  Co2FeAl (CFA) nanoparticles (NPs) of different sizes were synthesized by
chemical route. The effect of the size of NPs upon the structure and
magnetization compared to its bulk counterpart was investigated. The structure
and composition were determined from X-ray diffraction (XRD) and electron
microscopy. XRD analysis shows that the samples are having single (A2-type)
disordered phase. Magnetization measurements suggest that the samples are soft
ferromagnetic in nature with very low coercivity. Enhanced magnetic properties
like saturation magnetization, coercive force, retentivity, and
Curie-temperature are observed with a decrease in particle size. The effect of
particle size on hysteresis losses is also discussed. The smallest particles of
size 16 nm exhibited the highest saturation magnetization and transition
temperature of 180.73 emu/g and 1261 K, respectively. The origin of enhancement
in the magnetization of Co2FeAl nano-alloy is attributed to the strong Co-Co
exchange interaction due to disorder present in the systems.
