Si Sn Research Articles

Concentration and distribution of elements in Late Permian coals from western Guizhou Province, China

With the aim of better understanding geochemistry of coal, 71 Late Permian whole-seam coal channel samples from western Guizhou Province, Southwest China were studied and 57 elements in them were determined. The contents of Al, Ca, Co, Cr, Cu, Fe, Ga, Hf, K, Li, Mn, Mo, Nb, Ni, Sn, Ta, Ti, Th, U, V, Zr, and REEs in the Late Permian coals from western Guizhou Province are higher than the arithmetic means for the corresponding elements in the US coals, whereas As, Ba, Br, F, Hg, P, Se, and Tl are lower. Compared to common Chinese coals, the contents of Co, Cr, Cu, Ga, Hf, Li, Mn, Mo, Ni, Sc, Sn, Ti, U, V, Zn, and Zr in western Guizhou coals are higher, and As, F, Hg, Rb, Sb, Tl, and W are lower. Five groups of elements may be classified according to their mode of occurrence in coal: The first two, Group A, Tm–Yb–Lu–Y–Er–Ho–Dy–Tb–Ce–La–Nd–Pr–Gd–Sm, and Group B, As–Sr–K–Rb–Ba–F–Ash–Si–Sn–Ga–Hf–Al–Ta–Zr–Be–Th–Na, have high positive correlation coefficients with ash yield and they show mainly inorganic affinity. Some elements from Group B, such as Ba, Be, Ga, Hf, and Th, are also characterized by significant aluminosilicate affinity. In addition, arsenic also exhibits high sulfide affinity ( r S–Fe>0.5). The elements, which have negative or lower positive correlation coefficients with ash yield (with exceptions of Bi, Cs, Nb, Mn, Se, and Ti), are grouped in other four associations: Group C, Cr–V–Mo–U–Cd–Tl; Group D, Hg–Li–Sc–Ti–Eu–Nb–Cs–W; Group E, Bi–Sb; and Group F, Co–Ni–Cu–Pb–Zn–Mg–Se–Ca–Mn–S–Fe. The correlation coefficients of some elements, including Co, Cr, Cu, Fe, Hg, Li, Mo, Ni, P, S, Sc, U, V, and Zn, with ash yield are below the statistically significant value. Only Cr and Cu are negatively correlated to ash yield (−0.07 and −0.01, respectively), showing intermediate (organic and inorganic) affinity. Manganese and Fe are characterized by carbonate affinity probably due to high content of epigenetic veined ankerite in some coals. Phosphorus has low correlation coefficients with any other elements and is not included in these six associations. There are five possible genetic types of enrichment of elements in coal from western Guizhou Province: source rock, volcanic ash, low-temperature hydrothermal fluid, groundwater, and magmatic hydrothermal inputs.

Synthesis and Structure of the First Stannadisiloxanediol: [Me2N(CH2)2]2Sn(OSit‐Bu2OH)2. A Potential Precursor for the Preparation of Multi Component Oxides

AbstractThe synthesis of [Me2N(CH2)2]2Sn(OSit‐Bu2OH)2 (1) by the base‐assisted cohydrolysis of [Me2N(CH2)2]2SnCl2 and t‐Bu2SiCl2 is described. The molecular structure of 1, determined by single crystal X‐ray diffraction analysis, features a pentacoordinated tin atom owing to the intramolecular coordination of the nitrogen atom of one 3‐dimethylaminopropyl group, and reveals both intramolecular Si(Sn)O···H‐O and intermolecular N···H‐O hydrogen bonding. Compound 1 is a rare example of a metallasiloxanol and holds potential for the preparation of multi component oxide materials.

Electroless nickel–phosphorus plating on Ni–Zr–Ti–Si–Sn amorphous powder

In the present study, we investigated the feasibility of inhibiting high-temperature oxidation of Ni 57Zr 20Ti 18Si 3Sn 2 amorphous powder by depositing nickel–phosphorus on Ni 57Zr 20Ti 18Si 3Sn 2 amorphous powder. A Ni 57Zr 20Ti 18Si 3Sn 2 amorphous powder was produced by a gas-atomization technique, and subsequently, nickel–phosphorus was deposited on Ni 57Zr 20Ti 18Si 3Sn 2 amorphous powder by electroless plating. Fully amorphous Ni 57Zr 20Ti 18Si 3Sn 2 powder could be successfully obtained with a particle size smaller than 75 μm and exhibits a glass transition temperature ( T g) of 828 K, an onset crystallization temperature ( T x) of 886 K and a supercooled liquid region (Δ T) of 58 K. Electroless plating yielded a complete and uniform deposition of nickel–phosphorus on Ni 57Zr 20Ti 18Si 3Sn 2 amorphous powder. The coated nickel–phosphorus deposit can reduce the oxidation of Ni 57Zr 20Ti 18Si 3Sn 2 amorphous powder remarkably at the consolidation temperature of Ni 57Zr 20Ti 18Si 3Sn 2 amorphous powder.

Bulk glass formation in the Ni–Zr–Ti–Nb–Si–Sn alloy system

In this study, the effect of addition of Nb on glass formation in Ni–Ti–Zr–Si–Sn alloys has been studied. The composition range for bulk glass formation with Dmax > 2 mm (Dmax, maximum diameter for glass formation by injection cast method) becomes wider when compared with the non-Nb–containing alloy. The ΔTx (= Tx – Tg; Tx, crystallization onset temperature; Tg, glass transition temperature), Trg (= Tg/Tl; Tl, liquidus temperature) and γ [= Tx/(Tl + Tg)] values for the alloys Dmax > 2 mm are in the range of 40–59, 0.638–0.651, and 0.410–0.419, respectively. The compositions of the alloys (Dmax > 2 mm) are closer to pseudo-eutectic composition than that of the alloy without Nb, showing an improved glass forming ability. The critical cooling rate for glass formation (Dmax = 5 mm) is estimated to be order of approximately 40 K/s.

Bacterial adhesion to glass and metal-oxide surfaces

Metal oxides can increase the adhesion of negatively-charged bacteria to surfaces primarily due to their positive charge. However, the hydrophobicity of a metal-oxide surface can also increase adhesion of bacteria. In order to understand the relative contribution of charge and hydrophobicity to bacterial adhesion, we measured the adhesion of 8 strains of bacteria, under conditions of low and high-ionic strength (1 and 100 mM, respectively) to 11 different surfaces and examined adhesion as a function of charge, hydrophobicity (water contact angle) and surface energy. Inorganic surfaces included three uncoated glass surfaces and eight metal-oxide thin films prepared on the upper (non-tin-exposed) side of float glass by chemical vapor deposition. The Gram-negative bacteria differed in lengths of lipopolysaccharides on their outer surface (three Escherichia coli strains), the amounts of exopolysaccharides (two Pseudomonas aeruginosa strains), and their known relative adhesion to sand grains (two Burkholderia cepacia strains). One Gram positive bacterium was also used that had a lower adhesion to glass than these other bacteria ( Bacillus subtilis). For all eight bacteria, there was a consistent increase in adhesion between with the type of inorganic surface in the order: float glass exposed to tin (coded here as Si–Sn), glass microscope slide (Si-m), uncoated air-side float glass surface (Si-a), followed by thin films of (Co 1– y–z Fe y Cr z ) 3O 4, Ti/Fe/O, TiO 2, SnO 2, SnO 2:F, SnO 2:Sb, A1 2O 3, and Fe 2O 3 (the colon indicates metal doping, a slash indicates that the metal is a major component, while the dash is used to distinguish surfaces). Increasing the ionic strength from 1 to 100 mM increased adhesion by a factor of 2.0 ± 0.6 (73% of the sample results were within the 95% CI) showing electrostatic charge was important in adhesion. However, adhesion was not significantly correlated with bacterial charge and contact angle. Adhesion ( A) of the eight strains was significantly ( P < 10 −25) correlated with total adhesion free energy ( U) between the bacteria and surface ( A = 2162 e −1.8 U ).Although the correlation was significant, agreement between the model and data was poor for the low energy surfaces ( R 2 = 0.68), indicating that better models or additional methods to characterize bacteria and surfaces are still needed to more accurately describe initial bacterial adhesion to inorganic surfaces.

First-principles investigation of Sn 1− xSi x/Si(1 1 1) and Sn 1− xPb x/Si(1 1 1) surfaces

We investigate the structural and electronic properties of the Si(1 1 1) surface covered by 1/3 monolayer Sn (1− x) Si x as a function of x, by means of density functional theory–local density approximation calculations. Starting from the ideal α-phase Sn/Si(1 1 1), we perform computational experiments increasing the amount of substitutional Si on the adatom layer, a condition which is experimentally achieved through annealing. We find the occurrence of a metal–semiconducting phase transition found at 50% Si composition, related to band decoupling. The role of surface disorder is addressed comparing the theoretical predictions with the experimental results. Finally, we further extend our investigation considering other possible surface alloying, i.e. the Sn (1− x) Pb x /Si(1 1 1) surface.

Vacuum hot pressing of gas-atomized Ni–Zr–Ti–Si–Sn amorphous powder

Fully amorphous Ni 57 Zr 20 Ti 18 Si 3 Sn 2 powders without any crystallinity are successfully fabricated in the particle size range below 75 μm by gas-atomization method. Gas-atomized Ni 57 Zr 20 Ti 18 Si 3 Sn 2 amorphous powder exhibits the glass transition temperature ( T g ) of 828 K and the crystallization temperature ( T x ) of 886 K. The gas-atomized Ni 57 Zr 20 Ti 18 Si 3 Sn 2 amorphous powder posesses a supercooled liquid region (Δ T x ) of 58 K. Based on the determined consolidation condition, the gas-atomized Ni 57 Zr 20 Ti 18 Si 3 Sn 2 amorphous powder was consolidated by a vacuum hot pressing apparatus. The optimum consolidation conditions were determined by isothermal annealing of Ni 57 Zr 20 Ti 18 Si 3 Sn 2 amorphous powder. The consolidated bulk Ni 57 Zr 20 Ti 18 Si 3 Sn 2 samples show completely amorphous on processing after consolidation. The relative density and hardness of the consolidated bulk Ni 57 Zr 20 Ti 18 Si 3 Sn 2 compacts are greater than 99 % and 800 Hv, respectively.

Synthesis and structural characterization of ordered supermicroporous MSU type silica–tin molecular sieves

Supermicroporous Sn–Si molecular sieves, with different amounts of tin, have been prepared using polyethylene oxide type surfactants as structure directing agents and a silicon alkoxide as precursor. Syntheses have been carried out in acidic media. The structural and chemical properties of the prepared materials, have been studied using a variety of techniques such as Wide Angle X-Ray Scattering (WAXS), physisorption of N2 at 77K, FT-IR spectroscopy of chemisorbed pyridine, skeletal FT-IR, Temperature Programmed Desorption of ammonia (NH3-TPD) and 119Sn Mossbauer spectroscopy.

Magnesium and chlorostannanes—building blocks for novel tinmodified silanes

Cyclic stannasilanes with alternating Si–Sn sequences ([Ph 2Sn–Me 2Si] 3, 1; [ t-Bu 2Sn–Me 2Si] 2, 2) were synthesized by the reaction of dimethyldichlorosilane with diorganodichlorostannanes (R 2SnCl 2, R=Ph, t-Bu) in the presence of magnesium. The reaction pathway towards 2 via the unexpected intermediate product Cl–SiMe 2–( t-Bu 2Sn) 2–SiMe 2–Cl ( 5) is discussed. In addition, some thermodynamic and kinetic studies for the formation of the rings ( 1, 2) and the Grignard-type tin compounds are presented. All compounds were characterized by NMR, MS and elemental analysis. The solid state structures of 1, 2 and 5 were determined by X-ray crystallography.

Microstructural characterisation of fatigue crack initiation in Al-based plain bearing alloys

The fatigue initiation behaviour of two Al-based bearing lining alloys has been assessed by image analysis tessellation techniques and subsequent adaptive numerical classification approaches. Fatigue initiation occurs by decohesion at Si particles, and in the absence of Si particles decohesion occurs at Sn particles. In both cases, relatively unclustered, large particles initiate fatigue, and the relative position of the nearest neighbour particle seems to have significance. This can be explained qualitatively in terms of strain mismatch arising from differing elastic moduli between the particles and surrounding Al matrix and local stress concentration and superposition effects. The lining alloy containing no Si and high Sn content exhibits more directionality, and a heavier dependence on angular information is found by the classifier.

Influence of Tin on the Structure and Properties of As‐Cast Ti‐Rich Ti—Si Alloys.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Recombination current instability in epitaxial p +-n structures with impurity atoms locally incorporated into the n-type region and determination of the deep center parameters

The physical processes causing the recombination current instability in silicon epitaxial p+-n structures with a local contact formed in the n-type region of the structure and produced by incorporation of impurity atoms that introduced deep energy levels in the silicon band gap were studied. Based on the study of the current instability, the parameters (density, energy position, and cross section of electron capture) of deep-level centers generated by tin, lead, cadmium, and nickel in silicon, were determined.

Origin of 3×3 diffraction on the Sn 1− xSi x/Si(1 1 1) [formula omitted] surface

An evolution of an apparent 3×3 low-energy electron diffraction (LEED) pattern has been observed for the Sn 1− x Si x /Si(1 1 1) 3 × 3 surface alloy. The origin of this additional diffraction has been investigated in detail by scanning tunneling microscopy (STM). The 3×3 diffraction, which appears after annealing, is associated with the arrangement of the Sn and substitutional Si atoms in the surface layer, forming many local structures such as honeycombs, hexagons, and atomic lines. As revealed by Fourier-transforms of the STM-images, these local structures are the origins of the 3×3 diffraction and a weak 2 3 × 3 streaky background superposed on the 3 × 3 LEED pattern.

Influence of tin on the structure and properties of as-cast Ti-rich Ti–Si alloys

By the methods of DTA, X-ray diffraction, metallography and microprobe analysis, phase equilibria in the Ti-corner (more than 50 at.% Ti) of the Ti–Si–Sn system were studied. The solidus projection and the melting diagram (solidus+liquidus) were constructed. A new ternary compound T of composition Ti 5Si 1.2–1.6Sn 1.8–1.4 was found to form with the crystal structure of W 5Si 3-type. The ternary eutectic equilibrium L↔〈β-Ti〉+〈Ti 5Si 3〉+〈Ti 3Sn〉 was established to occur at 1460 °C with the composition of the invariant point E at ∼77Ti–9Si–14Sn. Microhardness measurements were carried out for the primary grains of the alloys with 5 at.% Si.

Core-level photoelectron study of Si( [formula omitted]) √7×√3-( [formula omitted]) surface

The Sn 4 d and Pb 5 d core-level photoelectron spectra have been studied in order to clarify their bonding properties and atomic arrangement on a Si(1 1 1) √7×√3-(Pb, Sn) surface, which is formed by the coadsorption of 0.4 ML Pb and 0.4 ML Sn and shows two kinds of bright spots in the scanning tunneling microscopic (STM) images: (A) those aligned zigzag on the T 1 site and (B) those on the T 1 and H 3 sites along the [1 1 −2] direction. The Pb 5 d spectrum shows a single spin–orbit-split feature with weak tailing towards the high binding energy side, while the Sn 4 d spectrum exhibits shoulder structures at the high binding energy side of the main peaks. This definitely indicates at least two different Sn–Si bonds or inequivalent Sn adsorbing sites and single bond or site for Pb. Thus the spots A at the T 1 site and those B at the T 1 and H 3 sites in the STM images are ascribed to Pb and Sn adatoms, respectively. The formation process of this surface will be also discussed in terms of the core-level spectra.

Mechanical behavior of a bulk Cu–Ti–Zr–Ni–Si–Sn metallic glass forming nano-crystal aggregate bands during deformation in the supercooled liquid region

The deformation behavior of a bulk Cu 47Ti 33Zr 11Ni 6Sn 2Si 1 metallic glass, fabricated by injection casting, has been characterized in the supercooled liquid region. The alloy deforms homogeneously and exhibits large elongation above the glass transition temperature at constant true strain rate below 1×10 −2s −1, but it shows a variation of the flow stress during deformation. The flow stress reaches a peak just after yielding and then decreases significantly with increasing strain. After the plateau level of remarkably low flow stress, it rises again and then the alloy finally fails in a brittle manner. DSC data and TEM observations for the tested alloy reveal that the alloy evolves to being crystallized during deformation. Nano-crystals are aggregated and the aggregates are aligned along the load direction. When the volume fraction of the crystalline phase is in the range up to 0.5, the nano-crystal aggregates effectively slide over each other, lowering the apparent stress level. However, as the amount of the crystalline phase further increases, the flow stress continuously increases. This behavior can be explained based on the volume-fraction rule between the crystalline phase and the amorphous phase.

Photoemission study of Sn on vicinal Si( [formula omitted])2×1 surface

We present high resolution photoemission studies of Sn on vicinal Si(1 0 0)2×1 surface in submonolayer regime. Deposition of Sn on clean Si(1 0 0) surface produces an abrupt epitaxial interface having a large variety of surface reconstructions. At room temperature at low coverages Sn dimer rows are formed. After annealing above 500 °C following superstructures are known to exist with increasing Sn coverage: c(4×4), 2×6, c(4×8), and 1×5. The Sn 4d core level spectra are now resolved in details displaying new components related to the different adsorption sites on the Si(1 0 0) surface. The spectra of the annealed phase reconstructions show components originating from dimer bonding, from bonding to the second layer, from Sn atoms in mixed Sn–Si dimers where Sn atoms have replaced one of the Si dimer pair atoms, and from adsorption onto defect sites. The photoemission results are in good agreement with the surface geometric structures.

Mechanism of the short range ordering in a 2D binary alloy

Direct comparison of scanning tunneling microscopy (STM) and high-resolution core level photo-emission experiments provides a rationale for the mechanism of short range ordering in a two-dimensional (2D) binary alloy (1/3 monolayer (ML) Sn (1− x) Si x /Si(1 1 1)-(√3×√3) R30°). The host pure Sn metal surface ( x=0) results partitioned into two classes (2/9 and 1/9 ML) of ad-atoms occupying non-equivalent T 4 sites. Sn substitution with Si ad-atoms preferentially takes place at the majority type adsorption sites. This occurrence explains the atomic intermixing and the short range ordering directly observed with STM and typical of a wide class of 2D binary alloys.

Powder forging of a sintered Al–3.8Cu–1Mg–0.8Si–0.1Sn alloy

The forging characteristics of an Al–Cu–Mg–Si–Sn alloy are examined using a new testing strategy which incorporates a double truncated cone specimen and finite element modelling. This sample geometry produces controlled strain distributions within a single specimen and can readily identify the specific strain required to achieve a specific microstructural event by matching the metallographic data with the strain profiles calculated from finite element software. The friction conditions were determined using the conventional friction ring test, which was evaluated using finite element software. The rheological properties of the alloy, evaluated from compression testing of right cylinders, are similar to the properties of conventional aluminium forgings. A hoop strain develops at the outer diameter of the truncated cones and this leads to pore opening at the outer few millimetres. The porosity is effectively removed when the total strain equals the net compressive strain. The strain profiles that develop in the truncated cones are largely independent of the processing temperature and the strain rate although the strain required for pore closure increases as the forging temperature is reduced. This suggests that the microstructure and the strain rate sensitivity may also be important factors controlling pore behaviour.

Tin-vacancy complexes in silicon

The structure and electrical properties of of ${\mathrm{SnV}}_{2},$ ${\mathrm{Sn}}_{2}\mathrm{V},$ and ${\mathrm{Sn}}_{2}{\mathrm{V}}_{2}$ complexes in Si are investigated using first-principles cluster and supercell methods. The formation of ${\mathrm{SnV}}_{2}$ and ${\mathrm{Sn}}_{2}{\mathrm{V}}_{2}$ is found to be energetically favorable, in agreement with the experimental results. All the tin-vacancy defects are found to possess deep donor and acceptor levels, although the number of the gap states decreases with increasing size of the defect. The diffusion of tin in silicon is considered and the mechanism found to be distinct from the diffusion of group V shallow donors. In contrast with these, the Sn-V interaction is found to extend only to the third nearest neighbor distance. This implies that the activation energy for Sn diffusion via vacancies should be nearly the same as self-diffusion by this mechanism. We find an activation energy of 3.5 eV which is close to some experimental findings but considerably less than given by others.