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The Preparation and Nonlinear Optical Effect Investigation of CdS/PVP, PbS/PVP Nanocomposite

Author: XuXinGuang
Tutor: JingChengBin
School: Qingdao University of Science and Technology
Course: Materials Physics and Chemistry
Keywords: Cadmium sulfide(CdS) Lead sulfide(PbS) Polyvinylpyrrolidone (PVP) Nanocomposite In situ synthesis Third order linear optical property
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 111
Quote: 1
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Abstract


The preparation, properties and applications of cadmium sulfide (CdS) nanocomposite materials and lead sulfide (PbS) sulfide nanocomposite materials using Polyvinylpyrrolidone (PVP) as matrix were introduced detailedly in this work. An in-situ formation process was used to synthesize CdS/PVP and PbS/PVPnanocomposites. Sulfide nanoparticles were in situ formed in the polymer matrix using various sorts of sulfur and lead precursors. The fabrication process was investigated udnder different conditions including adding cross-linker into the matrix, ultraviolet radiation, constant drying and decreasing temperature. The composition, structure and nonlinear optical properties of the as-obtained samples were studied.The experimental result showed that the size of nanoparticles in the matrix increased with the raise of the sulfide concentration. The addition of cross-linker and ultraviolet radiation could promote the cross-link of the PVP matrix at room temperature, preventing the nanoparticles from growing up. When the reaction took place at a lower temperature (icy water-bath), the particle size became smaller. The particle size distribution was influenced by the S2- release rate of sulfur precursors. The nanocomoposites obtained by using thioacetamide (TAA) and cadmium or lead nitrate exhibited smaller particle size.The SEM and TEM analyses showed that the PVP contributed largely to the modification of the nanoparticles. The polycrystalline sulfide nanopaticles were distributed evenly in the matrix. The UV-Vis spactra revealed that the absorption edge of the sulfide underwent blue-shift because of the quantum confinement effect of the nanoparticles. The crystallite size of the particles obtained under different fabrication conditions were calculated based on the UV-Vis spactra and the reasons responsible for the variation of the grain size were discussed. The Z-scan analyses showed that the obtained nanocomposite films have remarkable third order nonlinear optical effects. The nonlinear refraction coefficient and nonlinear absorption coefficient of the CdS/PVP nanocomposite reaches as high as 10-11cm2W-1 and 10-7cmW-1, respectively. This suggests that the as-synthesized nanocomposites have potential applications in fabrication of optical device.

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