Properties of Co2FeAl Heusler Alloy Nano-particles Synthesized by Coprecipitation and Thermal Deoxidization Method

Co2FeAl nanoparticles were synthesized by reducing the coprecipitated precursor of CoCl2·6H2O, Fe(NO3)3·9H2O and Al2(SO4)3·18H2O under H2 atmosphere with various annealing temperatures and durations. X-ray diffraction and transmission electron microscopy were used to characterize the crystal structure and microstructure of Co2FeAl particles, respectively. The investigation indicates that the crystal structure of Co2FeAl particles tends to be B2 structure, in which atoms are partially ordered. The saturation magnetization and hyperfine field of Co2FeAl particles, which were measured under a vibrating sample magnetometer and a 57Fe Mössbauer spectroscope, are consistent with those of the bulk sample and thin films. Furthermore, the higher annealing temperature and the longer annealing time, the better crystallinity of Co2FeAl and more ordered arrangement of atoms will be. It turned out that the coprecipitation thermal deoxidization method could be an easy and high efficient way to obtain the half-metallic Co2FeAl nanoparticles.