Uniform Fe3O4 Octahedra with Tunable Edge Length – Synthesis by a Facile Polyol Route and Magnetic Properties

Abstract

AbstractA straightforward and effective polyol route for the controllable synthesis of high‐quality magnetite (Fe3O4) octahedra with uniform edge length in ethylene glycol (EG) solution is presented. Fe3O4 octahedra with edge length in the range 70–1000 nm were selectively synthesized in high yield. The surfaces of octahedral Fe3O4 crystals correspond to (111) planes. Formation of Fe3O4 octahedra was attributed to the preferential adsorption of OH– ions onto the (111) planes of Fe3O4 nuclei, which inhibits the growth rate along the <111> direction. The release rate of Fe2+ ions in the synthesis can be rationally manipulated by varying the dose of N2H4·H2O. Control of the nucleation and growth rate by N2H4·H2O provides a facile and effective route to harvest Fe3O4 octahedra with different dimensions. The magnetic analysis shows that Fe3O4 octahedra with sharp tips possess attractive magnetic properties.