Research On Preparation And Characterization Of Tin Dioxide Nano Structures

As the dimension of the semiconductor material to nanosize, because of quantumsize effect, small size effect, surface effect, quantum tunnel effect, the nano-sizedsemiconductor materials presented novel electronic, optics, photoelectric conversionand photocatalysis properties. These fields have attracted many researchers’attention.With the development of nanotechnology,Nano-sized semiconductor materials would give human life great impact andinfluence every part of people’lives. In this paper, we have synthesized tin oxidenanostructures by simple thermal evaporation process. The morphology and size ofSnO₂nanostructures were changed by different conditions, such as temperature,annealing time, source materials, with or without catalyst and so on. The sampleswere characterized by scanning electron microscopy （SEM）, Transmission electronmicroscopy （TEM）, X-ray diffraction （XRD）, the energy dispersive X-rayspectrometer （EDS） and photoluminescence （PL） and the growth mechanism wasdiscussed. The details are summarized briefly as follows：（1）Tin oxide （SnO₂） nanoparticles were fabricated by evaporation of Sn powdersat 1000℃in air pressure. The as-deposited SnO₂particles were single crystalstructure, which were mostly spherical shape, the diameter of particles was rangingfrom 200nm to 600nm. As the annealing time was 50 min, agglomeratednanoparticles formed and presented random state. The photoluminescence （PL）spectrum showed that a sharp emission peak at around 393nm with the excitationwavelength at 325nm, which suggested possible applications in nanoscaledoptoelectronic devices. It was also found that the holding time affects the morphologyof the products. The formation mechanism of SnO₂particles was discussed.（2）Tin dioxide nanowires were synthesized by thermal evaporation of Snpowers at 1000℃without any catalyst. The as-prepared SnO₂nanowires wereuniform and straight. Photoluminescence spectrum exhibited broad emission bands,which are promising in a wide range of applications in nanoscaled optoelectronicdevices. The self-catalytic vapor-solid growth mechanisms of SnO₂nanowires havealso been discussed.（3）The single-crystalline branched SnO₂nanowires have been successfullysynthesized by thermal evaporation of Sn and SnO mixture at 900℃in differentannealing times （90min to 110min）. The nanowires were single-crystalline structureand were straight and uniform, which formed a net shape. The room temperaturephotoluminescence spectrum of the samples showed a broad and strong emissioncentered at 491nm and a weak shoulder emission centered at 368nm, which arepromising in a wide range of applications in nanoscale electronic and optoelectronicdevices. It was also found that the annealing time affects the morphology of theproducts. A possible quasi-vapor-liquid-solid growth mechanism of SnO₂nanowireswas proposed.（4） SnO₂nanowires have been successfully synthesized by thermal evaporationof Sn and SnO mixture at 900℃. The diameter of the as-prepared nanowires wasabout 100-300nm and lengths to tens micrometers. The room temperature photoluminescence spectrum of the samples showed a broad and strong yellowemission peak centered at 588nm, and the results of the peak were discussed.Otherwise, the growth mechanism of SnO₂nanowires was presented.Finally, the experimental results and innovations in this dissertation weresummarized and the following expectations were proposed.