Synthesis And Characterization Of ⅡB Group Compound Nanostructures Using Low Melting Point Metals As Catalyst

One-dimensional nanoscale materials,such as nanotubes,nanowires,nanorods and nanobelts,have been received considerable attentions,it is because that these nanoscale materials have novel physical and chemical properties compared with those of their bulk counterparts,which have shown the potential applications in the fields of electronic, optoelectronic,magnetic recording et al.Under the research for several years,many methods have been developed to synthesis the one-dimensional nanostructure materials. Among these,the technique of thermal evaporation is favourite because of its merit,include high output,easy control et al.In this dissertation,thermal evaporation method was used, Cd and Sn with low melting point rather than conventional Au were choosen as the catalyst, to synthesize one-dimensionalâ…¡B compound nanostructures,such as CdS nanoribbons, CdSiO₃ nanowire arrays,and ZnS nanorods.The structure and properties of these nanostructures were inversitgated.Some significant results are introduced as following:1.Mass and uniform CdS nanoribbons were synthesized by thermal evaporation on the Si wafer which has been electrodeposit Cd film at first.The CdS nanoribbons have smouth surface with thickness about 50nm and width about 300nm-1.5μm.The CdS nanoribbons were identified to be single crystals growing along the[001]direction and belong to wurtzite structure,we considered that the growth of CdS nanoribbons were demonstrated growing with self-catalytic Vapor-Liquid-Solid(VLS)combined with Vapor-Solid(VS)mechanism.Photoluminescence(PL)measurement revealed that the CdS nanoribbons exhibitted strong emission at 527nm caused by crystalline defects.2.Large-area and highly-ordered monoclinic CdSiO₃ nanowire arrays were synthesized uniformly on Si wafer which has been electrodeposit Cd at first via a simple thermal evaporation method.The CdSiO₃ nanowires are identified to be single crystals growing along the[001]direction and have good orientation,with the same diameter and length. The growth of the cluster-like CdSiO₃ nanowire arrays was the result of self-catalytic VLS mechanism.Photoluminescence(PL)measurement revealed that the CdSiO₃ nanowire arrays exhibitted three strong emission at 358,396 and 476nm,they can explained by self-activated luminescence theory and Quantum Confinement-Luminescence Centre (QC-LC)model respectively.Temperature luminescence spectra showed the as-prepared CdSiO₃ nanowires had three emission peaks at 340K,450K and 723K respectively and the energy level of the each was about 0.60eV,0.72eV and 0.87eV.Lifetime decay curves in the CdSiO₃ nanowire arrays had been analyzed by curve fitting,and the luminescent lifetime of the 390 nm emission of the CdSiO₃ phosphor was 101 ns.3.Large-area and uniformly ZnS nanorods were prepared on Si substrate by a simple thermal evaporation using a mixture of ZnS,SnO and acti,lated carbon powders as starting materials.Most of the as-synthesized ZnS products are single crystalline with a hexagonal wurtzite structure and c axial of(001)as growth direction..The individual ZnS nanorod has circular cross-section with the diameter rangingf from 100 to 200nm and length is about 20μm.The growth of ZnS nanorods was via a traditional vapor-liquid-solid(VLS) process,in which the Sn came from the metastable compound SnO acts as the catalyst. The existance of activated carbon made the reaction in reductive atmosphere. Photoluminescence(PL)measurement revealed that the as-prepared ZnS nanorods exhibit two strong emissions caused by vacancy transmission and defects.