets synthesized at 180 °C with size of 17 nm present high saturation magnetization (79.7 emu/g) and high coercivity (3100 Oe). The preparation conditions have significant effects on the crystal size and shape, magnetization and relaxation activation of the CFO nanoplatelets.