Evidence of alloy formation in CoNi nanoparticles synthesized by nanosecond-pulsed discharges in liquid nitrogen

Producing alloy nanoparticles by discharge-assisted erosion of electrodes immersed in liquid nitrogen is possible in the cobalt-nickel system. Several electrode configurations are tested. When one nickel electrode faces one cobalt electrode, CoxNi1-x alloy nanoparticles are produced with nickel cubic nanoparticles and cobalt round-shaped faceted nanoparticles. The possibility of forming alloys is attributed to a sufficiently long residence time of both parent clusters within the discharge and to their total miscibility. It is also possible to form submicrometric CoxNi1-x alloy particles when discharges between cobalt electrodes are run in liquid nitrogen loaded with nickel nanoparticles produced in a former step. Starting by discharges between Co electrodes before Ni electrodes do not produce any alloy. The two mechanisms responsible for alloy synthesis are discussed.