Rationale
Zinc isotopes are becoming increasingly applicable in high‐temperature geochemistry, for example in crust–mantle interaction and volatilization‐related processes. The published zinc isotope ...data for some commonly used reference materials, however, show large interlaboratory offsets. In addition, there is still limited data for zinc isotope compositions of many widely used geological reference materials.
Methods
For precise and accurate zinc isotopic ratio analysis of chemically diverse geostandards, including ultramafic to felsic igneous rocks, carbonatites, sediments and soils, an improved procedure for chemical purification of zinc was introduced in this study. The factors potentially affecting zinc isotopic ratio measurement were assessed. The accuracy and long‐term reproducibility were obtained by measurements on both synthetic solutions and well‐characterized geostandards.
Results
Purification of geologic samples with different zinc concentrations and matrix compositions yields consistent elution curves with nearly 100% recovery. Acidity and concentration mismatches and the presence of some matrix elements (e.g., Mg, Ti and Cr) have significant impacts on the precision and accuracy of zinc isotopic ratio measurement. The zinc isotope compositions of a suite of reference materials were measured using this method.
Conclusions
The present study describes methods for the chemical purification of zinc and high‐precision and accurate zinc isotopic ratio measurements using multicollector inductively coupled plasma mass spectrometer (MC‐ICP‐MS). The long‐term external reproducibility for δ66Zn values is ±0.04‰ (2SD). High‐quality zinc isotope data of chemically different geostandards were reported to stimulate future interlaboratory calibrations.
Soft soil improvement is an important subject in civil engineering, and searching for an effective admixture is an important research. Silica fume (SF) is a kind of recycled material, it can be used ...in engineering as a pozzolanic material. The main objective of this study is to assess the effectiveness of industrial waste silica fume (SF) as an admixture to improve the cement stabilized soft soil. The unconfined compressive test (UCT) and scanning electron microscopy (SEM) test of cement stabilized soil with different SF contents and different curing times have been carried out. UCT after 28 days revealed that the addition of SF can effectively increase the strength of cement stabilized soil and reduce the amount of cement, and 1.5% SF content is considered optimum, excessive SF will not further increase the strength. SF helped to accelerate the cement hydration reaction and significantly improve the early-age strength of stabilized soil even at 3 days, which can improve construction efficiency in actual projects. SEM analyses shows that the proper SF content could make the hydration product calcium silicate hydrate gel (CSH) fill the pores and increase the strength of the material, but excessive SF will increase the large pores content of the material and reduce the strength. This provided a basis for application of SF in improving soft soil.
Low‐temperature solution processing opens a new window for the fabrication of oxide semiconductors due to its simple, low cost, and large‐area uniformity. Herein, by using solution combustion ...synthesis (SCS), p‐type Cu‐doped NiO (Cu:NiO) thin films are fabricated at a temperature lower than 150 °C. The light doping of Cu substitutes the Ni site and disperses the valence band of the NiO matrix, leading to an enhanced p‐type conductivity. Their integration into thin‐film transistors (TFTs) demonstrates typical p‐type semiconducting behavior. The optimized Cu5%NiO TFT exhibits outstanding electrical performance with a hole mobility of 1.5 cm2 V−1 s−1, a large on/off current ratio of ≈104, and clear switching characteristics under dynamic measurements. The employment of a high‐k ZrO2 gate dielectric enables a low operating voltage (≤2 V) of the TFTs, which is critical for portable and battery‐driven devices. The construction of a light‐emitting‐diode driving circuit demonstrates the high current control capability of the resultant TFTs. The achievement of the low‐temperature‐processed Cu:NiO thin films via SCS not only provides a feasible approach for low‐cost flexible p‐type oxide electronics but also represents a significant step toward the development of complementary metal–oxide semiconductor circuits.
A solution combustion synthesis is utilized to fabricate p‐type oxide thin‐film transistors (TFTs) at 150 °C. The doping of Cu into the NiO matrix can replace the Ni sites and enhance the p‐type conductivity. The optimized Cu5%NiO TFTs on both Si and ITO (indium tin oxide)/glass with ZrO2 gate dielectrics exhibit an average hole mobility of >1 cm2 V−1 s−1 and Ion/Ioff of 104.
Adakites are commonly associated with porphyry Cu–Au ore deposits worldwide. Two groups of early Cretaceous adakites occur widely in central-eastern China but their association with mineralization ...contrasts sharply: adakites from the Lower Yangtze River Belt (LYRB) host one of the largest porphyry Cu–Au deposit belts in China, whereas those from the South Tan-Lu Fault (STLF), which is adjacent to the LYRB, are all ore-barren. These adakites, thus, provide a rare opportunity to explore the main factor that controls the genetic links between adakites and Cu–Au mineralization. Here we report new chronological, elemental and Sr–Nd–Pb isotopic data and present a comprehensive geochemical comparison for these two groups of adakites. At a given SiO
2, the STLF adakites show lower Al
2O
3 and higher K
2O, K
2O/Na
2O, MgO, Cr, Ni and Mg# than the LYRB adakites. These systematic differences may indicate a dry basaltic source for the STLF adakites and a water-enriched basaltic source for the LYRB adakites. The STLF adakites have high Sr/Y and (La/Yb)
N, which are positively correlated, and low Sr/La and Ce/Pb, while the LYRB adakites show lower (La/Yb)
N but higher Sr/Y, Sr/La and Ce/Pb than the STLF adakites. Furthermore, the LYRB adakites are characterized by highly radiogenic Pb isotopic compositions with
206Pb/
204Pb(t) up to 18.8, which are clearly distinct from the STLF adakites with low radiogenic Pb (
206Pb/
204Pb(t)
=
15.8–16.4). Although the high Mg# of the two groups of adakites suggest reaction with mantle peridotites during magma ascent, the geochemical comparisons indicate that the STLF adakites were derived from partial melting of the delaminated eclogitic lower continental crust, while the LYRB adakites were derived from partial melting of the seawater-altered oceanic crust that was being subducted towards the LYRB during the early Cretaceous. The petrogenetic contrasts between these two groups of high-Mg adakites, therefore, indicate that the large-scale Cu–Au mineralization is associated with oceanic slab melting, not delamination or recycling of the ancient lower continental crust, as previously proposed.
Rationale
Laser ablation multicollector inductively coupled plasma mass spectrometry (LA‐MC‐ICP‐MS) has become a powerful technique for in situ Cu isotopic analysis in natural geological samples. Cu ...isotopic compositions in natural chalcopyrites have been used to reveal aspects of the mineralization processes directly. However, internationally or commercially available matrix‐matched chalcopyrite reference materials for mass fractionation correction or quality control purposes are still lacking for in situ Cu isotopic analysis using LA‐MC‐ICP‐MS.
Methods
Three natural chalcopyrites 14ZJ12‐1, JGZ‐29 and JGZ‐78, and one copper metal GBW02141 with different Cu isotopic compositions were investigated as potential microanalytical reference materials by LA‐MC‐ICP‐MS. Ga element was used as an internal standard to correct the mass fractionation of Cu isotopes during LA‐MC‐ICP‐MS analysis.
Results
A large number of Cu isotope ratio measurements using femtosecond LA‐MC‐ICP‐MS were conducted and produced good intermediate precision of δ65CuNIST976 (0.07–0.08‰, 2 standard deviations), demonstrating the homogeneous Cu isotopic distribution in the recommended samples. The mean δ65CuNIST976 values of −0.21 ± 0.04‰, 0.46 ± 0.04‰, −0.06 ± 0.04‰ and 0.11 ± 0.05‰ (2 standard deviations) in 14ZJ12‐1, JGZ‐29, JGZ‐78 and GBW02141, respectively, were obtained using solution‐MC‐ICP‐MS in the four recommended samples.
Conclusions
Here, we describe three natural chalcopyrites 14ZJ12‐1, JGZ‐29, JGZ‐78, and one copper metal GBW02141 as the potential Cu isotopic reference materials for LA‐MC‐ICP‐MS analysis. Our analyses demonstrate that these recommended materials have a high degree of elemental and isotopic homogeneity, indicating that they are suitable for microanalysis techniques for data quality assurance or interlaboratory calibration.
The behaviours of Cu, Zn and their isotopes during seafloor fluid-peridotite interaction and its influence on oceanic Cu-Zn cycles were investigated by analyzing a series of unaltered to strongly ...altered oceanic peridotites. Most of the altered peridotites have δ66Zn values indistinguishable from those of the unaltered ones (0.19 ± 0.05‰; 2SD), suggesting that seafloor alteration generally induces a small Zn isotope fractionation. A few altered samples that seem to have gained Zn have elevated δ66Zn, probably due to adsorption by ubiquitous secondary phases (e.g. goethite). Almost all altered peridotites show Cu loss (up to 90%) and have Cu isotope ratios that are shifted toward heavy values relative to the unaltered ones. Given that Cu is organically-complexed in fluids over a wide range of temperature and such fluids have strong preferences for the heavy isotopes, alteration and weathering alone are unlikely to account for the substantial loss of Cu coupled with elevated δ65Cu. An alternative mechanism is that initial Cu in peridotites was partly lost by alteration and weathering, and then Cu was added via adsorption by secondary mineral phases preferring the heavy Cu isotopes. This is confirmed by leaching experiments that were designed to extract the adsorbed Cu fractions in secondary phases. The results show that the leachates and the residua have, respectively, higher and lower δ65Cu values in comparison with the bulk peridotites, demonstrating that adsorption is an important mechanism for generating heavy copper isotope enrichments in the altered peridotites. In any case, mass balance considerations indicate that oceanic alteration must have resulted in a net input of isotopically light Cu from oceanic peridotites into the ocean. Recent estimates found that the Cu isotopic composition of the modern ocean is imbalanced, because all characterized sinks are isotopically light relative to characterized input fluxes, which requires an additional, isotopically light input. Our results indicate that seafloor alteration of abyssal peridotites is an isotopically light input (δ65Cu = −0.4‰ to −0.1‰) to the modern ocean, up to ∼1‰ lighter than the riverine input (∼0.7‰). First-order flux estimates suggest that this process exerts an important control on the marine budget of Cu. Most of Zn released during seafloor alteration has δ66Zn similar to that of mantle peridotites and this input is thus slightly lighter than the riverine input (∼0.33‰). Current estimates of modern oceanic Zn isotope cycles require consideration of this isotopically light source.
Abstract
Intraplate basaltic volcanism commonly exhibits wide compositional ranges from silica-undersaturated alkaline basalts to silica-saturated tholeiitic basalts. Possible mechanisms for the ...compositional transition involve variable degrees of partial melting of a same source, decompression melting at different mantle depths (so-called ‘lid effect’), and melt-peridotite interaction. To discriminate between these mechanisms, here we investigated major-trace elemental and Sr–Nd–Mg–Zn isotopic compositions of a suite of intraplate alkaline and tholeiitic basalts from the Datong volcanic field in eastern China. Specifically, we employed Mg and Zn isotope systematics to assess whether the silica-undersaturated melts originated from a carbonated mantle source. The alkaline basalts have young HIMU-like Sr and Nd isotopic compositions, lower δ26Mg (-0·42‰ to -0·38‰) and higher δ66Zn (0·40‰ to 0·46‰) values relative to the mantle. These characteristics were attributable to an asthenospheric mantle source hybridized by carbonated melts derived from the stagnant Pacific slab in the mantle transition zone. From alkaline to tholeiitic basalts, δ26Mg gradually increases from -0·42‰ to -0·28‰ and δ66Zn decreases from 0·46‰ to 0·28‰ with decreasing alkalinity and incompatible trace element abundances (e.g. Rb, Nb, Th and Zr). The Mg and Zn isotopic variations are significantly beyond the magnitude (<0·1‰) induced by different degrees of fractional crystallization and partial melting of a same mantle source, excluding magmatic differentiation, different degrees of partial melting and the ‘lid effect’ as possible mechanisms accounting for the compositional variations in the Datong basalts. There are strong, near-linear correlations of δ26Mg and δ66Zn with 87Sr/86Sr (R2=0·75 − 0·81) and 143Nd/144Nd (R2=0·83 − 0·90), suggesting an additional source for the Datong basalts. This source is characterized by pristine mantle-like δ26Mg and δ66Zn values as well as EM1-like Sr–Nd isotopic ratios, pointing towards a metasomatized subcontinental lithospheric mantle (SCLM). Isotope mixing models show that mingling between alkaline basaltic melts and partial melts from the SCLM imparts all the above correlations, which means that the SCLM must have been partially melted during melt-SCLM reaction. Our results underline that interaction between carbonated silica-undersaturated basaltic melts and the SCLM acts as one of major processes leading to the compositional diversity in intracontinental basaltic volcanism.
The zinc (Zn) stable isotope system has great potential for tracing planetary formation and differentiation processes due to its chalcophile, lithophile and moderately volatile character. As an ...initial approach, the terrestrial mantle, and by inference, the bulk silicate Earth (BSE), have previously been suggested to have an average δ66Zn value of ∼+0.28‰ (relative to JMC 3-0749L) primarily based on oceanic basalts. Nevertheless, data for mantle peridotites are relatively scarce and it remains unclear whether Zn isotopes are fractionated during mantle melting. To address this issue, we report high-precision (±0.04‰; 2SD) Zn isotope data for well-characterized peridotites (n=47) from cratonic and orogenic settings, as well as their mineral separates. Basalts including mid-ocean ridge basalts (MORB) and ocean island basalts (OIB) were also measured to avoid inter-laboratory bias. The MORB analyzed have homogeneous δ66Zn values of +0.28±0.03‰ (here and throughout the text, errors are given as 2SD), similar to those of OIB obtained in this study and in the literature (+0.31±0.09‰). Excluding the metasomatized peridotites that exhibit a wide δ66Zn range of −0.44‰ to +0.42‰, the non-metasomatized peridotites have relatively uniform δ66Zn value of +0.18±0.06‰, which is lighter than both MORB and OIB. This difference suggests a small but detectable Zn isotope fractionation (∼0.1‰) during mantle partial melting. The magnitude of inter-mineral fractionation between olivine and pyroxene is, on average, close to zero, but spinels are always isotopically heavier than coexisting olivines (Δ66ZnSpl-Ol=+0.12±0.07‰) due to the stiffer Zn-O bonds in spinel than silicate minerals (Ol, Opx and Cpx). Zinc concentrations in spinels are 11–88 times higher than those in silicate minerals, and our modelling suggests that spinel consumption during mantle melting plays a key role in generating high Zn concentrations and heavy Zn isotopic compositions of MORB. Therefore, preferential melting of spinel in the peridotites may account for the Zn isotopic difference between spinel peridotites and basalts. By contrast, the absence of Zn isotope fractionation between silicate minerals suggests that Zn isotopes are not significantly fractionated during partial melting of spinel-free garnet-facies mantle. If the studied non-metasomatized peridotites represent the refractory upper mantle, mass balance calculation shows that the depleted MORB mantle (DMM) has a δ66Zn value of +0.20±0.05‰ (2SD), which is lighter than the primitive upper mantle (PUM) estimated in previous studies (+0.28±0.05‰, 2SD, Chen et al., 2013b; +0.30±0.07‰, 2SD, Doucet et al., 2016). This indicates that the Earth’s upper mantle has a heterogeneous Zn isotopic composition vertically, which is probably due to shallow mantle melting processes.
Studies on printable semiconductors and technologies have increased rapidly over recent decades, pioneering novel applications in many fields, such as energy, sensing, logic circuits, and information ...displays. The newest display technologies are already turning to metal oxide semiconductors, i.e., indium gallium zinc oxide, for the improvements needed to drive active matrix organic light‐emitting diodes. Convenience and portability will be realized with flexible and wearable displays in the future. This report summarizes recent progress on the development of solution‐processed thin film transistors, especially those deposited at low temperatures for next‐generation flexible smart displays. The first part provides an overview on the history and current status of displays. Then, recent advances in state‐of‐the‐art solution‐processed transistors based on different semiconductors are presented, including metal oxides, organic materials, perovskites, and carbon nanotubes. Finally, conclusions are drawn and the remaining challenges and future perspectives are discussed.
Semiconductor evolution has greatly promoted the development of high‐end displays over the past decades. Benefiting from the unique characteristics of low‐cost solution routes, recent progress in the development of solution‐processed thin film transistors (metal oxides, organics, carbon nanotubes, and perovskite) and their applications in next‐generation flexible smart displays are summarized. The challenges and prospectives for further development are also highlighted.
•Polyaniline is composited with MoS2 nanosheet-coated electrospun SnO2 nanotubes.•A highly selective NH3 sensing platform is developed at room temperature.•Good sensing performance of excellent ...selectivity, high response, favorable repeatability and acceptable flexibility.•The mechanism connected with the enhancing properties was also investigated and presented.
In this work, we developed a NH3 gas sensor based on polyaniline (PANI) composited with MoS2 nanosheet-coated SnO2 nanotubes (PMS) via electrostatic spinning, hydrothermal route and in-situ polymerization technique. The morphologies, nanostructures and compositions of the materials were obtained from X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM) and Brunauer-Emmett-Teller method (BET). Thanks to nanostructure and the synergistic properties of PANI and MoS2/SnO2, the designed PMS gas sensor exhibited response signal of 10.9 towards 100 ppm NH3 at room temperature and a low detection limit of 200 ppb with good response-recovery time, good repeatability, acceptable flexibility and excellent selectivity. This study offers a versatile platform to modify PANI for highly selective detection of NH3 gas sensor at room temperature.
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