Scandium Content Research Articles

An assessment of Rare Earth Elements in borehole cores from the Ermelo, Witbank and Waterberg Coalfields, South Africa: Focus on mode of occurrence

There is currently limited knowledge concerning South African coal deposits as hosts for rare earth elements (REE). This project aims to determine the concentration of REE, including yttrium and scandium (REY+Sc) in various coal seams and adjacent sediments in borehole cores from the Ermelo, Witbank, and Waterberg coalfields in South Africa. Coal petrography (maceral count and vitrinite reflectance), XRD, XRF, sequential chemical extraction procedure (SCEP) before ICP-MS, and mineral liberation analysis (MLA) were conducted on the coal and associated sediment samples. The coals were inertinite-rich, medium-rank bituminous coal, with moderate to high ash content. The two dominant minerals in all the coalfields are kaolinite and quartz, except for sample ZBS2M, where dolomite was dominant. The dominant major oxides are Al2O3, SiO2, Fe2O3, and CaO, which concur with the XRD results. The ICP-MS results following SCEP indicated that both coal and the associated sediments were light REY+Sc dominant. There was also an elevation of medium REY+Sc in the Witbank coal's associated sediment samples. Notably, the samples with the highest REY+Sc results were the sediment samples. The Waterberg samples had the lowest REY+Sc from both the coal (less than 2 μg/g to 7 μg/g) and associated sediments (2 μg/g to 15 μg/g). While the highest REY+Sc was yielded from the Witbank-associated sediments (500 μg/g to 2,500 μg/g). The carbonate fraction step proved to be the most successful leaching step, as most REY+Sc was recovered in that step for all coalfields. In addition to the carbonate fraction, the silicates and sulfide fraction in the Witbank samples, and the ion-exchangeable fraction for the Waterberg-associated sediments samples proved successful in leaching out the REY+Sc. MLA determined that monazite and xenotime in all the coal samples were the REY+Sc-bearing minerals.

Petrochemical characteristics of ancient weathering crusts with scandium concentrations in the Nakyn kimberlite field

Petrochemical characteristics of ancient weathering crusts with scandium concentrations in the Nakyn kimberlite field

Effect of scandium concentration on the performances of cantilever based AlN unimorph piezoelectric energy harvester with silicon nitride substrate

Microelectromechanical systems (MEMS) offer its ability to sense, control and actuate on sub-micron scale and exhibit its effect on macro scale. To implement any specific MEMS system, small, efficient and long-lifespan micro power sources are required. Piezoelectric energy harvester (PEH) along with radioactive source is one of the most promising approaches to harness electrical energy at micro to millimeter range. In this report, a scandium (Sc) doped Aluminium Nitride (AlN) unimorph piezoelectric energy harvester has been demonstrated. Unimorph piezoelectric layer is built on Silicon Nitride (Si3N4) substrate platform that act as cantilever beam and that can be vibrated by inbuilt radioactive system. In particular, Si3N4 as cantilever material and the impact of Sc doping concentration on electrical and mechanical properties of AlN piezoelectric thin film materials have been studied in MATLAB simulation platform. Results obtained from numerical study suggests that the proposed energy harvester model composed of AlScN unimorph piezoelectric (with 10% Sc doping concentration, Sc-10%) layer and Si3N4 cantilever can yield a maximum power output of ~ 19.33 μW and overall mechanical energy conversion efficiency of ~ 91.07%. These are the maximum output power and mechanical energy conversion efficiency numerically obtained from Sc doped AlN piezoelectric energy harvester systems to the best of our knowledge.

Efficiency of Cr3+ → Cr4+ conversion in YSAG:Cr ceramics

In this study, we investigated the influence of the position and quantitative content of scandium in YSAG:Cr on the efficiency of chromium cation valence conversion. YSAG:Cr ceramic powders were synthesized using the chemical precipitation method. It was determined that the microstructure of ceramics and the luminescent properties of YSAG:Cr4+ depend on the predominant position of scandium, whether it replaces octahedral or dodecahedral positions in the garnet crystal lattice. An increase in Scdod content contributed to a decrease in grain size and a shift of the emission peak of Cr4+ ions towards the short-wavelength region. Conversely, an increase in Scoct content led to an increase in grain size and a shift of the maximum of the luminescent band towards the long-wavelength region. It was found that increasing the quantitative content of scandium in the octahedral position in the garnet structure by up to 50 % enhances the efficiency of the conversion of Cr3+ to Cr4+, while an increase in the proportion of Scdod resulted in a decrease in conversion efficiency.

Detailed chemical analysis of soils and identification of priority pollutants on the territory of the state aviation airfield (Krymsk)

In connection with the intensification of military activities, environmental problems have worsened in large-scale territories. The primary task is to create lists of priority pollutants of environmental objects that are mandatory for control at landfills for various purposes, military bases, airfields. The paper presents the data of a detailed geochemical analysis of the soils of the state aviation airfield territory, on the basis of which priority contaminants were identified taking into account their gross content, hazard classes and the frequency of exceeding dangerous concentrations relative to the background. In the Krasnodar Territory (Krymsk), 32 samples from the territory of the state aviation airfield were analyzed over 4 years of research, and background concentrations of 22 metals, petroleum products, formaldehyde and nitrate nitrogen were also established. To determine the hazard classes of metals with unspecified maximum permissible concentrations, a correlation analysis was carried out comparing the hazard classes of substances and their clarks. Based on the results of the study, a list of pollutants recommended for control has been compiled including cesium, arsenic, scandium, niobium, lead (hazard class I); antimony, formaldehyde, nitrate nitrogen (II); petroleum products (III). The variability of the distribution of concentrations of pollutants on the airfield territory depends on the specifics of the operation of aircraft and special equipment for flight support. But at all sampling points (beginning – end, runway perimeter; taxiways; under the glide path), the main soil pollutant is arsenic, which concentrations exceed background concentrations by 16–36 times. The dangerously high content of petroleum products, formaldehyde, nitrate nitrogen, and scandium and caesium in some points in the airfield soils has been also found.

Effect of Scandium Concentration in the Y2O3–Sc2O3–Al2O3–Er2O3 Oxide Composition on the Thermophysical Properties of Optical Ceramics

Effect of Scandium Concentration in the Y2O3–Sc2O3–Al2O3–Er2O3 Oxide Composition on the Thermophysical Properties of Optical Ceramics

Four millennia of garnet trade in Northeast Africa—chemical analysis of ancient and Late Antiquity beads from Lower Nubian sites

AbstractRaman spectroscopy and laser ablation‐inductively coupled plasma‐mass spectrometry were used to characterize the chemical composition of 34 red garnet beads from Lower Nubian sites, dated between about 3200 BCE and 600 CE. All beads from the A‐Group to the Meroitic period feature a similar calcium‐poor almandine composition (69%–78% almandine, 15%–22% pyrope, 2%–6% grossular, 3%–9% spessartine), which differs from other calcium‐poor almandine garnet types, sourced mostly from Indian deposits in Antiquity. The Nubian beads constitute a new garnet type, named “cluster I”, featuring high yttrium (180 to 1205 ppm), moderately low chromium (13–70 ppm), and high scandium (119–213 ppm) concentrations. Their compositions match with previous and two new analyses from two alluvial garnet deposits, Wadi El‐Haraz and Wadi Abu Dom, near the Fourth Cataract of the Nile in Upper Nubia, about 670 km as the crow flies from the Lower Nubian graves. Garnet trade between the Bayuda desert and Lower Nubia sites, and possibly even Egypt, flourished for almost four millennia. Northeastern Africa is the cradle for the oldest use of a gemstone that is harder than quartz—the red almandine garnet.A Post‐Meroitic bead, the youngest in the assembly, displays an unusual faceting, a diamond tipped drill hole, excellent polish, distinct short‐ and long‐prismatic colorless mineral inclusions, and a calcium‐ and manganese‐poor pyrope composition. This suggests that it was not of a local, Nubian, production, but imported, most probably from a South Asian site.

Development and research of technology for obtaining and properties of welding wire from Al–Mg–Sc alloys using combined methods of thermal deformation treatment

The results of studies technological processes for obtaining welding wire from alloys of the Al–Mg system with a scandium content of 0.12 (alloy 1580) and 0.25 wt % (alloy 01570) presented. A feature of the technology is the production of a billet for further cold deformation by an energy-efficient method of ingotless rolling-extrusion (IRE). It was found that hot-extruded rods from the investigated alloys obtained by the IRE method have the required level of plastic and strength properties necessary for further cold deformation up to 80%. Thermomechanical processing of hot-extruded rods manufactured by IRE have been developed and experimentally tested, which made it possible to obtain a billet with a square side of 5 × 5 mm by sectional rolling and wire with a diameter of 3 mm by drawing. Studies of the structure and mechanical properties of deformed semi-finished products have shown that the developed modes make it possible to obtain a welding wire from the investigated alloys that meets the requirements of current standards. Studies of the operational properties of the obtained welding wire were carried out. It was found that alloy 1580 with a minimum content of scandium (0.12 wt %) is not inferior to alloy 01570 in terms of corrosion resistance and weld quality. Developed technology for the production of welding wire from alloys of the Al–Mg system with different scandium content can be recommended for industrial use. It is advisable to implement alloy 1580, which has a lower cost compared to alloy 01570.

New insights on scandium separation from scandium concentrate with titanium dioxide wastewater.

In this study, a scandium concentrate with Sc2O3 content of 66.24g/t was obtained from V-Ti magnetite tailings by physical concentration, and the main Sc-bearing minerals were augite and hornblende. A novel process of roasting and leaching was proposed to extract scandium from scandium concentrate with titanium dioxide wastewater. Scandium concentrate was pretreated by roasting, and titanium dioxide wastewater was used to directly leach scandium from the roasted ore. The effects of roasting and leaching parameters such as roasting temperature, roasting time, roasting agents, leaching temperature, leaching time, liquid-to-solid ratio, and leaching agents on scandium separation were thoroughly researched in the experimental procedure. The results show that a scandium leaching efficiency of 85.89% was obtained, and the scandium content of leaching residue decreased to 9.31g/t under the optimal conditions: a roasting temperature of 1123K, a roasting time of 120min, a leaching temperature of 343K, a leaching time of 120min, and a m (titanium dioxide wastewater)∶m (roasted ore)∶m (ammonium fluoride) ratio of 8∶1∶0.09. The main findings of the scandium separation mechanism show that Sc-bearing minerals can effectively decompose and release scandium element after roasting, and created favorable conditions for scandium leaching with titanium dioxide wastewater to achieve the purpose of scandium recovery.

Study on the impact of the resonant cavity and lateral acoustic edge reflector for AlSc0.095N-based S0 mode Lamb-wave resonators

In this paper, the impact of the resonant cavity and lateral acoustic edge reflector on the performance of the S0 mode Lamb-wave resonators based on Aluminum nitride film doped with scandium concentration of 9.5 % (AlSc0.095N) were systematically studied. Through the theoretical analysis and experimental verification, we found that the Q value of the resonator can be improved by defining a miniaturized resonant cavity due to the enhanced acoustic reflection effect at the anchor boundary. The effect of lateral reflection boundary width on the spurious modes, Q values, and electromechanical coupling coefficient (k2eff) of the resonators was analyzed. In addition, the k2eff and Q values of the interdigitated transducer (IDT)-IDT resonators are higher than those of the IDT-Floating resonators, due to the larger electromechanical conversion efficiency and smaller interface loss. The experimental results show that the Q and k2eff values of the optimized IDT-Floating and IDT-IDT resonators reach 853, 1.70 % and 1362, 2.69 %, respectively, meanwhile, they have clean spectrums.

Investigation of the effect of scandium concentration in the oxide composition Y<sub>2</sub>O<sub>3</sub>–Sc<sub>2</sub>O<sub>3</sub>–Al<sub>2</sub>O<sub>3</sub>–Er<sub>2</sub>O<sub>3</sub> on the thermophysical properties of optical ceramics

The influence of the concentration and position of scandium cations on the thermophysical characteristics of optical ceramics based on a solid solution of Y2O3–Er2O3–Sc2O3–Al2O3 oxides with a garnet structure has been studied. It is established that an increase in the total concentration of scandium leads to a decrease in the thermal conductivity coefficient in ceramics. The dependences of the thermal conductivity coefficient on the concentration and position of scandium cations in the garnet lattice are obtained. As a result the decrease in thermal conductivity of ceramics based on yttrium-erbium-scandium-aluminum garnet is due to structural disordering associated with partial substitution of cations in six- and eight-coordinate positions in the garnet lattice.

Scandium Ore Occurrences in the Ancient Weathering Crust in the Nakyn Kimberlite Field of Yakutia

In the Malo-Botuobinsky, Sredne-Markhinsky, and Ygyattinsky diamond-bearing areas of the Western Yakutian kimberlite province, the prerequisites and signs of scandium deposits in ancient weathering crusts overlying Lower Paleozoic rocks and associated with zones of ancient reservoir and soil oxidation. According to X-ray fluorescence and ICP MS analyses, in the Nakyn kimberlite field of the Sredne-Markhinsky diamond-bearing region, promising ore occurrences and scandium concentration halos have been established in clay deposits of redeposited weathering crusts of the Dyakhtar Formation of Late Triassic–Early Jurassic age. They are confined to the erosional surface of Lower Paleozoic carbonate rocks and Middle Paleozoic traps, with monzonite porphyries and kimberlites cutting through them, covered on top by a sedimentary cover of Jurassic terrigenous deposits. Concentration anomalies of scandium in clays of the Dyakhtar Formation are localized mainly in deluvial clay deposits of paleowatersheds and gravitate to the intersections of tectonic disturbances. The depth of their occurrence does not exceed 100 m, which is quite favorable for the extraction of scandium by borehole in situ leaching. Concentrations of scandium were detected at one of the sites before 262 g/t in Late Triassic weathering crust, including material from a Middle Paleozoic gabbro dike, as well as overlying colluvial clays of the Dyakhtar formations with a maximum of 462 g/t.

Rare Earth Elements in the Seagrass Zostera noltei and Sediments from the Black Sea Coast of Crimea

In the present work, we assessed the contents of rare earth elements (REEs), including yttrium and scandium, in rhizomes and leaves of the widespread seagrass Zostera noltei Hornemann 1832 and in the nearby sediments from the Black Sea coast. The total REE content in the sediments was found to be much higher than in Z. noltei. The order of decrease in the major REE contents in the sediments and the seagrass rhizomes was identical, except for La and Y. La was the most abundant in the sediments, and Y in the rhizomes. The contents of all REEs in rhizomes of Z. noltei were 1.5–10 times higher than in the leaves. The highest difference in the REE contents was found for the minor elements (Sm–Lu). The translocation factors for Sc and the minor elements (excluding Tb) from the sediments to the rhizomes and from the rhizomes to the leaves turned out to be pairwise equal, which indicates the similarity of the REE translocation mechanisms. Comparing our results with the literature data, it is possible to conclude that the seagrass Z. noltei does not have an advantage in the REE accumulation over marine macroalgae. At the same time, large coastal deposits of this seagrass after storms allow us to consider it as a possible source of REEs in the future.

Gemology, Spectroscopy, and Mineralogy Study of Aquamarines of Three Different Origins

New aquamarine deposits have been found around the world in recent years, and how to compare and distinguish aquamarines of different origin has become a significant problem. Aquamarines from Koktokay, Minas Gerais, and Namaqualand were collected for standard gemology tests, spectroscopy, and chemical analysis in this paper. The spectroscopy experiment included infrared spectroscopy and Raman spectroscopy. Chemical composition analysis comprises electron microprobe and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). The results show that infrared absorption peaks related to [Fe2(OH)4] and NaH are found in Koktokay and Minas Gerais aquamarines, respectively. Compared with other two origins, Namaqualand aquamarine have strongest type II water Raman peak related to alkali metal content. Compared with aquamarines from other sources, aquamarines from Xinjiang and Minas Gerais are characterized by relatively high aluminum and low alkali contents in chemical composition, while Namaqualand aquamarine have a high scandium content.

THE ROLE OF SCANDIUM CHLORIDE AND HYDROXIDE COMPLEXES IN THE FORMATION OF SCANDIUM DEPOSITS: INSIGHTS FROM EXPERIMENTS AND MODELING

Abstract Although scandium is commonly concentrated to economic levels by magmatic processes, hydrothermal fluids also play an important role in its concentration. Indeed, the most important source of scandium is currently the Bayan Obo deposit in China, where scandium is extracted from hydrothermally produced aegirine. To know how and why scandium is concentrated by hydrothermal fluids, it is necessary to understand the speciation of scandium in hydrothermal fluids. In a recently published study, we showed that scandium forms stable species with fluoride ions and proposed that such species may have been responsible for the hydrothermal transport of scandium in deposits like Bayan Obo. Chloride ions, which have been shown to form stable complexes with the other rare earth elements (REEs), however, are much more abundant in most hydrothermal fluids than fluoride ions, as are hydroxide ions, particularly at high pH. We, therefore, conducted solubility experiments designed to investigate the stability of scandium chloride and hydroxide complexes in hydrothermal fluids. The experiments investigating the role of chloride species considered the solubility of Sc2O3(s) in the H2O-NaCl-HCl system at 100°, 150°, 300°, and 350°C and saturated water vapor pressure. These experiments showed that scandium concentration is independent of chloride concentration over the range of chlorinity investigated, i.e., up to 3.6 mol Cl– and that scandium, therefore, does not form stable complexes with chloride ions. To evaluate the role of hydroxide species in scandium transport and avoid the effect of chloride ions in the complexation, a second set of experiments was conducted that determined the solubility of Sc2O3(s) in H2O-NaClO4-HClO4 solutions at 100°, 150°, 200°, and 250°C, and saturated water vapor pressure. The results of these experiments showed that the solubility of Sc2O3(s) depends on pH and temperature. Based on the former dependence, two scandium hydroxide complexes, Sc(OH)2+ and Sc(OH)3°, were identified at low and higher pH, respectively. The formation constant (log β) determined for Sc(OH)2+ is 10.29 ± 0.07, 10.32 ± 0.07, 10.35 ± 0.19, and 10.91 ± 0.20 at 100°, 150°, 200°, and 250°C, respectively. That of Sc(OH)3° is 27.22 ± 0.68, 26.66 ± 1.35, 27.04 ± 0.13, and 28.02 ± 0.14 at the same temperatures, respectively. These results demonstrate that, unlike the case for the other rare earth elements, chloride plays a negligible role in transporting scandium in hydrothermal fluids. Instead, they show that scandium hydroxide complexes can be important in the transport of scandium and could have contributed significantly to the formation of deposits like those at Bayan Obo.

Investigation of the Decomposition of Al–Sc Solid Solution during Annealing of Deformed Al–0.5% Mg–Sc Alloys

Abstract—The results of studies of the kinetics of solid solution decomposition during firing of fine-grained conductive alloys Al–0.5% Mg–Sc with different scandium content are presented. The alloys were obtained by induction casting, and the fine-grained microstructure was formed using equal-channel angular pressing. The kinetics of the decomposition of a solid solution has been studied using methods for measuring electrical resistivity and microhardness. The results were analyzed using the Johnson–Mel–Avrami–Kolmogorov equation. It is shown that during the firing of fine-grained alloys, the separation of Al3Sc particles along the nuclei of lattice dislocations is observed, and discontinuous precipitation of scandium in aluminum also occurs.

Critical raw materials associated with the lateritic bauxite and red mud in West Kalimantan, Indonesia

The Western Indonesia Bauxite Province in Kalimantan is a lateritic bauxite region with a complex history and poorly known sustainable metal contents within the bauxite residue. Bauxite residue produced using the Bayer process contains, notably, scandium. We present new geochemical, mineralogical and geological data from the lateritic bauxite and red mud from the active mine and deposit, which allow us to investigate the behaviour of critical elements during weathering. The geochemical analysis and translated isocon results have shown that the content of scandium in red mud is higher than the average concentration of crustal rocks and is concentrated in the ferrite layer and bauxite residue. A positive correlation between the existence of iron oxyhydroxide mineral in the residual iron-rich layer and red muds with the rare earth elements (REEs) and scandium concentrations may be interpreted as a scavenging effect of mobile REEs. The weathering and leaching processes in bauxite allows the adsorption of the trivalent scandium cation (Sc 3+ ) on goethite and are followed by ionic substitution with other trivalent cations in crystals of hematite. The study illustrates the importance of understanding processes during weathering and laterization for geochemical processes and REE exploration in tropical areas. Supplementary material: Material A, (A) Mineralogical profile of the bauxite, ferrite, and tonalite in Tayan and Mempawah, (B) Ternary diagram of bauxite and their parent rocks, (C) Trace element ratios in bauxite; Material B, Spearman's correlation rank of bauxite and associated rocks from Tayan mine ( n = 35); Material C, (A) XRD patterns of representative samples from the Tayan mine and Mempawah deposit, West Kalimantan, (B) Typical normal (left) and continuum (right) removed reflectance spectral curves of samples are available at https://doi.org/10.6084/m9.figshare.c.6689139 Thematic collection: This article is part of the Geochemical processes related to mined, milled, or natural metal deposits collection available at: https://www.lyellcollection.org/topic/collections/geochemical-processes-related-to-mined-milled-or-natural-metal-deposits

Density functional theory insights of phonons modes behaviours in AlScN for surface acoustic wave applications

In this work, we investigate the phonons modes behaviors of scandium-doped aluminum nitride (Sc-AlN) using first-principles density functional theory (DFT). We analyze the phononic dispersion, phonon density of states, group velocity, and Raman spectra of ScAlN for various scandium concentrations and compare them with undoped AlN. Our results show that Sc doping is significantly affect the phononic properties of AlN, including the formation of defect states within the phononic band gap and changes in the group velocities of phonon modes. Our analysis reveals that the introduction of Sc dopants causes a notable narrowing of the phononic band gap in AlN. Additionally, we observe a zero group velocity in the band gap, indicating the suppression of phononic transmission through the material. Moreover, Sc doping also affects the Raman spectrum of AlN, by inducing new vibrational modes. The known E2(high) peak in the Raman spectrum of AlN shifts to lower frequencies upon Sc doping, and new peaks appear due to the interactions of scandium and the AlN lattice. Our findings highlight the importance of understanding the effects of dopants on the phononic properties of AlScN and have implications for the design and optimization of AlScN-based devices for acoustic wave applications

Fabrication and optical properties of YSAG:Cr optical ceramics

YSAG:Cr3+ optical ceramics with compositions Y2.8Sc1.2Cr0.005Al3.995O12, and Y2,88Сr0,005Sc0.2Al4,915O12 were fabricated for the first time. The linear transmittances of the ceramic samples exceeded 80% in the visible and IR regions. It was observed that as the concentration of scandium in YSAG:Cr3+ solid solutions increased, the refractive index of ceramics at a wavelength of 632.8 nm increased from 1.828 ± 0.005 to 1.857 ± 0.005. The effect of scandium cations on the spectral-luminescent properties of Cr3+ cations in the crystal lattice of yttrium-scandium-aluminum garnet was also investigated. It was demonstrated that as the scandium content in dodecahedral site increased from 4 to 50 at%, the effective lifetime of excited states of Cr3+ cations increased from 1.71 ms to 2.72 ms. On the contrary, as scandium content in octahedral site increased, the effective lifetime of excited states of Cr3+ cations decreased from 1.71 ms to 0.71 ms.

Geochemistry and Mineralogy of Rare-Earth Elements in Ferruginous Deposits and Bottom Sediments of the Laptev Sea

Abstract —The geochemical and mineralogical aspects of the distribution of rare-earth elements (REE) in ferruginous deposits (FD) and bottom sediments of the southeastern Laptev Sea are analyzed. The FD are dominated by biomorphs developed after polychaete tubes. The REE patterns depend on the proportion of ore and non-ore substances. The ore substance is represented mainly by iron hydroxides (limonite). It is a product of suboxic diagenesis enhanced by bioturbation and determines the slight enrichment of FD in MREE and cerium deficiency (Cean = 0.94). The non-ore substance comes from terrigenous sediments and has an (alumino)silicate composition. It controls the scandium content and is the source of REE mineral grains, among which monazite-(Ce) prevails. The sediments demonstrate a common similarity in REE patterns to shales and suspended material transported to the Laptev Sea by the Lena River, with elevated LREE and MREE contents and the value of Ce anomaly almost equal to unity (Cean = 1.06). In the sediments, REE minerals occur mostly in the silt fraction (<63 μm in size). The high content of organic matter (Corg of up to 2.15%) of predominantly terrigenous origin (OMter of up to 85%) in the sediments explains the oxygen deficiency and weak diagenetic mineral formation with low accumulation of trace elements, including REE, in the FD. The total REE content in the FD is lower than that in the sediments (on average, 173 ppm against 206 ppm).