3-D flower like FeCo alloy nanostructures assembled with nanotriangular prism: Facile synthesis, magnetic properties, and effect of NaOH on its formation

Flower like FeCo alloy nanostructures assembled with nano triangular prisms have been synthesized via template free hydrothermal method at relatively low temperature (120 degrees C). The concentration of NaOH plays vital role in the formation of alloy phase and morphology. The excessive amount of NaOH is determined to be responsible for formation of alloy phase during hydrothermal reaction. X-ray diffraction analysis confirms the formation of good crystalline FeCo alloy with average crystallite size of 24 nm. Energy dispersive X-ray spectroscopy and inductive coupled plasma atomic emission spectroscopy reveal the nearly equiatomic composition (Fe0.5Co0.5) of prepared flower like nanostructures. Scanning electron microscope and transmission electron microscope observations show that flower like FeCo alloy structures are composed of six nano triangular prisms. The diameter of flower like structure is in the range of 0.5-1.0 mu m, and the base and height of nano triangular prism are in the range of 100-200 nm. Electron diffraction pattern shows the single crystalline nature of nano triangular prism. A step wise growth mechanism of flower like structure is proposed. Magnetic investigations show high saturation magnetization of 209 emu/g, low coercivity of 30 Oe, and remanent magnetization of 3.01 emu/g at 300 K. This nearly super-paramagnetic behavior of FeCo alloy nanostructures may be due to the crystallite size proximity to its super-paramagnetic critical size. (C) 2012 Elsevier B.V. All rights reserved.