Scandium

A 'critical metal' is one that has important economic uses, but which also faces supply risks for geopolitical or environmental and sustainability reasons. The constrained nature of critical metals supply means proposed solutions to the problem commonly involve reducing demand and therefore reliance, via recycling, substitution and thrifting. However, most critical metals are presently only small markets and therefore such an approach ignores the potential of transformational market growth to reduce supply risk, by creating large, diverse, transparent markets with multiple sources of primary mine supply, akin to modern base metals markets. Research is therefore required into which critical metals have the greatest potential for such transformational market growth. This study therefore conducts an evaluation of 49 critical metals to determine which are nearest to the combined breakthroughs in discovery, supply and demand that may lead to transformational market growth. The study concludes that 13 markets from the 49 critical metals, being magnesium, silicon, barium, boron, lithium, cobalt, chromium, vanadium, gallium, strontium, cerium, lanthanum and scandium have the highest potential for transformational market growth and thus efforts to resolve supply risk in these markets may be better focussed on overcoming current market constraints and growing these markets, rather than lessening reliance by reducing demand.

The disposal of voluminous, highly alkaline, bauxite residue (BR), the industrial by-product of alumina production by the Bayer process, constitutes an intricate global environmental problem. BR, containing valuable metals such as rare-earth elements (REEs)—in particular, scandium (Sc)—can be used as a secondary source for REE extraction. The scope of this study was the investigation of bioleaching as an innovative and environmentally friendly approach for the extraction of Sc from BR. The bioleaching parameters were studied on Greek BR and experiments were performed using different microbial cultures and solid to liquid ratios (S/L). The maximum extraction of Sc was 42% using Acetobacter tropicalis in a one-step bioleaching process at 1% S/L. The main organic acids produced were acetic, oxalic, and citric. The bioleaching data indicated a probable synergistic effect of the different organic acids produced by microorganisms along with a more targeted leaching mechanism.

Scandium-44g (half-life 3.97h) shows promise for application in positron emission tomography (PET), due to favorable decay parameters. One of the sources of (44g)Sc is the (44)Ti/(44g)Sc generator, which can conveniently provide this radioisotope on a daily basis at a diagnostic facility. Titanium-44 (half-life 60.0 a), in turn, can be obtained via proton irradiation of scandium metal targets. A substantial (44)Ti product batch, however, requires high beam currents, long irradiation times and an elaborate chemical procedure for (44)Ti isolation and purification. This study describes the production of a combined 175MBq (4.7mCi) batch yield of (44)Ti in week long proton irradiations at the Los Alamos Isotope Production Facility (LANL-IPF) and the Brookhaven Linac Isotope Producer (BNL-BLIP). A two-step ion exchange chromatography based chemical separation method is introduced: first, a coarse separation of (44)Ti via anion exchange sorption in concentrated HCl results in a (44)Tc/Sc s...

The overexpression of integrin αvβ3 has been linked to tumor aggressiveness and metastasis in several cancer types. Because of its high affinity, peptides containing the arginine-glycine-aspartic acid (RGD) motif have been proven valuable vectors for noninvasive imaging of integrin αvβ3 expression and for targeted radionuclide therapy. In this study, we aim to develop a (44)Sc-labeled RGD-based peptide for in vivo positron emission tomography (PET) imaging of integrin αvβ3 expression in a preclinical cancer model. High quality (44)Sc (t1/2, 3.97 h; β(+) branching ratio, 94.3%) was produced inexpensively in a cyclotron, via proton irradiation of natural Ca metal targets, and separated by extraction chromatography. A dimeric cyclic-RGD peptide, (cRGD)2, was conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and radiolabeled with (44)Sc in high yield (>90%) and specific activity (7.4 MBq/nmol). Serial PET imaging of mice bearing U87MG tumor xenografts show...

Laser Additive Manufacturing (LAM) of light metals such as high-strength Al-based alloys offers tremendous potential for e.g. weight reduction and associated reduced fuel consumptions for the transportation industry. Typically, commercial Sc-containing alloys, such as Scalmalloy®, rely on precipitation hardening to increase their strength. Conventional processing involves controlled ageing during which ordered and coherent Al 3 Sc precipitates form from a Sc-supersaturated solid solution. Here we show how the intrinsic heat treatment (IHT) of directed energy deposition (DED) can be used to trigger the precipitation of Al 3 Sc already during the LAM process. High number densities of 10 23 nano-precipitates per m 3 can be realized through solid-state phase transformation from the supersaturated Al-Sc matrix that results from the fast cooling rate in LAM. Yet, the IHT causes precipitates to coarsen, hence reducing their strengthening effect. We implement alternative solidification conditions to exploit the IHT to form a Zr-rich shell around the Al 3 Sc precipitates that prevents coarsening. Our approach is applicable to a wide range of precipitation-hardened alloys to trigger in-situ precipitation during LAM.

The first pyrrolidine and cyclopropane derivatives of the trimetallic nitride templated (TNT) endohedral metallofullerenes Ih-Sc3N@C80 and Ih-Y3N@C80 connected to an electron-donor unit (i.e., tetrathiafulvalene, phthalocyanine or ferrocene) were successfully prepared by 1,3-dipolar cycloaddition reactions of azomethine ylides and Bingel–Hirsch-type reactions. Electrochemical studies confirmed the formation of the [6,6] regioisomers for the Y3N@C80-based dyads and the [5,6] regioisomers in the case of Sc3N@C80-based dyads. Similar to other TNT endohedral metallofullerene systems previously synthesized, irreversible reductive behavior was observed for the [6,6]-Y3N@C80-based dyads, whereas the [5,6]-Sc3N@C80-based dyads exhibited reversible reductive electrochemistry. Density functional calculations were also carried out on these dyads confirming the importance of these structures as electron transfer model systems. Furthermore, photophysical investigations on a ferrocenyl–Sc3N@C80-fulleropyrrolidine dyad demonstrated the existence of a photoinduced electron-transfer process that yields a radical ion pair with a lifetime three times longer than that obtained for the analogous C60 dyad.

The aim of this study was to evaluate new ligands which can be applied for labeling biomolecules with scandium radionuclides. Two radionuclides of scandium, 47Sc and 44Sc, are perspective radioisotopes for radiotherapy and diagnostic imaging. 47Sc decays with a half-life of 3.35days and a maximum β− energy of 600keV and could be an alternative to carrier added 177Lu radionuclide for

A scandium analogue of hydtotalcite and a mixed sample containing both scandium and aluminum have been synthesized and characterized. It is known that both samples have a layered structure; the unit cell parameters of the scandium-containing samples are slightly higher than the respective values of an ordinary aluminum-containing sample. The mixed-metal scandium-aluminum sample easily regains its layered structure after a dehydration/rehydration cycle, while the scandium analogue after this treatment is restored only partially.

Adopting recently developed clean laboratory techniques, antimony (Sb) and scandium (Sc) deposition were measured in a 63.72 m-long ice core (1842–1996) and a 5 m deep snow pit (1994–2004) collected on Devon Island, Canadian High Arctic. Antimony concentrations ...

The quest for alternative drugs with respect to the well-known cis-platin and its derivatives, which are still used in more than 50% of the treatment regimens for patients suffering from cancer, is highly needed. In this context, organometallic compounds, which are defined as metal complexes containing at least one direct covalent metal-carbon bond, have recently been found to be promising anticancer drug candidates. A series of new metallocene complexes with scandium, yttrium, and neodymium have been prepared and characterized. Some of these compounds show a very interesting anti-proliferative activity in triple negative breast cancer cell line (MDA.MB231) and the non-hormone sensitive prostate cancer cell line (DU145). Moreover, the interaction of some of them with biological membranes, evaluated using liposomes as bio-membrane mimetic model systems, seems to be relevant. The biological activity of these compounds, particularly those based on yttrium, already effective at low conc...

In recent years, (47)Sc has attracted attention because of its favorable decay characteristics (half-life, 3.35 d; average energy, 162 keV; Eγ, 159 keV) for therapeutic application and for SPECT imaging. The aim of the present study was to investigate the suitability of (47)Sc for radionuclide therapy in a preclinical setting. For this purpose a novel DOTA-folate conjugate (cm10) with an albumin-binding entity was used. (47)Sc was produced via the (46)Ca(n,γ)(47)Ca[Formula: see text](47)Sc nuclear reaction at the high-flux reactor at the Institut Laue-Langevin. Separation of the (47)Sc from the target material was performed by a semi-automated process using extraction chromatography and cation exchange chromatography. (47)Sc-labeled cm10 was tested on folate receptor-positive KB tumor cells in vitro. Biodistribution and SPECT imaging experiments were performed in KB tumor-bearing mice. Radionuclide therapy was conducted with two groups of mice, which received either (47)Sc-cm10 (10 ...

In this work a detailed investigation of the exohedral reactivity of the most important and abundant endohedral metallofullerene (EMF) is provided, that is, Sc 3 N@ I hC 80 and its D 5h counterpart Sc 3 N@ D 5h-C 80, and the (bio) chemically relevant lutetium-and gadolinium-based M 3 N@ I h/D 5h-C 80 EMFs (M= Sc, Lu, Gd). In particular, we analyze the thermodynamics and kinetics of the Diels–Alder cycloaddition of s-cis-1, 3-butadiene on all the different bonds of the I hC 80 and D 5h-C 80 cages and their endohedral derivatives. ...