PbTe hierarchical nanostructures: solvothermal synthesis, growth mechanism and their electrical conductivities

PbTe micropeony consisting of nanosheet networks and PbTe hollow spheres composed of self-assembled nanocrystals have been synthesized by a simple solvothermal method in mixtures of water and ethanol at 180 degrees C with the help of glucose. By adjusting the experimental parameters, such as the amount of NaOH, volume ratio of ethanol to water, reaction time and concentration of glucose, the nucleation, growth, and self-assembly of the PbTe nanosheets could be readily tuned, resulting in different morphologies and nanostructures. Based on the electron microscopy observations, the formation mechanism of such hierarchical structures has been proposed as an Ostwald ripening process followed by anisotropic growth process. Nitrogen adsorption-desorption measurements and pore size distribution analysis revealed that both mesopores (2-50 nm) and macropores (>50 nm) existed in the products. Moreover, PbTe crystals with micropeony and hollow sphere morphology were measured to investigate the possible impact of morphology on the electrical conductivity.