Properties of PbS Nanocrystals Synthesized by Sonochemical and Sonoelectrochemical Methods

Lead sulfide nanocrystals have been synthesized via sonochemical and sonoelectrochemical methods from precursors such as lead acetate (Pb(Ac)(2): Pb(CH3COO)(2)center dot 3H(2)0), thioacetamide (TAA: CH3CSNH2) and cetyltrimethyl ammonium bromide (CTAB: C19H42BrN). The samples were characterized by X-ray diffraction, high resolution transmission electron microscopy, selected area electron diffraction and ultraviolet-visible absorption spectroscopy. The results showed that the samples prepared by sonoelectrochemical technique have a cluster-like form composed of the small nanocrystals with the size of 6-10 nm, while the samples prepared by sonochemical technique constituted of the nanoparticles with the size of about 20 nm, mixed with the nanorods of 20 nm in width and 80 nm in length. All the PbS nanocrystals have a face-centered cubic crystal structure. The optical absorption spectra exhibit a strong blue-shift due to the quantum size effect.