New insights into the growth mechanism of hierarchical architectures of PbTe synthesized through a triethanolamine-assisted solvothermal method and their shape-dependent electrical transport properties

摘要

In this article, a triethanolamine (TEA)-assisted solvothermal method has been devised to synthesize PbTe hierarchical nanostructures on a large scale with various shapes, including octapodal dendrites with a spiral step hollow cubic center, hopper structures, and nanowires with branched nanorods, by tuning the amount of KOH and the volume ratio of the solvent. Systematic variation of the kinetic factors, including the reaction temperature, the duration time, the ratio of source materials, and the KOH concentration, reveals that the morphology depends mainly on the supersaturation degree of the free Pb~(2+) ions released from Pb(TEA)_2~(2+) under elevated temperature. The formation processes of the PbTe octapodal dendrites with a spiral step cubic center and nanowires with branched nanorods were believed to follow the screw dislocation-driven growth and in situ template and secondary nucleation route, according to the extensive experimental data. In addition, the electrical transport properties of the bulk samples consisting of octapodal dendrites, hopper structures, and nanowires with branched nanorods were measured to investigate the possible impact of the morphology on the electrical transport properties. The unusual electrical behaviors with temperature are attributed to charge carrier scattering at grain boundaries.