Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials

Hydrothermal Synthesis of Inorganic Semiconductor Nanomaterials and Luminescent Rare Earth Nanomaterial

Author TaoPingFang
Tutor FangYuePing
School Guangxi Normal University
Course Inorganic Chemistry
Keywords Hydrothermal Method Silver Ttelluride Nanostructure Core/shell Microspheres Luminescence
CLC TB383.1
Type Master's thesis
Year 2008
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Hydrothermal or solvothermal approach is a commonly used methodology for generating nanostructures. The major advantage of this approach is that most materials can be made soluble in a proper solvent by heating and pressuring the system close to its critical point. Since Health and co-workers creatively synthesized semiconductor nanowires, this method has been extensively exploited to process a rich variety of materials into wires, tubes and rods. As a result, we choose it as a chief synthetic method in our study.In this thesis, we mainly focused on the synthesis of different inorganic semiconductor nanomaterial and luminescent rare earth materials via simple hydrothermal process. Combined with some general growth mechanism, appropriate mechanisms have been proposed to explain the growth of the as-obtained product based on the different characteriazations of the as-obtained product. To fabricate some special functional materials, we also tested the properties of the as-obtained product, i.e., photoluminescence properties.The main contents of our work are as follows:In chater one, we briefly introduced the development, properties, fabrication, characterization of nanomaterial and the research progress on luminescent rare earth material. The state of the synthesis on nanomaterial is reviewed, focusing on the application of hydrothermal method in fabricating nanomaterial.In chapter two, we mainly concerned the fabrication of silver telluride nanotubes by the hydrothermal process without a template or a surfactant. The as-prepared sample was characterized by X-ray diffraction(XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy(TEM), X-ray photoelectron spectra(XPS), and Raman spectra. The structural phase transition of the sample was discussed. A rolling-up mechanism is proposed to explain the formation of the silver telluride nanotubes based on the inherent crystal structure of low-temperatureβ-Ag2Te. Raman spectra analysis revealed an interesting Raman scattering enhancement phenomenon.In chapter three, we brief discriped the growth of dandelion-like microspheres using a simple solution-liquid-solid (SLS) method. The dandelion-like microsphere, about 2.5μm in diameter, is a nanorod-based superstructure, Sn@[In(OH)3 nanorods], and built from a solid Sn core about 1-1.5μm in diameter and a shell consisting of a single layer of radiating In(OH)3 nanorods about 100nm in diameter and 1-2μm in length, which wrap around the Sn core. The composition, morphology and microstructure were studied by powder-X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), high-resolution transmission electron microscopy (HRTEM), and energy dispersive X-ray spectroscopy (EDS), respectively. We also investigeted the growth mechanism of the Sn@[In(OH)3 nanorods] core/shell microshere. All the results confirm that a one-step solution-liquid-solid (SLS) growth mode, which is distinguished from the SLS growth by the use of an alloy droplet, has allowed the first synthesis of intricate dandelion-like Sn@[In(OH)3 nanorods] microspheres. It is possible to synthesis other core/shell heterostructure.In chapter four, we pay our attention on that using different raw material, S doped Y(OH)3 nanobelts with 4-15μm in length and 80 - 500 nm in diameter(most between 100 and 200 nm), S doped Y(OH)3: Eu3+ nanobelts with 6-15μm in length and 50-300 nm in width,and Yb3+/Er3+ ion-pair co-doped rare-earth fluoride(NaYF4 :Yb3+/Er3+) microcrystals , with diferent morphologise, have been successfully synthesized by a hydrothermal process. Photoluminescent S doped Y2O3: Eu3+ nanobelts was obtained through dehydration of S doped Y(OH)3: Eu3+ nanobelts. The photoluminescence properties have been studied and also revealed that we have successfully obtained photoluminescent S doped Y2O3: Eu3+ nanobelts and Yb3+/Er3+ ion-pair co-doped rare-earth fluoride microcrystals, NaYF4 :Yb3+/Er3+.In chapter five, a concise conclusion and a prospect are presented. We also state some aspects improved in our future work.

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