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Nano- telluride (Ag_2Te, PbTe) Synthesis and Properties of

Author: LiFeiYun
Tutor: HuChenGuo
School: Chongqing University
Course: Condensed Matter Physics
Keywords: CHM France Ag2Te PbTe Structural phase transition Thermoelectric materials
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 267
Quote: 2
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Abstract


Telluride nanomaterials because of its excellent electrical properties , optical properties and thermal properties which in chemical and biological sensors, field effect transistors , logic circuits, light sensors and high-performance thermoelectric devices has broad application prospects which attracted widespread interest. Morphology Control of nanomaterials is one of the key process of production of materials , nano-materials is currently a basic research topic. Study the morphology of nanoparticles influence factors also explain the growth mechanism of crystal morphology and size control is to achieve an important way . This paper uses a low temperature and pressure , simple operation , low cost , ease of synthesis of new ways to promote industrialization - composite hydroxide media law (composite-hydroxide-mediated, CHM) synthesized ultrafine nano- Ag 2 Te PbTe nanowires and nanorods . CHM method used between 180-225 ℃ monoclinic phase synthesis of silver telluride crystal nanowires, a high purity of the samples . Silver nanowires telluride about 20-30 nanometers in diameter , the length is as long as hundreds of nanometers , and can be changed by controlling the growth temperature and the growth time sample size. Our silver telluride nanowire growth mechanism were analyzed. In the heating process by testing / cooling process in the 148/133 ℃ was found near silver telluride from the monoclinic phase to a face-centered cubic phase reversible structural phase transition , and calculated the sample phase change latent heat. Resistance and thermoelectric power of the sample changes with temperature were analyzed and found that the sample resistivity and Seebeck coefficient of the structural phase transition temperature change drastically accessories . Heating and cooling process maximum Seebeck coefficient values ??were 170μV / K and 160μV / K or so, showing its one-dimensional thermoelectric materials in a broad application prospects. In the absence of any surface active agent under the conditions CHM synthesized lead telluride nanorods . Through experiments show that lead telluride as a face-centered cubic structure . Lead telluride nanorods diameter of about 50-120 nanometers and lengths of the long 200-1000 nm, and the growth time can be changed and the growth temperature to control the sample size. We lead telluride nanorod growth mechanism were analyzed. Through a transmission spectrum obtained lead telluride bandgap nanorods 0.26-0.43Ev.

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