Synthesis and Characteristics of Ag, Ag2S and Ag2(S, Se) Nanoparticles

• Main Authors: Yi-Hung Chang, 張翼泓
• Other Authors: Ray-Kuang Chiang
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/87882981325062266874

碩士 === 遠東科技大學 === 機械研究所 === 97 === In this study, Ag nanoparticles were prepared by thermal decomposition synthesis to achieve a control of particles size (5 nm - 18 nm) and homogeneity. AgNO3, Ag(Oleic), and AgSR were used as precursors to fabricate Ag nanoparticles, adding with 1-Hexadecylamin or Oleylamine surfactants in various concentrations. The connection between particle characteristics and different surfactants with various concentrations was explored. Due to Surface Plasmon Resonance (SPR) of Ag, absorbance maximum is observed in the UV-vis spectra. In general, the peak position of SPR in the absorbance spectra of UV-vis is related to particle shape, size, and dielectric constant. In our result, the influence of particle size on position of SPR is unapparent. On the other hand, Ag nanoparticles with different surfactant could lead to the variation of dielectric constant, resulting in the influence on resonant frequency of electron. Thus, the peak position of SPR changes from 400 nm to around 523 nm. According to the literature, the band gap of bulk silver sulfide is 1 eV (1240 nm), particle size of 9 nm (2.95 eV)、16 nm (3.1 eV) when the apparent large blue indicates that the nanoparticles are within the quantum size effect.The obtained nanoparticlesin the above-described reactions can be further treated with Se/1-ODE solutions of different concentration to produce Ag2(S1-XSeX) nanoparticles. The series of guanajuatite nanoparticles obtained also show tunable band-gap widths (2.95 eV to 2.80 eV, 0.67 eV for the bulk Ag2Se) with the variation in compositions in the absorption spectra. The morphology and the particle size of the Ag and Ag2S nanoparticles were investigated by using transmission electron microscopy (TEM). The characteristic crystal phases of nanoparticles were identified using powder x-ray diffraction (XRD). The nanoparticles with and without surfactant was determined using Fourier transform infrared spectroscopy (FTIR). The optical properties of the nanoparticles were measured with UV/Visible Spectrophotometer and photoluminescence excitation spectroscopy.