Synthesis And Properties Of PbTe/Pb Quasi-One-Dimensional Nanostructure Material

When the size of material falls down to as small as a few or tens of nanometers, the material would show the uniqure properties differing from conventional materials. Nanostructure material has been focuses in nano- materials field because of their important applications in many fields in future. Especially, the research on one dimensional ordered nanostructure material arrays is very important, which would affect the constructure of functional devices and the property research of materials. At present, there is still no effective way to the morphology control and the microsturcture adjustment in many syntehsis methods of nanomaterials. As an excellent synthesis method, electrochemical deposition has been widely attended because of its lower cost and accurate control of the growth process. In the thesis, the periodic PbTe/Pb nanostructure material with quasi-one dimen- sion is a main researched object. The aims of the research are to explore the contralllable preparation of nanostructure material arrays in morpho- logy, structure and to study the growth mechanism and properties of nanosturctrure materials.We firstly found the lagging phenomenon of ion transportion in the electrodeposition process and prepared the periodic nanomaterial using the lagging effect. We explained the forming mechanism of the periodic nanomaterial. The research resolved the problem on how the change of ions concentration in front of electrodepositon affected the morphology of electrodeposition. As there is the phase difference between the ion transportion and the potential shift, the lagging phenomenon could be showed out when the potential changed. With the process of electrode- posit, the ions concentration in front of electrodeposition would increase and bring the change of electrodeposition morphology. The experiment proved directly the existence of ion lagging phenomenon. Ion concen- tration in front of electrodeposition would continualy increase during the potential decrease and the formula of ion concentration in front of electrodeposition was concluded. These important conclusions were getted according to the growth mechanism. The research not only provides a new preparation method of namomaterials, but also provides the certain funda- mental research foundation for the structure materials.The large area of periodic PbTe/Pb nanostructure material with quasi-one dimension was electrodeposited by using a pulsed deposition potential of square waves. The morphology and structucture of nanost- ructure materials were characterized. It was found that there was a un- quire nanostructure in the PbTe/Pb nanostructure material. The forming mechanism of unquire nanostructure was explained according to the banl- ance between ion supply and consumption. The atomic force microcope was used to characterize the dimensions of nanostructure materials. Seve- ral key factors in the quasi-two dimensions were generally analysized.The distributions of electic fields and potential in front of nanos- tructure material arrays were computed using the created models accor- ding to the growth patterns. The reasons why the diameter of nanostruc- ture materials changed alternately were explained detailedly. It was found that there were three kinds of branched phenomena in the electro- deposition precess. The first kind of branched phenomenon appeared at the edge of nanostructure material arrays; the second kind of branched phenomenon appeared at the tip of nanostructure materials, which was induced by the morphology of tip; the third kind of branched phenomenon appeared in the middle of arrays, which was induced by the locations of nanostructure materials in the arrays. These branched phenomena were detailedly explainned by combining the computer simulation with the change of ion concentration in front of electrodepositon. The whole branching process of nanowire in the middle of arrays was recorded by using a CCD (charge coupled device). We explained the branched reseason by the computer simulation. The effective control to nanowire branch is the key preparing the high-quality and ordered nanowire array. So, it was an important and difficulty problem in the prepatation fields of one- dimension nanomaterials. These researches have important significations not only in the basic research but also in the applied research.It was explored that the effect of the structures and components of PbTe/Pb nanowires on their electronic transport properties by an ultrahigh vacuum (UHV) four-probe scanning tunneling microscopy (4P-STM) system. The resistance changes of two kinds of PbTe/Pb nanowires were compared. The I-V characteristic of single PbTe/Pb nanowire shows the conductance of nanowires decrease with the increase of PbTe content. The annealing result implies the annealing could favor the construction of microstructure. The electric characteristics of branch parts were measured and the change of resistance value in different parts could stem from the crystal boundaries and defects in nanowire. We compared the difference between the four-probe and two-probe measurement. The photoelectricity effect of quasi one-dimension PbTe/Pb nanos- ructure materials was measured. The nanostructure material showed the stronger photoconductive characteristics. The measurement showed that the annealing could improve the photoconductive characteristics of PbTe/ Pb nanostructure materials. The photoconductive mechanism of the nano- structure materials was also explained.A new photoelectricity device model was designed; the model could not only improve the photosensitivity but also extend the range of photo- sensive of devices. We designed a set of new equipment used to synthesize the semiconductor nanoparticals on the gas-liquid interface. Dilute magnetic semiconductor Zn1-xMnxS nanoparticls was synthesized using the set of equipment. The pressure-induced phase transition to the rock salt (B1) phase was studied by high pressure energy-dispersive X-ray diffraction experiments. The phase transition began at a pressure of around 17.70GPa for the 0.85% Mn ions doped-nanoparticles and at 18.29GPa for the 1.26% Mn ions doped-nanoparticle. It is indicated that the transition pressure of ZnxMn1-xS nanoparticles increases with the increase of Mn ions doped concentration. The photoelectricity device was constructed successfully by the PbTe/Pb nanostructure material arrays and the semiconductor nanoparticles. The photoelectricical properties of the device were also measured.?...