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

Octahedron-like Au/Fe
₃
O
₄
magnetic nanoparticles are synthesized using decomposition of FeO(OH) and HAuCl
₄
with the presence of oleic acid in 1-octadecene solvent. In the octahedron-like hybrid particles, Fe
₃
O
₄
mainly displayed the octahedral morphology and spherical Au nanoparticles partially embedded into one side of Fe
₃
O
₄
octahedron. The size of particle could be tuned from 25 to 240 nm for the whole particle (mainly for Fe
₃
O
₄
) and 10 to 40 nm for Au by changing the proportion of the starting materials. The hybrid particles showed the magnetic properties of Fe
₃
O
₄
with dependence on the size of Fe
₃
O
₄
octahedron composite and the proportion of Fe
₃
O
₄
to Au. Coercivity is observed in the hybrid Au/Fe
₃
O
₄
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/Fe
₃
O
₄
magnetic octahedron-like particles, inheriting the advantages of Au and Fe
₃
O
₄
nanoparticles, may evolve as useful building blocks for nano- and micro-electronic applications.