Tin Spheres Research Articles

Characterization of Surface α-Particle Radiation, Internal Traceability and Simulation of Typical Tin Spheres

Surface α-particle emissivity testing and spectral characterization of two leaded tin spheres (Sn10%Pb90%, Sn63%Pb37%) and one lead-free tin sphere (Sn96.5%Ag3.0%Cu0.5%, SAC305) were carried out. The results show that Sn10%Pb90% Sn spheres have the highest α-particle emissivity; Sn63%Pb37% Sn spheres are the next highest, which is an order of magnitude lower than the α-particle emissivity of Sn10%Pb90% Sn spheres; and SAC305 Sn spheres have the lowest emissivity, which is reduced by about 55.6% compared to the emissivity of Sn63%Pb37% Sn spheres. All three types of tin spheres, after purification treatment, achieved the grade of ultra-low alpha particle emissivity (<0.002 α/(cm2·h)). The internal radionuclide traceability of the tin sphere, combined with the energy spectrum, reveals that the emission spectrum of the tin sphere exhibits an obvious “single peak” characteristic, with the peak energy in the interval of 5 MeV~5.5 MeV. Comparative analyses revealed that 210Po is the main nuclide that produces alpha particles, and 210Po originates from the decay of 210Pb. Further Monte Carlo simulations show that α-particles with energies greater than 4.1 MeV in the measured energy spectrum all come from the contribution of radionuclides within 5 μm of the surface layer of the tin sphere, which accounts for 60% of the total radioactivity. Combining the experimental and simulation results, it is found that the internal radionuclides of the tin sphere are characterized by more surface layer and less internal layer. The above results are of great significance for the establishment of α-particle mitigation methods for tin spheres.

Reactant enrichment in yolk-shell structured Pd/TiN nanoreactors for boosting electrocatalytic hydrodechlorination performance

Enhancing the enrichment behavior of low-concentration chlorinated organic pollutants remains a significant challenge in electrocatalytic hydrodechlorination (EHDC) technology. Metal-loaded hollow nanoarchitecture has emerged as a promising nanoreactor to improve reaction enrichment behavior because of its tailorable microenvironments and electronic properties. Herein, a structural engineering strategy is developed to synthesize yolk-shell structured TiN spheres supported Pd nanoreactors (Pd/YS-TiN) with confined mesoscopic spaces. Characterization by multiple techniques reveals that the yolk-shell structure of YS-TiN, with high specific surface area (139.0 m2/g) and appropriately mesoporosity (6.9 nm), exposes numerous Pd nanoparticles (∼4.0 nm) on outer/inner surface of the shell and yolk-core solid sphere, ensuring an efficient utilization of active sites for enhancing the 2,4-DCP detoxification. Consequently, the structurally optimized Pd/YS-TiN nanoreactor consistently displays maximum reaction kinetics, dechlorination degree, faradaic current density, H* utilization and product selectivity, surpassing hollow TiN-supported Pd and Pd/C catalysts. The super EHDC performance of 91.8 % 2,4-DCP conversion, a specific activity of 1.68 min−1 molPd−1, and a mass activity of 6.06 min−1 gPd−1 is obtained at −0.85 V and 180 min, outperforming most reported catalysts. Combining experimental and density functional theory results, the exceptional reaction enrichment behavior of Pd/YS-TiN originates from (1) alleviating the overstrong adsorption of product phenol through strong metal-support interactions and (2) enhancing mass transport efficiency facilitated by the local concentration gradient and mesoporous shell. This study elucidates how metal-support interactions and mass transport synergistically enhance reaction enrichment behavior, showcasing potential benefits in environmental remediation applications.

Growth and characterization of gold nanoislands & quantum dots on marker-based SiO2/Si substrate for SEM resolution intercomparison studies

A scanning electron microscope (SEM) is the powerhouse tool of nanoscience & nanotechnology and the high resolution is one of the important parameters that decide the instrument’s quality. The reference materials (RM) like gold nanoislands or tin spheres on carbon substrate separated by a nanogap are often used to get the practically attainable resolution of the SEM instrument. Such RM contains millions of gold nanoislands and nanogaps but all of these RMs are non-traceable. Hence the practically obtained high resolution of an SEM remains doubtful unless and until intercompared with traceable RM. The development of a new SEM resolution test specimen sample with localized markers for the identification of a traceable critical dimension of a nanogap on a user-friendly SiO2/Si or Si3N4/Si chip is reported here. First, thin films of gold with thickness < 5 nm (ultra-thin film) and of about 10 nm (thin film) were deposited on a pre-patterned marker SiO2/Si chip to form the gold nanoparticles (Au NPs) by thermal annealing technique. The high-resolution SEM images show the formation of gold quantum dots (Au QDs) (average particle diameter <D> ∼ (18 ± 1) nm and average gap between two particles <S> ∼ (6 ± 1) nm) and gold nano-islands (Au NIs) (<D> ∼ (101 ± 3) nm and <S> ∼ (104 ± 2) nm). FESEM images show densely packed nano-islands exhibiting spherical geometry which is explained using dewetting mechanism followed by Ostwald ripening and coalescence resulting formation of Au QDs and Au NPs. Further, these marker-based resolution test chips can be used in inter or intra-comparison studies due to pre-patterned markers. First-time development of QDs on marker chip gives access to a particular nanogap among the millions of nanogaps present on the substrate, this type of RM will be used for inter-laboratory comparison studies in the future.

Epitaxial Lateral Overgrowth of Tin Spheres Driven and Directly Observed by Helium Ion Microscopy

Epitaxial Lateral Overgrowth of Tin Spheres Driven and Directly Observed by Helium Ion Microscopy

Facile synthesis of high‐melting point spherical TiC and TiN powders at low temperature

AbstractPreparation of high melting point sphere is of great practical value and remains a great challenge. Herein, for the first time a delicate chemical vapor deposition (CVD) process was developed for fabricating spherical TiN and TiC powders, which can hardly be attainable by conventional processes. The big equilibrium constant and released heats are key parameters for obtaining spherical TiN and TiC powders by the CVD process. Sphericity and crystallinity of these spherical powders can be controlled by adjusting nucleation and growth. The optimal TiN spheres (diameter 0.46 μm, sphericity 0.89) and TiC spheres (diameter 0.52 μm, sphericity 0.87) were obtained at 850°C under N2 and H2 and CH4, respectively. The design ideas explore a novel way to fabricate high melting point spheres.

Type-I superconductivity in carbon-coated Sn nano-spheres

Tin spheres of diameter ∼120 nm and ∼1400 nm coated with sub-nanometer carbon layers were fabricated, using a sonochemical technique. Samples of both spheres reveal a type-I superconducting behavior characterized by super-critical fields and an intermediate state manifested by a gradual increase of the magnetization to zero. However, the small and large tin spheres exhibit a similar critical field, Hc, contrary to the expected increase in Hc in spheres with size smaller than the coherence length (∼230 nm). Analysis of the data shows that a relative high degree of carbon doping in the small tin spheres, eliminates the expected size-effect on Hc. Simulations, based on the time dependent Ginzburg-Landau equations, imply that the intermediate state in both measured samples consists of only one superconducting domain surrounded by a normal domain, whereas a rich multi-domain structure is predicted for larger Sn spheres.

Fabrication of SnO2 Asymmetric Membranes for High Performance Lithium Battery Anode.

Alloy electrode material like tin dioxide (SnO2) possesses much higher specific capacity as compared to commercial graphite anode in lithium ion battery (783 vs 372 mAh g(-1)). However, the huge volume change (260%) of SnO2-based anode during the alloying and dealloying process can cause significant electrode pulverization and rapid capacity loss. Herein we report the synthesis of SnO2 asymmetric membranes via a unique combination of phase inversion and sol-gel chemistry to overcome this big challenge. The SnO2 asymmetric membrane electrode demonstrates a specific capacity of 500 mAh g(-1) based on the overall electrode mass at a current density of 280 mA g(-1) (∼0.5C) with >96% capacity retention after 400 cycles. When the current density is increased from 28 to 560 mA g(-1), its overall capacity is only reduced by 36%. Such an outstanding rate and cycling performance is attributed to the existence of networking porous structure in the membrane that can provide high electrical conductivity, multiple diffusion channels, and free volumes for electrode expansion. The carbonization temperature has a dramatic impact on the electrode performance. Membranes carbonized at 500 °C show an excellent cycling performance, whereas the capacity of the membrane carbonized at 800 °C decreases by 51% in 100 cycles. Such a drastic difference in cycle life is caused by the reduction of small SnO2 NPs (∼3.9 nm) into large metallic tin spheres (∼40 nm) at 800 °C. This is the first original report on using asymmetric membrane structure to stabilize an SnO2-based lithium ion battery anode with an excellent electrochemical performance.

Hierarchical micro/nano-structured titanium nitride spheres as a high-performance counter electrode for a dye-sensitized solar cell

Hierarchical micro/nano-structured TiN spheres (micro/nano-TiNs) counter electrodes are fabricated by coating hierarchical micro/nano-TiO2 paste onto Ti foil followed by a nitridation reaction. Compared with particulate TiN and TiN flat electrodes, the as-prepared hierarchical micro/nano-TiNs electrode based dye-sensitized solar cells (DSCs) delivers significantly improved photovoltaic performances due to the presence of the hierarchical structure. In particular, VOC is enhanced by about 60 mV, which may be predominantly attributed to the gaining of favourable interfacial active sites and the traces of N-doped carbon residues. After an initial optimization of the particle sizes of the hierarchical micro/nano-TiNs, the reflectance effect of large submicroscale particles is attempted to improve the ISC. The highest overall conversion efficiency yields 7.83%, which is 30% higher than that of Pt/FTO (6.04%).

Template Assisted Fabrication of Pt–Sn Core–Shell Nanospheres

Sub-micron or nano-scale spheres are typically fabricated using conventional powder metallurgy processes; however, it is difficult to control the diameter and shape of each nanoparticle such that they are uniform. In this work, tin (Sn) was first sputtered on an anodic aluminum oxide (AAO) template. Then tin spheres were formed on the AAO by sinking tin-deposited AAO into silicone oil through the thermal-reflowing process. The size and quantity of the spheres were controlled with the sputtering time and power. The thermal-reflowed tin nanospheres were subsequently coated with thin platinum (Pt) film by DC sputtering, forming Pt–Sn core–shell nanospheres. The total surface area of the tin sphere on AAO and specific surface area of the Pt spherical shell were determined. The specific surface areas of Pt shell on the Sn nanospheres were 8.1–16.2, 10.3–20.6, and 12.8–25.6 (m 2 g −1) with wetting angles at 100°, 120°, and 150°, respectively between the Sn sphere an AAO.

Facile Preparation of Mesoporous Titanium Nitride Microspheres for Electrochemical Energy Storage

In this study, mesoporous TiN spheres with tunable diameter have been fabricated via a facile template-free strategy. Under ammonia atmosphere, mesoporous TiO₂ spheres are directly converted into mesoporous TiN spheres with the addition of cyanamide to retain the original morphology. The electrochemical performance of the resultant mesoporous TiN spheres demonstrates that this material can be a promising electrode material for nonaqueous supercapacitors with high energy densities.

Technique for Self-Assembly of Tin Nano-Particles on Anodic Aluminum Oxide (AAO) Templates

Various pore sizes of anodic aluminum oxide (AAO) were fabricated using a two-step anodization process. AAO pores with diameters ranging from 5 to 500 nm were formed in diluted electrolyte solutions of sulfuric acid, oxalic acid, and phosphoric acid. Irregularly shaped tin particles in nano sizes were formed on the AAO using a thermo-vaporizing process. Tin spheres with diameters ranging from 3 to 500nm were then obtained by reflowing vaporized AAO in silicate oil. A transmission electron microscope (TEM JEOL 2000) was employed to characterize the crystalline structure of a tin sphere with 18 nm diameter.

Formation of Tin Whiskers and Spheres on Anodic Aluminum Oxide Template

Nanosized tin whiskers and spheres 15 nm in diameter form on anodic aluminum oxide (AAO) templates via a two-step anodization. The driving force, residual stress released from the template at a high temperature, causes tin whiskers of uniform size to grow on AAO within a few minutes. Various thicknesses AAO templates of in nano channels were fabricated from high-purity aluminum metals. The formation of hexagonal pores on aluminum was elucidated with reference to the equilibrium surface tension at each anodic condition. During a faster heating and cooling rate, tin formed coarser whiskers on the AAO, compared with fine nanowhiskers, which prefer slower rates of tempering. A series of scanning electron microscopy (SEM) images under various conditions of fabrication are introduced. Hence, the transformation of tin whiskers to a spherical shape is presented in detail in this study as well.

Measurement of Adhesion Forces between Particles and Rough Substrates in Air with the Vibration Method

Pull-off forces were measured using the vibration method at 30–50% relative humidity for glass and tin spheres on a variety of substrates. The results were compared with those obtained through the colloidal probe technique. Both methods show good agreement for small particle sizes. Since the vibration method causes sinusoidally alternating stresses, the method yields detachment and contact forces between particles and substrate of the same order of magnitude. Alternating contact forces of the vibration method can cause an increase in the adhesion force through flattening of asperities, which also depend on the surface roughness and the mechanical properties of particle and substrate.Pull-off force measurements with the colloidal probe technique and special attention to the influence of the contact force also show an adhesion force intensification with increasing contact forces depending on the surface roughness. No significant adhesion force intensification caused by increasing contact time to 30s at several contact forces was observed. For theoretical predictions based on van der Waals adhesion, an approach presented by Rabinovich and approximations of plastic micro-asperity flattening were combined.

Analysis of Adhesion Forces Between Particles and Wall Based on the Vibration Method

An indirect method for the measurement of adhesion forces between a particle and a wall is presented. The vibration method [1] is based on particle re-entrainment from a vertical-sinoidal vibrating surface caused by its inertia at a certain acceleration. Acceleration of the vibrating surface is measured and calibrated using a laser-scanning-vibrometer. Correlating particle re-entrainment events with acting acceleration permits the calculation of adhesion forces. For horizontal dislocation of re-entrained particles the vibrating surface is placed in a flow channel and exposed to a laminar air flow (Rechannel=1514) parallel to the surface. Adhesion force measurements were carried out for glass spheres (20–30 and 60-70 μm), tin spheres (20–30 μm) and corn starch-fumed silica mixtures (10–20 μm) on a silicon wafer substrate at an air temperature of 20–25°C and relative humidity 8–14%. Experimentally obtained values were compared with a model presented by Rabinovich et al. [2] based on the Rumpf model, which integrates the r.m.s value of the contact surfaces measured with atomic force microscopy (AFM). It was found that adhesive force agreed approximately with the van der Waals force.

Phase transition study of superheated planar arrays of tin cylinders

We have investigated the superheating and the supercooling fields of a planar array of tin cylinders with diameters ranging from 40 to 80 μm and thickness 8.3 μm evaporated onto a glass substrate and onto a kapton foil. Experimental values of the Ginzburg–Landau parameter have been obtained and compared with results from tin spheres. The spread of the superheating curves is below 5%.

Surface-enhanced Raman spectra of langmuir-blodgett monolayers of (hexadecamethyltetralino) porphyrazines

Langmuir monolayers of metal-free tetra(1,1,4,4-tetramethyl-6,7-tetralino) porphyrazine (HDMTLPH2) and its copper complex (HDMTLPCu) were formed on a water subphase. The surface pressure-area isotherms were measured and the floating monolayers were transferred to various substrates. The spectra of Langmuir-Blodgett (LB) films deposited on metal surfaces were studied. Surface-enhanced Raman spectra of a single LB monolayer of HDMTLPH2 and HDMTLPCu deposited on rough surfaces (silver-coated tin spheres and island films of silver and gold) are reported. Reflection absorption Fourier transform IR spectra of LB films on smooth silver are also presented. The spectroscopic characterization includes the UV-visible spectra of multilayer films on glass slides, solutions and the bulk materials. Characteristic vibrational wavenumbers are listed and used to discuss molecular orientation in the LB assemblies.

Progress in the development of a cryogenic granule detector for dark matter

Following our development of a SQUID read-out and a procedure for making planar arrays of indium and tin spheres with good uniformity in size and position, we have now fabricated arrays of smaller tin spheres suitable for detecting weakly interacting massive particles. The spherical granules, which form a square lattice, are 4 μm in diameter and are separated by 20 μm. Cryogenic tests show a narrow spread of transition temperatures which depends on the direction of the applied field. Both a single array and a multilayer detect low energy γ-radiation.

Progress in the development of the tin PASS granule detector

Progress in the development of a PASS granule detector is reported. Arrays with small tin spheres, with radius r⋍2µm, have been fabricated. The responses of tin PASS samples, with r⋍2 µm and r=8 µm, to low energy γ-radiation have been measured and analyzed. Also the performance of a multilayer PASS has been investigated.

Surface enhanced Raman scattering on silver-coated tin spheres

Surface enhanced Raman scattering (SERS) and surface enhanced resonant Raman scattering (SERRS) obtained on uniformly and well characterized structures formed by evaporation of tin onto glass slides and coated with silver are presented.

The electronic structure of UTe and UBi

Quasi-self-consistent band structure calculations using the relativistic KKR method and the Xα exchange approximation have been performed for UTe and UBi. For a discussion of the bonding mechanism the partial κ-like charges for a selection of one-electron-states and the κ-like total valence charges in the respective muffin tin spheres are given. The present investigation reveals that the interactions between the non-metal p-orbitals and the uranium f- and d-orbitals constitute the main bonding components in UTe and UBi.