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

Abstract

Abstract A straightforward and effective polyol route for the controllable synthesis of high‐quality magnetite (Fe 3 O 4 ) octahedra with uniform edge length in ethylene glycol (EG) solution is presented. Fe 3 O 4 octahedra with edge length in the range 70–1000 nm were selectively synthesized in high yield. The surfaces of octahedral Fe 3 O 4 crystals correspond to (111) planes. Formation of Fe 3 O 4 octahedra was attributed to the preferential adsorption of OH – ions onto the (111) planes of Fe 3 O 4 nuclei, which inhibits the growth rate along the <111> direction. The release rate of Fe 2+ ions in the synthesis can be rationally manipulated by varying the dose of N 2 H 4 · H 2 O. Control of the nucleation and growth rate by N 2 H 4 · H 2 O provides a facile and effective route to harvest Fe 3 O 4 octahedra with different dimensions. The magnetic analysis shows that Fe 3 O 4 octahedra with sharp tips possess attractive magnetic properties.