Synthesis and conductive performance of antimony-doped tin oxide-coated TiO2 by the co-precipitation method

The synthesis of Sb–SnO₂/TiO₂ (SST) composites by assembling antimony-doped tin oxide (Sb–SnO₂) nanoparticles on the surface of titanium dioxide (TiO₂) is systematically investigated. X-ray diffraction data show that the SST composite materials with good crystallinity can be indexed as anatase TiO₂ phase and cassiterite SnO₂ phase. The scanning electron microscopy and transmission electron microscopy indicate that Sb–SnO₂ particles with average diameter of 25 nm have been successfully coated on the surface of TiO₂. In addition, the Ti–O–Sn band can be detected on the surface of TiO₂ through Fourier translation infrared spectroscopy. The influences of pH, Sn/Ti mole ratio, hydrolysis temperature and calcination temperature on the electrical resistivity of the SST powders are studied. Under the optimum experimental conditions, the electrical resistivity of the composite conductive powders is 2.546 × 10³ Ω cm. Therefore, the SST composite conductive powders are useful as conductive fillers for the application in antistatic materials.     

A comparative study of dip coating and spray pyrolysis methods for synthesizing ITO nanolayers by using Ag colloidal sol

Indium tin oxide (ITO) films were deposited on glass substrates by dip-coating and thermal pyrolysis methods. Sn (IV) is often used in the spray method as a precursor salt, but in this research we have employed a new procedure that uses Sn (II) and In(NO₃)₃ for preparation of transparent conductive thin films. Then, colloidal Ag was deposited on the ITO layers in order to compare the two synthesis methods, and the structural and electrical properties of the resultant films were investigated by FESEM, XRD, and four-terminal resistometry. The obtained films are polycrystalline with a preferred orientation of (200). The XRD patterns of the films indicate that in both films, the Sn phase is crystallized separately from In₂O₃. The presence of a Sn peak and the overall low intensity of XRD peaks suggest relative crystallization of ITO structure. For this reason, Ag films were deposited by dip coating method using a colloidal sol. By analyzing the XRD patterns of Ag-ITO films after eliminating the Sn peak, the increased intensity of the peaks confirmed the relatively good crystallization of the ITO films. The results show that the films with a sheet resistance as low as 2 × 10^?2 Ω·cm, which is beneficial for solar cells, were achieved.     

Effect of addition of TiO2 nanoparticles on the microstructure,microhardness and interfacial reactions of Sn3.5AgXCu solder

In this work, TiO₂ nanoparticles were successfully incorporated into Sn3.5Ag and Sn3.5Ag0.7Cu solder, to synthesize novel lead-free composite solders. Effects of the TiO₂ nanoparticle addition on the microstructure, melting property, microhardness, and the interfacial reactions between Sn3.5AgXCu and Cu have been investigated. Experimental results revealed that the addition of 0.5 wt.% TiO₂ nanoparticles in Sn3.5AgXCu composite solders resulted in a finely dispersed submicro Ag₃Sn phase. This apparently provides classical dispersion strengthening and thereby enhances the shear strength of composite solder joints. After soldering, the interfacial overall intermetallic compounds (IMC) layer of the Sn3.5AgXCu lead-free solder joint was observed to have grown more significantly than that of the Sn3.5AgXCu composite solder joints, indicating that the Sn3.5AgXCu composite solder joints had a lower diffusion coefficient. This signified that the presence of TiO₂ nanoparticles was effective in retarding the growth of the overall IMC layer.     

Modeling the structural properties and energies of transparent conducting oxides

In the current study we evaluate the use of a dumped shifted force electrostatic interaction model for the study of the structural properties of indium oxide and tin-doped indium oxide (ITO). This model is found to be computationally efficient and accurate in the calculations. More specifically, the ion positions of In₂O₃, the preference of b-sites In substitution with Sn and the lattice constant of ITO anomalous dependency on Sn content varying from 3% to 6% calculated with this model agree with the experimental data and other theoretical first principle studies. For Sn content higher than 6% the calculated data deviate from the experimentally observed as the existence of the In₄Sn₃O₁₂ phase was not taken into account. Also, we found an agreement to the Vegard's law of the lattice constant with simple In substitution with Sn ions. Finally the bulk modulus calculated for the ITO (92-97 GPa) is in good agreement with experimental data for ITO films.     

Combination of pumpkin-derived biochar with nickel ferrite/FeNi3 toward low frequency electromagnetic absorption

The rapid development of electromagnetic communication and electronic technique has brought serious problems of EMI and electromagnetic radiation. Herein, a combined method of ball milling, hydrothermal and multiple calcination processes was utilized to synthesize pumpkin-derived biochar/nickel ferrite/FeNi₃ composite. The nickel ferrite and FeNi₃ nanoparticles are distributed uniformly on the surface of biochar, and the thin carbon layer formed on the surface of NPs endows a better impedance matching to the particles. The excellent low frequency absorption performance can be achieved via the cooperative effect of dielectric and magnetic wastage mechanisms i.e., low frequency natural resonance, abundant interface polarization, dipolar polarization, conductive loss, multi-reflection and scatter etc. The maximum RL value achieves ??59.29 dB at 1.30 GHz with the effective absorption bandwidth of 1.34 GHz (0.76–2.1 GHz), declaring this biochar/nickel ferrite/FeNi₃ ternary hybrid could be used as one kind of efficient low frequency electromagnetic absorbent.

     

Optically active polyurethane@indium tin oxide nanocomposite: Preparation,characterization and study of infrared emissivity

Optically active polyurethane@indium tin oxide and racemic polyurethane@indium tin oxide nanocomposites (LPU@ITO and RPU@ITO) were prepared by grafting the organics onto the surfaces of modified ITO nanoparticles. LPU@ITO and RPU@ITO composites based on the chiral and racemic tyrosine were characterized by FT-IR, UV–vis spectroscopy, X-ray diffraction (XRD), SEM, TEM, and thermogravimetric analysis (TGA), and the infrared emissivity values (8–14 μm) were investigated in addition. The results indicated that the polyurethanes had been successfully grafted onto the surfaces of ITO without destroying the crystalline structure. Both composites possessed the lower infrared emissivity values than the bare ITO nanoparticles, which indicated that the interfacial interaction had great effect on the infrared emissivity. Furthermore, LPU@ITO based on the optically active polyurethane had the virtue of regular secondary structure and more interfacial synergistic actions between organics and inorganics, thus it exhibited lower infrared emissivity value than RPU@ITO based on the racemic polyurethane.     

Study of annealing time on sol–gel indium tin oxide films on glass

Indium and tin salt-based precursors maintaining In:Sn atomic ratio as 90:10 were utilized for the development of sol–gel dip coated indium tin oxide films (ITO) on SiO₂ coated (∼ 200 nm thickness) soda lime silica glass substrate. The gel films were initially cured in air at ∼ 450 °C to obtain oxide films of physical thickness ∼ 250 nm. These were then annealed in 95% Ar–5% H₂ atmosphere at ∼ 500 °C. The annealing time was varied from 0.5 h to 5 h. Variation of annealing time did not show any considerable change of transmittance in the visible region. Thermal emissivity (ε_d, 0.67–0.79) of the films were evaluated from their hemispherical spectral reflectance. These passed through a minima with increasing annealing time as the reflectivity of the films in the mid-IR passed through a maxima. The microstructure of the films revealed systematic growth of the ITO grains. XRD and XPS studies revealed the presence of both In and Sn metals in addition to the metal oxides. The energy dispersive X-ray (EDX) analysis showed little lowering of tin content in the films with increasing annealing time.     

Enhancement of visible light activity in Ag modified SnO2/TiO2

Ag modified SnO₂/TiO₂ nanoparticles were successfully prepared by a modified sol–gel method, without adding any acid or alkali. The entire preparation differs from the traditional sol–gel synthesis of TiO₂ that the reaction can get controlled by adjusting the flow speed of water vapor. Ultraviolet–visible diffuse reflectance spectra (UV–vis) and spin-trapping electron paramagnetic resonance (EPR) were used to forecast the photocatalytic activity of the samples, and the results were proved by the degradation of methylene blue solution under visible light. Compared with pure TiO₂, as-prepared Ag modified SnO₂/TiO₂ nanoparticles exhibited not only an enhanced photocatalytic activity but also an improved stability. Among all of samples, the composite with 0.5% of Ag and 1% of Sn showed the best photocatalytic performance and stability. Further increasing the Ag proportion will result in the decrease of the photocatalytic activity. A relative mechanism was proposed and discussed in detail.     

Indium tin oxide films made from nanoparticles: models for the optical and electrical properties

Porous thin films comprising nanoparticles of In₂O₃:Sn (known as indium tin oxide, ITO) were made by spin coating followed by annealing. The nanoparticles were prepared by a wet chemical technique. The films had a luminous transmittance of ∼90% and an electrical resistivity of ∼10⁻² Ω cm. Spectral transmittance and reflectance were analyzed by first representing the ITO nanoparticles within the Drude theory, with a frequency-dependent scattering time characteristic for ionized impurity scattering, and then applying effective medium theory to account for the porosity. It was found that the individual nanoparticles had a resistivity of ∼2×10⁻⁴ Ω cm, i.e. their electrical properties were comparable to those in the best films made by physical or chemical vapour deposition. Temperature-dependent electrical resistivity data for the films could be reconciled with a model for fluctuation induced tunneling between micrometer-size clusters of internally connected ITO nanoparticles.     

Room-temperature ferromagnetic and photoluminescence properties of indium–tin-oxide nanoparticles synthesized by solid-state reaction

In the present study, indium–tin-oxide (ITO) nanoparticles were synthesized using solid-state reaction and studied for their structural, vibrational and magnetic properties. The ITO nanoparticles were prepared under reduced pressure, which can increase the oxygen vacancies in the samples. The X-ray diffraction studies confirmed singe-phase cubic bixbyite structure of ITO with average crystallite size of 47 nm. The lattice vibrational studies (FT-IR and Raman spectroscopy) at room temperature indicated that Sn ions were occupied in In₂O₃ lattice and gives corresponding active vibrational modes in the respective spectra. The magnetic studies at room temperature reveal the ferromagnetic nature of ITO and the strength of magnetization is superior to those of In₂O₃ and SnO₂. However, the magnetic studies at 100 K revealed reduced ferromagnetism, which could be attributed to reduced itinerary electrons at low temperature. Blue and blue–green emissions were found from the ITO nanoparticles, which could be due to vacancies or surface defects present in the system.     

Influence of small Sb nanoparticles additions on the microstructure, hardness and tensile properties of Sn–9Zn binary eutectic solder alloy

In the present study, different weight percentages of Sb nanoparticles (100–120 nm) ranging from 0 to 1.5 wt% were added to Sn–9Zn eutectic solder alloy to investigate the effect of third element addition on the microstructure, mechanical properties as well as thermal behavior of the newly developed composite solder alloys. The results indicate that the Sb nano-particle based intermetallic compounds (IMC) were found uniformly distributed, refined the microstructure and formed IMC particles in the eutectic solder alloy. After the addition of nano Sb particles in Sn–9Zn solder, fine α-Zn phase and ε-Sb₃Zn₄ IMC particles were clearly observed in the β-Sn matrix. The ε-Sb₃Zn₄ IMC particles were uniformly distributed in the β-Sn phase, which resulted in an increase in the tensile strength due to the second phase dispersion strengthening mechanism. However, in the doped Sn–9Zn/1.5Sb alloys, α-Zn phases were broken enormously, depleted and round shaped compared to the normal rod shaped α-Zn phase microstructure in plain Sn–9Zn solder. In comparison, the ε-Sb₃Zn₄ IMC particle in the doped Sn–9Zn/1.0Sb alloy were star shaped. The average tensile strength and micro-hardness of the Sb doped Sn–9Zn solder alloys were consistently higher than the plain un-doped Sn–9Zn solder. The tensile strength and the microhardness increased with increasing Sb nano-particle content, up to 1.0 wt% of Sb content, and then decreased beyond that threshold value. Consequently the percentage (%) elongation of the Sb nanoparticle doped Sn–9Zn solder decreased with increasing Sb nano-particle content, up to 1.0 wt% of Sb content, and then increased beyond that threshold value.     

Preparation and characterization of KGM/CdS nanocomposite film with low infrared emissivity

In this research, novel organic-inorganic nanocomposite films of Konjac glucomannan (KGM) and CdS were prepared by one-step synthesis. As-prepared films were characterized by IR, TEM and SEM. The results indicated that hexagonal CdS nanoparticles with the sizes of 10 to 100 nm were well dispersed in KGM. The infrared emissivities of the films were characterized by IR-1 infrared emissivity instrument. As results showed, the KGM/CdS nanocomposite films had significantly lower infrared emissivity (8-14 μm), meanwhile when the size of KGM nanoparticles was between 10 and 20 nm and the mole ratio of CdS to KGM was 1.2:1, the film got the lowest infrared emissivity value of 0.011, which would be attributed to the strong synergism effect existing between KGM and CdS nanoparticles.     

Fabrication and Wear Performance of (Cu–Sn) Solution/TiC<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Bonded Diamond Composites

The Cu(Sn)–TiC_x bonded diamond composites were prepared by in situ reaction sintering of Cu, Ti₂SnC and diamond powders. Effect of Ti₂SnC content on the phase composition, microstructure and grinding properties were studied. The result shows that Ti₂SnC was decomposed to TiC_x and Sn. And then, Sn atom dissolved into the crystal lattice of Cu and formed Cu(Sn) solution. The rich C formed at the interface between diamond and the matrix. Excess Ti₂SnC inhibited the formation of Cu solid solution and reacted with Cu to form Cu₃Sn. Additionally, its matrix was mainly composed of TiC_x with better wear resistance, which may improve obviously the grinding performance of the composites. The grinding ratio value of copper–diamond composite was only 132. The grinding ratio value of the composite contained higher Ti₂SnC content in the raw materials was 636.     

The anti-oxidation behavior and infrared emissivity property of SiC/ZrSiO4–SiO2 coating

In order to improve the oxidation resistance and decrease the infrared emissivity of carbon/carbon(C/C) composites, the SiC and SiC/ZrSiO₄–SiO₂ (SZS) coating were prepared by pack cementation and slurry painting method. The phase compositions and microstructures of the as-prepared coatings were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer. The anti-oxidation property, failure and infrared emissivity of single SiC coating and SZS coating were investigated. The results show that the weight loss of single SiC coated sample reached 2.1 ± 0.025 % after 58 h isothermal oxidation at 1,500 °C. While the SZS coating exhibits superior oxidation resistance and can protect C/C matrix from oxidation for more than 198 h with a weight-gain of 3.67 ± 0.025 %. The failure mechanisms of single SiC coating are mainly resulting from unself-healing defects caused by the CO₂ gas which generated during the oxidation process of SiC. The investigation of infrared emissivity property reveals that, the infrared emissivity of SZS coating increases gradually from 0.45 to 0.72 between 3 and 14 μm. The infrared emissivity at 500 °C increases gradually from 0.2 to 0.65 between 3 and 14 μm. The coupled effect between dipole moments and lattice vibration in higher temperature becomes weaker, which in turn lead to the reducing of infrared emissivity in turn. From the anti-oxidation and infrared emissivity property point of view, the SZS coating may be one of the most promising candidates for the anti-oxidation at high temperature and low infrared emissivity of C/C composite.     

A three-dimensional electrode for photoelectrochemical cell: TiO2 coated ITO mesoporous film

In this letter, TiO₂ coated ITO mesoporous film was prepared by dipping doctor-blade ITO mesoporous film in TiO₂ sol, followed by sintering at 500 °C for 30 min. The CdS quantum dots (QDs) were deposited on TiO₂ coated ITO mesoporous film using sequential chemical bath deposition (S-CBD) method to form a three-dimensional (3D) electrode. The photo-activity of ITO mesoporous film/TiO₂/CdS electrode was investigated by forming a photoelectrochemical cell, which indicated that the ITO mesoporous film/TiO₂/CdS electrode was efficient in photoelectrochemical cell as a working electrode. The 3D electrode showed lower performance than the conventional electrode of TiO₂ mesoporous film/CdS, and more works are needed to improve the performance of 3D electrode.     

Investigation on indium concentration dependence of solution processed indium tin oxide thin film transistors

The effect of the indium content in indium tin oxide (ITO) films fabricated using a solution-based process and ITO channel thin film transistors (TFTs) was examined as a function of the indium mole ratio. The carrier concentration and resistivity of the ITO films could be controlled by the appropriate treatments. The TFTs showed an increase in the off-current due to the enhanced conductivity of the ITO channel layer with increasing indium mole ratios, producing an increase in the field effect mobility. The characteristics of the a-ITO channel TFT showed the best performance (μ_FE of 3.0 cm² V^− 1 s^− 1, V_th of 2.0 V, and S value of 0.4 V/decade) at In:Sn = 5:1.     

镍-铬复合溶胶的制备及其在高发射率涂层中的应用

首先合成了镍-铬复合溶胶,然后向其中掺杂纳米SiC粉末得到喷涂用涂料,进而在镍基高温合金上制备了NiO-Cr2O3-SiC红外高发射率复合陶瓷涂层.结果表明,该涂层有很高的发射率,与基材结合良好,抗热震性能明显优于Al2O3-SiC陶瓷涂层.     

Adsorption of collagen to indium oxide nanoparticles and infrared emissivity study thereon

Adsorption of collagen to indium oxide nanoparticles was carried out in water–acetone solution at volumetric ratio of 1:1 with pH value varying from 3.2 to 9.3. As indicated by TGA, maximum collagen adsorption to indium oxide nanoparticles occurred at pH of 3.2. It was proposed that noncovalent interactions such as hydrogen bonding, hydrophilic and electrostatic interactions made main contributions to collagen adsorption. The IR emissivity values (8–14 μm) of collagen-adsorbed indium oxide nanoparticles decreased significantly compared to either pure collagen or indium oxide nanoparticles possibly due to the interfacial interactions between collagen and indium oxide nanoparticles. And the lowest infrared emissivity value of 0.587 was obtained at collagen adsorption of 1.94 g/100 g In₂O₃. On the chance of improved compatibility with organic adhesives, the chemical activity of adsorbed collagen was further confirmed by grafting copolymerization with methyl methacrylate by formation of polymer shell outside, as evidenced by IR spectrum and transmission electron microscopy.     

Growth of optically active multilayer metal oxide films on a plastic substrate

An optically active ITO/Au/ITO multilayer coating (where ITO stands for an indium tin oxide with the composition 90% In₂O₃ + 10% SnO₂ and Au is nanoparticulate gold on a thin-film poly(ethylene terephthalate) substrate) has been prepared by a solution-phase process using an ITO nanopowder dispersion in isopropanol and a solution of chloroauric acid, which was converted to colloidal gold by photolysis. A sol–gel process has been proposed for the synthesis of tin-doped indium oxide nanopowder. The properties and composition of the powder were assessed by IR spectroscopy, thermal analysis, electron microscopy, and X-ray diffraction. The phase composition of the ITO nanopowder and the optical properties of the films grown using the nanopowder have been shown to depend on the thermal annealing conditions during synthesis. Layer-by-layer growth of metal oxide films in ITO/Au/ITO coatings influences the absorption in the composite in the IR spectral region.     

Strengthening of basalt fibers with nano-SiO2–epoxy composite coating

Coatings, which were made from pure epoxy and SiO₂ nanoparticle modified epoxy composite, respectively, were applied onto the basalt fiber rovings. The SiO₂ nanoparticles were synthesized using a sol–gel method and modified using coupling agent. Fourier transform infrared spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC) analyses indicated the formation of modified SiO₂ nanoparticles. The SiO₂ nanoparticle–epoxy composite coating gave rise to a significant increase in the tensile strength of the basalt fibers as compared with the pure epoxy coating, and also the coating endowed the basalt fiber with a promising interfacial property in the basalt fiber reinforced resin matrix composite. The coating modification was an effective way in improving the mechanical properties of basalt fibers and the properties of basalt fiber/epoxy resin composites.