Novel Hybrid ${\hbox {Au}}/{\hbox {Fe}}_{3}{\hbox {O}}_{4}$ Magnetic Octahedron-like Nanoparticles with Tunable Size

Octahedron-like Au/Fe₃O₄ magnetic nanoparticles are synthesized using decomposition of FeO(OH) and HAuCl₄ with the presence of oleic acid in 1-octadecene solvent. In the octahedron-like hybrid particles, Fe₃O₄ mainly displayed the octahedral morphology and spherical Au nanoparticles partially embedded into one side of Fe₃O₄ octahedron. The size of particle could be tuned from 25 to 240 nm for the whole particle (mainly for Fe₃O₄) and 10 to 40 nm for Au by changing the proportion of the starting materials. The hybrid particles showed the magnetic properties of Fe₃O₄ with dependence on the size of Fe₃O₄ octahedron composite and the proportion of Fe₃O₄ to Au. Coercivity is observed in the hybrid Au/Fe₃O₄ octahedron-like nanoparticles (55 Oe for 25 nm, 135 Oe for 100 nm, and 159 Oe for 240 nm) at room temperature. These size-controllable hybrid Au/Fe₃O₄ magnetic octahedron-like particles, inheriting the advantages of Au and Fe₃O₄ nanoparticles, may evolve as useful building blocks for nano- and micro-electronic applications.