Structural and optical studies of yttrium oxide nanoparticles synthesized by co-precipitation method

Yttrium oxide (yttria) nanoparticles were successfully synthesized by co-precipitation method. As-synthesized and annealed powders were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), UV-visible (UV-vis), photoluminescence (PL) spectra and Fourier transform infrared spectrometer (FTIR). The XRD results show that the as-prepared sample has mixed phase of Y(OH)₃ and yttria (Y₂O₃). However, cubic yttrium oxide phase alone is found for annealed samples. The strain values are calculated from Williamson-Hall (W-H) plot for annealed samples. SEM and TEM micrographs show that the samples are composed of aggregated nanoparticles with different shapes and sizes. From the UV-vis spectra, it is found that the position of the absorption peak is shifted towards the lower wavelength side when particle size decreases. In the PL spectra, the broad emission bands are observed between 340 and 380 nm and the presence of metal oxide is confirmed by FTIR spectra.     

Structural,optical and electrical properties of Zn-doped SnO2 nanoparticles synthesized by the co-precipitation technique

Nanometric size Zn-doped SnO₂ particles with Zn concentration varying from 1 to 6 % were prepared using the co-precipitation method. X-ray diffraction patterns show for all samples a typical rutile-type tetragonal structure of SnO₂ without any additional peaks from spurious phases. These results together with transmission electron microscopy analyses have shown that the size of the nanoparticles decreases with Zn doping down to 4 nm. According to UV–visible absorption measurements this decrease of particle size is accompanied by a decrease of the band gap value from 3.34 eV for SnO₂ down to 3.28 eV for 6 % Zn doping. The electrical conductivity of the system has been investigated between 473 and 718 K, in the 200 Hz–5 MHz frequency range, by means of impedance spectroscopy. The temperature dependence of the bulk conductivity was found to obey the Arrhenius law with activation energies of 0.74 eV for SnO₂ and 0.69 eV for 6 % Zn doping.     

Synthesis of indium tin oxide (ITO) and fluorine-doped tin oxide (FTO) nano-powder by sol–gel combustion hybrid method

ITO and FTO nano-powders were synthesized employing a new route sol–gel combustion hybrid method using acetylene black as a fuel. The dried gels exhibited an auto-catalytic combustion behavior. ITO and FTO nano-powders with narrow size distribution were obtained at 750 °C. Crystal structures were examined by powder X-ray diffraction (XRD) and particle morphology as well as crystal size was investigated by scanning electron microscopy (SEM). The size of the nano-powder was found to be in the range of 16 nm to 33 nm.     

Effect of annealing temperature on structural,optical and humidity sensing properties of indium tin oxide (ITO) thin films

Tin doped indium oxide (ITO) thin films were prepared by sol–gel spin coating method with In (NO₃)·3H₂O and SnCl₄·5H₂O as indium and tin sources, respectively. The as deposited samples were annealed at various temperature such as, 300, 400, 500 and 600?°C for 2 h in ambient atmosphere. The grown ITO thin films are polycrystalline in nature with cubic structure of In₂O₃ with the space group La3 and the results are in good agreement with the standard JCPDS data (card no#06-0416). In addition crystalline size increases with increasing annealing temperature from 25 to 55 nm. Polycrystalline with uniform smooth surface was observed by SEM micrographs. The optical band gap energy was found to be decreased from 3.85 to 3.23 eV as the annealing temperature is increased from 300 to 600?°C. The humidity sensing performance (high sensitivity and fast response time) was significantly improved for 600?°C thin films samples, which is probably due to smaller energy band gap and physisorption between the water molecules and the surface of the thin films. The films were further characterized by PL and EDS analysis. The effect of temperature on humidity sensing mechanism of ITO thin films is also discussed.     

Structural and optical properties of indium tin oxide (ITO) thin films with different compositions prepared by electron beam evaporation

Tin-doped Indium oxide thin films in different compositions (Sn = 0,5,10,15,20 at.wt%) were prepared on glass substrates at the substrate temperature of 250 °C in an oxygen atmosphere by electron beam evaporation. The structural and morphological studies were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The grain size of the ITO films decreased when increasing the dopant concentration of Sn in the In₂O₃ lattice. Optical properties of the films were studied in the UV-Visible-NIR region (300-1000 nm). The optical energy band gap (E_g), as determined by the dependence of the absorption coefficient on the photon energy at short wavelengths was found to increase from 3.61 to 3.89 eV revealing the ascending loading profile of dopant concentration. Optical Parameters, such as absorption depth, refractive index (n), extinction coefficient (k), packing density, porosity, dispersion energy and single effective oscillator energy were also studied to show the composition dependence of tin-doped indium oxide films.     

化学共沉淀法制备纳米ITO粉体及结构表征

以InCl3·5H2O和SnCl4·5H2O为原料,在掺杂浓度In2O3与SnO2的质量比为9∶1的条件下,采用化学共沉淀法合成了纳米ITO粉体。利用TEM、XRD、IR、粒度分布仪等实验手段对粉体的形貌、物相、粒度进行了表征,讨论了煅烧温度对粉体物相和粒度的影响。研究结果表明:当煅烧温度>300℃时,可以获得立方In2O3结构的球形纳米ITO粉体。     

Effects of thermal treatment on the electrical and optical properties of silver-based indium tin oxide/metal/indium tin oxide structures

In this article, we report the results of the study of thermal treatment effects on the electrical and optical properties of silver-based indium tin oxide/metal/indium tin oxide (IMI) multilayer films. Heat treatment conditions such as temperature and gaseous atmosphere was varied to obtain better electrical and optical properties. We obtained improved electrical properties and observed considerable shift in the transmittance curves after heat treatment. Several analytical tools such as X-ray diffraction, spectroscopic ellipsometer and spectrophotometer were used to explore the causes of the changes in electrical and optical properties. The sheet resistance of the structure was severely influenced by deposition conditions of the indium tin oxide (ITO) layer at the top. Moreover, the shift of optical transmittance could be explained on the basis of the change in refractive indices of ITO layers during heat treatment. The properties of Ag-alloy-based IMI films were compared with those of pure Ag-based ones. Some defects originating from Ag layer corrosion were observed on the surface of ITO-pure Ag–ITO structures, however, their number decreased significantly in the cases of Ag-alloys containing Pd, Au and Cu, though the resistivity values of Ag-alloys were slightly higher than those of silver. Atomic force microscopy measurement results revealed that the surface of the IMI multilayer was so smooth that it meets the required qualifications as the bottom electrode of organic light emitting diodes.     

Optical and electrical properties of indium tin oxide nanofibers prepared by electrospinning

Indium tin oxide (ITO) nanofibers were successfully prepared via an electrospinning method, followed by annealing at 400?°C. Mixed solutions of ITO nanoparticle sol and polyethylene oxide (PEO) were used as precursors of the nanofibers. The PEO decomposed during annealing to yield ITO fibers. The fibers were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), thermo-gravimetric/differential thermal analysis (TG/DTA), UV-vis spectrophotometry and four-probe resistivity measurements. The diameter of the prepared fibers was controlled by adjusting the flow rate and the applied electric current. In(2)O(3) crystallized in the ITO nanofibers with a crystallite size of 27?nm. The optical transmittance in the visible region approached 90% in films deposited for 5?min, confirming that the nanofiber film is still transparent in the optical region. The sheet resistance of the nanofiber film was linearly dependent on the inverse of the deposition time and on the PEO/ITO ratio.     

Inkjet-printing of indium tin oxide (ITO) films for transparent conducting electrodes

Indium-tin-oxide (ITO) films have been prepared by inkjet-printing using ITO nanoparticle inks. The electrical and optical properties of the ITO films were investigated in order to understand the effects of annealing temperatures under microwave. The decrease in the sheet resistance and resistivity of the inkjet-printed ITO films was observed as the annealing temperature increases. The film annealed at 400 °C showed the sheet resistance of 517 Ω/sq with the film thickness of ∼580 nm. The optical transmittance of the films remained constant regardless of their annealing temperatures. In order to further reduce the sheet resistance of the films, Ag-grid was printed in between two layers of inkjet-printed ITO. With 3 mm Ag-grid line-to-line pitch, the Ag-grid inserted ITO film has the sheet resistance of 3.4 Ω/sq and the transmittance of 84% after annealing at 200 °C under microwave.     

Structural,electrical, optical properties and reliability of ultra-thin tin doped indium oxide films for touch panels

Ultra-thin ITO films with thickness of 4–56 nm were deposited on glass by dc magnetron sputtering using 5 wt% SnO₂ doped ITO target. The effect of film thickness on the structural, electrical, optical properties and reliability was investigated for its application to touch panels. The 4 nm thick ITO film shows amorphous structure and other films present polycrystalline structure and the (222) preferred orientation. The ultra-thin ITO films show smooth surface with low Ra surface roughness smaller than 1 nm. The sheet resistance and visible transmittance of the ITO films decrease with the increase in film thickness. The 4 nm thick ITO film shows the highest resistivity (3.08 × 10^?3 Ω cm) with low carrier density and Hall mobility, and other films have excellent conductivity (<4.0 × 10^?4 Ω cm). The ITO films show high transmittance (>85 %) in visible light range and do not generate interference ripples between film and substrate interface. The ITO films with thickness of 18–56 nm show stable reliability under high temperature, high temperature & high humidity and alkaline environmental conditions. The only electrical degradation corresponds to the increase of sheet resistance in the ITO films with thickness of 4–12 nm.     

Highly conducting indium tin oxide (ITO) thin films deposited by pulsed laser ablation

Highly conducting and transparent indium tin oxide (ITO) thin films were prepared on SiO₂ glass and silicon substrates by pulsed laser ablation (PLA) from a 90 wt.% In₂O₃-10 wt.% SnO₂ sintered ceramic target. The growths of ITO films under different oxygen pressures (P_O2) ranging from 1×10⁻⁴–5×10⁻² Torr at low substrate temperatures (T_s) between room temperature (RT) and 200°C were investigated. The opto-electrical properties of the films were found to be strongly dependent on the P_O2 during the film deposition. Under a P_O2 of 1×10⁻² Torr, ITO films with low resistivity of 5.35×10⁻⁴ and 1.75×10⁻⁴ Ω cm were obtained at RT (25°C) and 200°C, respectively. The films exhibited high carrier density and reasonably high Hall mobility at the optimal P_O2 region of 1×10⁻² to 1.5×10⁻² Torr. Optical transmittance in excess of 87% in the visible region of the solar spectrum was displayed by the films deposited at Po₂≥1×10⁻² Torr and it was significantly reduced as the P_O2 decreases.     

The effect of sputtering pressure on electrical, optical and structure properties of indium tin oxide on glass

Indium tin oxide (ITO) thin layers were deposited onto glass substrates by RF magnetron sputtering using different pressures. Subsequently, the films were annealed in a reducing atmosphere at 500 °C for 30 min. Electrical properties were measured by Hall Effect analysis and four-point probe measurements. Optical properties were determined by UV-Vis spectrophotometery. Film structures and compositions were analyzed by X-ray diffractometry and X-ray photoelectron spectroscopy, respectively. The effect of sputter pressure and additional anneals was investigated. The results revealed that the lowest resistivity of 1.69 × 10^− 4 Ω cm was achieved at low pressure (1.2 Pa) and the highest transmittance of ~ 90% was obtained after a second anneal. However, the second anneal decreased the mobility and the conductivity especially for high sputtering pressures. This study also describes the effect of Sn defect clustering on electrical properties of the ITO films.     

Patterned indium tin oxide nanofiber films and their electrical and optical performance

We report on the preparation and characterization of indium tin oxide (ITO) nanofiber films with a patterned architecture that are transparent and conductive with a uniform fiber size. ITO nanofiber films with a crisscross pattern were prepared by the electrospinning of a precursor solution containing ethanol, dimethyl formamide (DMF), indium chloride tetrahydrate, tin chloride pentahydrate and poly(vinyl pyrrolidone) (PVP K90) onto a metal mesh template, followed by calcinations after transfer to a glass substrate. The resulting ITO nanofibers had diameters of the order of 100?nm and were composed of single-crystalline nanoparticles that were pure in chemical composition. The morphology, crystallinity and performance of the resulting nanofibers could be controlled mainly by calcination. Optical and electrical investigations demonstrated that these nanofiber films are transparent conductors with an optical transmittance as high as 92%. The resulting patterned ITO nanofiber films would be suitable for applications such as solar cells, sensors and electromagnetic field filters.     

Preparation and optical properties of indium tin oxide/epoxy nanocomposites with polyglycidyl methacrylate grafted nanoparticles

Visibly highly transparent indium tin oxide (ITO)/epoxy nanocomposites were prepared by dispersing polyglycidyl methacrylate (PGMA) grafted ITO nanoparticles into a commercial epoxy resin. The oleic acid stabilized, highly crystalline, and near monodisperse ITO nanoparticles were synthesized via a nonaqueous synthetic route with multigram batch quantities. An azido-phosphate ligand was synthesized and used to exchange with oleic acid on the ITO surface. The azide terminal group allows for the grafting of epoxy resin compatible PGMA polymer chains via Cu(I) catalyzed alkyne-azide "click" chemistry. Transmission electron microscopy (TEM) observation shows that PGMA grafted ITO particles were homogeneously dispersed within the epoxy matrix. Optical properties of ITO/epoxy nanocomposites with different ITO concentrations were studied with an ultraviolet-visible-near-infrared (UV-vis-NIR) spectrometer. All the ITO/epoxy nanocomposites show more than 90% optical transparency in the visible light range and absorption of UV light from 300 to 400 nm. In the near-infrared region, ITO/epoxy nanocomposites demonstrate low transmittance and the infrared (IR) transmission cutoff wavelength of the composites shifts toward the lower wavelength with increased ITO concentration. The ITO/epoxy nanocomposites were applied onto both glass and plastic substrates as visibly transparent and UV/IR opaque optical coatings.     

Experimental and theoretical study of the optical and electrical properties of nanostructured indium tin oxide fabricated by oblique-angle deposition

Oblique-angle deposition of indium tin oxide (ITO) is used to fabricate optical thin-film coatings with a porous, columnar nanostructure. Indium tin oxide is a material that is widely used in industrial applications because it is both optically transparent and electrically conductive. The ITO coatings are fabricated, using electron-beam evaporation, with a range of deposition angles between 0 degrees (normal incidence) and 80 degrees. As the deposition angle increases, we find that the porosity of the ITO film increases and the refractive index decreases. We measure the resistivity of the ITO film at each deposition angle, and find that as the porosity increases, the resistivity increases superlinearly. A new theoretical model is presented to describe the relationship between the ITO film's resistivity and its porosity. The model takes into account the columnar structure of the film, and agrees very well with the experimental data.     

FeNi3/indium tin oxide (ITO) composite nanoparticles with excellent microwave absorption performance and low infrared emissivity

FeNi₃/indium tin oxide (ITO) composite nanoparticles were synthesized by a self-catalyzed reduction method and a sol–gel process. The dependence of the content of ITO phase with the mole ratios of In:Sn of different sols was investigated. The relation between the electrical conductivity, infrared emissivity of FeNi₃/ITO composite nanoparticles and the content of ITO phase was discussed. Electromagnetic wave absorption (EMA) performance of products was evaluated by using transmission line theory. It was found that EMA performance including the intensity and the location of effective band is significantly dependent on the content of ITO phase. The low infrared emissivity and superior EMA performance of FeNi₃/ITO composite nanoparticles can be both achieved when the mole ratio of In:Sn in sol is 9:1.     

Structural, electrical and optical properties of indium tin oxide thin films prepared by RF sputtering using different density ceramic targets

There is an active demand for the commercial indium tin oxide (ITO) target with density above 99% of the theoretical density (TD). Some works found the increase of the target density could lead to a slight decrease of the resistivity of the direct current (DC) sputtered ITO films, however, the possible effect of target density on the radio frequency (RF) sputtered ITO films is not clear. In this paper, ITO targets with different densities are successfully prepared. The structural, electrical and optical properties of the thin films deposited from these targets are studied at the substrate temperature of 750 °C. It is found that the target density has no effect on the above properties and the deposition rate of the RF sputtered ITO thin films, different from the DC sputtered films. So for the RF sputtered process, the target needs not high density so that the used target can be just compacted from the powders without sintering. All the as-prepared ITO films with different densities have a resistivity of 1.56 × 10⁻⁴ Ω cm and a transmittance of ∼87%, which are lower than the ITO films prepared at temperatures lower than 400 °C.     

分散剂对铟锡氧化物(ITO)粉末粒径的影响

以纯In、SnCl4·5H2O和盐酸为原料,氨水为沉淀剂,采用络盐法制备了纳米铟锡氧化物(ITO)粉末。主要研究了分散剂对ITO纳米粉体粒径的影响。用激光粒度仪、XRD、SEM对所得粉末进行表征。结果表明:随着分散剂的分子量的增加,所得ITO的粒径逐渐变小;加入不同分子量的PEG配合使用有利于制备纳米级颗粒,加入PEG(10000∶6000=1∶1)作分散剂所制ITO粉末粒径为50～100nm。     

Synthesis and electrical property of indium tin oxide nanofibers using electrospinning method

In this study indium tin oxide (ITO) nanofibers were synthesized using an electrospinning method. The morphological properties of the ITO nanofibers were considered and their specific resistances were measured to determine their applicability as filler for a transparent conducting film. ITO/PVP composite nanofibers were successfully obtained by electrospinning using a precursor solution containing indium nitrate, tin chloride, and poly(vinlypyrrolidone). After the heat treatment of ITO/PVP composite nanofibers at 600 degrees C and 1000 degrees C, ITO nanofibers with an average diameter of about 168 nm and 165 nm were synthesized, respectively.     

Characterization of indium tin oxide film and practical ITO film by electron microscopy

In order to clarify the structure of indium oxide film containing tin and tin oxides, various In₂O₃ based films prepared by vacuum evaporation were studied using high-resolution electron microscope (HREM). Indium tin oxide (ITO) film was composed of In₂O₃ and SnO. SnO crystal also contained (110) or (101) crystallographic shear (CS) structures that indicate excess amounts of tin. The CS structure was also found in a commercial ITO film having the resistivity of 2×10⁻⁴ Ω cm.