Phase composition, structure and magnetic properties of the ultrafine cobalt particles synthesized by spark erosion method

Ferromagnetic nanoscale Co particles in a nonferromagnetic matrix can be used as materials for spintronics and a magnetoelectronics engineering. Highly dispersive Co particles were produced by spark erosion method in distilled water, ethanol and toluene. The phase composition, crystalline structure and magnetic properties were studied. The analysis of the phase composition of spark eroded powders confirms contents alpha-Co and beta-Co phases. The biggest fraction of the alpha-phase was observed in the powder produced in water (approx. 5.3 pct.), while the smallest fraction (approx. 4.3 pct.) - in toluene. A fraction of the alpha-Co in the all studied powders increases as the annealing temperature grows. The spatial dimensions of the alpha-Co crystal phases are typically much smaller compared to beta-Cos. The intensity of a martensitic transformation is low in the studied interval of temperatures and small fraction of alpha-Co can be bound to the presence of large-size particles at samples for which a martensitic transformation is possible.