Preparation And Optical Properties Of Indium Oxide Compounds Nanofibers

Indium oxide (In2O3) is an important n-type wide band gap semiconductor material,which obtains good electrical conductivity and high visible light transmittance. The opticalperformance of the nanostructured In2O3and its doped products is more prominent than theothers. Therefore, they have been widely used in solar cells, light-emitting diodes, flat paneldisplays and other optoelectronic devices. In this paper, one-dimensional In2O3, GaInO3,In2O3: Eu3+inorganic nanofibers with porous structure were prepared by electrospinning andhigh-temperature calcination. Their optical properties were studied emphatically, shown as thefollowing parts:(1) PVP, In (NO3)34.5H2O, DMF and anhydrous ethanol were used as raw materials toprepare In2O3nanofibers by electrospinning and high-temperature calcination. Themorphology, structure, thermal decomposition performance, crystal phase, component, lightabsorption and photoluminescence properties of the nanofibers were investigated by scanningelectron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry(TG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–visspectra (UV-vis) and fluorescence spectrophotometer (PL). The results showed that a30%mass ratio of the In (NO3)34.5H2O to PVP was favorable to the formation of the precursornanofibers. As a consequence, the products calcinated at different temperatures still remainedfibrous structure, but the diameters of fibers were obviously reduced. The In2O3nanofiberscalcinated at800oC showed a hollow structure. Furthermore, a cubic bixbyite structure ofIn2O3was obtained at all different calcination temperatures. Particle size increased with theincrease of calcination temperature. The highest ultraviolet absorption peak of In2O3nanofibers was located around300nm. A strong green photoluminescence peak at553nmwas observed in its room temperature photoluminescence spectra.(2) Based on the studies of In2O3nanofibers, the Ga(NO3)3xH2O was further added asprecursor salt. The GaInO3ternary metal oxide nanofibers were prepared by the adjustment ofthe experimental parameters. SEM、TG、XRD、FT-IR were used to characterize the basicperformance of the corresponding products. The optical absorption, band gap andphotoluminescence properties were analyzed by UV-vis and PL. The results showed that a20%mass ratio of the nitrate to PVP was preferred to the formation of the precursornanofibers. The composite nanofibers calcinated at800oC,900oC and1000oC for4hours allremained fibrous structure. However, the hexagonal GaInO3could only be obtained when thecalcination temperature was not lower than900oC. The ultraviolet absorption band edges ofthe GaInO3nanofibers calcinated at900oC and1000oC were located at around340nm. Theirband gaps were3.48eV and3.66eV, respectively. A strong blue-green photoluminescence peak at496nm was observed in its room temperature photoluminescence spectra, which wasmoving to a shorter wavelength when compared with the In2O3.(3)1%,2%,4%and8%Eu3+doped In2O3nanofibers were prepared by using In2O3asthe matrix and Eu2O3as the Eu source. SEM、TG、XRD、EDX and PL were used tocharacterize the products. The SEM images demonstrated that the composite precursornanofibers with different concentration of doped Eu3+were well formed. The diameters of thenanofibers increased significantly with the increase of the doped concentration. A continuousfibrous structure was still kept by the calcinated samples. The XRD pattern of the In2O3: Eu3+nanofibers was consistent with that of the cubic In2O3, except the decreased diffraction peakintensity and the absence of the Eu2O3peak. The presence of Eu was further confirmed byEDX. The room temperature photoluminescence spectra revealed that the defectphotoluminescence peak gradually diminished and finally disappeared when the concentrationof Eu3+increased. The emission peaks of Eu3+were located at597nm,612nm and629nm, inwhich the red emission peak at612nm was the strongest. In this research, thephotoluminescence properties of the4%Eu3+doped In2O3nanofibers were the best.