Magnetic Fe2P nanowires and Fe2P@C core@shell nanocables

Abstract

We report the synthesis of one-dimensional (1-D) magnetic Fe2P nanowires and Fe2P@C core@shell nanocables by the reactions of triphenylphosphine (PPh3) with Fe powder (particles) and ferrocene (Fe(5H5)2), respectively, in vacuum-sealed ampoules at 380–400 °C. The synthesis is based on chemical conversion of micrometer or nanometer sized Fe particles into Fe2P via the extraction of phosphorus from liquid PPh3 at elevated temperatures. In order to control product diameters, a convenient sudden-temperature-rise strategy is employed, by means of which diameter-uniform Fe2P@C nanocables are prepared from the molecular precursor Fe(C5H5)2. In contrast, this strategy gives no obvious control over the diameters of the Fe2P nanowires obtained using elemental Fe as iron precursor. The formation of 1-D Fe2P nanostructures is ascribed to the cooperative effects of the kinetically induced anisotropic growth and the intrinsically anisotropic nature of hexagonal Fe2P crystals. The resulting Fe2P nanowires and Fe2P@C nanocables display interesting ferromagnetic-paramagnetic transition behaviors with blocking temperatures of 230 and 268 K, respectively, significantly higher than the ferromagnetic transition temperature of bulk Fe2P (T C = 217 K).