  Multicomponent nanoparticles can be synthesized with either homogeneous or
phase-segregated architectures depending on the synthesis conditions and
elements incorporated. To understand the parameters that determine their
structural fate, multicomponent metal-oxide nanoparticles consisting of
combinations of Co, Ni, and Cu were synthesized via scanning probe block
copolymer lithography and characterized using correlated electron microscopy.
These studies revealed that the miscibility, ratio of the metallic components,
and the synthesis temperature determine the crystal structure and architecture
of the nanoparticles. A Co-Ni-O system forms a rock salt structure largely due
to the miscibility of CoO and NiO, while Cu-Ni-O, which has large miscibility
gaps, forms either homogeneous oxides, heterojunctions, or alloys depending on
the annealing temperature and composition. Moreover, a higher ordered
structure, Co-Ni-Cu-O, was found to follow the behavior of lower ordered
systems.
