Stannous Research Articles

Sn/Pb ratio variation in spherical structures deposited on silicon surface using plasma focus

The deposition of Sn and Pb elements on top of Si surface was realized using plasma focus device. Due to the special characteristic of this type of plasma, the silicon substrate is heated by the bombardment of plasma ions, before the deposition of these elements sputtered from the anode. The deposition of the two elements was found to be influenced by substrate-anode distance as a consequence of surface heating. It was found that the relative amounts between the two deposited elements was not the same as their original ratio in the anode before sputtering. The ratio between Sn and Pb varies with increasing depth into the SnPb deposited on the Si substrate. Additionally, the size of micro spherical structures formed on the surface affected the ratio of the two deposited elements. The variation of the ratio is explained as result of deposition/evaporation competition influenced by the surface heating.

Dye‐linked Upconverting Nanophosphor‐based Ratiometric Chemosensor for NIR‐excited and FRET‐mediated Ultrasensitive Detection of Sulfide Ions

AbstractIn this article, a NIR‐excited ratiometric method for selective and ultrasensitive detection of sulfide (S2−) ions in an aqueous environment is presented, which is reliant on fluorescence resonance energy transfer (FRET). The chemosensor‐design is based on an upconverting nanophosphor (UCNP)‐linked coloured complex between a rhodamine‐B derivative and stannous ions (RBD‐Sn2+). Under the excitation of NIR light, the green emission of UCNP (at 542 nm) is reabsorbed by the linked RBD‐Sn2+ complex via FRET, which in turn emits in the orange (at 582 nm). S2− ions specifically interact with the linked RBD‐Sn2+ complex and quantitatively bleach its colour, leading to reduction in FRET and consequent recovery of the green emission of UCNP. We investigated the quantitative and ratiometric detection of S2− ions in aqueous phase using this NIR‐excited FRET‐based approach. The concentration of S2− ions is quantitatively connected to the ratiometric emission signal under NIR excitation. We have found that the detection limit for S2− ions using our FRET‐based nanoprobe is around ten times lower than that of colorimetric or fluorescence‐based approaches. Owing to the use of NIR‐light as excitation source, our proposed sensor can demonstrate background‐free sensing of S2− in complex environmental and biological samples.

Evolution of magmatic sulfide of the giant Jinchuan Ni-Cu deposit, NW China: Insights from chalcophile elements in base metal sulfide minerals

Chalcophile elements differentially distributed among base metal sulfides (BMS) and other discrete minerals are useful for assessing the evolution of magmatic sulfides. The world-class Jinchuan Ni-Cu sulfide deposit is composed of the western and eastern intrusions, but the differences in the distribution of chalcophile elements among BMS between two intrusions have not been well investigated. This study provides new data of in-situ chalcophile elements and platinum-group minerals (PGM) hosted in BMS of two intrusions, and discusses the discrepancy of chalcophile elements distribution and sulfide melt evolution. The variations of all compatible elements (Re, Co, Os, Ir, Ru, and Rh) and most incompatible elements (Pt, Ag, Zn, Cd, As, Sn, Sb, and Bi) in BMS versus whole-rock (Pt + Pd)/(Ir + Rh + Rh) ratios suggest these chalcophile elements were fractionated by progressive crystallization of the sulfide melt. Micro-textures of PGM suggested that (Ir-Rh-Pt)AsS crystallized almost simultaneously with the monosulfide solid solution, and Pd-semimetal minerals crystallized after the loop-textured pentlandite. As for the same type of sulfide mineralization, the contents of chalcophile elements in BMS minerals of the western intrusion are generally higher than those in BMS minerals of the eastern intrusion, which is consistent with the whole-rock variations. However, chalcopyrite of the eastern intrusion hosts significantly higher proportions of Pd and Te than chalcopyrite of the western intrusion with comparable amounts of Pd-semimetal micro- and nano-particles, indicating the diffusion of Pd and Te during the peritectic reactions in the eastern intrusion was inhibited. In terms of the negative correlation between Metal/S ratios of pyrrhotite and elemental ratios of Pd and Te between pentlandite and chalcopyrite, it is likely attributed to the lower sulfur fugacity (fS2) in the eastern intrusion which has been quantitatively calculated by pyrrhotite composition. We propose schematic models of the crystallization history of sulfide melts at Jinchuan, in which fractional crystallization of sulfide melts, crystallization of PGM and other discrete minerals, and formation of loop-textured pentlandite jointly control the distribution of chalcophile elements. The difference of fS2 between western and eastern intrusions resulted in the differential diffusion of Pd and Te from fractionated sulfide melt into loop-textured pentlandite.

Superelastic metastable Ti-Mo-Sn alloys with high elastic admissible strain for potential bio-implant applications

The demand for titanium alloys simultaneously having high elastic admissible strain and large recovery strain for bio-implant applications is increasing. Ni-free Ti-based shape memory alloys are promising candidates for obtaining the required multifunctional properties. In this study, a wide content range of (0–15)wt% of low-cost, toxicity-free, and high-biocompatible Sn element was added to the Ti-8Mo (wt%) alloy to study its effect on the superelastic recovery and mechanical properties of biomedical Ti-Mo-Sn alloys. By tailoring Sn content, desired multifunctional properties of high elastic admissible strain and room temperature superelasticity were achieved in the studied Ti-Mo-Sn alloys. It was found that the increase in Sn content stabilized the β phase and a single β phase was obtained at room temperature in Ti-8Mo-(13, 15)Sn alloys. The addition of Sn modified the lattice parameters of the α″ martensite and β phase and affected the lattice deformation stain of β → α″. The lattice deformation strain along the [011]β direction was found to be decreased by –0.26%/wt% Sn. The room temperature superelasticity with a recovery strain of 3.1% and an elastic admissible strain of 1% was obtained in the Ti-8Mo-13Sn alloy. As Sn content increased to 15 wt%, a high elastic admissible strain of 1.56% and a recovery strain of 2.0% were obtained. These Ti-Mo-Sn alloys with excellent multifunctional properties are promising candidates for bio-implant applications.

A multi-analytical approach to studying the chemical composition of typical carbon sink samples

Peatlands in southern South America (Tierra del Fuego region, TdF) play a key role in the ecological dynamics of Patagonia. It is, therefore, necessary to increase our knowledge and awareness of their scientific and ecological value to ensure their conservation. This study aimed to assess the differences in the distribution and accumulation of elements in peat deposits and Sphagnum moss from the TdF. Chemical and morphological characterization of the samples was carried out using various analytical techniques, and total levels of 53 elements were determined. Furthermore, a chemometric differentiation based on the elemental content of peat and moss samples was performed. Some elements (Cs, Hf, K, Li, Mn, Na, Pb, Rb, Si, Sn, Ti and Zn) showed significantly higher contents in moss samples than in peat samples. In contrast, only Mo, S and Zr were significantly higher in peat samples than in moss samples. The results obtained highlight the ability of moss to accumulate elements and to act as a means to facilitate the entry of elements into peat samples. The valuable data obtained in this multi-methodological baseline survey can be used for more effective conservation of biodiversity and preservation of the ecosystem services of the TdF.

The chemometric study of multi-elemental composition in cultivated rhubarb from Iraq Kurdish Region and Türkiye Siirt

ABSTRACT The concentrations of 30 elements (Li, Be, B, Na, Mg, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Sn, Sb, Ba, La, Ce, Pt, Tl and Pb) in cultivated stems of rhubarb samples collected from the Kurdish region of Iraq (Sor, Rash, Karajar, Gara and Qalandar) and the Siirt region of Turkey (Pervari and Şirvan) were determined by Inductively Coupled Plasma – Mass (ICP-MS) spectrometry after acid digestion by a microwave digestor (Berghof Speedwawe MWS-3). The analysis revealed that the levels of Mg, K and P in the samples found were higher than other metals. Conversely, the presence of metals such as Pt, Tl, Be and Ar was found to be at significantly lower concentrations. The levels of the elements determined in the cultivated rhubarb samples were subjected to chemometric analysis using correlation analysis, principal component analysis (PCA) and cluster analysis (CA) techniques for the classification of metal content and the places of samples. Linear correlation coefficient values representing the element-to-element correlation data were analysed at the 95% and 99% confidence levels. The results of the study showed that the rhubarb samples could be classified into three groups based on their elemental compositions, using the PCA method. These findings were found to be consistent with the results obtained through cluster analysis (CA). This suggests that the chemometric techniques used in this study are effective for identifying patterns and relationships in complex datasets and could be useful for analysing other samples and identifying their origins. Overall, this study provides important insights into the elemental composition of Rhubarb samples and could have implications for food safety and quality control.

Snx-0MnxS nanomaterial based electrodes for future-generation supercapacitor and data storage devices

In In this article, Mn-doped Snx-0MnxS (XMn = 0 – 9 %) were synthesized by solvothermal method and named MN1, MN2, MN3, MN4, MN5 and MN6 nanoparticles (NPs), respectively. The X-ray diffraction confirmed the single-phase orthorhombic crystal structure of MN1, MN2, MN3, MN4, MN5 and MN6 NPs. The FT-IR results showed a slight shift of the Sn-S stretching vibration towards the lower wavenumber from MN2 to MN5 NPs. The ball-like spherical shapes were observed in SEM and TEM images. The XPS spectrum of MN2 NPs confirms the binding energies of Sn, S, and Mn. EDX spectrum confirms the Sn, S and Mn elements in different ratios. To explore potential applications for supercapacitors (SCs), the nanospheres of MN1, MN2, MN3, MN4 and MN5 electrodes were used to check their Cyclic voltammograms (CV) and Galvanostatic charge-discharge (GCDs) measurements in a three electrode system in an aqueous solution of 2 M KOH. The increase in the specific capacitance values of MN1 electrode from 9 to 30 (F/g) with Mn dopant ratifies that external impurities have improved the electrochemical properties of pure SnS NPs and becomes an alternative source for energy storage devices. The magnetic performance recorded by VSM measurements demonstrated room temperature (RT) ferromagnetism and doping Mn ions induces alteration of ferromagnetism and therefore suggests potential applications in the data storage devices.

Mechanically Interlocked Vitrimer Based on Polybenzoxazine and Polyrotaxane

A mechanically interlocked vitrimer (MIV) based on a benzoxazine monomer and polyrotaxane (PR) has been prepared through a mechanically interlocked network (MIN) and dynamic covalent bond chemistry. The dynamic transacetalation exchange through the N,O-acetal-type polybenzoxazine (PBz) structure was catalyzed by a tin compound. Compared to the controlled PBz vitrimer without a MIN, the designed PBz MIV shows enhanced mechanical performance including ductility and tensile strength while maintaining relatively high Young’s modulus and glass transition temperature (Tg). The PBz MIV can be reprocessed several times without compromising mechanical performance and thermal stability. The PBz MIV also exhibits a faster dynamic bond exchange and a lower activation energy compared to the controlled PBz vitrimer due to the mobile intramolecular motions of PR in the network allowing for a dynamic bond exchange in the MIV more readily. The usefulness of the present study for the preparation of high-performance eco-friendly thermosetting vitrimers is discussed.

Turning waste into profit: Circular economic optimization of quartz sand from tin mining and processing

This paper analyzes whether the mining industry can apply circular economy principles in its investment, using two business scenarios of the circular economy. Scenario A utilizes quartz sand from tin mining residues and then processes it into concrete sand. Meanwhile, Scenario B is similar to Scenario A in the first stage, but the residue produced from the first stage is reprocessed to produce concrete sand. To compare the economic feasibility of both scenarios, this study applies a discounted cash flow technique and an incremental analysis. Material flow analysis investigates the circularity and productivity from resource utilization in every design. The two business scenarios are economically viable, but Scenario B is better than Scenario A. NPV of Scenarios A and B are US$ 513 thousand and US$ 322 thousand, respectively. The NPVB-A is US$ 147, whereas the IRR of Scenario A is 26.24 % and Scenario B is 34.05 %. The circularity of Scenarios A is 0.86 with a productivity of US$1.62/m3, and the circularity of Scenario B is 0.94 with a productivity of US$1.80/m3. Therefore, Scenario B is more efficient than that of Scenario A. Eventually, implementations of the circular economy principles in the mining industry are possible. These results can become a consideration for investors to innovate through circular economy approaches in their mining business for sustainable production and consumption purposes.

Low-Cost Tin Compounds as Seeds for the Growth of Silicon Nanowire–Graphite Composites Used in High-Performance Lithium-Ion Battery Anodes

Nanostructured silicon–graphite composites range among the best options for achieving next-generation high-energy anodes for high-performance lithium-ion batteries. Growing silicon nanowires on graphite give access to composites with high capacity and stability, as the silicon distributes homogeneously in the electrode, and the direct contact provides enhanced mechanical stability even in silicon-rich (>25 wt %) active materials. However, the cost-effective production of such composites remains a challenge. Here, we introduce low-cost catalysts, tin sulfide and tin oxide, enabling silicon nanowire growth at a lower temperature than with widely used gold catalysts, and investigate their impact on the composite nanostructure and composition. The small difference detected in the composition of the products obtained with both catalysts required the development of a reliable method to measure the low-level oxygen content and distribution within the composite. It revealed that oxygen from the SnO2 growth seeds is incorporated into the silicon nanowires, while no sulfur from the SnS catalyst could be detected. We show that SnS seeds result in an anode material of superior initial Coulombic efficiency of 81%, while capacity, stability in cycling, and rate capability are less affected by the choice of the catalyst. The composite anodes, optimized for a capacity of 1000 mAh g–1 at C/5 rate, deliver an areal capacity of up to 3.6 mAh cm–2 and 82% capacity retention over 200 cycles. Their rate capability of 780 mAh g–1 at 5C surpasses that of gold-seeded silicon–graphite composites. The insight obtained from this study provides guidance for the reliable low-cost synthesis and quality control of silicon-containing active materials for Li-ion battery anodes.

Mechanical Properties of the (81Sn–xCu–(19-x) In) % Alloys with x=1, 2, 3, 4, and 5

Research on Material Science has a long tradition, and lead has been used widely in many applications. Because of their low melting temperatures, low cost, and good wettability, tin -lead alloys have been preferred as solder alloys in industrial production, particularly in the electronics sector. However, due to the negative effects of lead on the environment and human health, studies on lead-free solder alloys have been increasing, and the subject is still important today. Furthermore, environmental protection agencies (RoHS and WEEE) have prohibited the use of lead-containing solder alloys in the manufacture of electronic and microelectronic products. In this work, the effect of adding Cu to alloys in five compositions of (81Sn-xCu-(19-x)In) % with x=1, 2, 3, 4, and 5 on the mechanical properties has been studied. The five samples were prepared from high purity (99%) elements (Sn –Cu –In ) using the melting technique. The creep of the ternary alloys was examined at different temperatures (25, 50, and 80 ) under three different loads (2.5, 6.3, and 11.4 MPa). It was found that the creep rate of the ternary alloys was increasing with the increases in Cu –content in all samples at different temperatures and loads. The mean values of the stress exponent were found to be in the range of (0.1-2.5) as well as the activation energies vaied in the range of (0.48-5.33) eV for all alloys under different loads (2.5, 6.3, and 11.4 MPa).

Bifunctional Hole-Transport Materials with Modification and Passivation Effect for High-Performance Inverted Perovskite Solar Cells.

Hole-transport materials (HTMs) play an important role in perovskite solar cells (PSCs) to enhance the power conversion efficiency (PCE). The innovation of HTMs can increase the hole extraction ability and reduce interfacial recombination. Three organic small molecule HTMs with 4H-cyclopenta[2,1-b:3,4-b']dithiophene (CPDT) as the central unit was designed and synthesized, namely, CPDTE-MTP (with the 2-ethylhexyl substituent and diphenylamine derivative end-group), CPDT-MTP (with the hexyl substituent and diphenylamine derivative end-group), and CPDT-PMTP (with the hexyl substituent and triphenylamine derivative end-group), which can form bifunctional and robust hole transport layer (HTL) on ITO and is tolerable to subsequent solvent and thermal processing. The X-ray photoelectron spectroscopy (XPS) results proved that CPDT-based HTMs can both interact with ITO through the nitrogen element in them and the tin element in ITO and passivate the upper perovskite layer. It is worth noting that the champion efficiency of MAPbI3 PSCs based on CPDT-PMTP achieved 20.77%, with an open circuit voltage (VOC) of 1.10 V, a short-circuit current (JSC) of 23.39 mA cm-2, and a fill factor (FF) of 80.83%, as three new materials were introduced into p-i-n PSCs as dopant-free HTMs.

Synergistic effect of residual elements on oxidation rates and oxide/metal interface characteristics in a low-carbon steel oxidized at 1180°C for 3 hours

ABSTRACT Residual elements (Cu, Ni and Sn) of various contents have been added to a low-carbon steel to simulate the scenario of increased use of scrap during steel production. The samples were oxidized in air to represent reheating before hot rolling, using thermogravimetry analysis (TGA). Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were employed to investigate the microstructure and the enrichments at the oxide/metal interface. Results showed the residual elements had an impact on the roughness of the scale/metal interface, internal Fe oxides formation, the amount of Ni&Cu enriched Fe phase and Cu&Sn enriched liquid phase at the interface, and the depth and spacing of the liquid phase penetrations along the grain boundaries. Thermodynamic simulation predicted the effect of residual elements on liquid phases formation at the interface, with good agreement between prediction and experimental results. The influence of residual elements on the oxidation rate was discussed.

Mechanism of incipient annular corrosion of high-tin bronze in simulated soil solution

ABSTRACT The mechanism of Cu–Sn–Pb bronze (18.2 wt-% Sn) in a simulated soil solution was examined using optical microscopy, scanning electron microscopy, scanning Kelvin probe, X-ray photoelectron spectroscopy, X-ray diffraction and electrochemical techniques. The findings demonstrated that the α-phase possessed a more negative corrosion potential, and the central annular position was more active owing to the difference in the solid-solution tin content during casting. Cl− was not directly involved in the production of corrosive products in the early stage of corrosion, but it damaged the copper oxide layer and promoted the loss of copper ions. Subsequently, the tin oxide was gradually produced on the surface, and the selective copper dissolution led to abundant tin compounds on the surface.

Effect of Sn and Zn alloying with Al on its electrochemical performance in an alkaline media containing CO2 for Al-air batteries application

Aluminum alloyed with other metals, such as Sn and Zn, was synthesized via fusion to trace the impact of alloying elements on the electrochemical characteristics of Al anodes. The corrosion inhibition and electrochemical tests were performed in a 5 M KOH medium in the absence and presence of CO2 for the Al–Sn, and Al–Zn anodes and compared to the commercial aluminum. Tafel polarization exhibited that the anodic and cathodic branches display lower current densities than Al metal in pure KOH. The steady state of the open circuit voltage (Ecorr.) for the studied alloys was shifted to a more negative magnitude than for Al. The corrosion current is sharply decreased, and potential is significantly shifted to less negative values in the presence of CO2. This is due to forming of a protective layer from the carbonate of Al, Sn, and Zn on the surface. Amazing results were obtained and discussed in the case of CO2. Electrochemical impedance spectroscopy (EIS) results exhibited that charge transfer resistance (Rct) values rise with alloying elements. The data of Tafel plots are consistent with those of EIS. The alloying of Al with Sn and Zn elements significantly affects capacitance, hydrogen evolution process suppression, and charge-discharge efficiency. This reveals that the highest potential value in the presence of CO2 in the charging process is obtained for Al–Zn alloy, while the most negative potential is obtained for Al in the discharging process with CO2. Moreover, the discharge time is higher in the alloys than in commercial Al in the absence and more in the presence of CO2. The produced alloys are thought to provide good anodes for long-life rechargeable batteries.

Preparation of Nanostructured Sn/Ti Oxide Hybrid Films with Terpineol/PEG-Based Nanofluids: Perovskite Solar Cell Applications.

Tin oxide (SnO2) and titanium dioxide (TiO2) are recognized as attractive energy materials applicable for lead halide perovskite solar cells (PSCs). Sintering is one of the effective strategies for improving the carrier transport of semiconductor nanomaterials. Using the alternative metal-oxide-based ETL, nanoparticles are often used in a way that they are dispersed in a precursor liquid prior to their thin-film deposition. Currently, the creation of PSCs using nanostructured Sn/Ti oxide thin-film ETL is one of the topical issues for the development of high-efficiency PSCs. Here, we demonstrate the preparation of terpineol/PEG-based fluid containing both tin and titanium compounds that can be utilized for the formation of a hybrid Sn/Ti oxide ETL on a conductive substrate (F-doped SnO2 glass substrate: FTO). We also pay attention to the structural analysis of the Sn/Ti metal oxide formation at the nanoscale using a high-resolution transmission electron microscope (HR-TEM). The variation of the nanofluid composition, i.e., the concentration of tin and titanium sources, was examined to obtain a uniform transparent thin film by spin-coating and sintering processes. The maximum power conversion efficiency was obtained for the concentration condition of [SnCl2·2H2O]/[titanium tetraisopropoxide (TTIP)] = 25:75 in the terpineol/PEG-based precursor solution. Our method for preparing the ETL nanomaterials provides useful guidance for the creation of high-performance PSCs using the sintering method.

Combining x-ray real and reciprocal space mapping techniques to explore the epitaxial growth of semiconductors

In the present work, the importance of determining the strain states of semiconductor compounds with high accuracy is demonstrated. For the matter in question, new software titled LAPAs, the acronym for LAttice PArameters is presented. The lattice parameters as well as the chemical composition of Al1−x In x N and Ge1−x Sn x compounds grown on top of GaN- and Ge- buffered c-Al2O3 and (001) oriented Si substrates, respectively, are calculated via the real space Bond’s method. The uncertainties in the lattice parameters and composition are derived, compared and discussed with the ones found via x-ray diffraction reciprocal space mapping. Broad peaks lead to increased centroid uncertainty and are found to constitute up to 99% of the total uncertainty in the lattice parameters. Refraction correction is included in the calculations and found to have an impact of 0.001 Å in the lattice parameters of both hexagonal and cubic crystallographic systems and below 0.01% in the quantification of the InN and Sn contents. Although the relaxation degrees of the nitride and tin compounds agree perfectly between the real and reciprocal-spaces methods, the uncertainty in the latter is found to be ten times higher. The impact of the findings may be substantial for the development of applications and devices as the intervals found for the lattice match the condition of Al1−x In x N grown on GaN templates vary between ∼1.8% (0.1675–0.1859) and 0.04% (0.1708–0.1712) if derived via the real- and reciprocal spaces methods.

Pyrite Textures and Compositions in the Dunbasitao Gold Deposit, NW China: Implications for Ore Genesis and Gold Mineralization Processes

The process and mechanism of gold mineralization are frontier issues. The Dunbasitao deposit is the most important gold deposit discovered along the Armantai suture zone, East Junggar, NW China, which indicates the potential for future ore exploration in this area. Orebodies are mainly hosted in Lower Carboniferous Jiangbasitao Formation volcano-sedimentary rocks, and the ores are characterized by multistage pyrites. Based on microscopy and backscattered electron imaging studies, pyrites are classified into five types: the pre-ore framboidal/colloidal Py0; the early-stage coarse-grained, cubic, and homogeneous Py1; and the middle-stage fine-grained, cubic/pyritohedron Py2 that includes Py2a (core), Py2b (mantle), and Py2c (rim). The results of the EPMA and in situ LA-ICP-MS analyses show that trace elements of pyrite mainly occur in two forms: solid solutions and invisible or visible inclusions. Mn, Co, Ni, and As enter the pyrite lattice, whereas Ti occurs as mineral inclusions, and Au, Cu, Zn, Sb, and Pb can occur in both forms. Au and As show a positive linear relationship with r = 0.850. Py2b has much higher Au contents (20.1 to 201 ppm) than other pyrite types (Py0: 0.01 to 0.36 ppm; Py1: 0.01 to 0.02 ppm; Py2a: 0.31 to 2.48 ppm; and Py2c: 0.18 to 18.0 ppm). The Dunbasitao deposit is classified as an orogenic gold deposit using the two latest machine learning classifiers based on pyrite trace element data. Fluid immiscibility, sudden cooling, and the substitution of S1− with As1− might be crucial mechanisms leading to Au precipitation. Initial ore-forming fluids brought major amounts of As, Au, Co, Ni, Se, Zn, Ag, Cd, Sn, and other elements, and the Jiangbasitao Formation host rocks contributed a certain amount of As, Ni, Cu, Sb, Pb, and Bi, at least.

Human health risks associated with trace metals in dust of residential arid areas

Composite dust samples were collected on a monthly basis over a full year from Doha, Qatar. Inductively Coupled Plasma Mass Spectrometry (ICPMS) was used for the determination of total concentrations of Na, K, Mg, Ca, Li, Be, B, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Se, Sr, Cd, Ba, Al, Pb, Ag, TI, U, Sb, Si, Sn, Mo and Bi. A combined approach, merging conventional sampling and analysis with subsequent numerical calculations of the risk of exposure to toxic elements, was employed. For assessment of the health risks associated with the regular exposure to dust, the exposure routes related to the dermal contact and inhalation were considered. Our results indicate that the total non-carcinogenic health risk through exposure to different elements (Hazardous Quotients, HQ's) that are contained in the dust are quite low (well below unity) for both dermal contact and inhalation routes in all months of the year, i.e., there is no risk to the human health. There is no clear explanation for the seasonal variation of metals in the dust in the Qatar area. Several elements in the dust collected in the summertime have higher concentration than in the wintertime. This could be due to the weather conditions and natural depositions. However, the content of several elements (Pb, Zn, Cu, Sn and Li) showed elevation in the wintertime. For dermal exposure, the dominant contribution to the Hazardous Index (HI) comes from thallium (Tl) while for inhalation exposure several comparable contributions are related to Mn, Sb, Si, Ni, and Co. Long-term monitoring strategies are still needed for detailed research on dust pollutants and potential risks.

Tailoring precipitates in Mg–12Gd-3Y alloys by Sn addition to obtain superior elevated temperature mechanical properties

The precipitation phase was tailored by adding different Sn contents to the Mg-12Gd-3Y alloy to achieve multiphase composite strengthening. Adding different Sn contents has different effects on the microstructure and mechanical properties. Adding 1.0 wt% Sn to the Mg-12Gd-3Y alloy produced Mg5RE, Sn3RE5, and β′ precipitates, which were uniformly diffusely distributed within the alloy. When Sn elements were added up to 1.5 wt%, Mg5RE and Sn3RE5 precipitates increased and aggregated into lumps. The prepared Mg-12Gd-3Y-1.0Sn alloy exhibited excellent room and elevated temperature (ET) mechanical properties. The ultimate tensile strengths (UTS) of Mg-12Gd-3Y-1.0Sn alloy after extrusion and aging (E-A) treatment were 476, 415, 383 MPa at RT, 200 °C, and 250 °C, respectively. The fine grain size inhibits dislocation sliding, and the uniformly diffuse multi-scale phase structure inhibits the expansion of grain boundary cracks, resulting in excellent strength of Mg-12Gd-3Y-1.0Sn at room temperature (RT). The excellent ET strength of the Mg-12Gd-3Y-1.0Sn alloy is derived from the homogeneous diffusion of multi-scale heat-resistant precipitates within the alloy.