多树枝结构和立方结构PbS的水热合成及形成机理

在无模板条件下，用Pb(NO₃)₂做铅源，(CH₄N₂S)做硫源，用水热法在160 ℃反应24 h制备了结晶度好的多树枝结构PbS。利用XRD、SEM、EDX、TEM对产物进行了表征，结果表明所得产物为面心立方多树枝状结构，单个树枝的长度为1.0～3.0 μm。此外，在碱性条件下丙三醇/水体系中制备了具有不同凹面的立方结构PbS，边长为2.0～5.0 μm。对2种不同形态PbS的影响因素进行了讨论，并提出了形成机理。同时对其荧光及紫外性质进行了研究，结果表明立方结构的PbS在309和373.5 nm处出现了2个荧光峰，在211和232 nm处出现了2个紫外吸收峰。

Multiple-dendritic/Cuboidal Structured PbS: Hydrothermal Synthesis and Growth Mechanism

Well-crystalline multiple-dendritic structured lead sulfide(PbS)were prepared via a template-free,facile hydrothermal route using Pb(NO3)2 as the lead ion source,thiourea(CH4N2S)as the sulfur source at 160℃for 24 h.X-ray powder diffraction(XRD),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDX)and transmission electronic microscopy(TEM)studies showed that the obtained products were face-centered cubic multi-ple-dendritic structured PbS with length of each dendrite from 1.0-3.0μm.Additionally,cuboidal PbS with different concave faces was obtained through a facile hydrothermal process in an alkaline glycerol/water solution system.The edge lengths of these cuboidal microcrystals range from 2.0～5.0μm as observed by SEM.The influencing factors for the two morphologies were discussed and the formation mechanisms were proposed based on their shape evolutions.Emission spectra of the cuboidal structure PbS was detected at 309 and 373.5 nm using a photoluminescence(PL)spectrometer,two excitonic peaks at 211 and 232 nm were observed in UV-Vis absorption spectra.