静电纺丝法制备纳米氧化铟锡及其导电性能

采用静电纺丝-溶胶凝胶法,以SnCl2、InCl3、聚乙烯吡咯烷酮(PVP)等为原料,乙醇胺为水解控制剂,合成了超细氧化铟锡(ITO)纳米纤维及富氧缺陷的ITO纳米颗粒。采用透射电子显微镜(TEM)、选区电子衍射(SAED)、扫描电子显微镜(SEM)、热重分析(TGA)、X射线衍射(XRD)、X射线电子能谱(XPS)、四探针电阻仪,系统研究了超细ITO纤维及颗粒的形貌、晶型、氧缺陷及导电性能。在400℃空气煅烧后,纤维中的PVP高分子骨架发生热分解,获得超细、多孔ITO纳米纤维,晶型为立方相。进一步升高煅烧温度至800℃,ITO纳米纤维转变为富氧缺陷的纳米颗粒,晶格氧空位含量高达38.9%。随着煅烧温度升高,Sn4+掺入到In₂O₃晶格中,发生晶格膨胀,晶面间距增大。煅烧温度由400℃升高至800℃,未发生立方相向六方相的转变,晶型稳定,晶粒尺寸从32 nm生长到44 nm,晶格应变(ε0)从1.943×10^-3减小至1.422×10^-3,应变诱导的晶格弛豫逐渐减小。此外,高温煅烧可抑制In₂O₃晶粒(111)晶面的增长,随着In₂O₃的(400)与(222)晶面比值(I₍₄₀₀)/I₍₂₂₂))的增加,ITO电导率逐渐升高。在800℃获得的ITO纳米颗粒导电率最高。

Fabrication of Indium Tin Oxide Nanostructures by Electrospinning and Their Electrical Conductivity

Indium tin oxide(ITO)nanofibers and ITO nanoparticles with enriched oxygen-defects were synthesized through facile electrospinning and sol-gel method.SnCl2,InCl3,and PVP(polyvinylpyrrolidone)were selected as precursors,while ethanolamine was employed as a hydrolysis controlling agent.The morphology,crystal structure,oxygen defects,and electrical performance of the ultrafine ITO nanofibers and nanoparticles were systematically characterized by transmission electron microscope(TEM),selection electron diffraction(SAED),scanning electron microscope(SEM),thermogravimetric analysis(TGA),X-ray diffraction(XRD),X-ray electron spectroscopy(XPS),and four point resistance tester.The ITO nanofibers were obtained by removal of the PVP matrix at 400℃,and featured with ultrafine diameter,porous structure,and cubic phase.Furthermore,the resultant ITO nanofibers changed to oxygen-deficient nanoparticles with a high oxygen vacancy content of 38.9%at 800℃.The doping of Sn4+ions into the In₂O₃lattices leads to the expansion of the lattice and thus the increase of crystal plane spacing at elevated temperatures.When the temperature increased from 400 to 800℃,the size of ITO nanoparticles grown from 32 to44 nm.Meanwhile,the lattice strain(ε0)decreased from 1.943×10^-3to 1.422×10^-3and the strain-induced lattice relaxation decreased accordingly.No phase change from cubic structure to hexagonal structure was observed.Additionally,calcination at elevated temperature could hamper the(111)growth and thus cause the increase in the ratio of I₍₄₀₀)/I₍₂₂₂)in In2 O3 that is proportional to the electrical conductivity of ITO.The maximized electrical conductivity of ITO nanoparticles was obtained upon a calcination temperature of 800℃.