Controlled Synthesis And High Magnetic Field Induced Growth Of Bi-related Semiconductor Nanomaterials

Controlled synthesis of nanomaterials is one of the most important sections of nanoscience and nanotechnology, and also the base to investigate the distinctive properties and applications of nanostructures. This thesis studied solution-based controlled synthesis of Bi-related semiconductor nanomaterials, emphasizing on the effect of high magnetic field on the growth of diamagnetic materials, controlled synthesis of Bi2S3 nanocrystals and Sb2S3 microcrystals via a single precursor route, the relationship between the properties and size/shape of the nanocrystals, manipulated growth of Bi2Te3 nanoplates by surfactant assisted route, the dependent connection between crystal structure and the two dimensional (2D) growth trade and the controlled growth of Bi2(Te,Se)3 and (Bi,Sb)2Te3 solid solution through a simple aqueous chemical method at low temperature. The major contents of this dissertation are epitomized as follows:1. High magnetic field induced growth of Bi nanostructures. With the introduction of high magnetic field, one dimensional Bi nanostructure could be obtained. The effect of synthetic conditions on the shape of the nanocrystals was studied. Furthermore, the synthetic notion was extended to the growth of Te microrods. Besides, the effect of magnetic field on the one dimensional (1D) growth of diamagnetic materials was discussed. The results showed that when the magnetic field was introduced, the reaction process was slowed down, the crystal face was modified and the 1D growth trade was induced.2. Controlled synthesis of Bi2S3 nanocrystals via a single precursor route. With the help of surfactant, monodisperse Bi2S3 nanorods were obtained. Based on the IR observation, the effect of surfactant on the growth nucleus was discussed. Furthermore, a simple single precursor route without surfactant was issued, and the Bi2S3 nanocrystals with controlled shapes could be synthesized. The solvent effect held an important role during the crystal growth, which would induce the shape changes. Moreover, the novel idea was extended to the growth of Sb2S3 microrods with controllable shapes. The results showed that the band gap of Bi2S3 nanocrystals was larger than that in bulk materials. The PL performance of Bi2S3 nanocrystals and Sb2S3 microcrystals showed typical shape dependence.3. Manipulated growth of Bi2Te3 nanoplates by surfactant assisted route. Under the condition of surfactant assisted hydrothermal or solvothermal route, large amount of Bi2Te3 nanoplates were obtained. It showed that the crystal structure could act on the split process during the crystal growth. The surfactant molecules (PVP, CTAB) could adsorb to the crystal face, manipulate the growth process. The Bi2Te3 nanoplates with the growth direction perpendicular to c axis could be synthesized. Furthermore, an artificial lamellar structure has been adopted during the growth of Bi2Te3 nanoplates. With the help of lamellar precursor, pure Bi2Te3 nanocrystals could be prepared in an acidic reaction system, and the cognition that Bi2Te3 should be synthesized in an alkaline reaction system was overthrown.4. Controlled growth of Bi2(Te,Se)3 and Bi2(Te,Se)3 through a simple aqueous chemical method at low temperature. Large amount of Bi2(Te,Se)3 and (Bi,Sb)2Te3 nanocrystals could be synthesized via a chemical route. It showed that once Se doped into the lattice, it held the effect on the crystal split process, induced the two dimensional (2D) growth trade, and 2D Bi2(Te,Se)3 nanocrystals could be finally obtained. While Sb doped into the lattice, it did not show this effect. Furthermore, the Sb source is the key to synthesize pure Bi2(Te,Se)3 solid solution...