Pure Tin Oxide Research Articles

Anodic Tin Oxide Thin Films with Nano-Channeled Structure for Lithium Battery Anode

One-dimensional (1-D) nano-channeled structure has attracted attention as electrode design for the high performance electrochemical devices. This is mainly because its 1-D nano porous structure would allow for the fast ionic transport through it and rapid interfacial reactions. One of the conventional preparation methods of 1-D nano-channeled structure is anodic oxidation. Since the first introduction of anodic aluminum oxide (AAO), different anodic metal oxides with 1-D structure have been reported for the past few decades.Among the various 1-D metallic oxides reported in the literature, tin oxide might be utilized for various applications, such as catalysis, gas sensing, and electrochemical energy storage. In particular, when the nano-channeled tin oxide is used as the anode of the lithium battery, both of the lithia(Li2O) network and nano-channeled structure accommodate the volume change of the tin-lithium phase during the charging/discharging cycles. Although there are some attempts to use the anodic tin oxide thin film as the electrode material for lithium battery, the active material on the substrate was not pure tin oxide but tin - tin oxide bilayer. Since the tin layer underneath anodic tin oxide undergoes a significant reaction-induced volume change, 1-D structure of bilayer collapses during the cycling,In this work, pure anodic tin oxide with well-defined 1-D structure was prepared for the use as the anode for rechargeable lithium battery. Anodic tin oxides with different pore sizes and wall thicknesses were fabricated under various anodizing conditions and their electrochemical properties were characterized by cyclic voltammetry and charge-discharge experiment.In this presentation, cycling stability and rate capability of anodic tin oxides with different porous structures will be presented. Moreover, the feasibility of creating 1-D tin-based anodic oxide composite will be discussed for the further improvement of cycling stability.

Synthesis and room-temperature ferromagnetism of pure and Cu-doped SnO2 nanowires grown by thermal evaporation

We report ferromagnetism in pure and Cu-doped tin oxide (SnO2) nanowires grown on silicon substrate using a thermal evaporation process at atmospheric pressure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images indicated the growth of wire-like nanostructures on silicon substrate with average diameter of 30–110nm and length of 60–100µm. The EDX spectra confirmed the growth of pure and Cu-doped SnO2 nanowires with Cu concentration of 0.25 at%, 0.5 at% and 2 at%. X-ray diffraction study revealed that as-grown nanowires have a tetragonal rutile structure of SnO2, without any secondary phase and were polycrystalline in nature. The room temperature photoluminescence (PL) spectra of as-grown nanowires showed strong emission at 590nm and 600nm originated due to oxygen vacancies and defect-related electronic states in the band gap. The ferromagnetism was observed in the pure and Cu-doped SnO2 nanowires at room temperature as well as at lower temperature of 5K. At room temperature (300K), pure SnO2 nanowires were ferromagnetic with a very small saturation magnetization (Ms) of ~0.06emu/g, a remanent magnetization (Mr) of ~16.67% of Ms, and a coercivity of ~101Oe while the nanowires doped with 0.25 at%, 0.5 at% and 2 at% of Cu were ferromagnetic with a saturation magnetization of ~10.25emu/g, ~11.64emu/g and 15.65emu/g, a remanent magnetization of ~31.70%, ~46.13% and 56.29% of Ms, and a coercivity of ~162Oe, ~181Oe and 273Oe, respectively. The magnetization of as-grown nanowires increases from 0.06emu/g to 15.65emu/g with increase in Cu-dopant concentration from 0 at% to 2 at%. Electron Spin Resonance (ESR) spectra also confirmed the room temperature ferromagnetism in Cu-doped SnO2 nanowires. The origin of room temperature ferromagnetism can be attributed to both surface defects and oxygen vacancies.

Effect of processing and palladium doping on the properties of tin oxide based thick film gas sensors

In the present work, solid-state reaction and sol–gel route derived pure tin oxide (SnO2) powders have been used to develop the palladium (Pd)-doped SnO2 thick film sensors for detection of liquefied petroleum gas (LPG). Efforts have been made to study the gas sensing characteristics i.e., sensor response, response/recovery time and repeatability of the thick film sensors. The response of the sensors has been investigated at different operating temperatures from 200 to 350 °C in order to optimise the operating temperature which yields the maximum response upon exposure to fixed concentration of LPG. The optimum temperature is kept constant to facilitate the gas sensing characteristics as a function of the various concentration (0.25–5 vol%) of LPG. The structural and microstructural properties of Pd-doped SnO2 powder and developed sensors have been studied by performing X-ray diffraction and field emission electron microscopy measurements. The improvement in the response along with better response and recovery time have been correlated to the reduction in crystallite size of SnO2 powder and morphology of printed sensor in thick film form. It is found that the thick film sensor developed by using sol–gel route derived SnO2 powder with an optimum doping of 1 wt% Pd is extremely sensitive (86 %) to LPG at 350 °C.

Fabrication and Characterization of SnO₂/Graphene Composites as High Capacity Anodes for Li-Ion Batteries.

Tin-oxide and graphene (TG) composites were fabricated using the Electrostatic Spray Deposition (ESD) technique, and tested as anode materials for Li-ion batteries. The electrochemical performance of the as-deposited TG composites were compared to heat-treated TG composites along with pure tin-oxide films. The heat-treated composites exhibited superior specific capacity and energy density than both the as-deposited TG composites and tin oxide samples. At the 70th cycle, the specific capacities of the as-deposited and post heat-treated samples were 534 and 737 mA·h/g, respectively, and the corresponding energy densities of the as-deposited and heat-treated composites were 1240 and 1760 W·h/kg, respectively. This improvement in the electrochemical performance of the TG composite anodes as compared to the pure tin oxide samples is attributed to the synergy between tin oxide and graphene, which increases the electrical conductivity of tin oxide and helps alleviate volumetric changes in tin-oxide during cycling.

Dependence of Si/SnO2 Heterojunction Properties on Growth Temperature and Type of Silicon**

AbstractPolycrystalline pure tin oxide thin films of tetragonal rutile structures are deposited on two kinds of single‐crystal and polycrystalline p‐type Si at three substrate temperatures of 300, 400, and 500 °C. Structural, electrical, and optical properties of these thin films are characterized by X‐ray diffraction (XRD), two‐point probe method, and UV‐vis spectrophotometry, respectively. I–V measurements of these heterojunctions show that the barrier height and series resistance will increase with increasing substrate temperature in single‐crystal Si, while in polycrystalline Si, they will decrease. These heterojunctions are found to be rectifying with a maximum forward‐to‐reverse current ratio of about 1000 in the applied voltage range −4 V to +4 V for single‐crystal Si/SnO2.

Fast response time alcohol gas sensor using nanocrystalline F-doped SnO2 films derived via sol–gel method

Pure and fluorine-modified tin oxide (SnO2) thin films (250–300 nm) were uniformly deposited on corning glass substrate using sol–gel technique to fabricate SnO2-based resistive sensors for ethanol detection. The characteristic properties of the multicoatings have been investigated, including their electrical conductivity and optical transparency in visible IR range. Pure SnO2 films exhibited a visible transmission of 90% compared with F-doped films (80% for low doping and 60% for high doping). F-doped SnO2 films exhibited lower resistivity (0· 12 × 10 − 4 Ω cm) compared with the pure (14·16 × 10 − 4 Ω cm) one. X-ray diffraction and scanning electron microscopy techniques were used to analyse the structure and surface morphology of the prepared films. Resistance change was studied at different temperatures (523–623 K) with metallic contacts of silver in air and in presence of different ethanol vapour concentrations. Comparative gas-sensing results revealed that the prepared F-doped SnO2 sensor exhibited the lowest response and recovery times of 10 and 13 s, respectively whereas that of pure SnO2 gas sensor, 32 and 65 s, respectively. The maximum sensitivities of both gas sensors were obtained at 623 K.

Deposition and Characterization of Chromium Doped Tin Oxide Transparent Conducting Thin Films Prepared by Spray Pyrolysis Technique

Emergenceof innovative technological deposition technique of spray pyrolysis enabled the enhancement of structural, optical, and electrical properties of Sn1-xCrxO2 (x=0.0, 0.02, 0.04, 0.06, 0.10, 0.15) transparent semiconductors thin films in the present study. To evaluate these properties, X-Ray diffraction (XRD) spectroscopy were usedto study the elemental component and the crystalline nature of the materials while the optical properties and structure of the samples were evaluated using UV—vis spectroscopy and field emission scanning electron microscopy (FE-SEM).Finding showed that the Cr-doped SnO2 films were tetragonal in shape. Transmission spectra of the deposited films showed high transparency of ~ 70-90% in visible region with optical edge of 3.7eVfor SnO2. Resistivity of pure tin oxide samples was 0.01 Ω-Cm and increases with increase in dopant level. The Hall voltage showed that the type of semiconductor changed with increasing of dopant.

Kinetics, isotherm and thermodynamics for uranium and thorium ions adsorption from aqueous solutions by crystalline tin oxide nanoparticles

This study focused mainly on the synthesis of nano tin oxide as an adsorbent via homogeneous precipitation using urea as a reagent to control the pH and to obtain a pure and dense hydrous tin oxide precipitate. XRD and BET surface area showed that prepared tin oxide was crystallized in cassiterite phase and had a BET surface area of 27.5m2/g. The synthesized adsorbent was then used for the removal of uranium (VI) and thorium from aqueous solution and factors such as adsorption kinetics, isotherm models and the influence of initial pH of the solution on the adsorption were investigated in a batch system. The kinetic data corresponds well to the pseudo second order equation. In order to specify the type of adsorption reaction, thermodynamic parameters such as the standard enthalpy, entropy, and Gibbs free energy were also determined. ΔH° and ΔS° values for thorium and uranium sorption were calculated from the slope and intercept of plots of lnKd versus 1/T. The evaluated ΔG° and ΔH° indicate the spontaneous and endothermic nature of the reactions. The adsorption data for uranium (VI) were well fitted by the Freundlich isotherm.

Structural, electrical and optical properties of transparent conducting SnO2 films: effect of the oxygen flow rate

Pure tin oxide films were deposited onto glass substrate at different oxygen flow rates by a simple and inexpensive method of air pressure chemical vapor deposition. The deposition temperature was kept constant at about 500 °C, and oxygen with a flow rate of 0–400 sccm was used as both a carrier gas and the oxidizing agent. Investigation of the electrical parameters variations showed that these parameters vary with oxygen flow rate, reaching an optimum value at the flow rate of 100 sccm. X-ray diffraction (XRD) also revealed the structure to be polycrystalline for all films deposited at different oxygen flow rates. In agreement with the XRD results, field emission scanning electron microscopy micrographs showed a reduction in grain size corresponding to increasing flow rates until 200 sccm, and after that, with a further increase of flow rate, the grain size increased.

Indium oxide, tin oxide and indium tin oxide nanostructure growth by vapor deposition

Indium oxide, tin oxide and indium tin oxide nanowires have been grown by vapor deposition on Si and quartz substrates. Under the growth conditions used, pure SiOx nanowires, a mixture of SiOx and indium oxide, tin oxide or indium tin oxide nanostructures, or pure indium oxide, tin oxide or indium tin oxide nanostructures could be obtained at different substrate temperatures. The growth mechanism of the obtained nanostructures at different substrate temperatures is discussed. Optical and electrical properties of the deposited pure indium oxide, tin oxide or indium tin oxide nanostructures have been measured, and low sheet resistances on quartz substrates have been obtained for indium oxide and indium tin oxide nanostructures.

Analysis of optical and related properties of tin oxide thin films determined by Drude-Lorentz model

In this paper, optical parameters, such as refractive index n and extinction coefficient κ, of tin oxide thin films determined by fitting the measured and simulated optical reflectance spectra, are presented and analysed. Among the various classical dispersion relations for the dielectric function, we use the Drude model combined with the Lorentzian oscillators to get a good fit of R in the measured spectral range. Results on related parameters such as high frequency dielectric constant, plasma frequency, relaxation lifetime, electron density, film thickness and band gap are discussed. Pure tin oxide films deposited at different temperature exhibit the same reflectance behaviour in the entire range while antimony doped films exhibit a deep minimum of reflectance in the visible domain and a maximum in the infrared domain. The results show also that the refractive index and extinction coefficient of antimony-doped SnO2 films increase with the increase of the Sb/Sn ratios. The dispersion of κ of doped films is higher than that the undoped ones in a wide photon energy spectral range while the dispersion of n exhibit an opposite behaviour. The high frequency dielectric constant ε∞ decreased with increasing percentages of Sb in SnO2 and the optical band gap Eg depend on the doping amount. The deposited films present a great reflection in the NIR wavelength region which may originate from the fact that these layers contain many carriers resulting in a large nonstochiometry in the chemical composition. The optically determined film thickness agrees with that obtained by ellipsometry.

Preparation and characterization of nanocomposites in system as: SnO2–xTiO2 (where x = 25, 50 and 75 mol%)

Nanocomposite samples containing various molar compositions of tin and titanium oxides were synthesized by a sol–gel method using octadecylamine as controlling template agent. The structural and the crystalline features of the samples were investigated with Fourier Transformer Infra-red, X-ray diffraction, Transmission electron microscope (TEM) where the surface area was estimated by BET analysis. The crystalline parameters and the particle size were estimated by Rietveld quantitative phase analysis. It is interesting to mention that a reduction in the lattice parameters was detected upon introduction of various molar compositions of titanium oxide revealing that a part of titania is incorporated into the SnO2 lattice forming Ti1−xSnxO2 solid solution. The quantitative analysis claims that part of titanium oxide is incorporated substitutionally in the crystal lattice of SnO2, forming a solid solution and other parts are either segregated as separate rutile titania phase or dispersed as amorphous phase on the grain boundary of SnO2. The results show a remarkable reduction in particle size from 42 to 5 nm and increasing in the specific surface area up to 176 m2/g upon introduction of various content of titania implying the role of titania particles in preventing SnO2 crystallites from further growing up during the progress of calcination. TEM images show that pure tin oxide particles arranged in large aggregation in wormhole like structure, while the existence of titanium oxide are successfully creates spherical nanoparticles system organized in a definite structure. The optical absorbance spectra indicate a red shift and band gap narrowing upon introduction of titania which increase with increasing in titania contents.

Tin–copper mixed metal oxide nanowires: Synthesis and sensor response to chemical vapors

Tin–copper mixed metal oxide nanowires were successfully prepared by thermally oxidizing electrodeposited metallic nanowires (Sn–8 at.% Cu, Sn–43 at.% Cu and Sn–86 at.% Cu). The structure and composition of these nanowires before and after thermal oxidation were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). Dielectrophoresis was utilized to align the nanowires in contact with pre-fabricated interdigitated electrodes to form a chemiresistive gas sensor circuit. The sensitivity variation of the nanowires with different compositions was tested with acetone, ethanol and ethyl acetate vapors at different concentration levels, and the temperature effect was studied at five operating temperatures, ranging from 200 °C to 440 °C. All the three mixed metal oxide nanowire sensors exhibited higher sensitivity than that of pure tin oxide nanowire sensor. The sensor performance was also investigated in terms of response/recovery time and repeatability. An interesting positive/negative response was observed by varying the element composition of the mixed oxide nanowires.

Porous SnO2/CNT composite anodes: Influence of composition and deposition temperature on the electrochemical performance

Porous SnO2/multiwalled carbon nanotube (CNT) thin film composites as anode material for Li-ion batteries were prepared using the electrostatic spray deposition (ESD) technique. The morphologies of the samples were found to be affected mainly by deposition temperatures. Electrochemical test cells were assembled using the as-prepared samples without any conductive additive or binder. The influence of deposition temperature and CNT content on the electrochemical performance of the anodes was investigated. Compared to pure tin oxide and pure CNT, the composite anode materials showed better discharge capacity and cyclability. Among the composites, the sample deposited at 250 °C with 30 wt% CNT content was found to show better energy capacity. This can be ascribed to the porous nature of the anodes and the improvement in the conductivity by the addition of CNTs.

Gas sensors based on multiwall carbon nanotubes decorated with tin oxide nanoclusters

Abstract Hybrid nanomaterials based on oxygen plasma treated multiwall carbon nanotubes decorated with tin oxide nanoclusters were synthesised by the precipitation of a SnO 2 colloidal suspension in the presence of carbon nanotubes dispersed in the mother solution of precursor tin (II) acetate in a water free acetic acid. TEM analysis revealed that the size of tin oxide nanoclusters anchored at the carbon nanotube sidewalls is about 5 nm. Hybrid nanomaterials with different carbon nanotube to tin oxide ratios were prepared and their gas sensing properties when operated at room temperature and at 150 °C were investigated and compared against the properties of pure tin oxide or pure oxygen plasma treated multiwall carbon nanotube sensors. When an appropriate ratio between the amount of plasma treated nanotubes and tin oxide precursors is employed, hybrid sensors show superior performance in the detection of nitrogen dioxide in the ppb range and carbon monoxide in the low ppm range. Furthermore, these optimised sensors show a significantly reduced moisture cross-sensitivity. Detection mechanisms are discussed.

Synthesis of vanadium-doped tin oxide nanocrystallites for CO gas sensing

Vanadium-doped tin oxide nanoparticles have been synthesized by a hydrolysis and co-precipitation method from vanadium(III) acetylacetonate and tin tetrachloride. Addition of vanadium species into the tin oxide matrix resulted in a decrease in the grain size, as indicated by X-ray diffraction (XRD) and electron microscopy. X-ray photoelectron spectroscopy (XPS) revealed an interaction between tin and vanadium atoms in the mixed oxide structure and the presence of oxygen vacancies and vanadium cations with multiple oxidation states in the surface region. The binary solid solution exhibited a higher sensitivity to CO gas than pure tin oxide, after both were evaluated in a semiconductor gas sensor. Results demonstrate the feasibility of vanadium dopant for use to enhance sensor response.

Evolution of Thermophysical Characteristics in Tin Oxide: From Pressed Powder Compact to Fired Porous Body

The thermal response of a ceramic body during firing will be controlled by its thermophysical characteristics. Laser flash measurements have been used to investigate the thermal conductivity of pressed powder compacts of pure tin oxide as a function of temperature. After an initial decrease up to 150°C attributed to removal of surface species, the thermal conductivity increases progressively with thermal treatment up to 1000°C. Because there is almost no variation in the pore volume fraction, the behavior is explained by grain boundary formation and neck growth, which increase the contact area between particles. Supporting evidence is given by an increase in mechanical strength. Finally, thermal treatment above 1000°C increases the thermal conductivity due to a reduction in the number of grain boundaries per unit length of heat path.

The Optical and Electrical Properties of Antimony-Doped Tin Oxide Transparent Conducting Thin Films Prepared by Sol-Gel Dip-Coating Technique

Antimony-doped tin oxide (ATO) transparent conducting thin films were prepared by sol-gel dip-coating technique in the alcohol solution of metal salts of tin (II) chloride dehydrate and antimony tri-chloride. Usual glass slides (25×76×1mm3) were used as the substrates. As-prepared thin films were dried at temperature of 343K and annealed at temperatures of 673~823K. Their optical properties were analyzed by Hitachi U-3310 spectrophotometer. The good optical transmission of the ATO thin films has been obtained as high as 80%-90% in visible region by the optimization of deposition conditions, but decreased substantially in IR region. From the X-ray diffraction (XRD) measurements, it showed that ATO films had the similar structures with the pure tin oxide films, i.e. tetragonal rutile structure, despite of some rhombic SnO crystals. We analyzed the transmittance in the visible region depending on the vary Sb doped level, temperature, and dip-coating times. The sheet resistance of the investigated thin films was determined by four-probe method, showing that it was about 85-1009/□, which decreased with the increase of antimony doped concentration.

Electrical Properties of Electrospun Sb-Doped Tin Oxide Nanofibers

Transparent and conducting tin oxide fibers are of considerable interest for solar energy conversion, sensors and in various electrode applications. Appropriate doping can further enhance the conductivity of the fibers without loosing optical transparency. Undoped and antimony-doped tin oxide fibers have been synthesized by our group in previous work using electrospinning and metallorganic decomposition techniques. The undoped tin oxide fibers were obtained using a mixture of pure tin oxide sol made from tin (IV) chloride : water : propanol : isopropanol at a molar ratio of 1:9:9:6, and a viscous solution made from poly(ethylene oxide) (PEO) and chloroform at a ratio of 200 mg PEO/10 mL chloroform. In this work, antimony doped fibers were obtained by adding a dopant solution of antimony trichloride and isopropanol at a ratio of 2.2812 g antimony trichloride/10 ml isopropanol to the original tin oxide precursor solution. The Sb concentration in the precursor solution is 1.5%. After deposition, the fibers were sintered 600°C in air for two hours. The electrical conductivity of single fibers measured at room temperature increases by up to three orders of magnitude when compared to undoped fibers prepared using the same method. The resistivity change as a function of the annealing temperature can be attributed to the thermally activated formation of a nearly stoichoimetric solid. The resistivity of the fibers changes monotonically with temperature from 714Ω-cm at 2 K to 0.1Ω-cm at 300 K. In the temperature range from 2 to 8 K the fibers have a positive magnetoresistance (MR) with the highest value of 155 % at 2 K and ±9 T. At temperatures of 10 and 12 K the sign of MR changes to negative values for low magnetic fields and positive for high magnetic fields. For higher temperatures (15 K and above) the MR becomes negative and its magnitude decreases with temperature.

Surface morphologies and properties of pure and antimony-doped tin oxide films derived by sol–gel dip-coating processing

A simple laboratory technique for the routine preparation of antimony-doped tin oxide (ATO) on float glass substrates (25 mm × 76 mm × 1 mm) was described. As-prepared thin films were dried at temperature of 100 ± 5 °C and annealed at temperatures of 400–550 °C. Microstructural and morphological analyses of as-prepared films were performed at different conditions. The evolution of grain size and the morphologies of ATO films were analyzed by means of atom force microscopy (AFM) and digital microscope. The studies suggested that higher Sb-doped level and higher annealing temperature led to a decrease in the surface roughness of the deposited films. The XRD patterns revealed that as-prepared ATO films were in the crystallization of a tetragonal rutile structure of SnO 2 with highly (1 1 0) preferred orientation. Their optical properties were analyzed by U-3310 spectrophotometer. The transmission of the ATO thin films was obtained as high as 80–90% in visible region, but decreased substantially in IR region. The sheet resistance of the investigated thin films was determined by four-probe method, showing that it was about 85–100 Ω □ −1which decreased with the increase of antimony-doped concentration.