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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Sc(Ga5Mo)8 by Materials Project

Sc(MoGa5)8 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Sc is bonded in a 8-coordinate geometry to two equivalent Mo and six equivalent Ga atoms. Both Sc–Mo bond lengths are 3.07 Å. All Sc–Ga bond lengths are 2.88 Å. There are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a 10-coordinate geometry to one Sc and nine Ga atoms. There are a spread of Mo–Ga bond distances ranging from 2.62–2.68 Å. In the second Mo site, Mo is bonded in a 10-coordinate geometry to ten Ga atoms. There are a spread of Mo–Ga bond distances ranging from 2.54–2.70 Å. There are eight inequivalent Ga sites. In the first Ga site, Ga is bonded in a cuboctahedral geometry to twelve Ga atoms. There are six shorter (2.92 Å) and six longer (3.04 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a distorted linear geometry to two equivalent Mo atoms. In the third Ga site, Ga is bonded in a 2-coordinate geometry to two equivalent Mo and seven Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.70–3.03 Å. In the fourth Ga site, Ga is bonded in a distorted bent 150 degrees geometry to two equivalent Mo and two Ga atoms. In the fifth Ga site, Ga is bonded in a distorted bent 150 degrees geometry to two Mo and two Ga atoms. In the sixth Ga site, Ga is bonded in a 2-coordinate geometry to two equivalent Mo and three Ga atoms. The Ga–Ga bond length is 2.79 Å. In the seventh Ga site, Ga is bonded in a 2-coordinate geometry to two Mo and three Ga atoms. There are one shorter (2.79 Å) and one longer (3.05 Å) Ga–Ga bond lengths. In the eighth Ga site, Ga is bonded in a 8-coordinate geometry to one Sc, two Mo, and five Ga atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(P2Rh3)2 by Materials Project

Sc(Rh3P2)2 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. Sc is bonded to six equivalent Rh and six equivalent P atoms to form face-sharing ScP6Rh6 cuboctahedra. All Sc–Rh bond lengths are 2.98 Å. All Sc–P bond lengths are 2.92 Å. There are two inequivalent Rh sites. In the first Rh site, Rh is bonded in a 5-coordinate geometry to five P atoms. There are a spread of Rh–P bond distances ranging from 2.42–2.59 Å. In the second Rh site, Rh is bonded in a 6-coordinate geometry to two equivalent Sc and four P atoms. There are a spread of Rh–P bond distances ranging from 2.28–2.51 Å. There are two inequivalent P sites. In the first P site, P is bonded in a 9-coordinate geometry to nine Rh atoms. In the second P site, P is bonded in a 8-coordinate geometry to two equivalent Sc and six Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(P2Ru3)2 by Materials Project

Sc(Ru3P2)2 crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Sc is bonded to six equivalent Ru and six equivalent P atoms to form face-sharing ScP6Ru6 cuboctahedra. All Sc–Ru bond lengths are 3.00 Å. All Sc–P bond lengths are 2.90 Å. There are two inequivalent Ru sites. In the first Ru site, Ru is bonded in a 6-coordinate geometry to two equivalent Sc and four P atoms. There are two shorter (2.31 Å) and two longer (2.47 Å) Ru–P bond lengths. In the second Ru site, Ru is bonded in a 5-coordinate geometry to five P atoms. There are one shorter (2.44 Å) and four longer (2.49 Å) Ru–P bond lengths. There are two inequivalent P sites. In the first P site, P is bonded in a 8-coordinate geometry to two equivalent Sc and six Ru atoms. In the second P site, P is bonded in a 9-coordinate geometry to nine Ru atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(Fe2Si)2 by Materials Project

Sc(Fe2Si)2 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Sc is bonded in a 6-coordinate geometry to twelve equivalent Fe and six equivalent Si atoms. There are four shorter (3.00 Å) and eight longer (3.13 Å) Sc–Fe bond lengths. There are two shorter (2.75 Å) and four longer (2.83 Å) Sc–Si bond lengths. Fe is bonded in a 3-coordinate geometry to three equivalent Sc and three equivalent Si atoms. There are one shorter (2.31 Å) and two longer (2.35 Å) Fe–Si bond lengths. Si is bonded in a 9-coordinate geometry to three equivalent Sc and six equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Effect of Zr and Sc additions on coarsening- and creep resistance of AlSi10Mg fabricated by laser powder bed fusion

Microstructure and creep properties are studied in a eutectic AlSi10Mg alloy modified with Zr and Sc additions (Al-9.8Si-0.32Mg-0.70Zr-0.23Sc, wt%) manufactured through laser powder-bed fusion (L-PBF). Three types of Zr/Sc-bearing powders - elemental, master-alloy, and pre-alloyed - are employed in the fabrication process, with the pre-alloyed powders providing the highest incorporation of Zr and Sc in the Al matrix. Here, the as-printed alloy exhibits a fine cellular Al-Si eutectic structure which fragments and coarsens into micron-sized Si particles during aging at 300 ºC, leading to a steady drop in alloy microhardness between 0.1 and 1000 h. Coarsening of the eutectic Si phase during aging is not measurably affected by Zr and Sc in solid solution, which precipitate during aging and increases strength, compensating weakening from Si coarsening between 1 and 200 h at 300 ºC. Atom-probe analysis in the peak-aged condition (96 h/300 °C) confirms the presence of Al 3 (Sc,Zr) secondary nano-precipitates with an average radius of 1.0 nm and some Si solubility. Micron-sized grains are present throughout the alloy, with ultra-fine-grained regions at the melt pool boundaries, neither of which coarsen during long-term aging at 300 ºC. Under creep conditions at 300 °C, the Zr/Sc-bearing alloy with Al 3 (Sc,Zr) nano-precipitates exhibits power-law behavior, with a high apparent stress exponent (n a = 9) and a high threshold stress (σ th = 43 MPa), exhibiting nearly double the strength of a Zr/Sc-free AlSi10Mg control alloy (σ th = 22 MPa).

36 MATERIALS SCIENCE↗
DOE OSTI2023

Photonuclear production of 47 Ca for 47 Ca/ 47 Sc generator from natural CaCO 3 targets

Here this work investigated the indirect production of 47 Sc from natural Ca targets via 48 Ca(γ,n) 47 Ca → 47 Sc +β - +$\bar{\nu}_e$ with incident electron energies of 30, 35, and 40 MeV. The 47 Ca production yields were simulated using the PHITS Monte Carlo simulation code and compared to experimental data. The simulated production rates for all three irradiations are in good agreement with experimental data within uncertainties. As a demonstration of the 47 Ca/ 47 Sc generator system, one of the irradiated CaCO 3 targets was dissolved in nitric acid, and 47 Sc was isolated from the target material using commercially available Eichrom DGA resin. The 47 Sc was allowed to grow in, and the purification process was repeated with promising 47 Sc and Ca recovery yields.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2025

48 Ca(p,pn) 47 Ca linac production for the preparation of a 47 Ca/ 47 Sc generator

Here, the production of 47 Sc via the nuclear reaction 48 Ca(p,pn) 47 Ca→(β-, T 1/2 = 4.54 d) 47 Sc and the assembly of a 47 Ca/ 47 Sc generator system has been investigated at Brookhaven National Laboratory. To produce 47 Ca, a pressed nat CaCl 2 target was irradiated with a proton beam at energy on target of 27.5 MeV at Brookhaven Linac Isotope Producer. Irradiated targets were dissolved in water and then acidified with concentrated HCl before separation using extraction chromatography through a diglycolamide (DGA) resin column. After ingrowth, 47 Sc was collected at >90 % with low contamination from both nonradioactive metals and coproduced radionuclides. A total of four 47 Ca/ 47 Sc separations were performed with 6–7 days between the irradiation and the separation to allow the equilibration of the ingrowing 47 Sc.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Critical Role of Sc Substitution in Modulating Ferroelectricity in Multiferroic LuFeO 3

Understanding how individual dopants or substitutional atoms interact with host lattices enables us to manipulate, control, and improve the functionality of materials. However, because of the intimate coupling among various degrees of freedom in multiferroics, the atomic-scale influence of individual foreign atoms has remained elusive. Here, we unravel the critical roles of individual Sc substitutional atoms in modulating ferroelectricity at the atomic scale of typical multiferroics, Lu 1–x Sc x FeO 3 , by combining advanced microscopy and theoretical studies. Atomic variations in polar displacement of intriguing topological vortex domains stabilized by Sc substitution are directly correlated with Sc atom-mediated local chemical and electronic fluctuations. The local FeO 5 trimerization magnitude and Lu/Sc–O hybridization strength are found to be significantly reinforced by Sc, clarifying the origin of the strong dependence of improper ferroelectricity on Sc content. We find that this study could pave the way for correlating dopant-regulated atomic-scale local structures with global properties to engineer emergent functionalities of numerous chemically doped functional materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Bonding similarities and differences between Y–Sb–Te and Sc–Sb–Te phase-change memory materials

The scandium (Sc) – alloyed Sb 2 Te 3 phase-change alloy has recently been found to enable ultrafast crystal nucleation due to the formation of Sc-stabilized octahedral motifs in the amorphous phase, rendering cache-type phase-change memory feasible. When yttrium (Y) is added, however, non-octahedral bonding patterns form in the amorphous Sb 2 Te 3 -based network even though Y has a valence electron configuration similar to that of Sc and also forms perfect octahedral bonding environments with tellurium in the YTe crystal. Here we elucidate the origin of this difference between Sc and Y, by carrying out thorough ab initio simulations and orbital-based bonding analyses on amorphous Y–Sb–Te and Sc–Sb–Te compounds. We also demonstrate how the smooth overlap of atomic positions (SOAP) similarity kernel can be used to quantify the structural similarity of local motifs in the amorphous phase with respect to various crystalline yttrium and scandium tellurides, both in the nearest-neighbor shell and beyond. We discover that the bonding contrast of Y- and Sc-centered structural motifs in amorphous Sb 2 Te 3 stems from their parent crystals at high Te concentrations. The larger atomic radius of Y and the weaker charge transfer when bonded with Te is found to allow more Te neighbors and cause a more open bonding environment, leading to higher coordination numbers and non-octahedral environments. We discuss the implications of the different local environments for practical applications in memory devices.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Low leakage current in heteroepitaxial Al 0.7 Sc 0.3 N ferroelectric films on Ga N

Wurtzite ( Al , Sc ) N ferroelectrics are attractive for microelectronics applications due to their chemical and structural compatibility with wurtzite semiconductors, such as Ga N and ( Al , Ga ) N . However, the leakage current in epitaxial stacks reported to date should be reduced for reliable device operation. Here, we demonstrate low leakage current in epitaxial Al 0.7 Sc 0.3 N films on Ga N with well-saturated ferroelectric hysteresis loops that are orders of magnitude lower (i.e., 0.07 A cm − 2 ) than previously reported films (1–19 A cm − 2 ) having similar or better structural characteristics. We also show that, for these high-quality epitaxial ( Al , Sc ) N films, structural quality (edge and screw dislocations), as measured by diffraction techniques, is not the dominant contributor to leakage. Instead, the small leakage in our films is limited by thermionic emission across the interfaces, which is distinct from the large leakage due to trap-mediated bulk transport in the previously reported ( Al , Sc ) N films. To support this conclusion, we show that Al 0.7 Sc 0.3 N on lattice-matched In 0.18 Ga 0.82 N buffers with improved structural characteristics but higher interface roughness exhibit increased leakage characteristics. This demonstration of low leakage current in heteroepitaxial ( Al , Sc ) N films and understanding of the importance of interface barrier and surface roughness can guide further efforts toward improving the reliability of wurtzite ferroelectric devices. Published by the American Physical Society 2025

36 MATERIALS SCIENCE↗
DOE OSTI2022

Vertical and Lateral Etch Survey of Ferroelectric AlN/Al 1-x Sc x N in Aqueous KOH Solutions

Due to their favorable electromechanical properties, such as high sound velocity, low dielectric permittivity and high electromechanical coupling, Aluminum Nitride (AlN) and Aluminum Scandium Nitride (Al 1-x Sc x N) thin films have achieved widespread application in radio frequency (RF) acoustic devices. The resistance to etching at high scandium alloying, however, has inhibited the realization of devices able to exploit the highest electromechanical coupling coefficients. In this work, we investigated the vertical and lateral etch rates of sputtered AlN and Al 1-x Sc x N with Sc concentration x ranging from 0 to 0.42 in aqueous potassium hydroxide (KOH). Etch rates and the sidewall angles were reported at different temperatures and KOH concentrations. We found that the trends of the etch rate were unanimous: while the vertical etch rate decreases with increasing Sc alloying, the lateral etch rate exhibits a V-shaped transition with a minimum etch rate at x = 0.125. By performing an etch on an 800 nm thick Al 0.875 Sc 0.125 N film with 10 wt% KOH at 65 °C for 20 min, a vertical sidewall was formed by exploiting the ratio of the {$10\overline{11}$ planes and {$1\overline{1}00$ planes etch rates. This method does not require preliminary processing and is potentially beneficial for the fabrication of lamb wave resonators (LWRs) or other microelectromechanical systems (MEMS) structures, laser mirrors and Ultraviolet Light-Emitting Diodes (UV-LEDs). It was demonstrated that the sidewall angle tracks the trajectory that follows the {$\overline{1}2\overline{12}$ of the hexagonal crystal structure when different c/a ratios were considered for elevated Sc alloying levels, which may be used as a convenient tool for structure/composition analysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Sc(MnAl2)4 by Materials Project

Sc(MnAl2)4 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sc is bonded in a 4-coordinate geometry to twelve Al atoms. There are four shorter (2.87 Å) and eight longer (3.22 Å) Sc–Al bond lengths. Mn is bonded in a 12-coordinate geometry to two equivalent Mn and eight Al atoms. Both Mn–Mn bond lengths are 2.58 Å. There are four shorter (2.53 Å) and four longer (2.62 Å) Mn–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Sc, four equivalent Mn, and five Al atoms. There are a spread of Al–Al bond distances ranging from 2.75–2.92 Å. In the second Al site, Al is bonded in a 12-coordinate geometry to two equivalent Sc, four equivalent Mn, and six Al atoms. Both Al–Al bond lengths are 2.73 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(ClO4)3 by Materials Project

Sc(O4Cl)3 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. Sc is bonded in a 9-coordinate geometry to nine O atoms. There are six shorter (2.24 Å) and three longer (2.48 Å) Sc–O bond lengths. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Cl atom. The O–Cl bond length is 1.42 Å. In the second O site, O is bonded in a distorted bent 150 degrees geometry to one Sc and one Cl atom. The O–Cl bond length is 1.46 Å. In the third O site, O is bonded in a bent 150 degrees geometry to one Sc and one Cl atom. The O–Cl bond length is 1.48 Å. Cl is bonded in a tetrahedral geometry to four O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Incorporation of rare earth elements $\text{Sc}$, $\text{Y}$ and $\text{La}$ into gibbsite

Rare earth elements (REE) are increasingly critical resources in technological applications, but the current understanding of their separation by uptake into minerals remains limited. We examined the adsorption and solubilization of scandium (Sc), yttrium (Y), and lanthanum (La) into aluminum hydroxide (gibbsite, Al(OH) 3 ). Based on spectroscopic investigations such as inductively coupled plasma-optical emission spectroscopy (ICP-OES) and time of flight-secondary ion mass spectrometry (ToF-SIMS), only Sc exhibited favorable incorporation and adsorption (0.66 and 0.06 atom%, respectively). Analysis of solid state 45 Sc magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR) indicated that Sc exhibits an octahedral coordination consistent with isolated substitutions for Al in the gibbsite structure, leading to a increase in lattice constants detectable by X-ray diffraction. Density functional theory (DFT) calculations reinforced this interpretation by reproducing the detected structural distortion as well as demonstrating the relatively favorable energetic basis for Sc incorporation into gibbsite by substitution.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Sluggish atomic dynamics in a Y-Sc-Co-Al high entropy bulk metallic glass

We present how 20 at% Sc addition affects the atomic packing and dynamics in a Y-Co-Al metallic glass (MG) and find that it greatly suppresses the dynamics of Co atoms by reducing the atomic packing difference in their surroundings. The Co atoms tending to be mobile or static depend on their nearest neighbors, i.e., possessing more Y/Y+Sc atoms but fewer Co atoms or vice versa. The X-ray absorption fine structure results confirm that Sc addition mainly changes the local environment around Co atoms, forming more Co-Co and Co-Sc pairs but significantly fewer Co-Y pairs than in the ternary counterpart, which can seriously slow the atomic dynamics and stabilize the competing phases. Our findings shed new light on the understanding of strong glass forming ability of the Sc-added Y-based high entropy MG from its local structure and dynamics and will be helpful in developing new bulk MGs.

36 MATERIALS SCIENCE↗
DOE OSTI2020

In situ high-temperature X-ray diffraction study of Sc-doped titanium oxide nanocrystallites

Titanium dioxide is an inexpensive wide-gap highly ionic semiconductor with striking photocatalytic capabilities in several heterogeneous photoredox reactions. A small crystal size is desirable to maximize the surface area, since photocatalytic reactions occur at the surface of a photocatalyst. Presented in this work are the synthesis and microstructural characterization of 4 at.% Sc-doped TiO 2 (4SDT) prepared by water-based co-precipitation. The crystal structure of 4SDT was examined via in situ high-temperature powder X-ray diffraction experiments from 25 to 1200°C. Rietveld analysis revealed single-phase anatase up to 875°C, while at 900°C the anatase-to-rutile phase transformation occurred and at higher temperatures additional reflections of Sc-rich phases (Sc 2 TiO 5 from 975°C and Ti 3 Sc 4 O 12 or Sc 2 O 3 at 1200°C) were observed. Debye function analysis (DFA) was applied to model the total scattering pattern directly in reciprocal space, allowing the reconstruction of Ti vacancies. Both Rietveld and DFA methods were applied to estimate the nanocrystallite size and shape with consistent growth in crystallite size with temperature: an ellipsoid shape with equatorial ~4.7 nm / axial (001) ~6.9 nm at 25°C to equatorial ~27.9 nm / axial (001) ~39.6 nm at 900°C refined by Rietveld analysis, versus a cylinder shape with D a , b = 4.3 nm and size dispersion σ ab = 1.5 nm, L c = 4.9 nm and σ c = 2.3 nm at 25°C to D a , b = 21.4 nm, σ ab = 8.3 nm, L c = 23.9 and σ c = 10.9 nm at 900°C estimated by DFA. The microstructural changes obtained by Rietveld and DFA methods were supported by high-resolution transmission electron microscopy image analysis, as well as by the less direct nitrogen sorption techniques that provide information on the size of non-agglomerated and dense particles. The Ti site-occupancy factor showed a linear increase from 0.6–0.8 at 25°C to unity at 900°C for anatase, and from ~0.7 at 900°C to unity at 1200°C for rutile, via Rietveld analysis and DFA.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc by Materials Project

Sc is Tungsten structured and crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Sc is bonded in a distorted body-centered cubic geometry to eight equivalent Sc atoms. All Sc–Sc bond lengths are 3.18 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc by Materials Project

Sc is Copper structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Sc is bonded to twelve equivalent Sc atoms to form a mixture of edge, face, and corner-sharing ScSc12 cuboctahedra. All Sc–Sc bond lengths are 3.27 Å.

36 MATERIALS SCIENCE↗