Crystallite Size Controls the Crystal Structure of Cu60Pd40 Nanoparticles

Structurally disordered (Cu type of structure) or ordered (CsCl type of structure) modifications of intermetallic Cu60Pd40 nanoparticles can be synthesized by co-reduction of Cu- and Pd-acetylacetonate using LiBEt3H in THF or annealing in tetradecane, respectively. It is shown by X-ray diffraction, transmission electron microscopy, selected area electron diffraction, differential centrifugal sedimentation, and thermal analysis that the formation of the ordered or the disordered modification depends oil the crystallite size of the nanoparticles rather than on temperature. Crystallites smaller than similar to 20 nm form the disordered modification of Cu60Pd40, whereas crystallites larger than 20 nm prefer the ordered modification.