One-step aqueous synthesis of stoichiometric Fe-Cu nanoalloy

摘要

Fe_(50-x)Cu_(50-x)B_(2x) alloy was obtained by an aqueous chemical reduction at pH = 7.0, using fast and slow NaBH_4 solution addition methods. According to X-ray diffraction patterns, TEM and HRTEM observations, smaller than 10 nm nanocrystals of fcc-FeCuB were formed when the fast method was employed. The room temperature Moessbauer spectrum of this FeCuB nanoalloy shows a quadrupole doublet with an isomer shift of 0.355(1) mm/s and a quadrupole splitting of 0.772(2) mm/s, and a broadened magnetic sextet with a quadrupole splitting of 0.020(3) mm/s and an isomer shift of 0.436(5) mm/s, exhibiting a distinctive high average magnetic field of 40.57(5) T. Grains with a size larger than 10 nm were obtained for a slow method nanoalloy, and its Moessbauer spectrum consisted only of a broadened sextuplet characteristic of an fcc-FeCuB alloy.