Preparation of pure CdSe nanocrystals through mechanical alloying

Abstract

Pure CdSe nanocrystals have been successfully synthesized by mechanical alloying Cd and Se elemental powders. XRD results show that pure CdSe compound in wurtzite structure has been fabricated after mechanical alloying the elemental powders for 130 min. All the diffraction peaks from elemental Cd and Se disappeared completely in those XRD patterns of as-milled CdSe nanocrystals for more than 3 h. When the mechanical alloying process was carried out for 40 h, typical zinc blende structure diffraction mode was exhibited in the XRD pattern. Structural evolution of CdSe nanocrystal with ball milling time has been discussed in detail. A phase transformation from wurtzite to zinc blende structure took place when the mechanical alloying process prolonged to 40 h. HRTEM images of the individual as-milled CdSe nanocrystals confirmed such phase transformation. The grain size of the as-milled CdSe nanocrystals ranges from 2 to 30 nm, with majority being distributed within the range from 2 to 8 nm.