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In-situ preparation of nanometer zinc sulfide and its control on the luminescence of porous silicon composite system

wallpapers News 2021-11-18
In-situ preparation of nanometer zinc sulfide and its control on the luminescence of porous silicon composite system
Porous silicon-zinc sulfide nanocomposite(PS-ZnS) was prepared by in situ synthesis of ZnS via a simple polyphase reaction on the base of nano-PS. The formation of the composite was confirmed by X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), energy dispersive spectroscopy(EDS), and photoluminescence(PL) measurements. Based on the XRD data and the Debye-Scherrer equation, the size of the formed ZnS particles both on the surface and in the holes of the PS was calculated to be nano-scaled, ca. 5—7 nm. FE-SEM observation showed agglomeration for the ZnS particles with an average crystallite size of 30—40 nm, and the hole diameter of the PS was below 100 nm. PL measurements and CIE diagram analysis for the PS-ZnS composite samples indicated that the emitted light color from the composites could be modulated and controlled by changing the annealing conditions, from orange to violet-blue, and finally, the white-light emitter of the composite was obtained.
The CDS particles of the average size of 3.2 nm were produced from 0.1 mol/L Na 2S and CdCl 2 solutions via transmembrane transportation and molecular assembly under the inducement of polytetrafluoroethylene(PTFE) porous membrane. XRD results indicated that the products are of cubic zinc blende structure. The particles exhibit a strong emission peak at 522 nm in the photoluminescence(PL) spectrum. The surface of CdS nanoparticles has been modified with HSCH 2COOH, and there is a characteristic peak of the group C O at 1 680 cm -1 in the FTIR spectrum of the modified crystals.
The film of surface-active agents spread out on the surface of the electrolyte of Thioacetamide and cadmium chloride. US nanofilm was deposited at the interface of surface-active agents and electrolytes by the method of electrodeposition. The optimal conditions on which the nanofilm was prepared of the least crystals and uniform particles could be attained via analytical results of L-16(4(5)) orthogonal experiments. The optimal conditions: castor oil/hexadecane 0.06 mL.cm(-2),CdCl2/CH3CSNH2 4 mmol.L-1, cell voltage 5 V, electrodeposition temperature 15 degrees. The effects on the grain size of temperature, surface-active agent, electrolyte concentration, cell voltage, and pH become smaller in the series. If the temperature was high, the movement of molecules of surface-active agent and electrolyte would be faster, thus the preparation of the film would be difficult. The grain size of thin-film varied with the surface-active agents, however, when the number of surface-active agents reached a certain value, the grain size would remain unchanged. The higher the electrolyte concentration, the larger the grain size of the nanofilm. The surface forms were changed at the same time. If the pH of the electrolyte was higher or lower, nanofilm could not be prepared successfully, thus the pH range should be is 3similar to6. SEM image of the nanofilm shows the occurrence of dendrite. The successful preparation of nanofilm is closely related to the nature of the surface-active agent due to the nanofilm growth mechanism.
 

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