Photoluminescence properties of hexagonal indium tin oxide nanopowders prepared by solvothermal method

Hexagonal structure indium tin oxide(ITO)nanopowders were prepared by a solvothermal process at only 175 ℃ for 24 h and post-annealing at 400 ℃, using metal indium and SnCl_4·5 H_2 O as the raw materials. The morphology, crystal structures and structure defects of products were, respectively, analyzed by scanning electron microscopy(SEM), X-ray diffraction(XRD) and confocal microprobe Raman system, the elemental state was investigated by X-ray photoelectron spectroscopy(XPS), and the optical properties were carried out by ultraviolet-visible(UV-Vis) and photoluminescence(PL) spectrophotometers. The results show that the products are hexagonal structure with a particles size of 28-41 nm; the morphology of products consists of sphere and irregular cubic.When pH values of solution increase, the content of oxygen vacancies increases and the optical band gap varies from3.59 to 3.78 eV. The products exhibit strong emission at417 nm with an excitation of 370 nm, and the PL intensity of samples increases with pH values increasing. Contrasting to cubic structure ITO powder, the hexagonal structure ITO has narrower optical band gap and higher PL intensity under the same excitation wavelength.     

Preparation of antimony-doped nanoparticles by hydrothermal method

Antimony-doped tin oxide (ATO) nanoparticles were prepared by the mild hydrothermal method at 200℃ using sodium stannate, antimony oxide, sodium hydroxide and sulfuric acid as the starting materials. The doped powders were examined by differential thermal analysis(DTA), X-ray diffractometry(XRD) and transmission electron microscopy(TEM). The doping levels of antimony were determined by volumetric method and iodimetry.The results show that antimony is incorporated into the crystal lattice of tin oxide and the doping levels of antimony in the resulting powders are 2.4%, 4.3%and 5.1%(molar fraction). The mean particle size of ATO nanoparticles is in the range of 25 - 30 nm. The effects of antimony doping level on the crystalline size and crystallinity were also discussed.     

Preparation of silver tin oxide powders by hydrothermal reduction and crystallization

Silver tin oxide composite powders were synthesized by the hydrothermal method with a silver ammine solution and a Na2SnO3 solution as raw materials. H2C2O4 was used as the co-precipitator of silver ions and tin ions. The co-precipitation conditions were investigated. The results show that the co-precipitate of Ag2C2O4 and Sn（OH）4 is available when the pH value of the solution is 4.27-8.36. Using the obtained precipitate as precursor,the reduction of Ag＋ and the crystallization of tin oxide were carried out simultaneously by the hydrothermal method and silver tin oxide composite powders were obtained. The composite powders were characterized by X-ray diffraction （XRD） analysis,scanning electron microscope （SEM）,and energy spectrum analysis. The results show that the silver tin oxide composite powders are small with a diameter of about 2 μm and with homogeneous distribution of tin.     

Effect of Sn~(4+) content on properties of indium tin oxide nanopowders

Indium tin oxide(ITO)nanopowders were prepared by a modified chemical co-precipitation process.The influence of different SnO2 contents on the decomposition behavior of ITO precursors,and on the phase and morphology of ITO precursors and ITO nanopowders were studied by X-ray diffractometry,transmission electron microscopy and differential thermal and thermogravimetry analysis methods.The TG-DSC curves show that the decomposition process of precursor precipitation is completed when the temperature is close to 600 ℃and the end temperature of decompositionis somewhat lower when the doping amount of SnO2 is increased.The XRD patterns indicate that the solubility limit of Sn4+ relates directly to the calcining temperature. When being calcined at 700℃,a single phase ITO powder with 15%SnO2(mass fraction)can be obtained.But,when the calcining temperature is higher than 800℃,the phase of SnO2 will appear in ITO nanopowders which contain more than 10%SnO2.The particle size of the ITO nanopowders is 15-25 nm.The ITO nanoparticles without Sn have a spherical shape,but their morphology moves towards an irregular shape when being doped with Sn4+.     

Synthesis and sintering of indium tin oxide nanoparticles by citrate-nitrate combustion method

Spherical indium tin oxide(ITO) nanoparticles were synthesized by combustion method using citric acid as fuel and nitrates as oxidizer.The obtained ITO nanoparticles were characterized by TG-DSC,FT-IR,XRD,BET,TEM,and SEM.The ITO nanoparticles grew steadily with the increase of heat treatment temperature,and the 700℃ calcined particles had a crystallite size of 25.3 nm and a specific surface area of 26.1 m2·g-1.The avoidance of chlorine ions in the synthesis process decreases particle agglomeration and promotes powder densification.The 900℃ sintered pellet had a density of 67.6% of theoretical density(TD) and increased steadily to 97.3% for the 1400℃ sintered ceramics,respectively.     

Preparation of indium tin oxide targets with a high density and single phase structure by normal pressure sintering process

The present work mainly describes the technology for preparing indium-tin oxide (ITO) targets by cold isostatic pressing (CIP) and normal pressure sintering process.ITO powders were produced by chemical co-precipitation and shaped into an ITO green compact with a relative density of 60% by CIP under 300 MPa.Then,an ITO target with a relative density larger than 99.6% was obtained by sintering this green compact at 1550 ℃ for 8 h.The effects of forming pressure,sintering temperature and sintering time on the...     

Surface modification of indium tin oxide films with Au ions implantation: Characterization and application in bioelectrochemistry

Indium tin oxide (ITO) thin film coated glass substrates have been implanted with 21 keV Au ions at a fluence of 1.0 × 10¹⁷ ions/cm² at room temperature. The resulting gold film was characterized with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectra and electrochemical methods. The results reveal that the implanted Au atoms were in the zero-valent metallic state and these Au atoms precipitated to form nanoclusters on the ITO surface whose average radius was estimated between 2 and 5 nm. The preferentially growing orientation was Au (111) plane during the formation process of gold film and the value of gold active surface area normalized by the geometric electrode areas was 0.48 for Au ion implanted ITO (Au/ITO) electrode. The potential utility of Au/ITO films was investigated. The Au/ITO electrode exhibited effective catalytic responses towards biomolecules such as ascorbic acid (AA) oxidation and lowered oxidation potential of AA by 0.6 V when compared with the bare ITO electrode. Myoglobin (Mb) was also successfully immobilized on the Au/ITO electrode and the direct electron transfer between proteins and electrode surface was realized. It was demonstrated that the Au/ITO film offered a favorable microenvironment for the orientation of biomolecules. New biomaterials with specific electrocatalytic and electrochemical features could be fabricated using this method.