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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Investigating the Theranostic Potential of Elementally Matched [ 43 Sc]Sc-PSMA-617 and [ 47 Sc]Sc-PSMA-617

The theranostic approach, which employs diagnostic radiopharmaceuticals to select patients who would benefit from targeted radiotherapy agents, has become an invaluable strategy for effective medical care. Scandium radionuclides offer the advantage of forming elementally matched and chemically identical diagnostic and therapeutic compounds, making them ideal candidates for this strategy. PSMA-617 is an established prostate-specific membrane antigen targeting agent and can be used as a proof of concept to investigate 43 Sc, the diagnostic nuclide, and 47 Sc, the therapeutic nuclide, as a theranostic pair. Methods: Cellular uptake, competitive binding assays, and internalization studies were carried out using LNCaP or PC-3 cell lines. [ 43 Sc]Sc-PSMA-617 was used in PET imaging studies in LNCaP or PC-3 tumor models, with time points ranging from 1–9 h. LNCaP tumor-bearing mice injected with [ 47 Sc]Sc-PSMA-617 were imaged using SPECT up to 48 h. A longitudinal study was carried out using LNCaP tumor-bearing mice imaged with [ 43 Sc]Sc-PSMA-617 prior to receiving a therapeutic dose of [ 47 Sc]Sc-PSMA-617. Results: 43 Sc and 47 Sc were incorporated into PSMA-617 at radiochemical yields of >99%. Cellular uptake studies demonstrated high uptake and specificity to PSMA receptors for [ 47 Sc]Sc-PSMA-617. In vivo PET studies showed specificity of [ 43 Sc]Sc-PSMA-617 while SPECT studies demonstrated tumor retention of [ 47 Sc]Sc-PSMA-617 up to 48 h. [ 47 Sc]Sc-PSMA-617 demonstrated therapeutic efficacy by delaying tumor growth and increasing survival rates from a single administered dose in xenograft models. More importantly, the PET results from [ 43 Sc]Sc-PSMA-617 PET were highly correlated with the therapeutic response from [ 47 Sc]Sc-PSMA-617, showing that 43 Sc PET data can predict therapeutic outcomes in individual animals from 47 Sc agents, even in animals sharing a genetic background and implanted with tumors from the same cell line. Conclusions: Two chemically identical, PSMA-targeting radioscandium pharmaceuticals demonstrated in vivo stability, specificity and retention in PSMA+ tumor models. A theranostic study showed that a higher 43 Sc PET SUVmean was strongly correlated to therapeutic response from the 47 Sc agent, demonstrating that 43 Sc and 47 Sc can be used as an elementally matched theranostic pair.

Biodistribution↗
DOE OSTI2025

Synthesis of DOTA-Based 43 Sc Radiopharmaceuticals Using Cyclotron-Produced 43 Sc as Exemplified by [ 43 Sc]Sc-PSMA-617 for PSMA PET Imaging

The implementation of theranostics in oncologic nuclear medicine has exhibited immense potential in improving patient outcomes in prostate cancer with the implementation of [ 68 Ga]Ga-PSMA-11 PET and [ 177 Lu]Lu-PSMA-617 into clinical practice. However, the correlation between radiopharmaceutical biodistributions seen with [ 68 Ga]Ga-PSMA-11 PET imaging and downstream [ 177 Lu]Lu-PSMA-617 therapy remains imperfect. This suggests that prostate cancer theranostics could potentially be further refined through the implementation of true theranostics, tandem pairs of diagnostic and therapeutic radiopharmaceuticals that utilize the same ligand and element, thus yielding identical pharmacokinetics. The radioscandiums are one such group of true theranostic radiopharmaceuticals. The radioscandiums consist of two β+ emitting scandium isotopes ( 43 Sc/ 44 Sc), as well as a β − emitting therapeutic isotope ( 47 Sc), which can all conjugate with PSMA-targeting PSMA-617. This potential has led to extensive investigations into the production of the radioscandiums as well as pre-clinical assessments with several ligands; however, there is a lack of literature extensively describing the complete synthesis of scandium radiopharmaceuticals. which therefore limits the accessibility of radioscandium research in theranostics. As such, this work aims to present an easily translatable protocol for the synthesis of [ 43 Sc]Sc-PSMA-617 from a [ 42 Ca]CaCO 3 starting material, including target formation, nuclear production via 42 Ca(d,n) 43 Sc reaction, chemical separation, radiolabeling, solvent reformulation, and target recycling.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2025

Towards a Deeper Fundamental Understanding of (Al,Sc)N Ferroelectric Nitrides

Density functional theory (DFT) calculations, within the virtual crystal alloy approximation, are performed, along with the development of a Landau-type model employing a symmetry-allowed analytical expression of the internal energy and having parameters determined from first principles, to investigate properties and energetics of Al1-xScxN ferroelectric nitrides in their hexagonal forms. These DFT computations and this model predict the existence of two different types of minima, namely, the fourfold-coordinated wurtzite (WZ) polar structure and a five-fold coordinated paraelectric hexagonal phase (denoted as H5), for any Sc composition up to 40%. The H5 minimum progressively becomes the lowest-energy state within hexagonal symmetry as the Sc concentration increases from 0 to 0.4. Furthermore, the model points to several key findings. Examples include the crucial role of the coupling between polarization and strains to create the WZ minimum, in addition to polar and elastic energies, and that the origin of the H5 state overcoming the WZ phase as the global minimum within hexagonal symmetry when increasing the Sc composition mostly lies in the compositional dependency of only two parameters-one linked to the polarization and another one being purely elastic in nature. Other examples are that forcing Al1-xScxN systems to have no or a weak change in lattice parameters when heating them allows us to reproduce their finite-temperature polar properties well and that a value of the axial ratio close to that of the ideal WZ structure implies a large polarization at low temperatures but not necessarily at high temperatures because of the ordered-disordered character of the temperature-induced formation of the WZ state. Such findings should allow for a better fundamental understanding of (Al,Sc)N ferroelectric nitrides, which may be used to design efficient devices having, e.g., low operating voltages.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Cross-sections for 43 Sc, 44 m Sc, and 44 g Sc from two heavy ion reactions

Two different heavy ion reactions were used to produce 43 Sc (t$_{\frac12}$ = 3.891 h), 44g Sc (t$_{\frac12}$ = 4.042 h), and 44m Sc (t$_{\frac12}$ = 58.61 h) among other stable or long-lived chemically separable products. Production cross sections for 19 F + 27 Al and the reverse kinematic reaction 35 Cl + nat B were measured using an MC-SNICS ion source and the Notre Dame FN Tandem Accelerator. 19 F beams from 35 to 60 MeV were produced with beam currents between 40–80 pnA and 35 Cl beams were produced at six entrance energies with comparable beam currents. This work reports nuclear reaction cross sections 27 Al ( 19 F, x) 43 Sc, 27 Al ( 19 F, pn) 44g Sc, and 27 Al ( 19 F, pn) 44m Sc at six energies between 35 and 60 MeV lab energy. Cross sections within the same energy range were measured for 27 Al ( 19 F, 3pn) 42 K and 27 Al ( 19 F, 3p) 43 K. Comparative measurements were performed for the same compound nucleus produced from nat B( 35 Cl, x) 43 Sc, nat B( 35 Cl, pn) 44g Sc, and nat B( 35 Cl, pn) 44m Sc. The measured thin target cross sections show an overestimation by several statistical models for the scandium radioisotopes. This is corroborated by the measured thick target production rates for both entrance channels. This may be due to angular momentum effects of a heavy ion entrance channel compared to light-ion production, but additional work is required to understand this discrepancy. Finally, these measurements demonstrate that the medically useful 43 Sc, 44g Sc, and 44m Sc radioisotopes can be free of the long-lived contaminant 46 Sc without the use of enriched targets, using heavy ion beams and robust target materials.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2021

Accelerator Production of Scandium Radioisotopes: Sc-43, Sc-44, and Sc-47

Scandium radioisotopes are increasingly considered viable radiolabels for targeted molecular imaging (Sc-43, Sc-44) and therapy (Sc-47). Significant technological advances have increased the quantity and quality of available radio scandium in the past decade, motivated in part by the chemical similarity of scandium to therapeutic radionuclides like Lu-177. Finally, the production and radiochemical isolation techniques applied to scandium radioisotopes are reviewed, focusing on charged particle and electron linac initiated reactions and using calcium and titanium starting materials

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2020

Synthesis of precipitation-strengthened Al-Sc, Al-Zr and Al-Sc-Zr alloys via selective laser melting of elemental powder blends

Selective laser melting is used to create Al-1.5Sc, Al-1.5Zr and Al-0.75Sc-0.75Zr (at.%) alloys from blends of elemental Al, Sc, and Zr powders. This study investigates elemental alloying elements (Sc and Zr) which are high-melting and highly reactive, unlike previous work which focused on more concentrated elemental additions of lower-melting, lower-reactivity Cu and Si to aluminum. High-speed in situ synchrotron x-ray imaging and diffraction show that the 20–30 μm Al, Sc, and Zr powders fully melt and sufficiently mix in the molten state to create, on solidification, a homogeneous distribution of primary, micron-size L12 precipitates (Al 3 Sc, Al 3 Zr, and Al 3 (Sc,Zr), respectively) and nucleate micron-size Al matrix grains, as confirmed by SEM imaging of cross-sections. Here, a second laser pass, simulating a realistic additive-manufacturing build condition, fully remelts the initial volume which shows, after solidification, the same Al 3 (Sc,Zr) L1 2 primary micro-precipitates and very fine Al grains. After aging at 300–400°C, the alloys show large increases in hardness, consistent with an exceptionally high number density (1.4 × 10 24 m –3 ) and volume fraction (2.5%) of secondary Al 3 (Sc,Zr) nano-precipitates with a Sc-rich core and Zr-rich shell, as measured via atom-probe tomography.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Formation of Al 3 Sc in Al 0.8 Sc 0.2 thin films

We report the formation of Al 3 Sc, in 100 nm Al 0.8 Sc 0.2 films, is found to be driven by exposure to high temperature through higher deposition temperature or annealing. High film resistivity was observed in films with lower deposition temperature that exhibited a lack of crystallinity, which is anticipated to cause more electron scattering. An increase in deposition temperature allows for the nucleation and growth of crystalline Al 3 Sc regions that were verified by electron diffraction. The increase in crystallinity reduces electron scattering, which results in lower film resistivity. Annealing Al 0.8 Sc 0.2 films at 600 °C in an Ar vacuum environment also allows for the formation and recrystallization of Al 3 Sc and Al and yields saturated resistivity values between 9.58 and 10.5 μΩ-cm regardless of sputter conditions. Al 3 Sc was found to nucleate and grow in a random orientation when deposited on SiO 2 , and highly {111} textured when deposited on 100 nm Ti and AlN films that were used as template layers. The rocking curve of the Al 3 Sc 111 reflection for the as-deposited films on Ti and AlN at 450 °C was 1.79° and 1.68°, respectively. Annealing the film deposited on the AlN template reduced the rocking curve substantially to 1.01° due to recrystallization of Al 3 Sc and Al within the film.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(TiFe3)2 by Materials Project

Sc(TiFe3)2 is Hexagonal Laves-derived structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are four inequivalent Sc sites. In the first Sc site, Sc is bonded in a 12-coordinate geometry to three equivalent Sc, one Ti, and twelve Fe atoms. All Sc–Sc bond lengths are 2.98 Å. The Sc–Ti bond length is 2.97 Å. There are a spread of Sc–Fe bond distances ranging from 2.84–2.93 Å. In the second Sc site, Sc is bonded in a 12-coordinate geometry to four Ti and twelve Fe atoms. There are three shorter (2.98 Å) and one longer (3.00 Å) Sc–Ti bond lengths. There are a spread of Sc–Fe bond distances ranging from 2.84–2.87 Å. In the third Sc site, Sc is bonded in a 12-coordinate geometry to four Ti and twelve Fe atoms. There are three shorter (2.98 Å) and one longer (2.99 Å) Sc–Ti bond lengths. There are a spread of Sc–Fe bond distances ranging from 2.84–2.86 Å. In the fourth Sc site, Sc is bonded in a 12-coordinate geometry to three equivalent Sc, one Ti, and twelve Fe atoms. The Sc–Ti bond length is 2.99 Å. There are a spread of Sc–Fe bond distances ranging from 2.84–2.91 Å. There are eight inequivalent Ti sites. In the first Ti site, Ti is bonded in a 12-coordinate geometry to three equivalent Sc, one Ti, and twelve Fe atoms. The Ti–Ti bond length is 2.93 Å. There are a spread of Ti–Fe bond distances ranging from 2.83–2.91 Å. In the second Ti site, Ti is bonded in a 12-coordinate geometry to three equivalent Sc, one Ti, and twelve Fe atoms. The Ti–Ti bond length is 2.93 Å. There are a spread of Ti–Fe bond distances ranging from 2.83–2.90 Å. In the third Ti site, Ti is bonded in a 12-coordinate geometry to one Sc, three equivalent Ti, and twelve Fe atoms. All Ti–Ti bond lengths are 2.95 Å. There are a spread of Ti–Fe bond distances ranging from 2.78–2.83 Å. In the fourth Ti site, Ti is bonded in a 12-coordinate geometry to four Ti and twelve Fe atoms. All Ti–Ti bond lengths are 2.94 Å. There are three shorter (2.76 Å) and nine longer (2.83 Å) Ti–Fe bond lengths. In the fifth Ti site, Ti is bonded in a 12-coordinate geometry to four Ti and twelve Fe atoms. All Ti–Ti bond lengths are 2.94 Å. There are three shorter (2.78 Å) and nine longer (2.83 Å) Ti–Fe bond lengths. In the sixth Ti site, Ti is bonded in a 12-coordinate geometry to one Sc, three equivalent Ti, and twelve Fe atoms. There are a spread of Ti–Fe bond distances ranging from 2.76–2.83 Å. In the seventh Ti site, Ti is bonded in a 12-coordinate geometry to one Sc, three equivalent Ti, and twelve Fe atoms. There are a spread of Ti–Fe bond distances ranging from 2.76–2.84 Å. In the eighth Ti site, Ti is bonded in a 12-coordinate geometry to one Sc, three equivalent Ti, and twelve Fe atoms. There are three shorter (2.77 Å) and nine longer (2.83 Å) Ti–Fe bond lengths. There are twelve inequivalent Fe sites. In the first Fe site, Fe is bonded to six Sc and six Fe atoms to form FeSc6Fe6 cuboctahedra that share corners with twelve FeSc3Ti3Fe6 cuboctahedra, edges with six equivalent FeSc6Fe6 cuboctahedra, and faces with twenty FeTi6Fe6 cuboctahedra. There are three shorter (2.49 Å) and three longer (2.50 Å) Fe–Fe bond lengths. In the second Fe site, Fe is bonded to three equivalent Sc, three equivalent Ti, and six Fe atoms to form FeSc3Ti3Fe6 cuboctahedra that share corners with twelve FeSc2Ti4Fe6 cuboctahedra, edges with six equivalent FeSc3Ti3Fe6 cuboctahedra, and faces with twenty FeTi6Fe6 cuboctahedra. There are three shorter (2.46 Å) and three longer (2.48 Å) Fe–Fe bond lengths. In the third Fe site, Fe is bonded to three equivalent Sc, three equivalent Ti, and six Fe atoms to form FeSc3Ti3Fe6 cuboctahedra that share corners with twelve FeSc2Ti4Fe6 cuboctahedra, edges with six equivalent FeSc3Ti3Fe6 cuboctahedra, and faces with twenty FeTi6Fe6 cuboctahedra. All Fe–Fe bond lengths are 2.46 Å. In the fourth Fe site, Fe is bonded to six Ti and six Fe atoms to form FeTi6Fe6 cuboctahedra that share corners with twelve FeSc2Ti4Fe6 cuboctahedra, edges with six equivalent FeTi6Fe6 cuboctahedra, and faces with twenty FeSc6Fe6 cuboctahedra. There are three shorter (2.39 Å) and three longer (2.40 Å) Fe–Fe bond lengths. In the fifth Fe site, Fe is bonded to six Ti and six Fe atoms to form FeTi6Fe6 cuboctahedra that share corners with twelve FeSc3Ti3Fe6 cuboctahedra, edges with six equivalent FeTi6Fe6 cuboctahedra, and faces with twenty FeSc6Fe6 cuboctahedra. There are three shorter (2.39 Å) and three longer (2.40 Å) Fe–Fe bond lengths. In the sixth Fe site, Fe is bonded to six Ti and six Fe atoms to form FeTi6Fe6 cuboctahedra that share corners with twelve FeSc2Ti4Fe6 cuboctahedra, edges with six equivalent FeTi6Fe6 cuboctahedra, and faces with twenty FeSc3Ti3Fe6 cuboctahedra. All Fe–Fe bond lengths are 2.41 Å. In the seventh Fe site, Fe is bonded to three Sc, three Ti, and six Fe atoms to form FeSc3Ti3Fe6 cuboctahedra that share corners with eighteen FeSc6Fe6 cuboctahedra, edges with six FeSc3Ti3Fe6 cuboctahedra, and faces with eighteen FeSc6Fe6 cuboctahedra. There are two shorter (2.38 Å) and two longer (2.46 Å) Fe–Fe bond lengths. In the eighth Fe site, Fe is bonded to two equivalent Sc, four Ti, and six Fe atoms to form FeSc2Ti4Fe6 cuboctahedra that share corners with eighteen FeSc3Ti3Fe6 cuboctahedra, edges with six FeSc2Ti4Fe6 cuboctahedra, and faces with eighteen FeSc3Ti3Fe6 cuboctahedra. There are two shorter (2.36 Å) and two longer (2.47 Å) Fe–Fe bond lengths. In the ninth Fe site, Fe is bonded to two equivalent Sc, four Ti, and six Fe atoms to form a mixture of corner, edge, and face-sharing FeSc2Ti4Fe6 cuboctahedra. There are two shorter (2.37 Å) and two longer (2.46 Å) Fe–Fe bond lengths. In the tenth Fe site, Fe is bonded to three Sc, three Ti, and six Fe atoms to form FeSc3Ti3Fe6 cuboctahedra that share corners with eighteen FeSc6Fe6 cuboctahedra, edges with six FeSc3Ti3Fe6 cuboctahedra, and faces with eighteen FeSc6Fe6 cuboctahedra. There are two shorter (2.38 Å) and two longer (2.45 Å) Fe–Fe bond lengths. In the eleventh Fe site, Fe is bonded to one Sc, five Ti, and six Fe atoms to form a mixture of corner, edge, and face-sharing FeScTi5Fe6 cuboctahedra. There are two shorter (2.38 Å) and two longer (2.46 Å) Fe–Fe bond lengths. In the twelfth Fe site, Fe is bonded to one Sc, five Ti, and six Fe atoms to form FeScTi5Fe6 cuboctahedra that share corners with eighteen FeSc3Ti3Fe6 cuboctahedra, edges with six FeSc2Ti4Fe6 cuboctahedra, and faces with eighteen FeSc3Ti3Fe6 cuboctahedra. There are two shorter (2.38 Å) and two longer (2.46 Å) Fe–Fe bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Engineering a modular 44 Ti/ 44 Sc generator: eluate evaluation in preclinical models and estimation of human radiation dosimetry

Background: 44 Sc/ 47 Sc is an attractive theranostic pair for targeted in vivo positron emission tomographic (PET) imaging and beta-particle treatment of cancer. The 44 Ti/ 44 Sc generator allows daily onsite production of this diagnostic isotope, which may provide an attractive alternative for PET facilities that lack in-house irradiation capabilities. Early animal and patient studies have demonstrated the utility of 44 Sc. In our current study, we built and evaluated a novel clinical-scale 44 Ti/ 44 Sc generator, explored the pharmacokinetic profiles of 44 ScCl 3 , [ 44 Sc]-citrate and [ 44 Sc]-NODAGA (1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid) in naïve mice, and estimated the radiation burden of 44 ScCl 3 in humans. Methods: 44 Ti/ 44 Sc (101.2 MBq) in 6 M HCl solution was utilized to assemble a modular ZR resin containing generator. After assembly, 44 Sc was eluted with 0.05 M HCl for further PET imaging and biodistribution studies in female Swiss Webster mice. Based on the biodistribution data, absorbed doses of 44 / 47 ScCl 3 in human adults were calculated for 18 organs and tissues using the IDAC-Dose software. Results: 44 Ti in 6 M HCl was loaded onto the organic resin generator with a yield of 99.97%. After loading and initial stabilization, 44 ScCl 3 was eluted with 0.05 M HCl in typical yields of 82.9 ± 5.3% (N = 16), which was normalized to the estimated generator capacity. Estimated generator capacity was computed based on elution time interval and the total amount of 44 Ti loaded on the generator. Run in forward and reverse directions, the 44 Sc/ 44 Ti ratio from a primary column was significantly improved from 1038 ± 440 to 3557 ± 680 (Bq/Bq) when a secondary, replaceable, ZR resin cartridge was employed at the flow outlet. In vivo imaging and ex vivo distribution studies of the reversible modular generator for 44 ScCl 3 , [ 44 Sc]-citrate and [ 44 Sc]-NODAGA show that free 44 Sc remained in the circulation significantly longer than the chelated 44 Sc. The dose estimation of 44 ScCl 3 reveals that the radiation burden is 0.146 mSv/MBq for a 70 kg adult male and 0.179 mSv/MBq for a 57 kg adult female. Liver, spleen and heart wall will receive the highest absorbed dose: 0.524, 0.502, and 0.303 mGy/MBq, respectively, for the adult male. Conclusions: A clinical-scale 44 Ti/ 44 Sc generator system with a modular design was developed to supply 44 ScCl 3 in 0.05 M HCl, which is suitable for further radiolabeling and in vivo use. Our data demonstrated that free 44 ScCl 3 remained in the circulation for extended periods, which resulted in approximately 10 times greater radiation burden than stably chelated 44 Sc. Stable 44 Sc/ 47 Sc-complexation will be more favorable for in vivo use and for clinical utility.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2020

Materials Data on Sc(NiGe)6 by Materials Project

Sc(NiGe)6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. there are two inequivalent Sc sites. In the first Sc site, Sc is bonded to twelve equivalent Ni and eight Ge atoms to form distorted corner-sharing ScNi12Ge8 hexagonal bipyramids. All Sc–Ni bond lengths are 3.23 Å. There are two shorter (2.68 Å) and six longer (2.94 Å) Sc–Ge bond lengths. In the second Sc site, Sc is bonded to twelve Ni and eight Ge atoms to form a mixture of distorted face and corner-sharing ScNi12Ge8 hexagonal bipyramids. There are four shorter (3.21 Å) and eight longer (3.22 Å) Sc–Ni bond lengths. There are a spread of Sc–Ge bond distances ranging from 2.66–2.95 Å. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 12-coordinate geometry to two Sc, four Ni, and six Ge atoms. All Ni–Ni bond lengths are 2.55 Å. There are a spread of Ni–Ge bond distances ranging from 2.44–2.66 Å. In the second Ni site, Ni is bonded in a 12-coordinate geometry to two equivalent Sc, four Ni, and six Ge atoms. Both Ni–Ni bond lengths are 2.55 Å. There are a spread of Ni–Ge bond distances ranging from 2.44–2.65 Å. There are six inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to two equivalent Sc and six Ni atoms. In the second Ge site, Ge is bonded in a 6-coordinate geometry to six equivalent Ni atoms. In the third Ge site, Ge is bonded in a 12-coordinate geometry to three equivalent Sc and six equivalent Ni atoms. In the fourth Ge site, Ge is bonded in a 8-coordinate geometry to one Sc, six equivalent Ni, and one Ge atom. The Ge–Ge bond length is 2.47 Å. In the fifth Ge site, Ge is bonded in a 8-coordinate geometry to one Sc, six Ni, and one Ge atom. The Ge–Ge bond length is 2.50 Å. In the sixth Ge site, Ge is bonded in a 7-coordinate geometry to one Sc and six Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc by Materials Project

Sc crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. there are two inequivalent Sc sites. In the first Sc site, Sc is bonded in a 8-coordinate geometry to ten Sc atoms. There are a spread of Sc–Sc bond distances ranging from 3.15–3.44 Å. In the second Sc site, Sc is bonded in a 8-coordinate geometry to ten Sc atoms. Both Sc–Sc bond lengths are 3.44 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Plasma-Assisted Epitaxy of Piezoelectric Sc x Al 1-x N Films on Sapphire for Use in Harsh-Environment Microwave Acoustic Sensors

The Sc x Al 1-x N wurtzite structure has been shown theoretically and experimentally to exhibit significantly higher piezoelectric coupling compared to pure AlN. In this work, a plasma-assisted epitaxial growth method has been used to synthesize epitaxial (0002) Sc x Al 1-x N films on c-sapphire substrates from x = 0.07 to 0.30 by co-evaporating high-purity Sc and Al sources in the presence of a nitrogen plasma generated by an RF plasma source. Epitaxial Sc x Al 1-x N films with highly oriented (0002) grains and in-plane registry were produced on c-sapphire substrates that were pre-exposed to the nitrogen plasma to form an oxynitride seed layer. Growth of Sc x Al 1-x N films was carried out at 930°C under both metal-rich and N-rich conditions using precisely controlled Sc, Al, and N-plasma fluxes. Metal-rich depositions yielded non-(0002)-oriented Sc x Al 1-x N grains and intermetallic ScAl grains. Nitrogen-rich growth with a Sc/Al flux ratio of 1/3 produced the best (0002) epitaxy as determined by x-ray diffraction analysis. Surface acoustic wave resonator (SAWR) devices were fabricated from 500-nm-thick Sc x Al 1-x N and AlN films to extract their electromechanical coupling coefficients, k 2 . As the Sc concentration in the films increases, the degree of (0002) epitaxy is reduced, yet the value of k 2 increases becasue there is more Sc in the wurzite lattice despite the decreased level of (0002) grain alignment. As a result, the use of a 10-nm-thick Si x N y capping layer on top of the Sc x Al 1-x N films aids in preventing etching during SAWR device photolithography and also helps hinder film oxidation up to 800°C.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Development of a SnO 2 -based 44 Ti/ 44 Sc generator for medical applications

Towards application of 44 Sc for diagnostic nuclear medicine, a 44 Ti/ 44 Sc generator based on an inorganic resin has been evaluated. Unlike other radionuclide generators used for medical applications, the long-term retention of the parent 44 Ti is vital due to its long half life. In this work, tin dioxide (SnO 2 ), a robust inorganic-based resin, has been synthesized and used as the stationary phase for a 44 Ti/ 44 Sc generator. The sorption behavior of 44 Ti/ 44 Sc was tested on SnO 2 with varying acids, concentrations, and times. Preliminary batch study results showed >88 % 44 Ti retention to the resin at lower acid concentrations (0.05 M HNO 3 and 0.05 M HCl). A pilot generator was evaluated for a year, demonstrating 85.3 ± 2.8 % 44 Sc elution yields and 0.71 ± 0.14 % 44 Ti breakthrough in 5 M HNO 3 . Based on capacity studies, a 7.4 MBq (200 µCi) upscaled generator system was constructed for further evaluation of the SnO 2 resin stability and the efficacy of the eluted 44 Sc for radiolabeling. 44 Sc could be regularly eluted from this generator in 5 M HNO 3 with an overall average radiochemical yield 84.7 ± 9.5 %. Post-elution processing of the 44 Sc with DGA-normal resin removed all 44 Ti present and allowed for high 44 Sc-DOTA labeling yields of 94.2 ± 0.5 %. Overall, SnO 2 has been shown to be a viable material for a 44 Ti/ 44 Sc generator.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2020

Materials Data on Sc(TiGa2)2 by Materials Project

Sc(TiGa2)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sc is bonded in a distorted square co-planar geometry to twelve Ga atoms. There are four shorter (2.81 Å) and eight longer (3.31 Å) Sc–Ga bond lengths. Ti is bonded in a 10-coordinate geometry to two equivalent Ti and eight Ga atoms. Both Ti–Ti bond lengths are 2.73 Å. All Ti–Ga bond lengths are 2.75 Å. There are six inequivalent Ga sites. In the first Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Sc, four equivalent Ti, and four Ga atoms. There are two shorter (2.65 Å) and two longer (2.88 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Sc, four equivalent Ti, and four Ga atoms. Both Ga–Ga bond lengths are 2.65 Å. In the third Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Sc, four equivalent Ti, and four Ga atoms. There are one shorter (2.65 Å) and two longer (2.88 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Sc, four equivalent Ti, and four Ga atoms. There are one shorter (2.65 Å) and two longer (2.88 Å) Ga–Ga bond lengths. In the fifth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Sc, four equivalent Ti, and four Ga atoms. There are two shorter (2.65 Å) and two longer (2.88 Å) Ga–Ga bond lengths. In the sixth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Sc, four equivalent Ti, and four Ga atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(AlFe)6 by Materials Project

Sc(FeAl)6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Sc is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.20 Å) and eight longer (3.25 Å) Sc–Fe bond lengths. There are a spread of Sc–Al bond distances ranging from 2.80–2.94 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Sc, four Fe, and six Al atoms. There are two shorter (2.47 Å) and two longer (2.48 Å) Fe–Fe bond lengths. There are two shorter (2.51 Å) and four longer (2.57 Å) Fe–Al bond lengths. In the second Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Sc, four equivalent Fe, and six Al atoms. There are four shorter (2.56 Å) and two longer (2.59 Å) Fe–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Sc, six Fe, and three Al atoms. There are one shorter (2.69 Å) and two longer (2.83 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Sc, six Fe, and one Al atom. The Al–Al bond length is 2.83 Å. In the third Al site, Al is bonded in a 6-coordinate geometry to two equivalent Sc, six Fe, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗