Low Tin Research Articles

Fabrication and characterization of Er+3 doped SiO2/SnO2 glass-ceramic thin films for planar waveguide applications

Glass-ceramics are a kind of two-phase materials constituted by nanocrystals embedded in a glass matrix and the respective volume fractions of crystalline and amorphous phase determine the properties of the glass-ceramics. Among these properties transparency is crucial in particular when confined structures, such as, dielectric optical waveguides, are considered. Moreover, the segregation of dopant rare-earth ions, like erbium, in low phonon energy crystalline medium makes these structures more promising in the development of waveguide amplifiers. Here we are proposing a new class of low phonon energy tin oxide semiconductor medium doped silicate based planar waveguides. Er3+ doped (100-x) SiO2-xSnO2 (x= 10, 20, 25 and 30mol%), glass-ceramic planar waveguide thin films were fabricated by a simple sol-gel processing and dip coating technique. XRD and HRTEM studies indicates the glass-ceramic phase of the film and the dispersion of ~4nm diameter of tin oxide nanocrystals in the amorphous phase of silica. The spectroscopic assessment indicates the distribution of the dopant erbium ions in the crystalline medium of tin oxide. The observed low losses, 0.5±0.2 dB/cm, at 1.54 μm communication wavelength makes them a quite promising material for the development of high gain integrated optical amplifiers.

A study into the impact of interface roughness development on mechanical degradation of oxides formed on zirconium alloys

As a cladding material used to encapsulate nuclear fuel pellets, zirconium alloys are the primary barrier separating the fuel and a pressurised steam or lithiated water environment. Degradation mechanisms such as oxidation can be the limiting factor in the life-time of the fuel assembly. Key to controlling oxidation, and therefore allowing increased burn-up of fuel, is the development of a mechanistic understanding of the corrosion process. In an autoclave, the oxidation kinetics for zirconium alloys are typically cyclical, with periods of accelerated kinetics being observed in steps of ∼2μm oxide growth. These periods of accelerated oxidation are immediately preceded by the development of a layer of lateral cracks near the metal-oxide interface, which may be associated with the development of interface roughness. The present work uses scanning electron microscopy to carry out a statistical analysis of changes in the metal-oxide interface roughness between three different alloys at different stages of autoclave oxidation. The first two alloys are Zircaloy-4 and ZIRLO™ for which analysis is carried out at stages before, during and after first transition. The third alloy is an experimental low tin alloy, which under the same oxidation conditions and during the same time period does not appear to go through transition. Assessment of the metal-oxide interface roughness is primarily carried out based on the root mean square of the interface slope known as the Rdq parameter. Results show clear trends with relation to transition points in the corrosion kinetics. Discussion is given to how this relates to the existing mechanistic understanding of the corrosion process, and the components required for possible future modelling approaches.

Sound velocity and phase transition for low porosity tin at high pressure

Shock and release experiments are performed on the porous Sn with sub-micropores with porosity m=1.01. Time-resolved interfacial velocities between the porous Sn and LiF window are measured with Doppler pins system under seven pressure points from 31.8 GPa to 66.1 GPa. From the interfacial velocity, the Euler longitudinal sound velocities and the bulk sound velocities are obtained. The corresponding Poisson ratio and shear modulus are determined, too. From the transition of longitudinal sound velocity to bulk sound velocity at high pressures, the shock-induced melting of Sn with porosity 1.01 occurs at about 49.1 GPa. With the Euler longitudinal sound velocities, the bulk sound velocities and the shear moduluses of porous and dense Sn, the melting pressure zone of dense Sn can be determined to be between 53.5 GPa and 62.3 GPa. Comparing the melting zone of porous Sn and that of dense Sn, micropores in the material reduce the the shock melting pressure obviously. The Exact shock melting pressure of dense Sn needs further experimental data in the corresponding pressure zone. From the longitudinal velocity of porous Sn in the measured solid zone, no bcc phase transition takes place for this material. This may relate with the micropores in the material or the difference in material component, which needs further investigating.

The Study of a New Type of Cast Iron Material Used in the Glass Mould

Develop a new type of alloy cast iron material.Design experimental scheme and research method, choose low tin vermicular cast iron as raw materials, to determine the main alloying element and trace alloying elements, formulate the necessary particularizing alloy. On the basis of strict technology and process, to complete the cast iron smelting, produce vermicular cast iron that has a good comprehensive performance. To observe the metallographic structure of cast iron under a microscope. Finally，test the stretchability of the developed vermicular cast

Deposition of low sheet resistance indium tin oxide directly onto functional small molecules

We outline a methodology for depositing tin-doped indium oxide (ITO) directly onto semiconducting organic small molecule films for use as a transparent conducting oxide top-electrode. ITO films were grown using pulsed laser deposition onto copper(II)phthalocyanine (CuPc):buckminsterfullerene (C60) coated substrates. The ITO was deposited at a substrate temperature of 150°C over a wide range of background oxygen pressures (Pd) (0.67–10Pa). Deposition at 0.67≤Pd≤4.7Pa led to delamination of the organic films owing to damage induced by the high energy ablated particles, at intermediate 4.7≤Pd<6.7Pa pressures macroscopic cracking is observed in the ITO. Increasing Pd further, ≥6.7Pa, supports the deposition of continuous, polycrystalline and highly transparent ITO films without damage to the CuPc:C60. The free carrier concentration of ITO is strongly influenced by Pd; hence growth at >6.7Pa induces a significant decrease in conductivity; with a minimum sheet resistance (Rs) of 145Ω/□ achieved for 300nm thick ITO films. To reduce the Rs a multi-pressure deposition was implemented, resulting in the formation of polycrystalline, highly transparent ITO with an Rs of ~20Ω/□ whilst maintaining the inherent functionality and integrity of the small molecule substrate.

Iron redistribution in a zirconium alloy after neutron and proton irradiation studied by energy-dispersive X-ray spectroscopy (EDX) using an aberration-corrected (scanning) transmission electron microscope

Zirconium alloys used as cladding materials in nuclear reactors can exhibit accelerated irradiation induced growth, often termed linear growth, after sustained neutron irradiation. This phenomenon has been linked to the formation of <c>-component dislocation loops and to the concentration of interstitial solute atoms. It is well documented for the Zircaloys that Fe dissolves from second phase particles (SPPs) during irradiation thus increasing the interstitial solute concentration in the matrix. However, no progress has yet been made into understanding whether a similar process occurs for the newer ZIRLO™ alloys. We aim to overcome this shortcoming here by studying compositional changes in second phase particles in Low Tin ZIRLO™ after neutron and proton irradiation using energy dispersive X-ray (EDX) spectroscopy. Material irradiated to 18dpa (displacements per atom) using neutrons and to 2.3 and 7dpa by protons was investigated. The results show that Fe is lost from Zr–Nb–Fe-SPPs during both neutron and proton irradiation. Prior to irradiation, Fe was detected at the interface of β-Nb-SPPs. This Fe enrichment is also dispersed during irradiation. Qualitatively, excellent agreement was found regarding the elemental redistribution processes observed after proton and neutron irradiation.

ChemInform Abstract: Low Coordinate Germanium(II) and Tin(II) Hydride Complexes: Efficient Catalysts for the Hydroboration of Carbonyl Compounds.

AbstractThe first examples for utilization of well‐defined, low‐valent p‐block metal hydrides, e.g. (I), in organic catalysis are presented.

Dehydroaromatization of methane over doped Pt/Mo/H-ZSM-5 zeolite catalysts: The promotional effect of tin

The effect of tin (0.05–s0.2wt.%) on the dehydroaromatization of methane over Pt/Mo/H-ZSM-5 zeolite catalysts was investigated. The 2Mo/H-ZSM-5, 0.5Pt/2Mo/H-ZSM-5 and Sn-modified 0.5Pt/2Mo/H-ZSM-5 zeolite catalysts were prepared by an incipient wetness co-impregnation method and characterized by BET, XRD, H2-TPR, NH3-TPD and TGA-DTG analysis. The addition of platinum increased methane conversion from 4 to 7% and the aromatics selectivity was 65%. A reduction of about 50% in the total amount of carbonaceous deposit occurred when platinum was added to the 2Mo/H-ZSM-5 catalyst. A decrease in methane conversion was observed (from 7.2 to 4.3%) with an increase in the tin loading (from 0.05 to 0.2wt.%). Although the addition of tin decreased the methane conversion, the selectivity towards aromatics increased (64–83%) and a selectivity to benzene above 55% was achieved at 0.1wt.% tin loading. The coke selectivity was reduced from 30 to 15% at low tin loadings (0.05wt.%).

Thermocapillary Convection of Low Prandtl Number Fluids under Uniform Magnetic Fields

Numerical simulations on thermocapillary convection of low Pr number molten tin under uniform magnetic field have been conducted under microgravity. The Navier-Stokes equations coupled with the energy conservation equation are solved on a staggered grid, and the free surface is captured by using the level set method. The present results show that the transverse uniform magnetic field can restrain the thermocapillary convection, and the fluid velocity at the hot corner fluctuates with a constant frequency at the steady state.

Characterization of the patina formed on a low tin bronze exposed to aqueous hydrogen sulfide

The dark gray corrosion layer (patina) formed on the surface of a polished low tin bronze alloy following exposure to a deoxygenated and saturated aqueous solutions of H2S has been characterized by X‐ray photoelectron spectroscopy, scanning electron microscopy‐energy dispersive spectroscopy and X‐ray diffraction. The system represents a model for bronze corrosion in reducing conditions where sulfate‐reducing bacteria in soils or deoxygenated seawater may generate H2S during respiration. The initial surface was dominated by metallic copper together with Sn, Pb and Zn oxides and hydroxides. Surface enrichment of Pb and Zn was noted because of a smearing effect during polishing. At least some of the lead was crystalline. In contrast, the corrosion layer formed by H2S(aq) exposure was dominated by polycrystalline Cu2S (low and high chalcocite) and smaller concentrations of CuSO4 · nH2O. This surface was enriched with Zn as Zn(OH)2. Lead was present as redeposited PbS (galena) crystallites in at least two different morphologies. Unlike bronzes exposed to oxidizing conditions, which develop protective SnO2 layers, the H2S(aq)‐exposed surface was considerably depleted in Sn. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Effect of Novel Substrates on Zinc Anode - Secondary Alkaline Battery Performance

Zinc electrodeposition in alkaline battery has important effect on the performance of the battery and the substrate metal has a strong effect on the performance of zinc anodes, especially at the earliest stages. Rotating disk electrodes were fabricated using 99.9%+ pure metal rods to investigate the performance of zinc deposition on silver, bismuth, copper, iron, nickel and tin substrates. The amount of charge passed in all the experiments was 5 C/cm2. Iron and nickel do not have desirable performance, due to hydrogen evolution. The hydrogen evolution on iron is rapid and soon covers the entire surface of the electrode. Bismuth and tin have desirable performance. The coulombic efficiency on each of these substrates is well in excess of 90% when deposited at -20 mA/cm2. Due to their relatively low cost, tin and bismuth are seen as promising choices of substrate metals in zinc anodes.The morphology of zinc deposition and crystal orientation on copper, nickel and tin substrates was investigated. Zinc deposition is more compact on Sn than on Ni and Cu for the same amount of charge passed. Additionally, Ni and Cu have a propensity to evolve mossy zinc much more easily.The extent of preferred orientation decreases with zinc deposition, and mossy zinc is depositied with almost no texture. Compact zinc has preferred orientation, strongest on Sn.Zinc-based rechargeable batteries are attractive electrical energy storage systems due to their low cost, high energy density and low toxicity. However, zinc redistribution on periodic cycling and dendrite formation is known to severely limit battery life. Short cycle life due to internal short circuits have prevented wide spread secondary storage applications.Zinc electrodeposition in alkaline battery has important effect on the performance of the battery and the substrate metal has a strong effect on the performance of zinc anodes, especially at the earliest stages. Rotating disk electrodes were fabricated using 99.9%+ pure metal rods to investigate the performance of zinc deposition on silver, bismuth, copper, iron, nickel and tin substrates. The amount of charge passed in all the experiments was 5 C/cm2. Iron and nickel do not have desirable performance, due to hydrogen evolution. The hydrogen evolution on iron is rapid and soon covers the entire surface of the electrode. Bismuth and tin have desirable performance. The coulombic efficiency on each of these substrates is well in excess of 90% when deposited at -20 mA/cm2. Due to their relatively low cost, tin and bismuth are seen as promising choices of substrate metals in zinc anodes.The morphology of zinc deposition and crystal orientation on copper, nickel and tin substrates was investigated. Zinc deposition is more compact on Sn than on Ni and Cu for the same amount of charge passed. Additionally, Ni and Cu have a propensity to evolve mossy zinc much more easily.The extent of preferred orientation decreases with zinc deposition, and mossy zinc is depositied with almost no texture. Compact zinc has preferred orientation, strongest on Sn.

Optimization of Sputtering Parameters for the Deposition of Low Resistivity Indium Tin Oxide Thin Films

Indium tin oxide (ITO) thin films have been deposited using RF sputtering technique at different pressures, RF powers, and substrate temperatures. Variations in surface morphology, optical properties, and film resistances were measured and analyzed. It is shown that a very low value of sheet resistance (1.96 Ω/sq.) can be achieved with suitable arrangement of the deposition experiments. First, at constant RF power, deposition at different pressure values is done, and the condition for achieving minimum sheet resistance (26.43 Ω/sq.) is found. In the next step, different values of RF powers are tried, while keeping the pressure fixed on the previously found minimum point (1–2 Pa). Finally, the minimum resistivity is obtained by sweeping the substrate temperatures, while keeping RF power and the working pressure at their optimum values. Furthermore, the effects of process parameters on properties, such as the surface morphology and the optical transmission, are discussed. Although the point of minimum resistivity does not coincide with that of the maximum transparency of ITO film, relatively acceptable values of transmittance (approximately 75% on a glass substrate with intrinsic transparency of 89%) can be obtained.

Low resistance indium tin oxide contact to n-GaAs nanowires

Indium tin oxide (ITO) was deposited by RF sputtering on n-GaAs nanowires grown by the Au-assisted vapor–liquid–solid process in a molecular beam epitaxy (MBE) system. The ITO formed an Ohmic contact with n-doped (n = 8 × 1018 cm−3) GaAs nanowires with a specific contact resistance of <1.41 Ω cm2. Insertion of a 25 nm thick indium layer between 500 nm thick ITO and the GaAs nanowires resulted in a reduction of specific contact resistance to <0.13 Ω cm2 after annealing at 400 °C for 30 s. The In/ITO film had an average transmittance of 89% from 400 to 900 nm and a sheet resistance of 13 Ω/□, which is well suited for nanowire-based optoelectronic applications.

Complementary use of X-ray methods to study ancient production remains and metals from Northern Portugal

Archaeological artefacts recovered at Castanheiro do Vento (Northern Portugal) were characterised by integrating macro and micro-energy dispersive X-ray fluorescence spectrometry (EDXRF) and scanning electron microscopy with X-ray microanalysis. The collection includes metallurgical remains (ceramic crucibles, a metallic nodule and a vitrified fragment) and metals (tools and ornaments) whose chronology spans from the Chalcolithic to the Roman Age. The study of production remains was able to identify distinct copper-based metallurgical operations including the smelting of copper ores, the melting of copper and tin and/or the melting of bronze scrap. Micro-EDXRF identified copper and arsenical copper tools as well as bronze and leaded bronze ornaments. The composition of tools (Cu with varying As contents: 0.46–3.6%) reveals an incipient technology, typical of the Chalcolithic till the Middle Bronze Age. On the contrary, ornaments are composed by different alloys – low tin bronze (4.8% Sn), high tin bronze (14.9% Sn) and high tin-leaded bronze (16.5% Sn and 2.4% Pb) − evidencing technological and economic choices that clearly indicate a late period such as the Roman Age. In conclusion, this multiproxy approach was able to study those ancient artefacts with a minimum impact on their archaeological and museological significance while providing important answers to the interpretation of the archaeological settlement and to better understand the metallurgical evolution in the Portuguese territory. Copyright © 2014 John Wiley & Sons, Ltd.

ChemInform Abstract: A Practical Procedure of Low Valent Tin Mediated Barbier Allylation of Aldehydes in Wet Solvent.

Abstract Use of aluminium as the reducing metal in spontaneous bimetal redox reaction has been elegantly exploited for allylation/crotylation of aldehydes in wet solvent. Here, low valent tin was prepared in situ by reduction of SnCl 2 ·2H 2 O with aluminium in THF/water. The resulting low valent tin acted as an efficient mediator for allylation and crotylation of aldehydes ( 3a – q ) producing the corresponding homoallylic alcohols. The efficacy of this procedure was due to its operational simplicity, practical viability, inexpensiveness, good yields of the products and short reaction time.

Crystallization kinetics in a lithium alumosilicate glass using SnO2 and ZrO2 additives

The crystallization sequence, volume fractions and crystal sizes of nucleating agents, high-quartz (HQ-ss) and keatite (K-ss) solid solutions in a lithium alumosilicate glass with additions of SnO2 and ZrO2 were studied using high-temperature X-ray diffraction, differential thermal analysis and optical dilatometry. At low tin oxide fractions primary crystals were tetragonal zirconia solid solution, while at higher tin oxide fractions orthorhombic stannic srilankite solid solutions were detected. For continuously heated glasses we found that the substitution of zirconium by tin shifts in agreement with DTA and shrinkage curves the crystallization of HQ-ss and K-ss towards lower temperatures while only a minor effect on the glass transition temperature was evident. Isothermal annealing showed that the increase in the tin oxide fraction of the parent glass increases mainly the nucleation rate of HQ-ss (up to one order of magnitude) while the increase in the crystal growth rate is less pronounced. Dwelling of mixed ZrO2/SnO2-bearing glasses at the temperature of maximum nucleation results in fine-grained glass-ceramics (crystal size=50nm) of crystal number densities up to 1013mm−3.

Low Coordinate Germanium(II) and Tin(II) Hydride Complexes: Efficient Catalysts for the Hydroboration of Carbonyl Compounds

This study details the first use of well-defined low-valent p-block metal hydrides as catalysts in organic synthesis. That is, the bulky, two-coordinate germanium(II) and tin(II) hydride complexes, L(†)(H)M: (M = Ge or Sn, L(†) = -N(Ar(†))(SiPr(i)3), Ar(†) = C6H2{C(H)Ph2}2Pr(i)-2,6,4), are shown to act as efficient catalysts for the hydroboration (with HBpin, pin = pinacolato) of a variety of unactivated, and sometimes very bulky, carbonyl compounds. Catalyst loadings as low as 0.05 mol % are required to achieve quantitative conversions, with turnover frequencies in excess of 13 300 h(-1) in some cases. This activity rivals that of currently available catalysts used for such reactions.

Thin film characterization of zinc tin oxide deposited by thermal atomic layer deposition

Zinc tin oxide (ZTO) thin films are of interest for many applications, including transparent conducting oxides and buffer layers in thin film solar cells. In this work, the ability of atomic layer deposition (ALD) to control both thickness and composition of the ternary material is explored and the resulting film properties are characterized. ZTO was deposited at 150°C by alternating growth of tin oxide (SnOx) and zinc oxide (ZnO) using tetrakis(dimethylamido)tin and diethyl zinc as metal precursors and water as the oxygen source. The growth behavior of ZTO was systematically examined as a function of the relative fraction of SnOx to ZnO ALD cycles and their bilayer period. Variable angle spectroscopic ellipsometry (VASE) showed that the ZTO growth rate was strongly reduced as compared to the growth rates of the binaries, especially at low bilayer periods and low tin cycle fractions. Inductively-coupled plasma optical emission spectroscopy showed that the composition, together with other properties of ZTO films, was not simply proportional to the binary ALD cycle fractions utilized in the deposition. Structurally, the deposited films were shown by X-ray diffraction to be amorphous for tin content exceeding 10%, for which only smooth features were observed by scanning electron microscopy. Optically, VASE revealed a minimum refractive index in the visible range for intermediate compositions and a maximum for the pure SnOx phase. Conversely, the ZTO bandgap was maximized for intermediate metal compositions near ~50%, and converged to the direct ZnO bandgap of 3.3eV for compositions with decreasing amounts of Sn in the films. Linear extrapolations gave a range of 2.9 to 4.0eV for SnOx bandgap depending on the bandgap type (indirect or direct).

CuO/CexSn1−xO2 catalysts with low tin content for CO removal from H2-rich streams

CuO/CexSn1−xO2 catalysts with low tin content (X ≥ 0.95) were synthesized and their activity was screened in CO-PROX, WGS and OWGS (Oxygen-enhanced WGS) reactions for CO removal from hydrogen rich streams. The samples were deeply characterized to evaluate their textural, structural and redox properties, as well as the surface composition and oxidation state of the elements. The activity of the catalysts in the three reactions was correlated to those physico–chemical properties. It is found that the addition of very low amount of tin (up to Sn/Ce atom ratio of 0.0525) increases both the OSC and the reducibility at low temperatures and is beneficial for CO-PROX as well as for OWGS reactions, while was detrimental for WGS reaction.

High Transmission and Low Resistivity Cadmium Tin Oxide Thin Films Deposited by Sol-Gel

ABSTRACTTransparent conducting cadmium tin oxide (CTO) thin films were obtained from a mixture of CdO and SnO2 precursor solutions by the dip-coating sol-gel technique. The thin films studied in this work were made with 7 coats (∼200 nm) on corning glass and quartz substrates. Each coating was deposited at a withdrawal speed of 2 cm/min, dried at 100°C for 1 hour and then sintered at 550°C for 1 hour in air. In order to decrease the resistivity values of the films, these were annealed in a vacuum atmosphere and another set of films were annealed in an Ar/CdS atmosphere. The annealing temperatures (Ta) were 450°C, 500°C and 550°C, as well as 600°C and 650°C, when corning glass and quartz substrates were used, respectively. X-Ray diffraction (XRD) patterns of the films annealed in a vacuum showed that there is only the presence of CTO crystals for 450°C≤ Ta ≤ 600°C and CTO+SnO2 crystals for Ta=650°C. The films annealed in Ar/CdS atmosphere were only constituted of CTO crystals independent of the Ta. The minimum resistivity value obtained was ∼4 x 10-4 Ωcm (Rsheet= 20 Ω/□) for the films deposited on quartz and annealed at Ta=600°C under an Ar/CdS atmosphere. The films deposited on quartz showed the higher optical transmission (∼90%) with respect to the films deposited on corning glass substrates (∼85%) in the Uv-vis region. For their optical and electrical characteristics, these films are good candidates as transparent electrodes in solar cells.