Gallium Research Articles

Analysis of rain-deposited dust on polysulfone membranes using proton-induced X-ray emission spectroscopy

Proton-induced X-ray emission spectroscopy (PIXE) is a long-established method of nondestructive elemental analysis for environmental samples. While a standard method of recovery of solids from rainwater involves filtration onto polysulfone media, PIXE analysis has not typically been used on such substrates. We describe methodologies of the University of North Texas Ion Beam Laboratory for PIXE analysis of dust in Texas rainwater on polysulfone membranes from the National Atmospheric Deposition Program (NADP). PIXE analyses utilized a 2 MeV proton beam of 1 × 1 mm2 spot size with beam currents of 1–5nA. A 100 µm Al absorber attenuated X-rays produced by S native to the polysulfone and minimized pileup, allowing use of higher beam currents at the expense of detecting elements of Z < 22. Uniformity of dust deposition on the membranes was evaluated by utilizing Fe concentration as a dust tracer. Areas of uniform particulate deposition with comparable results to averages across the entire membrane were located, allowing reduced acquisition time. GeoPIXE software was used for quantitative analysis, and 18 elements (Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Y, Zr, Hg and Pb) were investigated for a collaborative project. Average minimum detection limits (MDL) were ≤ 10 ng/cm2 for 21 > Z greater than 36 and 10–30 ng/cm2 for 36 < Z < 83. Polysulfone is shown to be an appropriate substrate for PIXE analysis of environmental samples, especially when quantification of low-Z elements is not a priority.

Universal Renaissance Strategy of Metal Fluoride in Secondary Ion Batteries Enabled by Liquid Metal Gallium.

All-solid-state alkali ion batteries represent a future trend in battery technology, as well as provide an opportunity for low-cost metal fluoride electrode materials, if certain intrinsic problems can be resolved. In this work, a liquid metal activation strategy is proposed in which liquid Ga elements are generated in situ and doped into the LiF crystal structure by introducing a small amount of GaF3 . Benefiting from these two Ga states of existence, in which the liquid metal Ga can continuously maintain conformable ion/electron-transport networks, while doped Ga in the LiF crystal structure catalyzes LiF splitting, the lithium-ion storage capacity of MnF2 significantly increasesby 87%. A similar effect can be obtained in FeF3 , where the sodium-ion storage capacity is enhanced by 33%. This universal strategy with few restrictions can be used to realize a complete renaissance of metal fluorides, as well as offer an opportunity for the new application of liquid metals in the field of energy storage.

Nano sized gallium oxide surface features for enhanced antimicrobial and osteo-integrative responses

Gallium oxide has known beneficial osteo-integrative properties. This may have importance for improving the osteointegration of orthopedic implants. At high concentrations gallium is cytotoxic. Therefore, integration of gallium into implant devices must be carefully controlled to limit its concentration and release. A strategy based on surface doping of gallium although challenging seems an appropriate approach to limit dose amounts to minimize cytotoxicity and maximize osteointegration benefits. In this work we develop a novel form of patterned surface doping via a block copolymer-based surface chemistry that enables very low gallium content but enhanced osteointegration as proven by comprehensive bioassays. Polystyrene-b-poly 4vinyl pyridine (PS-b-P4VP) BCP (block copolymer) films were produced on surfaces. Selective infiltration of the BCP pattern with a gallium salt precursor solution and subsequent UV-ozone treatment produced a surface pattern of gallium oxide nanodots as evidenced by atomic force and scanning electron microscopy. A comprehensive study of the bioactivity was carried out, including antimicrobial and sterility testing, gallium ion release kinetics and the interaction with human marrow mesenchymal stomal cells and mononuclear cells. Comparing the data from osteogenesis media assay tests with osteoclastogenesis tests demonstrated the potential for the gallium oxide nanodot doping to improve osteointegration properties of a surface.

Structural, magnetic and electronic properties of L2[formula omitted]-ordered Ru2–xMn1+xAl Heusler alloy thin films

The cubic Heusler alloy Ru2–xMn1+xAl is grown in thin film form on MgO and MgAl2O4 substrates. It is a highly spin-polarised ferrimagnetic metal, with weak magnetocrystalline anisotropy. Although structurally and chemically similar to Mn2RuxGa, it does not exhibit ferrimagnetic compensation, or large magneto galvanic effects. The differences are attributed to a combination of atomic order and the hybridisation with the group 13 element Al or Ga. The spin polarisation is around 50% to 60%. There is a gap in the density of states just above the Fermi level in fully ordered compounds.

Optimization of the grain boundary diffusion process by doping gallium and zirconium in Nd–Fe–B sintered magnets

As the channel for grain boundary diffusion (GBD) in Nd–Fe–B magnets, grain boundary (GB) phases have a very important effect on GBD. As doping elements that are commonly used to regulate the GB phases in Nd–Fe–B sintered magnets, the influences of Ga and Zr on GBD were investigated in this work. The results show that the Zr-doped magnet has the highest coercivity increment (7.97 kOe) by GBD, which is almost twice that of the Ga-doped magnet (4.32 kOe) and the magnet without Ga and Zr (3.24 kOe). Microstructure analysis shows that ZrB2 formed in the Zr-doped magnet plays a key role in increasing the diffusion depth. A continuous diffusion channel in the magnet can form because of the presence of ZrB2. ZrB2 can also increase the defect concentration in GB phases, which can facilitate GBD. Although Ga can also improve the diffusion depth, its effect is not very obvious. The micromagnetic simulation based on the experimental results also proves that the distribution of Tb in the Zr-doped magnet after GBD is beneficial to coercivity. This study reveals that the doping elements Ga and Zr in Nd–Fe–B play an important role in GBD, and could provide a new perspective for researchers to improve the effects of GBD.

Multiscale in-situ elemental characterization of critical elements in low rank coal, implications for modes of occurrence

This study investigated the distribution characteristics and modes of occurrence of rare elements (Li, V, Co, Mo, Ni, Sb, W, Nb), dispersed elements (Ga, Ge), and rare earth elements (REEs) in two selected coal samples: the Al-Li-Ga-rich coal from the Jungar Coalfield in the Ordos Basin, China, and the Ge-rich coal from the Shengli Coalfield in the Erlian Basin, China. Multiscale in-situ elemental characterization techniques, including BSE-EDS, EMPA mapping, and LA-ICP-MS mapping, were used for this purpose. The results showed that in the Al-Li-Ga-rich Jungar coal, Li was mainly associated with kaolinite with various origins, dominated by epigenetic kaolinite, followed by syngenetic kaolinite. Gallium was highly concentrated in organic matter, led by collodetrinite, followed by collotelinite. The majority of Nb was associated with organic matter, while a minority was distributed in Al-bearing minerals, including boehmite and epigenetic and syngenetic kaolinite. In the Ge-rich Shengli coal, Ge, W, and Sb were consistently distributed in coal and concentrated in organic matter, mainly semifusinite. V was widespread in organic matter, including textinite, fusinite, and semifusinite. Cobalt, Mo, and Ni occurred in a similar distribution and were associated with organic matter, led by collodetrinite in the Al-Ga-rich coal and cutinite in the Ge-rich coal. REEs, except for La and Ce, were associated with organic matter, led by vitrinite in Al-Ga-rich coal and huminite in Ge-rich coal. Lanthanum and Ce were highly concentrated in La, Ce-rich minerals, even if they were widespread in organic matter as well. The visualized results of this study confirm most of the previous findings obtained from indirect analyses but also reveal some differences. Gallium was rarely detected in Al-rich minerals such as boehmite and kaolinite, but highly concentrated in organic matter. Lithium was detected in both epigenetic and syngenetic kaolinite. Ge, W, and Sb were organically associated and concentrated in semifusinite in Shengli Ge-rich coal. Overall, this study provides a way to determine the modes of occurrence of trace elements in organic matter in coal, and these findings could be applied to coal from other geological backgrounds.

Geochemistry and mineralogy of fly ash from the high-alumina coal, Datong Coalfield, Shanxi, China

The abundance and distribution of minerals and elements in high-alumina coal fly ash (HACFA) is the basis for evaluating the resource utilization potential of HACFA and the key to developing a rare element extraction process. The geochemistry and mineralogy of HACFA were investigated by using alkali desilication and particle size screening, combined with multiple analytical techniques. As fly ash particles become finer, the content of mullite decreases, the content of quartz, corundum, and glass increases, and the content of hematite decreases first and then increases. The molecular structure of the glass phase is silicon-oxygen tetrahedron Q4(0Al). Minerals containing REE appear in the shape of fish eggs or oolitic particles, mainly composed of Ai, Si, REE, O. The maximum contents of Al, Li, Ga, and REE in HACFA are 67.65%, 240.57 μg/g, 77.97 μg/g, and 672.95 μg/g, showing a high utilization potential. However, the high contents of harmful elements Cd and Cr need special attention. Most of the trace elements in HACFA mainly reside in the glass phase. The iron-rich minerals are the main carriers of the ferrophilic elements Fe, Zn, Cr, Co, Mn, and Mg. The oxyphilic elements Al, Sc, Ta, Nb, and Ga mainly occur in corundum or mullite.

Trace elements of sulfides in the Dengjiashan Pb–Zn deposit from West Qinling, China: Implications for mineralization conditions and genesis

Dengjiashan is a large‐scale Pb–Zn deposit discovered in the western part of the Xicheng ore field within the West Qinling metallogenic belt. Information regarding the distribution and occurrence of trace elements in ore minerals and mineralization, as well as the genesis of this deposit, remains scarce. Laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) analysis and elemental mapping were used to determine the distribution and occurrence of trace elements in the sulfide minerals of the Dengjiashan deposit, as well as delineate the process of its genesis. Our results showed that the trace elements enriched in the different sulfides were significantly different. Sphalerite is the main carrier mineral of the scattered elements Cd, Ge and Ga. Based on the trace element content and ratio, principal component analysis and colour of the sphalerite and pyrite, the deposit likely formed in a medium‐temperature environment. The comparative analysis of trace elements from multiple deposits of different origins, combined with the geological characteristics and distribution of sulfide trace elements, suggests that Dengjiashan is a sedimentary exhalative (SEDEX)‐type deposit. As the metallogenic process had a closer relationship to medium‐low temperature hot brine and later tectonic metamorphic hydrothermal fluid, than with magmatic hydrothermal fluid, the deposit is likely of non‐magmatic SEDEX–hot brine superimposed transition origin. This study provides additional insight on the distribution of trace elements in the sulfide minerals of the Dengjiashan deposit, as well as the processes that led to its formation, and may further facilitate ongoing and future key metal prospecting and exploration efforts.

Mineralogy and enrichment of critical elements (Li and Nb-Ta-Zr-Hf-Ga) in the Pennsylvanian coals from the Antaibao Surface Mine, Shanxi Province, China: derivation of pyroclastics and sediment-source regions

As a critical element, lithium plays an important role in a wide range of modern industries and in particular, battery storage and new energy technologies. Lithium in coal has attracted much attention in recent years because some coals are highly enriched in this element and consequently their corresponding coal combustion products may provide anm alternative source for this element. Previous studies showed that highly enriched Li in coals is generally associated with chlorite group minerals and in most cases attributed to the action of hydrothermal solutions. This paper provides mineralogical and geochemical data on the No. 9 Coal, the major minable coal from the Antaibao Surface Mine, Ningwu Coalfield, Shanxi Province, northern China, and focuses on the modes of occurrence and source of Li in this coal. The No. 9 Coal is a medium ash, medium sulfur, high volatile bituminous coal. The mineralogy of the No. 9 Coal is dominated by kaolinite, calcite, and pyrite, with minor amounts of anatase, rutile, goyazite, quartz, illite, boehmite, and bassanite, and traces of orthoclase, zircon and galena. The studied coal samples are characterized by high contents of Al2O3 (39.80% on average) in comparison with average Chinese coals, and high concentrations of Li, Ga, Se, Zr, Nb, Ta and Th compared with world hard coals. In addition to Li and Al, the critical elements Nb, Ta, Zr, Hf, and Ga in this coal also have a potential economic significance. The geochemical indicators (high Al2O3/TiO2, low Nb/Yb ratios and the specific rare earth element distribution patterns) and the mineral compositions (e.g., very low content of boehmite) indicate that the mineral matter in most coal benches and host rocks is dominantly derived from the Precambrian calc-alkaline granites of the Yinshan and northern Trans North China Orogens, and possibly from the bauxite of the Benxi Formation. Additionally, the geochemical and mineralogical characteristics of the intra-seam partings and some coal benches (quartz-free, kaolinite-dominated mineralogy, high Al2O3/TiO2 and Nb/Yb values) indicate that they were derived from an alkaline intermediate-felsic volcanic source. The highly enriched Li in the studied samples mainly occurs in kaolinite and is attributed to the input of material from sediment-source regions, rather than hydrothermal fluids. In addition, interaction of terrestrial and marine waters may have promoted the Li enrichment process in the partings.

Effect of miscible and immiscible element microalloying on crystallization behavior and soft magnetic properties of Fe-P-C-B amorphous alloy

Microalloying is an efficient strategy to promote nano-crystallization of Fe-based amorphous alloys to improve soft magnetic properties. Here, the Fe-P-C-B amorphous alloy is selected as a typical system to investigate the effect of microalloying of immiscible elements (In and Sn) and miscible elements (Al, Ga and Ge) in Fe on crystallization behavior and soft magnetic properties of Fe-based amorphous alloys. Microalloying of immiscible elements leads to slightly increased energy barrier for α-Fe nuclei growth as evaluated by Kissinger equation, yielding fine and uniform α-Fe nanograins and low coercivity after annealing. In contrast, miscible elements cause high growth energy barrier, resulting in few huge α-Fe grains and large coercivity. This work suggests a strategy of obtaining amorphous-nanocrystalline alloys with good magnetic properties by microalloying of immiscible elements.

Health risk assessment of trace elements in the Tonle Sap Great Lake and the Tonle Sap River in Cambodia during the rainy season.

To investigate the potential health risk of trace elements in the Tonle Sap Great Lake system, lake (n = 37) and river (n = 14) water samples were collected and analyzed for 19 trace elements (Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Se, Tl, U and Zn) using inductively coupled plasma mass spectrometry. As a result, Cd was not detected in any river and lake water samples. Al, Fe and Mn in lake water exceeded the regulation limits of Cambodia, USEPA and WHO. Health risk assessment using the USEPA model indicated that male and female Cambodian residents are at minimal risk of non-carcinogenic effects from single and mixed trace elements through lake and river water consumption. Nevertheless, As, Tl, Co, Ba, Mn and Cr might pose high potential health risks to consumers which requires more attention. Therefore, regular monitoring and further studies are required to investigate the pollution trends and toxic behavior of these trace elements in the Tonle Sap Great Lake system.

Enhancement of terbium efficiency by gallium and copper co-doping in (Pr, Nd)-Fe-B sintered magnets

It is well known that Tb substitution for (Pr, Nd) in (Pr, Nd)-Fe-B based sintered magnetic materials is an effective way to increase intrinsic coercivity, but it is not quite clear whether the increment depends on the different matrix phases with various doping ingredient or not, which is essential to develop high quality magnets with high coercivity more efficiently and effectively with economic consumption of expensive Tb and other costly heavy rare earths. In this paper, we investigated the efficiency of Tb substitution for magnetic property in (Pr, Nd)-Fe-B sintered permanent magnets by co-doping Ga and Cu elements. It is shown that Ga and Cu co-doping can effectively improve the efficiency of Tb substitution to increase the thermal stability and the coercivity. The intrinsic coercivity increases up to 549 and 987 kA/m respectively by 1.5 wt% and 3.0 wt% Tb substitution in Ga and Cu co-doped magnets while the intrinsic coercivity increases up to only 334 and 613 kA/m respectively by the same amounts of Tb substitution in non-Ga and low-Cu magnets. In other words, it demonstrates that there is about 329–366 kA/m linear equivalent enhancement of intrinsic coercivity by 1.0 wt% Tb substitution for (Pr, Nd) in Ga and Cu co-doped magnets. The temperature coefficients of both intrinsic coercivity β and remanence α at 20–150 °C by 3.0 wt% Tb substitution for the magnets with Ga and Cu co-doping are −0.47%/K and −0.109%/K respectively, and in contrast those values are −0.52%/K and −0.116%/K respectively for the non-Ga and low-Cu magnets. It is the principal reason for more efficient enhancement of magnetic property by Tb substitution in the Ga and Cu co-doped magnets in which Tb atoms are expelled from triple junction phases (TJPs) to penetrate into the grain boundary phases (GB phases) and thus modify the grain boundary. It is prospected that the efficiency of Tb substitution would rely on different matrix phases with various doping constituents.

Characterization and Differentiation of Wild and Cultivated Berries Based on Isotopic and Elemental Profiles

The isotopic content (δ13C, δ2H, δ18O) and concentrations of 30 elements (Li, Na, Mg, P, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Ag, Cd, Ba, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, and Tb) were determined in different wild and cultivated berries (raspberry, seaberry, blackberry, cranberry, and blueberry). Partial least squares discriminant analysis (PLS-DA) was applied in order to develop models for differentiating berries according to their botanical origin and growing system. δ13C, δ2H, δ18O, Li, Na, Mg, P, Ca, V, Mn, Co, Ni, Zn, As, Rb, Sr, Ba, and Eu were identified as significant elements for the differentiation of berry species, based on which an 85% PLS-DA model accuracy was obtained. Similarly, the PLS-DA model developed for the growing system differentiation correctly classified 94.4% of the cultivated berries and 77.2% of the wild ones, based on the main predictors: δ13C, δ18O, Li, Na, Ca, Cr, Mn, Ni, Rb, and Ba. The developed PLS-DA model for the discrimination of wild blueberries from cultivated ones showed excellent levels of sensitivity (100%), specificity (100%), and accuracy (100%).

Mineralogical and Geochemical Constraints on the Occurrence Forms of REEs in Carboniferous Karst Bauxite, Central Guizhou Province, Southwest China: A Case Study of Lindai Bauxite

Karst bauxite is a major source of aluminum and contains high concentrations of trace elements such as Li, Ga, Sc, and rare earth elements (REEs). It is regarded as a potential non-conventional REE source due to the increasing demand for REEs. This study provides new mineralogical and geochemical evidence of a Lindai bauxite deposit in central Guizhou Province, aiming to analyze the genesis of REE minerals and reveal the forms of REEs occurring in these deposits. The results indicate that a large number of detrital and authigenic rare-earth phosphate minerals, including monazite and xenotime, were identified. In terms of their genesis, the authigenic monazite was mainly precipitated under alkaline and reducing conditions, whereas the authigenic xenotime was formed in acidic and reducing conditions. The mineralogical evidence detected by scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) and a TESCAN Integrated Mineral Analyzer (TIMA) suggests that the REEs in the Lindai bauxite exhibit multiple forms, including rare-earth phosphate minerals (monazite and xenotime) and REE scavenging by hematite and anatase phases. Among them, the anatase controls some LREE (such as La, Ce, and Pr) distributions in addition to monazite, whereas the hematite also controls relatively large amounts of Sm, Eu, and HREE (such as Gd, Tb, Dy, Ho, Er, Tm, and Lu) distributions. According to the calculation of the percentage of REE-bearing mineral phases obtained by a TIMA analysis, REE scavenging by hematite accounted for 93.28% of all forms of REEs, REE scavenging by anatase accounted for 5.88%, monazite accounted for 0.67%, and xenotime accounted for 0.17%. This study provides new evidence of the forms of REEs occurring in Carboniferous karst bauxite in central Guizhou Province.

Elemental Fluctuation in Gd3Al2Ga3O12:Ce Crystals Imposed by Li+ and Mg2+ Co-Doping: The Impact on Defects, Luminescence, and Scintillation Properties

This research revealed the response of Ga and Al sublattices to the incorporation of mismatching substituents in Gd3Al2Ga3O12:Ce single crystals. Incompatible in size and charge, Li+ and Mg2+ substituents violated configurational entropy. This led to lattice distortion and triggered structural rearrangements. The radial fluctuation of the Ga and Al elements was proven by multi-elemental energy-dispersive X-ray spectroscopy mapping and elemental composition analysis. Further evidence was observed by the shift of the exciton creation energy toward higher energy in the vacuum ultraviolet excitation spectra recorded with synchrotron radiation. In the Li+ and Mg2+ co-doped samples, the crystal core was depleted with Ga atoms and enriched with Al elements. The crystal rim showed the opposite behavior. The change in thermoluminescence peak positions revealed a different mechanism for the formation of localized traps. As a result, Li+ co-doping slightly improved the light yield value, but at the same time decelerated the scintillation decay time. On the contrary, Mg2+ co-doping markedly diminished scintillation parameters.

Discrimination of Pb-Zn deposit types using sphalerite geochemistry: New insights from machine learning algorithm

Due to the combined influences such as ore-forming temperature, fluid and metal sources, sphalerite tends to incorporate diverse contents of trace elements during the formation of different types of Lead-zinc (Pb-Zn) deposits. Therefore, trace elements in sphalerite have long been utilized to distinguish Pb-Zn deposit types. However, previous discriminant diagrams usually contain two or three dimensions, which are limited to revealing the complicated interrelations between trace elements of sphalerite and the types of Pb-Zn deposits. In this study, we aim to prove that the sphalerite trace elements can be used to classify the Pb-Zn deposit types and extract key factors from sphalerite trace elements that can discriminate Pb-Zn deposit types using machine learning algorithms. A dataset of nearly 3600 sphalerite spot analyses from 95 Pb-Zn deposits worldwide determined by LA-ICP-MS was compiled from peer-reviewed publications, containing 12 elements (Mn, Fe, Co, Cu, Ga, Ge, Ag, Cd, In, Sn, Sb, and Pb) from 5 types, including Sedimentary Exhalative (SEDEX), Mississippi Valley Type (MVT), Volcanic Massive Sulfide (VMS), skarn, and epithermal deposits. Random Forests (RF) is applied to the data processing and the results show that trace elements of sphalerite can successfully discriminate different types of Pb-Zn deposits except for VMS deposits, most of which are falsely distinguished as skarn and epithermal types. To further discriminate VMS deposits, future studies could focus on enlarging the capacity of VMS deposits in datasets and applying other geological factors along with sphalerite trace elements when constructing the classification model. RF’s feature importance and permutation feature importance were adopted to evaluate the element significance for classification. Besides, a visualized tool, t-distributed stochastic neighbor embedding (t-SNE), was used to verify the results of both classification and evaluation. The results presented here show that Mn, Co, and Ge display significant impacts on classification of Pb-Zn deposits and In, Ga, Sn, Cd, and Fe also have relatively important effects compared to the rest elements, confirming that Pb-Zn deposits discrimination is mainly controlled by multi-elements in sphalerite. Our study hence shows that machine learning algorithm can provide new insights into conventional geochemical analyses, inspiring future research on constructing classification models of mineral deposits using mineral geochemistry data.

Cobalt-Free Double Perovskite Oxide as a Promising Cathode for Solid Oxide Fuel Cells.

Double perovskite oxide PrBaFe2O5+δ is a potential cathode material for intermediate-temperature solid oxide fuel cells. To improve its electrochemical performance, the trivalent element Ga is investigated to partially replace Fe, forming PrBaFe2-xGaxO5+δ (PBFGx, x = 0.05, 0.1, and 0.15). The doping effects on physicochemical properties and electrochemical properties are analyzed regarding the phase structures, element valence states, amount of oxygen vacancies, content of oxygen species, oxygen surface exchange coefficients (kchem), electrochemical polarization resistance, and single-cell performance. Specifically, PBFG0.1 exhibits improved kchem, such as a 19% improvement from 4.09 × 10-4 to 4.86 × 10-4 cm s-1 at 750 °C, due to the increased concentration of reactive oxygen species and oxygen vacancies. Consequently, the interfacial polarization resistance is decreased by 28% from 0.057 to 0.041 Ω cm2 at 800 °C. The subreaction steps of the oxygen reduction reaction in the PBFG0.1 cathode are further investigated, which suggests that the oxygen dissociation process is greatly enhanced by doping Ga. Meanwhile, doping Ga increases the peak power density of the anode-supported single cell by 36% from 629 to 856 mW cm-2 at 800 °C. The single cell with the PBFG0.1 cathode also exhibits good stability in 100 h of long-term operation at 750 °C.

Geochemical Anomalies of the Late Permian Coal in the Guishan Coalfield, Eastern Yunnan, China

The coal-bearing sequences of the Late Permian in southwest China are enriched in critical elements Sc, V, Co, Ni, Cu, Zn, Nb, Ta, Zr and Hf. Ascertaining the conditions and basis for the enrichment of critical elements in this area is very important to support the critical metal demands of China. In this study, we analyzed the concentrations of elemental compositions of coal samples collected from the Late Permian Guishan coalfield in the eastern Yunnan, China. The results show that the C4-Upper coal seam of the Feilongma mine and C5 + 10 coal seam of the Shipeng mine are indeed rich in critical elements. The average concentration coefficients (CC) of transition metal elements Sc, V, Co, Ni, Cu, and Zn are 3.23 and 2.93, respectively, in the two coal seams. The average CCs of high-field-strength elements Nb, Ta, Zr, and Hf and non-variable valence chalcophile elements Ga and In are 2.21 and 2.53, respectively, in the two coal seams. The C4-Upper coal seam of the Feilongma mine can be divided into two sections based on the different ash contents, and the CCs of the critical elements in the two sections are almost equal. The main minerals in the two coal seams are kaolinite, siderite, quartz, gypsum, rozenite and marcasite. Multiple indicators of provenance show that the enrichment of critical elements in the Guishan coalfield is controlled by clastic terrigenous material. The source area of the Guishan coalfield is Kangdian Oldland in the northwest, and the main clastic materials are related with high-Ti basalts from the Emeishan Large Igneous Province.

Exploring the Co-Crystallization of Kojic Acid with Silver(I), Copper(II), Zinc(II), and Gallium(III) for Potential Antibacterial Applications.

Co-crystallization of kojic acid (HKA) with silver(I), copper(II), zinc(II), or gallium(III) salts yielded three 1D coordination polymers and one 0D complex in which kojic acid was present as a neutral or anionic terminal or bridging ligand. All reactions were conducted mechanochemically via ball milling and manual grinding, or via slurry. All solids were fully characterized via single-crystal and/or powder X-ray diffraction. As kojic acid is a mild antimicrobial compound that is widely used in cosmetics, and the metal cations possess antibacterial properties, their combinations were tested for potential antibacterial applications. The minimal inhibition concentrations (MICs) and minimal biocidal concentrations (MBCs) for all compounds were measured against standard strains of the bacteria P. aeruginosa, S. aureus, and E. coli. All compounds exerted appreciable antimicrobial activity in the order of silver, zinc, copper, and gallium complexes.

Efficiency enhancement of copper indium gallium selenide solar cells fabricated on polyimide foils with multiple metal layers

In this work, we report the fabrication method using a Cu(In,Ga)Se2 (CIGS) quaternary target containing NaF to obtain thin-film solar-cell devices on polyimide (PI) foils. In order to improve the efficiency of the CIGS solar cells, multiple metal layers were prepared on both sides of the PI substrate, and the annealing process was investigated. The sandwich structure of Ti/Cr/Mo multiple layers prepared on PI foils can improve thermal budget of the substrate as it endures higher annealing temperature (520 °C) for short time (5 min). A 2-step annealing process was adopted to ensure the integrity and fewer electrical defects of the absorber film. The distribution of Na and Ga elements in the annealed films was improved by adding a high-temperature selenization process. CIGS cells with better conversion efficiency can be obtained by this fabrication process. An average power conversion efficiency of 13.6% has been achieved for the prepared cells.