High Sn Content Research Articles

Mixed metal halide perovskite CsPb1-xSnxBr3 quantum dots: insight into photophysics from photoblinking studies.

Mixing different metal ions at the B site of ABX3 perovskites offers a promising approach for addressing challenges related to toxicity, stability and performance in optoelectronic applications. One such example is CsPb1-xSnxBr3 which addresses the toxicity issue posed by lead while allowing us to tune optoelectronic properties such as the band gap. In this work, nearly monodisperse CsPb1-xSnxBr3 quantum dots (QDs) were synthesized with variable Pb/Sn compositions, i.e. CsPbBr3, CsPb0.9Sn0.1Br3 and CsPb0.7Sn0.3Br3. The photoluminescence quantum yield (PLQY) of CsPb1-xSnxBr3 first increases for x = 0.1 and then decreases for x = 0.3 with respect to x = 0. Such an effect of Sn incorporation on the PLQY was investigated using photoblinking studies which revealed three levels of blinking statistics namely ON, GRAY and OFF. These results along with the excited state lifetime measurements enabled us to understand charge carrier dynamics in the CsPb1-xSnxBr3 QDs. Based on our findings, we propose that the photogenerated hot electrons of Sn enhance the PLQY by filling the trap states centered on Pb, which otherwise promote non-radiative relaxations in the Sn-free CsPbBr3. However, at higher Sn concentrations, non-radiative recombination becomes more pronounced, reducing the PLQY.

Evolution of a seafloor massive sulfide deposit on axial volcanic ridges: a case study of the Duanqiao hydrothermal field, Southwest Indian Ridge

The mineralization process below the surface of the seafloor in a hydrothermal field has an important influence on the distribution and enrichment of elements. The Duanqiao hydrothermal field (DHF) is located on the new axial volcanic ridge of the ultraslow-spreading Southwest Indian Ridge. Owing to the limited surface sulfide samples, the metallogenic processes occurring below the seafloor surface such as the element enrichment mechanism and the temporal evolution of the sulfide deposits remain unclear. In this study, we conducted mineral texture, geochemical, 230Th/U dating, and laser ablation inductively coupled plasma mass spectrometer analyses of a drill core containing shallow sulfide deposits to study their evolution process. The results revealed that pyrite is enriched in Mn, Co, As, Mo, Ag, Cd, Sb, Tl, and Pb, chalcopyrite is characterized by high concentrations of Se, Sn, In, As, Ag and Pb, and sphalerite is enriched in Co, Ga, Ge, As, Ag, Cd, Sb, and Pb. The 230Th/U dating data suggested five different mineralization periods during 4,552–2,297 years. Apart from the top and bottom, the core exhibited obvious characteristics of gradual accumulation of mineralization. Results revealed that the variations in the elemental contents of different layers and different types of pyrite were controlled by the interaction of seawater and hydrothermal fluids within the sulfide mound over five different mineralization periods. Compared with other hydrothermal fields on other mid-ocean ridges, DHF pyrite is generally enriched in Zn, Pb, As, Ag, Cd, Mo, and Sb, which might reflect shallow subsurface mixing during different periods of hydrothermal activity.

ELECTROCHEMICAL CORROSION EVALUATION OF SnSb ELECTRODEPOSITED COATINGS

SnxSb(1−x) coatings were electrodeposited from 1ChCl:2EG on copper. The corrosion resistance of the electrodeposits was evaluated in 0.1 mol dm-3 of NaCl. The characterization was performed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Voltammetric profiles showed that the electrodeposition potential shifted towards less positive values with increasing Sb3+ concentration. SEM images revealed that the coatings exhibited grains and clusters. EDS analyses showed that the Sb content increased with the Sb3+ concentration. XRD results indicated the formation of the SbSn phases such as Cu2Sb, Cu6Sn5, and Cu6(Sn,Sb)5. The potentiodynamic polarization (PP) curves showed that Sn and Sn77Sb23 presented a passive potential region, while Sn37Sb63 had an active dissolution in the electrolyte. Immersion tests were performed for 24 h and XRD results revealed Cu, Sn, SnO, SbSn and Sb2O4 phases. Considering 48 h, Cu, CuSn, SnO2 and SnSb phases were identified. The polarization resistance values of 4.60, 14.69 and 1.81 kΩ cm2 were achieved for Sn, Sn77Sb23, and Sn37Sb63, respectively. The EIS results suggested that adding Sb3+ improves corrosion resistance for SnSb samples with higher Sn content. For Sn77Sb23, the charge transfer resistance was 10.5 kΩ cm2, for Sn and Sn37Sb63 1.15 and 1.46 kΩ cm2, respectively.

In situ formed CuSn alloy from multivariate metal-organic frameworks for tunable CO2 electroreduction.

A molecular ligand separation method based on multivariate metal-organic frameworks (MOF) is developed to precisely regulate CuSn alloy for tuning the selectivity of HCOOH and CO in CO2 reduction. With this method, the agglomeration and heterogeneous nucleations of metals are effectively inhibited during the in situ electrochemical transformation of CuSn-MOFs into highly pure CuSn alloy. The low Sn content favors CO production, while the high Sn concentration facilitates HCOOH formation.

Comprehensive study on epitaxial growth of GeSn(111) layers with high Sn content on Si(111) featuring Ge buffer layer

Spin MOSFETs are attractive for new functional devices having both switching and memory functionalities. We focused on germanium tin (GeSn), which is a group-IV alloy semiconductor, for channel materials because they can be direct transition semiconductor with a sufficiently high Sn content and strain [1]. Direct transition nature will lead larger spin diffusion length and spin lifetime than those of germanium (Ge) because inter-valley scattering of electron can be suppressed at the conduction band of L points [2]. The objective of this study is to realize (111) orientated direct transition GeSn toward the epitaxial growth of Co-based Heusler alloy thin films, which are promising ferromagnetic electrodes for realizing highly efficient spin injections [3]. Theoretical calculation suggests that GeSn(111) can show the direct transition nature even at a lower Sn content under a biaxial compressive strain [2]. However, the growth and characterization of direct transition GeSn(111) epitaxial layers have not been achieved yet.In this study, we examined the pseudomorphic growth of compressively strained GeSn epitaxial layer on a strain-relaxed Ge buffer prepared on Si(111) substrate. After the chemical and thermal cleaning of Si(111) wafer, a Ge buffer layer was grown by the two-step growth method [4] using molecular beam epitaxy (MBE) system; a 100 nm-thick Ge layer was firstly grown at a low temperature (LT-Ge) of 320 °C and then a 300–900 nm-thick Ge layer was grown at a high temperature of 400 °C (HT-Ge). Subsequently, a 100 nm-thick GeSn layer with a Sn content of 8–9% was grown at 150 °C.The crystalline structure of Ge and GeSn layers was characterized using X-ray diffraction two-dimensional reciprocal lattice space mapping. All samples exhibit the complete strain-relaxation of the Ge buffer layers and the partly strain relaxation of GeSn layers on the Ge layers; the compressive strain to GeSn with a Sn content of 8–9% was estimated to an approximately 0.9–1.0%. Considering the theoretical estimation [3], the prepared compressively strained GeSn layers with a high Sn content are likely to become a direct transition semiconductor.Furthermore, the 𝜔-rocking curve for the GeSn layers revealed that the full-widths of half maximum (FWHM) decreases with increasing the HT-Ge thickness and FWHM was saturated for the samples with a HT-Ge thickness of 500 nm or greater. However, the samples with a HT-Ge thickness of 700 nm or greater showed a slight increase in the intensity at the tail region of the diffraction peak which related to the existence of low-crystalline-quality region. Therefore, the thickness of 500 nm for HT-Ge buffer layer was the optimum condition to achieve with the smallest FWHM and tail intensity in this study. In the presentation, the photoluminescence properties of GeSn layers will be also discussed.

A Computational Chemistry Study of the CVD Growth of Germanium-Tin Materials

Despite the expansion of GeSn and SiGeSn epitaxial growth research there remains only a small volume of work on fundamental CVD chemistry and kinetics for this material. There is a comparably large volume of work on the fundamental surface chemistry related to Si, Ge, and SiGe epitaxy, in both experimental and theoretical studies. There remain several open questions as to how exactly the chemical vapor deposition of GeSn occurs. Because of the low solubility of Sn in Ge, epitaxial growth typically must be done at temperatures < 400°C - and higher Sn contents can even require temperatures below 300°C. It has been a point of debate as to how the precursors GeH4, Ge2H6, and SnCl4 are able to react and sustain deposition at such low temperatures. In fact, the addition of SnCl4 acts to increase the growth rate beyond what can be achieved with GeH4 alone, when it is intuitively expected that the addition of Cl to the chemistry should decrease the growth rate. In this work a theoretical/computational chemistry exploration of the gas-phase and surface chemistry of GeH4 and SnCl4 on Ge and GeSn surfaces is presented. Molecular orbital DFT was used, in-which the semiconductor surfaces are approximated as clusters to reduce the computational cost relative to plane-wave DFT methods. The Gibbs free energy changes at 325°C, ΔGr, and kinetic activation barriers, Ea, for relevant gas-phase and surface reactions were calculated.An analysis of possible gas-phase reactions reveals that GeH4 and SnCl4 have dissociation barriers of Ea = 237 kJ/mol and 305 kJ/mol respectively. However, they readily undergo H/Cl exchange reactions of the form GeH4 + SnCl4 → SnHCl3+ GeH3Cl. This reaction is found to be thermodynamically favorable with ΔGr = -18 kJ/mol with a relatively low activation barrier of Ea = 139 kJ/mol. The products SnHCl3 and GeH3Cl are much more reactive than the starting precursors and readily dissociate into SnCl2 and GeHCl with Ea = 168 kJ/mol and 190 kJ/mol. At typical growth temperatures it is expected that most surface sites will be H or Cl terminated such that the removal of adsorbed H and Cl to generate open surface sites is the kinetically limiting factor. On the Ge-Ge surface we find an interdimer H2 desorption Ea = 215 kJ/mol, and on a Ge-Sn surface dimer we find the H2 interdimer desorption Ea = 184 kJ/mol. This result may at least partially explain the growth rate enhancement of GeSn relative to Ge, however large surface-Sn concentrations would be required to produce a growth rate enhancement. Sub-surface Sn incorporation was found to reduce the interdimer H2 desorption barrier from two surface Ge atoms to a value of Ea = 207 kJ/mol. This result suggests that Sn can increase the H desorption rate non-locally via strain and or electronic effects, however the change is minimal and cannot explain observed growth rate enhancements. A more likely explanation is that the generation of GeHCl allows for insertion reactions into the Ge-H surface bonds. Indeed, it is found that ΔGr = -87 kJ/mol and Ea = 45 kJ/mol for this insertion reaction. This theoretical activation barrier closely matches Arrhenius activation energy values reported from CVD growth studies. Therefore, the gas-phase reactions between GeH4 to SnCl4 to form more reactive intermediates appears to be the enabling factor in explaining the enhanced growth rates of GeSn relative to Ge. Figure 1

In-Situ n-Type Doped Carrier-Injection Layers in GeSn Direct Bandgap LEDs for Methane Sensing

GeSn-based group-IV alloys are attracting great attention in the Si photonics community, as they are considered to be compatible with Complementary Metal Oxide Semiconductor (CMOS) technology. Alloying germanium with more than 8% of tin (Sn) results in direct bandgap semiconductors, with some optical gain in devices such as lasers. Recently, room temperature optically pumped lasing was achieved thanks to high Sn content stacks. GeSn alloys can be used for near, short and mid wavelength infra-red spectral range operation, notably for gas detection. Current efforts are focused on electro-optical GeSn IR devices such as light-emitting devices (LEDs), electrically pumped lasers and photodetectors.In this paper, we evaluate the impact of various types of in situ n-type doped carrier injection layers on top of GeSn direct bandgap LEDs. More precisely, we compare the performances of GeSn:P and Ge:P –capped mid IR LEDs. Using reduced pressure chemical vapor deposition and metastable growth conditions (e.g. fast growth rates at low temperature), high crystalline quality GeSn layers were grown on 200 mm diameter Ge-buffered Si(001) wafers (Figure a). In situ n-type doped Ge layers (sample A) and GeSn layers (sample B) were used to inject carriers into direct band gap Ge0.87Sn0.13 active layers beneath (Figure b). I(V) curves (Figure c) and Electro-Luminescence spectra (Figure d) were compared for sample B (GeSn:P) and sample A (Ge:P). Very similar I(V) behaviors were observed under forward bias for both samples. However, a higher dark current was measured under reverse bias for sample B than for sample A. This could be due to a higher number of defects in the thicker capping layer of sample B (240 nm) compared to that of sample A (50 nm). However, a 2-fold increase in the EL signal was obtained for sample B than sample A (Figure d). Temperature dependence electroluminescence measurements and atom probe tomography data will be used to explain the electroluminescence behavior differences between Samples A and B.Finally, even higher Sn content LEDs were fabricated to emit light at 3.3 µm (Figure e). A direct band gap Ge0.846Sn0.154LED (Sample C) with an in situ n-type doped Ge cap was placed in a gas cell filled with diluted methane. Its emission overlapped well with the absorption of methane (Figure f). The methane detection limit of our setup was evaluated (data not shown). To further increase the emitted power of GeSn LEDs, current spreading was studied for different top contact geometries. Emission maps collected by an InSb camera at room temperature showed a definite dependence of light emission on electrical contact geometry (Figure g). Investigations are underway to further increase light extraction from LEDs and improve their performances for use in environmental sensors. Acknowledgement: This work was supported by the European Union’s Horizon 2020 LASTSTEP Project under the grant agreement ID: 101070208, the EDEN Carnot project and the CEA DRF-DRT Phare project. We gratefully acknowledge the clean room staff from LETI and IRIG for their technical support. Figure 1

Multiple generations of garnet and their genetic significance in the Niukutou cobalt-rich Pb-Zn-(Fe) skarn deposit, East Kunlun orogenic belt, western China

The Niukutou deposit, situated within the Qimantagh ore-concentrated area of the East Kunlun Orogenic Belt (EKOB), represents a typical skarn-type Pb-Zn-(Fe) deposit that is also associated with cobalt (Co) mineralization. The main ore minerals include galena, sphalerite, magnetite, hematite, Co-bearing arsenopyrite, cobaltite and glaucodot. This study conducted geochronological and chemical composition analyses of multi-generational garnets from the deposit, aiming to elucidate their genetic significance in the mineralization process. Field and mineralogical observations indicate the presence of three generations of garnets: Grt-I, Grt-II, and Grt-III. The earliest garnet generation (Grt-I) formed during the prograde stage, typically in garnet skarns, and is often replaced by epidote. The second generation (Grt-II), which coexists with pyroxene, also formed during the prograde stage, whereas the third generation (Grt-III) is associated with pyrrhotite stockworks, suggesting its formation during the sulfide stage. Using in-situ LA-ICP-MS U-Pb dating, garnets yield ages of approximately 230–234 Ma, which aligns with the age of 231.8 ± 7.5 Ma obtained from hydrothermal titanite in the deposit. These ages, combined with those of the previous studies, indicate major magmatic and metallogenic activity of 220–240 Ma in the Qimantagh area. Each generation of garnets displays oscillatory zoning characterized by alternating andradite and grossular compositions. The variations in Sn and high field-strength element (HFSE) contents across different garnet generations indicate an increasing trend in oxygen fugacity as mineralization progresses. The high Sn contents in the Niukutou garnets provide geochemical clues for the potential of Sn-W mineralization in this deposit, which should pay attention to in future exploration. Additionally, the high As concentrations in the Niukutou garnets suggest an As-rich hydrothermal fluid, which, owing to the stronger affinity of cobalt for sulfarsenides over sulfides, provides a geochemical indicator for the formation of abundant Co-bearing sulfarsenides rather than cobaltiferous sulfides in the deposit.

Fluid inclusion LA-ICP-MS constraint on hydrothermal evolution of proximal cassiterite-bearing quartz veins in the giant Gejiu orefield: Implications for controls on metallogenic potential of granite-related skarn system

Sn and Cu are proposed to have their mineralization potential predetermined by their contents in initial fluids of granite-related magmatic-hydrothermal systems. However, it remains ambiguous whether the giant Sn-mineralized skarn system is applicable, and whether the Sn-Cu association in some deposits is predominantly determined by their initial metal contents. The Gejiu orefield is one of the most essential Sn-polymetallic districts worldwide, with proven resources of 3.27 million tons of tin, 3.25 million tons of copper, 4.29 million tons of lead and zinc, and >20 other metals with economic significance. Sn-polymetallic mineralization at Gejiu constitutes a composite skarn ore system that includes proximal skarn and related cassiterite-sulfide, greisen, and tourmaline-vein types. The Laochang Sn-polymetallic deposit hosts several largest skarn and cassiterite-sulfide orebodies in the eastern part of Gejiu. Recent exploitation at Laochang discovered Sn-mineralized quartz veins hosted in the concealed granite, providing a valuable opportunity to characterize the proximal magmatic-hydrothermal process of the mineralizing granitic system. Here, fluid inclusion analysis is carried out on these veins to discuss the fluid evolution, cassiterite precipitation mechanism and whether metal content in early proximal magmatic fluids determines the metal association and endowment in the deposit.Based on the paragenesis of ore and gangue minerals, three hydrothermal stages are distinguished, including quartz-tourmaline stage (Stage I), cassiterite-arsenopyrite-quartz stage (Stage II) and late sulfide stage (Stage III). Fluid evolution controlling vein formation is constrained by microthermometry and LA-ICP-MS analysis of four fluid inclusions generations successively entrapped in quartz and cassiterite. The fluids involved during vein formation show an interplay between single-sourced magmatic fluids and meteoric water. The intermediate-density single phase fluid recorded at stage I quartz is derived from initial fluids directly exsolving from granitic magma. At stage II, fluid immiscibility occurred and the separated brines were entrapped in quartz and early-formed cassiterite. Along with cassiterite precipitation, brines were mixed with low-salinity and cooler meteoric water, leading to entrapment of low-salinity aqueous fluid in outer growth zones of cassiterite at stage II. The constructed fluid evolution history suggests that fluid immiscibility may have facilitated the nucleation of cassiterite crystals at the onset of deposition while mixing of magmatic fluid with meteoric water likely dominate later cassiterite mineralization.Compared with the fluid dataset of barren and mineralized granitic systems worldwide, pre-ore fluids of the studied quartz veins are enriched in Sn, confirming that high Sn content in the initial magmatic fluid can serve as indicator to distinguish mineralized system. In contrast, although Cu mineralization is economically important in the Laochang deposit, predicted Cu contents in pre-ore proximal magmatic fluids are as low as those obtained from Cu-barren system. This implies introduction of Cu into the hydrothermal system from other sources.

Mid-infrared silicon photonic lasers based on GeSn slab waveguide on silicon.

GeSn alloy has emerged as an attractive active material for Si-based mid-infrared (MIR) lasers due to its direct bandgap nature at higher Sn concentrations. Here, we report on an optically-pumped GeSn MIR lasers based on planar slab waveguide with a top Si ridge structure. The inclusion of 10% Sn transforms the GeSn active layer into a direct bandgap material. The Si ridge structure ensures appropriate optical confinements with reduced scattering loss from the waveguide sidewall. Lasing action was achieved under optical pumping with a low threshold of 60.85 kW/cm2 and an emission wavelength of 2238 nm at T = 40 K. Lasing action was also observed up to T = 90 K with a threshold of 170 kW/cm2.

Comprehensive study on epitaxial growth of GeSn(111) layers with high Sn content on Si(111) featuring Ge buffer layer

The study comprehensively discussed the crystalline properties of GeSn(111) epitaxial layers on Si(111) using Ge double buffer layers toward the formation of the direct transition GeSn(111) with a Sn content around 10%. We found that the introduction of Ge double buffer layers is rather effective to improve the crystallinity of GeSn(111) than the single buffer case. However, thicker Ge buffer layer degrades the crystallinity of GeSn(111) because the strain relaxation of GeSn layer is likely to occur. In this study, through optimizing the thicknesses of Ge buffer layers formed at low and high temperatures (LT-Ge and HT-Ge, respectively), it was clarified that 100 and 500 nm for LT- and HT-Ge thicknesses, respectively, are suited to realize a high quality GeSn(111). The grown GeSn(111) epitaxial layer includes a Sn content of ~8–11% with a compressive strain of ~1–2%, which is contained within the region of direct transition GeSn(111).

Comparison of GeSn alloy films prepared by ion implantation and remote plasma-enhanced chemical vapor deposition methods

Thin films of germanium-tin (GeSn) alloy with Sn content well above its equilibrium solubility limit in Ge are produced using both remote plasma-enhanced chemical vapor deposition (RPECVD) directly on silicon substrates and ion implantation of Sn into Ge. For RPECVD, the growth temperature of 302 °C resulted in fully relaxed GeSn alloys with high defect density, principally threading dislocations related to the large lattice mismatch between Si and GeSn. For the implantation case, pulsed laser melting was used to melt and crystallize the GeSn layer on a time scale of a few tens of nanoseconds. The resulting GeSn layers were also relaxed and defective, presumably again as a result of lattice mismatch with the underlying Ge lattice. However, the nature of the defects was quite different to the RPECVD method, whereby the line defects were not threading dislocations but stackinglike defects, which developed into arrays of these defects in the high Sn content region close to the surface. For the purpose of comparing RPECVD and ion-implantation methods, alloy films of similar thickness (400–450 nm) and Sn content (4.5–6.5 at. %) were examined. Film parameters (thickness, Sn content, Sn solubility, and segregation), as well as film quality and defect structures, were examined for both fabrication methods using several analytical techniques. This comparison provided us with a better physical understanding of our GeSn films and will help inform future growth/fabrication strategies targeted at minimizing defects formed in the GeSn films for the realization of optoelectronic devices.

Perhitungan Volume Stockpile dan Pengoptimalan Waktu Pengolahan Stockpile 3, 5 dan 6 Terhadap Produksi Alat Gali muat dan Alat Angkut pada TB Primer Batubesi PT Timah Tbk

PT Timah Tbk's Batubesi Primary Large Mine has experienced a significant decline in production in recent years, causing a change in the mining process to stockpile management that is still economical with a grade of 0.2%. This study aims to determine the volume and production of stockpiles 3, 5 and 6, the type of sediment and Sn content of stockpile material and the time required to spend stockpile material 3, 5 and 6 in order to get the optimal time. The method used is a quantitative method by taking cycle time data as much as 30 data and analyzing sample levels using XRF on each stockpile. The results of this study obtained the volume of stockpile 3 material is 132,648.42 m3,, stockpile 5 is 162,570.25 m3, and stockpile 6 is 33,090.19 m3. The calculated machine productivity at stockpile 3 is 42.17 tons/hour, stockpile 5 is 48.11 tons/hour and stockpile 6 is 39.53 tons/hour. The highest Sn content is found in stockpile 6 which is 0.33% with the type of skarn sediment. While the lowest Sn content is found in stockpile 3 which is 0.2% with oxide clay sediment type. In stockpile 5, the Sn content is 0.31% with the type of oxide clay sediment. The remaining volume of stockpile material in stockpiles 3, 5 and 6 can be spent with a time of 2.78 years using 1 unit of excavation equipment and 1 unit of transportation equipment. Optimization is carried out so that the remaining stockpile reserves can be spent within 1.74 years using 1 unit of excavation equipment and 2 units of transport equipment.

Magmatic–Hydrothermal Evolution at the Barren Wushan Pluton, Southeast China: Insight into Controls on Mineralization Potential

Abstract A-type granites typically exhibit enrichment and mineralization of critical metals such as molybdenum and tin, essential for emerging technologies. However, the key factors influencing their mineralization potential remain elusive. The scarcity of studies on barren systems impedes the understanding of this question. Here, a detailed melt and fluid inclusion study was conducted on the barren Wushan pluton to reconstruct its magmatic evolution and magmatic–hydrothermal transition and explore the factors controlling the metallogenic potential of Mo and Sn in A-type granites. The Wushan pluton displays apparent lithological zoning consisting of two major phases, i.e., medium-grained seriate to porphyritic alkali feldspar granite and fine-grained porphyritic granite. Miarolitic cavities are widely developed in each lithofacies. The silicate melt inclusions from two granitic phases are rhyolitic, with moderate F contents (0.06–0.53 wt %) and depleted H2O contents (2.0–3.5 wt %). Melt inclusions show a wide range of incompatible element contents, such as Cs (9–1977 μg/g) and Rb (268–2601 μg/g), suggesting that Wushan has undergone a high degree of magma evolution. Mo behaves incompatibly in the magmatic evolution, and its content is enriched with the increasing degree of fractional crystallization, but remains constant after the Cs content exceeds 50 μg/g. Rayleigh fractionation model suggests that a large amount of Mo is extracted from fluid exsolution, which restrains Mo from further enrichment. In contrast, Sn behaves as a mildly incompatible element during the entire magmatic evolution history. The contents of Sn increase slowly compared to the trend of Mo, and the maximum contents reach ~30 μg/g in the highly evolved melts. The separation and crystallization of Sn-bearing minerals such as biotite, magnetite, and titanite inhibit the enrichment of Sn. Intermediate-density (ID-type) fluid inclusions hosted in the miarolitic quartz, representing the initial fluid exsolving from magma, display high Mo but low Sn concentrations. Constrained from two assemblages of coexisting ID-type fluid and melt inclusions, the fluid/melt partition coefficients of metals are obtained, with DMo, fluid/melt at 16–19, while DSn, fluid/melt is only about 1. The comparison between Mo-mineralized and barren intrusions worldwide shows that the metal contents in melts and fluids are not fundamentally different. The mineralized intrusions are characterized by the lower melt viscosity and the development of apophyses, both of which facilitate the extraction of metals and fluids from large magma chambers, followed by their concentration into a small rock volume. Consequently, it appears that physical and structural conditions rather than chemical compositions play a crucial role in the Mo mineralization process. Enrichment of Sn in melts is necessary but not decisive for Sn mineralization, whereas Sn enrichment in the initial exsolving fluid determines the Sn mineralization potential of a given granitic system. Compared to Sn enrichment in source melting and fractional crystallization which commonly enhance final Sn fertility in the highly evolved melts, the efficiency of Sn partitioning between melt and fluid plays a fundamental role in converting melt fertility into Sn-enriched fluids and thereby high mineralization potential of the magmatic–hydrothermal system. Our findings suggest a prospect for Mo exploration in the coastal A-type granite belt in South China, while the potential for Sn mineralization is expected to be limited.

Mineralogy and 40Ar-39Ar dating of the recently discovered tainiolite occurrences in the Kaerqiaer fluorite Belt, western Altyn Tagh Terrane

The Kaerqiaer Fluorite Belt (KFB) contains the Kaerqiaer, Xiaobaihegou, Kumutashi, Northern Layidan, and Gaijike fluorite deposits in the western Altyn Tagh Terrane of NW China. An occurrence of Li-bearing mica tainiolite (KLiMg2(Si4O10) F2) has been recently discovered, associated with fluorite-bearing alkali feldspar granite. The tainiolite is hosted by fluorite-calcite veins that contain assemblages of tainiolite-fluorite-calcite and apatite-bastnaesite-tainiolite-fluorite-calcite along the contact zone with alkali feldspar granite. The tainiolite occurs as euhedral crystals and has high concentrations in the veins. 40Ar-39Ar dating of the tainiolite from Xiaobaihegou yields an age of 421 ± 2 Ma, and single-crystal X-ray diffraction confirms the tainiolite has a monoclinic 1 M−type with a C2/m (#12) space group. Minor structural variations in the mica are attributed to the substitution of Li for Mg. EPMA and LA-ICP-MS analyses show that the tainiolite has high Li, Rb, Cs, Sn and Nb concentrations, and low Ta, total REE concentrations. The average Li2O content of the fluorite-tainiolite veins reaches 0.36 %, surpassing the economic cut-off grade. We suggest that the fluorite deposits formed from highly fractionated Li-F-P-rich residual melt evolved from the parental magmas of alkali feldspar granite. The tainiolite mineralisation may result from subsequent hydrothermal activities caused by the reactivation of regional faults under the extensional regime between the Middle Altyn and Eastern Kunlun terranes. The discovery of tainiolite occurrences made KFB a potential area for not only F but also Li resources.

Growth of single-crystalline GeSn films with high-Sn content on InP substrates by sputtering and rapid thermal annealing

In this work, the polycrystalline GeSn film with Sn content of 25.3 % on InP is obtained by sputtering at room temperature and then rapid thermal annealing (RTA) at 300 ℃. The single-crystalline GeSn film with Sn content of 24.7 % on InP is obtained by sputtering at 200 ℃ and then RTA at 300 ℃. This indicates that the growth temperature is one of the key factors affecting the formation of single-crystalline films. The effects of the sputtering power and film thickness on the crystallization of the GeSn films are investigated. The competition between the spontaneous and substrate-induced crystallization of the films limits the preparation of single-crystalline GeSn films. The strain relaxation of the film (R = 69.3 %) is achieved by annealing. The device fabricated by the GeSn film exhibits a high response of 18.1 A/W @-1 V at room temperature with the 1550-nm-line excitation. These suggest that sputtering epitaxy can be an effective method for growing single-crystalline GeSn films with high-Sn content on InP substrates, which is of great significance for developing high-performance mid-infrared devices.

Investigation of sensing properties of Sn-doped NiO thin films for the detection of ammonia gas

In this study, we detail the fabrication of Sn-doped nickel oxide thin films using the spin-coating technique, elucidating the impact of Sn doping on structural, optical, and gas sensing properties. Systematic analysis via XRD, SEM, AFM, and UV–Visible spectroscopy delves into the structural and optical characteristics of the films. Notably, gas sensing capabilities, specifically towards NH3, are investigated. XRD analysis reveals the polycrystalline nature of NiO thin films, with crystallinity diminishing as Sn concentration increases. SEM and AFM analyses highlight a uniform film surface with spherical-shaped particles, and increased surface roughness with higher Sn content, a crucial factor for gas sensing applications. Raman analysis showcases first-order phonon modes of vibrations of Ni-O, while optical studies affirm the films' transparency in the visible wavelength. Notably, in ammonia gas sensing tests at room temperature, the 8 mol% Sn-doped NiO thin film exhibits an exceptional response of 3200 %, with a rapid 40-second response time and a 25-second recovery time at a 150 ppm concentration of ammonia gas. These findings suggest that Sn-doped NiO thin films hold promise as effective gas sensors for NH3 detection.

Simultaneously enhanced strength and elongation capacity in Cu–15Sn-0.3Ti alloy via regulation of IMCs

Due to the technical requirements of preparing Nb3Sn superconducting wires using the bronze method, the Cu–Sn–Ti alloy with high Sn content and matching mechanical properties with pure Nb as the substrate is the key to the smooth preparation of superconducting wires. However, the high content of Sn leads to the generation of a large number of intermetallic compounds (IMCs) in Cu–Sn–Ti alloy are the main reasons for the deterioration of the elongation and strength of Cu–Sn–Ti alloy. This work uses unidirectional solidification (US) and homogenization annealing (HA) methods to regulate the volume fraction and types of IMCs in Cu–15Sn-0.3Ti alloy. The volume fraction of IMCs decreases from 20.6 % to 0.1 % after HA, and the network δ phases (Cu41Sn11) transform to fine γ phase (Cu3Sn) and CuSn3Ti5. The ultimate tensile strength (UTS) and elongation of the samples treated with HA increase by 2000 % and 94 %, respectively, and deformation twins are found in the stretched samples. The research results indicate that the elongation and UTS of Cu–15Sn-0.3Ti alloy are improved by the decrease of IMCs volume fraction and deformation twins formed during the tensile process.

Tin contamination in sediments of Lake Zurich: source, spread, history and risk assessment.

Industrial activities of a silk dyeing factory in Thalwil, on the shore of Lake Zurich, Switzerland, caused extreme Sn contamination of lake sediments. In this study, we determine the contamination source, spread, and age using a multiproxy approach. We used X-ray fluorescence spectroscopy (XRF) core scanning and further geochemical analyses to assess the contamination spreading and thickness in the sedimentary column. We found elevated Sn levels throughout sediments of Lake Zurich, ranging from 177 in front of the former silk factory to 0.05 at the southeast end (background: ca. 0.006 ). The rapid concentration drop away from the shore suggests quick precipitation of a sparingly soluble inorganic Sn compound, which is confirmed by Scanning Electron Microscope Imaging in tandem with Energy-dispersive XRF spectroscopy (SEM-EDX) data. The Sn XRF profile of a varved core indicates a contamination onset in the early 1890s, a maximum around 1900, and a gradual decrease to low levels in the 1940s. High Sn concentrations in turbidite layers from the deep basin indicate that mass movements physically remobilised Sn. However, in stable conditions, in-situ porewater measurements (conc. < 0.5 ) using dialyse plates show little Sn remobilisation into the lake water (0.05 ). The low remobilisation, reducing conditions, and high sulphide contents in the contaminated layers suggest that Sn is firmly bound to the sediments. Combined with the low toxicity of Sn, we conclude that the Sn contamination poses no threat to lake biota or drinking water production. The online version contains supplementary material available at 10.1186/s00015-024-00471-6.

Cluster-doping in silicon nanocrystals.

Creating tin-alloyed silicon nanocrystals with tailored bandgap values is a significant challenge, primarily because a substantial concentration of tin is essential to observe useful changes in the electronic structure. However, high concentration of Sn leads to instability of the silicon-tin nanocrystals. This work introduces a completely new approach to doping and the modification of the electronic structure of nanoparticles by incorporating few-atom clusters in nanocrystals, deviating from isolated atom doping or attempting alloying. This approach is exemplified via a combined theoretical and experimental study on tin (Sn) 'cluster-doping' of silicon (Si) nanocrystals, motivated by the opportunities offered by the Si-Sn system with tailored band energy. First-principles modelling predicts two noteworthy outcomes: a considerably smaller bandgap of these nanocrystals even with a modest concentration of tin compared to an equivalent-sized pure silicon nanocrystal and an unexpected decrease in the bandgap of nanocrystals as the diameter of nanocrystals increases, contrary to the typical quantum confined behaviour. Experimental verification using atmospheric pressure microplasma synthesis confirms the stability of these nanocrystals under ambient conditions. The plasma-synthesised nanocrystals exhibited the predicted atypical size-dependent behaviour of the bandgap, which ranged from 1.6 eV for 1.4 nm mean diameter particles to 2.4 eV for 2.2 nm mean diameter particles.