Synthesis, characterization and magnetic properties of Fe–Al nanopins

We report the synthesis of Fe–Al nanopins using arc discharge. The morphology and chemical composition of the Fe–Al nanopins were studied by means of X-ray diffraction, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HRTEM). The nanopins are composed of a spherical base of about 20–100 nm and a needle-like tip of about several hundred nanometers. EDX and HRTEM studies indicate that the spherical base is mainly composed of -Fe and FeAl core coated with a thin Al₂O₃ layer, while the needle-like part contains only Al and O and corresponds to Al₂O₃. The formation mechanism of the nanopins is suggestive of a vapor–liquid–solid (VLS) growth process. The as-prepared Fe–Al nanopins show ferromagnetic properties. The temperature dependence of the magnetization at high temperatures indicates the existence of some phase transformations.