High Ge Research Articles

Lateral Mn5Ge3 spin-valve in contact with a high-mobility Ge two-dimensional hole gas

Abstract Ge two-dimensional hole gases (2DHG) in strained modulation-doped quantum-wells represent a promising material platform for future spintronic applications due to their excellent spin transport properties and the theoretical possibility of efficient spin manipulation. Due to the continuous development of epitaxial growth recipes extreme high hole mobilities and low effective masses can be achieved, promising an efficient spin transport. Furthermore, the Ge 2DHG can be integrated in the well-established industrial complementary metal-oxide-semiconductor (CMOS) devices technology. However, efficient electrical spin injection into a Ge 2DHG—an essential prerequisite for the realization of spintronic devices—has not yet been demonstrated. In this work, we report the fabrication and low-temperature magnetoresistance (MR) measurements of a laterally structured Mn5Ge3/Ge 2DHG/ Mn5Ge3 device. The ferromagnetic Mn5Ge3 contacts are grown directly into the Ge quantum well by means of an interdiffusion process with a spacing of approximately 130 nm, forming a direct electrical contact between the ferromagnetic metal and the Ge 2DHG. Here, we report for the first time a clear MR signal for temperatures below 13 K possibly arising from successful spin injection into the high mobility Ge 2DHG. The results represent a step forward toward the realization of CMOS compatible spintronic devices based on a 2DHG.

Tracing fluid signature and metal mobility in complex orogens: insights from Pb-Zn mineralization in the Pyrenean Axial Zone

AbstractOrogenic processes encompass a complex interplay of deformation and metamorphic events, which can impact the formation of ore deposits to various degrees. However, distinguishing fluid signatures from orogenic versus post-orogenic events presents a significant challenge due to the scarcity of robust geochemical indicators that remain unaffected during multiple post-mineral reworking events. This study carefully examines the properties and chemistry of primary and secondary fluid inclusions (FIs), identifying distinct signatures of two fluid populations linked to different styles of Pb-Zn mineralization in the Pyrenean Axial Zone (PAZ) of Southern-France/Northern-Iberia: These included late-Carboniferous stratabound epigenetic Pb-Zn deposits and Mesozoic crosscutting Pb-Zn(-Ge) vein systems. Population (I) is identified in primary and secondary FIs in a few crosscutting Pb-Zn veins and constitutes a minor component in stratabound epigenetic bodies. It exhibits Na-dominated low to intermediate salinity (< 20 wt% NaCl eq.), intermediate temperatures (200–350 °C), abundant CO2-rich FIs and shows low homogeneous Cl/Br molar ratios. These characteristics are consistent with a metamorphic origin of the fluids, associated with Late-Variscan metamorphism. Population (II) is commonly observed in the crosscutting vein systems where it occurs as primary and pseudosecondary FIs, as well as in stratabound epigenetic bodies where it represents the main fluid component of secondary FIs. Population (II) is Ca-dominated with intermediate to high salinity (15–35 wt% NaCl eq.), relatively low temperature (< 200 °C), and shows high Cl/Br molar ratios with significant variations. This last characteristic is typical of mixing of at least two fluids, one with a probable low Cl/Br molar ratio at shallow crustal levels and another with high Cl/Br molar ratio at deeper levels. Characteristics of population (II) are consistent with a fluid of basinal origin that interacted with the basement while circulating in the Pyrenees during the Mesozoic, although a Pyrenean-Alpine age cannot be excluded. Locally, in sphalerite-hosted secondary FIs that form trails in the crosscutting veins, we find evidence of high Ge concentrations (up to few 1000s ppm), which correlate with anomalous Pb and Tl concentrations. Very high metal concentrations (up to 1–2 wt% Pb, Zn), which are inversely proportional to Cl/Br molar ratios, are found in FIs mainly within veins hosted in deep-seated high-grade metamorphic rocks. Based on a compilation of fluid data from the literature, a first-order correlation can be deduced between the metamorphic grade of the rocks hosting the mineralization and the Pb and Zn content in the FIs. Early stratabound orebodies are considered likely sources of metal for the development of the late crosscutting vein mineralization. This study demonstrates the significance and complexity of orogen-scale fluid circulation and supports the importance of pre-existing metal enrichment in the crust, especially in high-grade metamorphic rocks as a prerequisite for the formation of Pb-Zn veins in complex multi-stage orogens.

Boosting the Thermoelectric Properties of Ge0.94Sb0.06Te via Trojan Doping for High Output Power.

GeTe stands as a promising lead-free medium-temperature thermoelectric material that has garnered considerable attention in recent years. Suppressing carrier concentration by aliovalent doping in GeTe-based thermoelectrics is the most common optimization strategy due to the intrinsically high Ge vacancy concentration. However, it inevitably results in a significant deterioration of carrier mobility, which limits further improvement of the zT value. Thus, an effective Trojan doping strategy via CuScTe2 alloying is utilized to optimize carrier concentration without intensifying charge carrier scattering by increasing the solubility of Sc in the GeTe system. Because of the high doping efficiency of the Trojan doping strategy, optimized hole concentration and high mobility are obtained. Furthermore, CuScTe2 alloying leads to band convergence in GeTe, increasing the effective mass m* in (Ge0.84Sb0.06Te0.9)(CuScTe2)0.05 and thus significantly improving the Seebeck coefficient throughout the measured temperature range. Meanwhile, the achievement of the ultralow lattice thermal conductivity (κL ∼ 0.34 W m-1 K-1) at 623 K is attributed to dense point defects with mass/strain-field fluctuations. Ultimately, the (Ge0.84Sb0.06Te0.9)(CuScTe2)0.05 sample exhibits a desirable thermoelectric performance of zTmax ∼ 1.81 at 623 K and zTave ∼ 1.01 between 300 and 723 K. This study showcases an effective doping strategy for enhancing the thermoelectric properties of GeTe-based materials by decoupling phonon and carrier scattering.

An Assessment of the Lateral Selective Etching, with HCl, of High Versus Low Ge Content SiGe Layers

We have evaluated the feasibility of selectively etching, with gaseous HCl, high versus low Ge content SiGe layers. To that end, we have grown {20 to 25 nm thick Si / ~ 12-15 nm thick Si0.8Ge0.2 or Si0.75Ge0.25 / ~ 11-14 nm thick Si0.5Ge0.5} multilayers on SOI substrates. After a low temperature capping with SiN, such stacks were patterned into regular arrays of square mesas or lines with a stop on the buried oxide, to laterally etch the layers of interest. We first determined, at 500°C, 600 Torr, the (001) blanket HCl etch rates of SiGe 30% and 40%: 1.4 and 5.3 nm min.-1. We then switched over to patterned wafers. The lateral selective etching of Si0.5Ge0.5 versus Si0.8Ge0.2 (and Si) was feasible and the following features highlighted: (i) Si0.5Ge0.5 lateral etch rates along the <110> directions were much smaller than in the vertical [001] direction and (ii) because of micro-loading, lateral etch rates were definitely higher for squares than for lines (0.9-1.1 nm min.-1 for lines, to be compared with 1.7–2.1 nm min.-1 for squares). Meanwhile, the lateral selective etching of Si0.5Ge0.5 versus Si0.75Ge0.25 was far from being perfect, with much higher Si0.5Ge0.5 etch rates and a significant Si0.75Ge0.25 recessing at tunnel entrances. Si0.75Ge0.25 floors and ceilings were otherwise far more etched and thus tilted than Si0.8Ge0.2 ones. Inserting very thin Si spacers between Si0.5Ge0.5 cores and Si0.75Ge0.25 claddings partly solved those issues, with no recessing and lesser etchings at the entry points of tunnels.

Advanced SiGe:B Raised Sources and Drains for p-type FD-SOI MOSFETs

We have evaluated the feasability of selectively growing, with a chlorinated chemistry, 20 to 30 nm thick SiGe:B Raised Sources and Drains with Ge concentration gradients (from 50% down to 20%-30%, typically) on each side of FD-SOI transistors. The motivation was twofold: (i) inject meaningful amounts of compressive strain in the channel of p-type MOS devices thanks to high Ge concentrations in layers sitting in the same plane than Si or SiGe channels and (ii) benefit from lower Ge concentration SiGe layers on top that are easier to germano-silicide. Growing a thin Si(:B) cap on SiGe:B otherwise yields more uniform and stable contacts. We have thus studied the Si capping of SiGe 20% or 30% layers. As growth has to be conducted, for Si, at temperatures significantly higher than that of SiGe (750°C, to be compared with 700°C for SiGe 20% and 650°C for SiGe 30%, typically), we have quantified the impact of using temperature ramping-ups with SiH2Cl2 + HCl flowing into the growing chamber. The purpose of such active ramps was to prevent elastic strain relaxation, e.g. the formation of SiGe surface undulations that would happen with temperature ramps under H2 only.

Germanium distribution in Mississippi Valley-Type systems from sulfide deposition to oxidative weathering: A perspective from Fule Pb-Zn(-Ge) deposit, South China

Abstract Germanium (Ge) is a critical raw material for emerging high-tech and green industries, resulting in considerable recent interest in understanding its distribution and geochemical behavior in ore deposits. In this contribution, the distribution of Ge and related trace elements in the Fule Pb-Zn(-Ge) deposit, South China, is investigated to reveal the distribution of Ge in the hydrothermal ores and during sulfide weathering, using multiple microanalytical techniques, including scanning electron microscopy, electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In the Fule MVT deposit, sphalerite (ZnS) is the most significant Ge-carrier relative to other sulfides, though the five recognized textural types of sphalerite display progressive depletion in Ge from the first sphalerite generation to the late one. In the early stage, sphalerite with fine-grained chalcopyrite inclusions has the highest Ge concentrations, probably accounting for a significant proportion of the total Ge. We interpret that high Ge concentrations in the early sphalerite may be attributable to high Cu activity in the mineralizing fluids. During oxidative weathering, Ge was redistributed from its original host, sphalerite, to the weathering product willemite (Zn2SiO4) rather than smithsonite (ZnCO3), with high levels of Ge (up to 448 μg/g) present in the willemite. The formation of abundant willemite largely prevents the dispersion of Ge during weathering. In principle, willemite-hosted Ge should be fully recoverable, and the Zn-silicate ores may, therefore, be a potential target to meet future demand. This study provides new information on how Ge behaves from sulfide- to weathering-stage in MVT systems, which directly impacts Ge mobility and deportment changes and the development of metal-lurgical strategies for Ge recovery.

High-Quality Ge-Rich Nanosheets on Silicon on Insulator Substrates Based on Ultra-Low Temperature Epitaxy

Ge and Ge-rich SiGe channel materials are expected to enhance performance in next-generation electronic devices, such as e.g. reconfigurable field effect transistors [1]. However, an inherent lattice mismatch exists between Ge and Si of about 4%. Ge layers on Si grow under compressive in-plane strain, drastically limiting the thickness of high-quality Ge layers on Si to a few monolayers, i.e., far too thin for practical device applications.In principle, vertically grown nanowires grown by vapor-liquid-solid growth (VLS) can be used to overcome these limitations as their small footprint can mitigate the strain. That is why, to date, basically all Ge-rich nanoelectronics device concepts are based on VLS nanowires.However, for device fabrication, the nanowires grown on untypical (111) substrates need to be picked and placed onto Si(001) substrates, which is a serial process and, thus, barely scalable.Thus, whenever two-dimensional nanosheets of a material are available, they provide distinct advantages with respect to device integration. In this context, pure Ge and SiGe alloyed nanowires formed from through top-down lithography from nanosheets would enable extended device functionalities.The problem is that for high Ge contents, the achievable thickness of pseudomorphic, defect-free (Si)Ge epilayers is just a couple of monolayers if grown directly on Si(001) substrates [2] as the inherent strain between the layer and substrate leads to harmful plastic or elastic relaxation under common growth conditions. Thus, using conventional epitaxy, the attainable defect-free SiGe/Si layer thicknesses are typically far from usable in electronic transport devices.Therefore, we depart from established (Si)Ge epitaxy temperatures of ≥500°C and employ molecular beam epitaxy (MBE) growth at ultra-low temperatures (ULT), ranging from 100°C to 350°C.[3] We show that the lowered surface kinetics leads to a pronounced layer supersaturation, allowing us to access layer thicknesses that are more than an order of magnitude larger than previously reported values. We highlight that pristine growth pressures deep in the ultra-high vacuum range ( ≤10-10 mbar) are crucial to keep the density of unwanted impurities in the (Si)Ge layers to a minimum and, thus, enable excellent electrical and optical properties of the grown heterostructures. These low growth pressures are particularly important in ULT growth since the low thermal budget impedes the efficient desorption of residual gas molecules from the substrate.We show that such fully strained, defect-free (Si)Ge epilayers grown directly on SOI substrates form high-quality nanosheets [4] for which properties like thickness, SiGe(Sn) content, and barrier material, doping can be conveniently tuned during the epitaxy process beyond past limitations. These nanosheets are the highly scalable base for advanced transport devices, such as reconfigurable transistors with excellent performance characteristics [4,5,6].

Reduced-Toxicity and Highly Luminescent Germanium-Lead Perovskites Enabled by Strain Reduction for Light-Emitting Diodes.

Germanium-lead (Ge-Pb) perovskites provide a promising solution for perovskite optoelectronic devices with reduced toxicity. However, Ge-Pb perovskite light-emitting diodes (PeLEDs) with >30 mol % Ge showed low emission efficiencies [Yang, D.; Zhang, G.; Lai, R.; Cheng, Y.; Lian, Y.; Rao, M.; Huo, D.; Lan, D.; Zhao, B.; Di, D. Germanium-Lead Perovskite Light-Emitting Diodes. Nat. Commun. 2021, 12 (1), 4295]. Here, we apply strain engineering to effectively improve the light emission efficiency and stability of Ge-Pb perovskite films and PeLEDs with 30 and 60 mol % Ge, through A-site modulation. The maximum external quantum efficiencies of the Ge-Pb PeLEDs with 30 and 60 mol % Ge are 8.5% and 3.0% at 3.32 mA cm-2 (∼922 cd m-2) and 0.53 mA cm-2 (∼60 cd m-2), respectively. Time-resolved transient absorption spectroscopy analysis of Ge-Pb perovskite films on different hole-transport layers shows that incorporating 30 mol % Ge into the perovskite with mixed A-site cations can effectively suppress trap-assisted recombination. Further analysis of their current density-voltage (J-V) curves reveals the efficiency loss mechanisms of Ge-Pb PeLEDs with high Ge fractions, indicating the possibility of further improvements.

Effect of concentration of CuO on radiation shielding characteristics of Epoxy-resin materials

In this work, a new composite based on epoxy resin impeded with both micro and nano size of copper oxide (CuO) for photon shielding application were investigated. Four Epoxy-CuO composites were prepared including pure Epoxy resin material, EP-10%CuOm (90% Epoxy +10% CuO-MPs), EP-30%CuOm (70% Epoxy +30% CuO-MPs) and EP-50%CuOm (50% Epoxy +10% CuO-MPs). The same composites were prepared with CuO-nanoparticles (EP-10%CuOn, EP-30%CuOn and EP-50%CuOn) as well as three other composites with micro and nano together (EP-10%CuOm + n, EP-30%CuOm + n and EP-50%CuOm + n). The linear attenuation coefficient (LAC) was found via the narrow beam technique employing HPGe (high pure Ge) detector at different abroad energies from 0.060 to 1.333 MeV. Comparison of the experimental values with those of micro composites obtained from XCOM software revealed a good agreement. Additional attenuator parameters (half and tenth value layers, mean free path, and transmission factor) have been calculated. The results approved that the composites with varying weight percent of mixture of nano and micro particles of CuO have higher attenuation preference than composites with nano and micro particles, separately at all discussed energies. It was observed that the attenuation preference of EP-50%CuO > EP-30%CuO > EP-10%CuO > Pure Epoxy, in addition to, the LAC of EP-50%CuOm + n > EP-50%CuOn > EP-50%CuOm.

Obtaining ultra-high hardness in spark plasma sintered Ge40As40Se20 bulk glass

In order to overcome the narrow glass-forming compositional range with traditional melt-quenching method, we here performed the mechanical milling and Spark Plasma Sintering technology to fabricate a high Ge content chalcogenide glass, the Ge40As40Se20 glass, which locates edge of the Ge-As-Se glass-forming domain. By using the optimal ball milling time of 50 h and sintering stress of 37.5 MPa, the large size Ge40As40Se20 bulk glasses were obtained, which possesses both a large Vickers hardness of 369 kgf/mm2 and a relative high infrared optical transmission of 43 % (@5 and 9 μm). Moreover, it was found there are pores in the sintered glasses more or less, and the pore size and number significantly affect the transmission, i.e., the optimal Ge40As40Se20 bulk glasses were demonstrated has the smallest and least pores via scanning electron microscope. The combination of mechanical milling and low-temperature sintering methods has been confirmed can be used to improve the glass formability and then obtain the high Ge content component with a potential high hardness glass to break through the limited mechanical property of chalcogenides.

Cardiac magnetic resonance - aided ventricular tachycardia substrate ablation

Abstract Objectives To assess feasibility and reliability of Cardiac magnetic resonance (CMR)-derived pixel signal intensity (PSI) maps obtained by Three Dimensional (3D)- Late Gadolinium Enhancement (LGE) images for detecting potential targets for VT substrate ablation procedures. Background Parametric imaging with color-coded PSI maps obtained from pre-ablation 3D LGE -CMR imaging can be used for identification and characterization of arrhythmic abnormal substrate. Recent publications have shown that PSI maps permit visualization of border zone areas inside the scar. Specifically, corridors of viable tissue within the scar connecting healthy myocardium define VT corridors that may be the electrical equivalent of the abnormal conducting channels on the electroanatomical mapping (EAM). Methods 8 patients with scar-dependent monomorphic VTs who underwent 3D-LGE CMR imaging prior to substrate ablation were included in the study. The studies were performed at 1.5T scanner. We obtained two data sets of 3D whole heart LGE imaging with high resolution. Patients underwent two acquisitions: the conventional respiratory navigated, electrocardiographically-gated 3D fast gradient echo (1.3slice thickness, 256x256 matrix acquisition) and the image-navigated isotropic high resolution 3D GE with Dixon water-fat separation. 3D LGE-CMR images were processed with ADAS-VT software to produce a 3-dimensional model of the heart with 10 layers from the endocardium to epicardium and PSI maps color-coded from the LGE data projected to each of the shells (Figure 1). In the LGE-CMR PSI maps, VT corridors were obtained automatically by the ADAS VT software. Subsequently, data were given to the electrophysiologists and merged with the CARTO3 system EAM data obtained for the ablation (Figure2). CMR information was used to facilitate the identification of target ablation sites in the areas identified by CMR as abnormal substrate and radiofrequency was applied in the presence of both a pathological electrogram (EGM) and a VT corridor as identified by CMR. Results There was a 95% agreement between the abnormal conducting channels as detected by abnormal electrograms in the EAM and the VT corridors identified by 3D LGE CMR imaging. In two occasions, there was one VT corridor that did not correlate with abnormal electrograms and was not ablated. The two 3D LGE sequences used for ADAS-VT corridors analysis showed complete agreement in the number and location of VT corridors. Mean acquisition time for 3D LGE imaging was 11±4minutes for the conventional fast gradient echo sequence, and 5±2minutes for the novel 3D self-image navigated LGE sequence. The image quality of 3D LGE was superior with the Dixon fat-water separation. Overall CMR-aided VT ablation reduced the procedural and fluoroscopy time by 40%. Conclusions CMR-aided VT ablation is feasible, reliable and significantly reduces the procedural time.

High detectivity Ge photodetector at 940 nm achieved by growing strained-Ge with a top Si stressor.

We have developed a self-powered near-infrared photodetector (PD) with high detectivity using a tensile strained Ge layer capped with a thick Si layer. The Si layer acts as a stressor and maintains the strain of Ge with minimal dislocations by creating a rough surface. By using Raman spectroscopy, we confirmed that the Ge layer has a 1.83% in-plane tensile strain. The Ge PD exhibits a high responsivity of 0.45 A/W at -1 V bias voltage for 940 nm wavelength. The PD's dark current density is as low as ∼1.50 × 10-6 A/cm2 at -1 V. The high responsivity and low dark current result in a detectivity as high as 6.55 × 1011 cmHz1/2/W. This Ge PD has great potential for applications in light detection and ranging (LiDAR), Internet of Things (IoTs), and Optical Sensing Networks.

The R-Process Alliance: detailed chemical composition of an r-process enhanced star with UV and optical spectroscopy

ABSTRACT We present a detailed chemical-abundance analysis of a highly r-process-enhanced (RPE) star, 2MASS J00512646-1053170, using high-resolution spectroscopic observations with Hubble Space Telescope/STIS in the UV and Magellan/MIKE in the optical. We determined abundances for 41 elements in total, including 23 r-process elements and rarely probed species such as Al ii, Ge i, Mo ii, Cd i, Os ii, Pt i, and Au i. We find that [Ge/Fe] = +0.10, which is an unusually high Ge enhancement for such a metal-poor star and indicates contribution from a production mechanism decoupled from that of Fe. We also find that this star has the highest Cd abundance observed for a metal-poor star to date. We find that the dispersion in the Cd abundances of metal-poor stars can be explained by the correlation of Cd i abundances with the stellar parameters of the stars, indicating the presence of NLTE effects. We also report that this star is now only the sixth star with Au abundance determined. This result, along with abundances of Pt and Os, uphold the case for the extension of the universal r-process pattern to the third r-process peak and to Au. This study adds to the sparse but growing number of RPE stars with extensive chemical-abundance inventories and highlights the need for not only more abundance determinations of these rarely probed species, but also advances in theoretical NLTE and astrophysical studies to reliably understand the origin of r-process elements.

Expansion of chromatic color range and improvement of mechanical properties on Cu–Ge supersaturated solid solution alloys

The Cu–Ge solid solution alloys have a limited color range and relatively low strength due to its limitation of Ge solubility for a solid solution α-Cu phase at room temperature. To extend chromatic color range and to improve mechanical properties of Cu–Ge solid solution alloys, the Cu–Ge alloys with relatively higher Ge content than solubility limit on equilibrium state were fabricated by induction casting. The as-cast Cu–Ge alloys with 7–10 at.%Ge exhibited dual-phase structure composed of α-Cu and ζ-Cu17Ge3 phases with dendritic structure. By annealing at 700 °C for various times and followed quenching processing, the alloys successfully transformed into the supersaturated α-Cu single-phase structure. To confirm the color difference between the supersaturated single α-phase alloys with a high Ge content and the as-cast single α-phase alloys with low Ge content, the reflectivity analysis, CIE L*a*b* color space system, and color difference indicator were used. As a result, it was confirmed that there was a distinct color difference between supersaturated single α-phase alloys and as-cast single α-phase alloys, and the reflectivity and color difference of the alloys significantly depended on Ge content. Moreover, the Vickers hardness of as-cast and solution treated single α-phase alloys highly improved with an increase of Ge content. The influence of Ge content on phase formation, chromaticity and mechanical properties of solid solution Cu–Ge alloys was systematically discussed.

Two-step phase manipulation by tailoring chemical bonds results in high-performance GeSe thermoelectrics

In thermoelectrics, phase engineering serves a crucial function in determining the power factor by affecting the band degeneracy. However, for low-symmetry compounds, the mainstream one-step phase manipulation strategy, depending solely on the valley or orbital degeneracy, is inadequate to attain a high density-of-states effective mass and exceptional zT. Here, we employ a distinctive two-step phase manipulation strategy through stepwise tailoring chemical bonds in GeSe. Initially, we amplify the valley degeneracy via CdTe alloying, which elevates the crystal symmetry from a covalently bonded orthorhombic to a metavalently bonded rhombohedral phase by significantly suppressing the Peierls distortion. Subsequently, we incorporate Pb to trigger the convergence of multivalence bands and further enhance the density-of-states effective mass by moderately restraining the Peierls distortion. Additionally, the atypical metavalent bonding in rhombohedral GeSe enables a high Ge vacancy concentration and a small band effective mass, leading to increased carrier concentration and mobility. This weak chemical bond along with strong lattice anharmonicity also reduces lattice thermal conductivity. Consequently, this unique property ensemble contributes to an outstanding zT of 0.9 at 773 K for Ge0.80Pb0.20Se(CdTe)0.25. This work underscores the pivotal role of the two-step phase manipulation by stepwise tailoring of chemical bonds in improving the thermoelectric performance of p-bonded chalcogenides.

Mineralization processes at the Daliangzi Zn-Pb deposit, Sichuan-Yunnan-Guizhou metallogenic province, SW China: Insights from sphalerite geochemistry and zoning textures

The Daliangzi deposit is the second largest Mississippi Valley-type (MVT) Zn-Pb deposit in the Sichuan-Yunnan-Guizhou metallogenic province (SYG), SW China. However, detailed mineralization processes that occurred at different ore-forming stages and spatial locations are poorly understood. In this contribution, we report LA-ICP-MS trace element spot analysis and elemental mapping of sphalerite to reconstruct the mineralization processes. Three stages of sphalerite (SpI–SpIII) with different colours and crystallographic morphology have been identified in Daliangzi. Generally, the colloform SpI is enriched in Cd, Pb, Ag, Sb, As, and Tl. The crystalline SpII is relatively concentrated in Fe, Cu, Ga, Ge, and Mn. The colourless SpIII is depleted in most of the analysed trace elements. Trace elements were incorporated into sphalerite in various ways. For instance, Ge may be incorporated in the SpI by direct substitution of Ge4+ + □ ↔ 2Zn2+ but via coupled substitution of Ge4+ + 2Cu+↔ 3Zn2+ in the SpII and SpIII, and also can enter the SpIII as Ge-bearing mineral micro-inclusions. The temperature and sulfur fugacity estimations based on the sphalerite trace element contents show that the SpI was precipitated in a high-temperature condition with fluctuating sulfur fugacity. The SpII was crystallized during a dramatic decrease in temperature and sulfur fugacity, while the SpIII was formed in a low-temperature environment at the end of the mineralization. Combined with the growth histories of the typical zoning textures, we inferred that (i) the Cd-rich SpI with colloform texture precipitated from a rapid fluid mixing process triggered by the pulsed ingress of metal-rich fluid in open spaces with abundant organic matter; (ii) the SpII with high Ge content crystallized from a slow fluid mixing process associated with the temperature decrease and low organic matter abundance. Especially, the Ga-rich subtype with typical rhythmic bands formed from a self-organizing process that occurred in a closed environment under the stratigraphic unconformity; (iii) the pure SpIII probably formed by the replacement and recrystallization as late fluids flowed through the early sphalerite generations along fissures.

F127/PDA dual-assisted fabricating high dispersed Ge nanoparticles /N-doped porous carbon composites with efficient lithium storage

Nanocrystallization and carbon composite are effective methods to solve the mechanical instability and low conductivity of Ge-based anode materials. In this work, a meaningful phenomenon is discovered that F127 can effectively disperse GeO2 polycrystalline particles, which facilitates the formation of Ge nanoparticles embedded in N-doped carbon (Ge/N-C) composites. Polydopamine (PDA) has cross-linking effect, effectively alleviating the reaggregation of GeO2 nanoparticles, and its derived N-doped carbon ensures the uniform dispersion and independent structure of Ge nanoparticles. When assessed as anode material for lithium-ion batteries (LIBs), Ge/N-C composites exhibit a high discharge capacity of 1323 mA h g−1 in the second cycle at 0.2 A g−1 and 981 mA h g−1 after 100 cycles, with a capacity retention rate of 74%. Additionally, the composites show high-rate capability of 959 mA h g−1 at 2 A g−1. The excellent lithium storage performance is attributed to that the synergistic effect between three-dimensional carbon network structure and Ge nanoparticles, which provides stable mechanical structure and abundant redox sites, suppressing volume expansion and accelerating the electrochemical reaction kinetics.

Highly-efficient process for recovering gold from discarded mobile phones using pretreatment and mild extraction

Existing methods for recovering gold from electronic waste are based on mechanical and hydrometallurgy approaches. However, these methods usually use toxic chemicals and demonstrate low gold extraction efficiency (Ge) due to the negative influence of organic materials and other industrial metals also present in the waste. In this work, a more efficient and more environmentally friendly process is proposed that can achieve a high Ge from electronic waste by pre-treatment and pre-extraction before gold extraction. The powdered waste was first pre-treated by a supercritical water oxidation (SWO) process to remove organic materials and then pre-extracted using a mixture of FeCl3 and HCl to remove industrial metals. The solid powder thus produced was then re-extracted by a DMF-CuCl2-NaCl mild extraction system to complete the recovery of the gold content. Experimental results indicated that pre-treatment temperature, pre-treatment time, and the concentration of the FeCl3 and HCl solutions all significantly influenced the amount of gold extracted. The optimal parameters for achieving the highest Ge extraction (99.6%) using the DMF-CuCl2-NaCl extraction system were determined as follows: an extraction temperature of 65 °C, an extraction time of 70 min, a stirring speed of 420 rpm, a sample size of ≤ 850 µm, a solid/liquid (S/L) ratio of 1:12 g·mL−1, a CuCl2 concentration of 0.8 mol·L−1, and a NaCl concentration of 1.6 mol·L−1. After gold extraction, water was then used to precipitate the gold in the form of nanoparticles. Under optimal conditions (70%v/v water, 80 min), over 98.4% of the gold could be recovered in this way.

High-Performance Industrial-Grade CsPbBr3 Single Crystal by Solid-Liquid Interface Engineering.

All-inorganic metal halide perovskite CsPbBr3 crystal is regarded as an attractive alternative to high purity Ge and CdZnTe for room temperature γ-ray detection. However, high γ-ray resolution is only observable in small CsPbBr3 crystal; more practical and deployable large crystal exhibits very low, and even no detection efficiency, thereby thwarting prospects for cost-effective room temperature γ-ray detection. The poor performance of large crystal is attributed to the unexpected secondary phase inclusion during crystal growth, which traps the generated carriers. Here, the solid-liquid interface during crystal growth is engineered by optimizing the temperature gradient and growth velocity. This minimizes the unfavorable formation of the secondary phase, leading to industrial-grade crystals with a diameter of 30mm. This excellent-quality crystal exhibits remarkably high carrier mobility of 35.4cm2 V-1 s-1 and resolves the peak of 137 Cs@ 662keV γ-ray at an energy resolution of 9.91%. These values are the highest among previously reported large crystals.

ZnO-based scintillating bolometers: new prospects to study double beta decay of 64Zn

The first detailed study on the performance of a ZnO-based cryogenic scintillating bolometer as a detector to search for rare processes in zinc isotopes was carried out. A 7.2 g ZnO low-temperature detector, containing more than 80% of zinc in its mass, exhibits good energy resolution of baseline noise 1.0–2.7 keV FWHM at various working temperatures resulting in a low-energy threshold for the experiment, 2.0–6.0 keV. The light yield for β/γ events was measured as 1.5(3) keV/MeV, while it varies for α particles in the range of 0.2–3.0 keV/MeV. The detector demonstrates an effective identification of β/γ events from α events using time-properties of only heat signals. The radiopurity of the ZnO crystal was evaluated using the Inductively Coupled Plasma Mass Spectrometry, an ultra-low-background High Purity Ge γ-spectrometer, and bolometric measurements. Only limits were set at the level of 𝒪(1–100) mBq/kg on activities of 40K, 137Cs and daughter nuclides from the U/Th natural decay chains. The total internal α-activity was measured as 22(2) mBq/kg, with a major contribution caused by 6(1) mBq/kg of 232Th and 12(2) mBq/kg of 234U. Limits on double beta decay (DBD) processes in ^64Zn and 70Zn isotopes were set on the level of 𝒪(1017–1018) yr for various decay modes, profiting from 271 h of acquired background data in the above-ground lab. This study shows a good potential for ZnO-based scintillating bolometers to search for DBD processes of Zn isotopes, especially in 64Zn, with the most prominent spectral features at ∼ 10–20 keV, like the two-neutrino double electron capture. A 10 kg-scale experiment can reach the experimental sensitivity at the level of 𝒪(1024) yr.