Research Of Properties, Preparations And Characteristics Of Several One Dimensional Nanomaterials

One dimensional (1D) nanomaterials, including nanowires (rods), nanotubes,nanobelts, nanocables, heterojunction and superlatice nanowires, are ideal systems forinvestigating the dependence of electrical transport, optical properties, magneticproperties, and mechanical properties on size and dimensionality. In addition, they areexpected to play an important role as interconnects and functional components in the"botom up" design and fabrication of new electronic and optoelectronic devices. Now theresearch of the 1D nanomaterials has already become one of the centre subjects ofnanomaterial science. The hydrothennal method has advantages to obtain highcrystallized powders with narrow grain size-distribution and high purity without treatmentat high temperature. The particle properties such as morphology and size can becontrolled via the hydrothermal process by adjusting the reaction temperature, time andadditives. Hydrothermal method has been an important method for 1D nanomaterialspreparation. This thesis is mainly about the controlled growth of novel 1D nanomaterialsand their composite structures, their growth mechanism, and some physical properties.The main content and contribution are as follows:In the first part, Tungsten oxide with various morphologies and particle sizes have been synthesizedby a hydrothermal method in the presence of various salts. The properties of products were characterizedby SEM, TEM, XRD and EDX. Effects of morphologies and particle sizes on the photoluminescence ofWO₃ nanocrystals were also investigated. Photoluminescence mechanism of tungsten oxide with variousmorphologies and particle sizes is proposed.In the second part, The M_xH_yTi₃O₇ (M=K, Fe, Zn, Co, Na, Ag,) nanotubes wereprepared by Ion-exchange reactions in solution with K₂SO₄, Na₂SO₄, Fe(NO₃)₃, ZnSO₄,Co(NO₃)₂, AgNO₃, respectively. The properties of products were characterized by SEM,TEM, XRD and EDX. Synthesis of M_xH_yTi₃O₇ nanotubes by ion-exchanged process wasproved by our experimental results. The adsorption properties of M_xH_yTi₃O₇ nanotube formethylene blue in aqueous solution were studied.In the third part, During the hydrothermal synthesis of MnO₂ nanorods, XRD wasused to study the influence of temperature on crystalline form. The morphologies of products, characterized by transmission electron micrograph (TEM) and scanning electronmicrograph (SEM), were rod-like particles of the diameter 60 nm and several micronslength. The temperature has influence on morphologies also. The as-prepared manganeseoxide nanorods have different catalytic effect on the oxidation and decomposition of themethylene blue (MB) dye with H₂O₂.In the fourth part, The Dy₂O₃ dissolve and the hydroxides form under hydrothermaltreatment; subsequently it recrystallize and grow into rod-like nanostructures through adissolution-recrystallization process. The growth of the nanorods is not assisted bycatalyst or directed by a template, Pure Dy₂O₃ bulk crystals are generally described asbeing insoluble in water at room temperature and atmospheric pressure. Underhydrothermal conditions, our experimental results show it can dissolve in and then stallize.As the concentration of the hydroxides increases to supersaturation, the hydroxiderecrystallizes as a single crystal with rod-like morphology.