Electron Microscopy of Nanoparticles With a Sphalerite-Type Lattice on the Example of Cadmium Sulfide

Abstract

In the present work by high resolution transmission electron microscopy on the device JEM-2010 cadmium sulfide powder with a particle size of 3-12 nm after short-term (one minute) processing in the Fritsch Planetary Micro Mill PULVERISETTE 7 Premium Line was studied. This material can be applied in such innovative practical applications as photocatalysis, new sources of radiation, biosensors, drug delivery, solar cells. The electronic and optical properties of CdS nanoparticles, which determine the application areas of the substance, directly depend on the crystal structure. Therefore, it is so important to determine the structure of cadmium sulfide nanoparticles. Analysis of electron microscopic images shows that mechanical milling leads to the formation of a hexagonal phase in the original cubic CdS. By electron microscopy methods the orientation relationship between sphalerite and wurtzite phases was established. In addition, fragments containing marginal dislocations and deformation bands were found in the milled powder. The formation of marginal dislocations, which are linear defects, underlies the process of plastic deformation. Such reoriented regions, as deformation bands deployed at various angles with respect to adjacent regions, are common in various materials: metals, ceramics, ionic crystals, polymers, polycrystalline alloys and fullerenes. The appearance of deformation bands leads to changes in the crystal lattice of cadmium sulfide nanoparticles. Thus, it was shown that the plastic deformation of cadmium sulfide nanoparticles can occur not only because of the symmetrical reorientation of the crystal regions, but also because of the formation of deformation bands.