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Sc crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Sc is bonded in a 11-coordinate geometry to eleven equivalent Sc atoms. There are a spread of Sc–Sc bond distances ranging from 2.87–3.38 Å.
Sc is Protactinium-like structured and crystallizes in the hexagonal P6_122 space group. The structure is three-dimensional. Sc is bonded in a 10-coordinate geometry to ten equivalent Sc atoms. There are a spread of Sc–Sc bond distances ranging from 3.13–3.23 Å.
Sc is Magnesium structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Sc is bonded to twelve equivalent Sc atoms to form a mixture of face, edge, and corner-sharing ScSc12 cuboctahedra. There are six shorter (3.22 Å) and six longer (3.32 Å) Sc–Sc bond lengths.
Sc is alpha Po structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Sc is bonded to six equivalent Sc atoms to form a mixture of corner and edge-sharing ScSc6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Sc–Sc bond lengths are 2.99 Å.
Supercritical carbon dioxide (sc-CO 2 ) is an alternative to water for stimulation of low permeability systems such as shale gas and geothermal resources. Previously core-scale experimental studies have compared the behavior of CO 2 to water injection for sample breakdown. Due to differences in experimental setup and core sample preparation, inconsistent or even apparently contradictory conclusions have resulted. To reconcile this contradiction, a phase-field numerical model is applied to understand hydraulic fracturing experiments using Green River shale found in the literature. The finite element numerical model incorporates a rate-dependent phase-field fracture model developed separately to describe fracture initiation and growth. We investigate the impact of various material and fluid properties on the resulting fractures. Most importantly, we study the effect of fluid properties and boundary conditions on the breakdown pressure, including the direction of the resulting fracture plane. Model results predict that (1) sc-CO 2 injection in the laboratory may result in greater breakdown pressure than that of water under no-flow boundary conditions because lower viscosity sc-CO 2 may result in pressure build up at the core boundary that opposes fracture initiation and (2) lower viscosity sc-CO 2 also produces fast-propagating fractures that are less influenced by the bedding plane on their resulting fracture topology. Here our model offers a straightforward explanation and reconciliation of existing experimental observations, as well as a means to extrapolate to new conditions. Exploration of field-scale conditions suggests less pronounced or no elevation in breakdown pressure when sc-CO 2 is injected because the pressure build up effect at the system boundary is significantly less or absent at field length scales.
Powders of Sm(Fe,Co) 11.2 Ti 0.8 alloys modified with Sc, Nb and Zr, as well as with additional Ti were prepared by reducing mechanically activated raw oxides with Ca metal in the furnace preheated to 990–1250 °C. Expansion of the crystal lattice upon introduction of Nb or additional Ti implies that atoms of these elements replace the smaller Fe atoms in the tetragonal ThMn 12 -type structure. On the other hand, contraction of the lattice upon introduction of Sc or Zr was smaller than what was expected for replacement of the Sm atoms, which suggests that the Sc and Zr atoms replace both the Sm and Fe atoms. Washing away the reduction byproducts expands the crystal lattice of the 1:12 particles and increases their coercivity. The lattice expansion associated with the washing is believed to be caused by interstitial H atoms; more research, however, is needed to establish the mechanism(s) of the washing effect on the coercivity. The earlier reported development of a high coercivity in zirconium-modified monocrystalline particles achieved by increasing the reduction annealing temperature to ≈1200 °C was similarly characteristic of the particles modified with Sc (the coercivity reaches 11.5 kOe) and Nb (8.1 kOe), but not for the particles prepared with additional Ti where the maximum coercivity of 8.3 kOe develops for a lower annealing temperature. Furthermore, it is concluded that Sc, Nb and Zr modify the high-temperature phase equilibria of the Sm(Fe,Co) 11.2 Ti 0.8 alloys allowing for an effective high-temperature processing, whereas the alloy coercivity increases with the synthesis temperature through a different, still unknown mechanism which may involve suppression of the defects specific to the 1:12 crystals.
A 2 M 3 O 12 -based materials have received considerable attention owing to their wide range of negative thermal expansion (NTE) and chemical flexibility toward novel materials design. However, the structure and NTE mechanism remain challenging. In this paper, Zr 4+ and V 5+ are used as a unit to compensatorily replace Sc 3+ and Mo 6+ in Sc 2 Mo 3 O 12 to tune its thermal expansion. Its crystal structure, phase transition, NTE property, and corresponding mechanisms are studied by high-resolution synchrotron X-ray diffraction, powder X-ray diffraction, ultralow-frequency Raman spectroscopy, and density functional theory calculations. The results show that Zr 0.3 Sc 1.7 Mo 2.7 V 0.3 O 12 adopts an orthorhombic (Pbcn) structure at room temperature, with V atoms occupying the position of Mo1 atoms and Zr atoms occupying the position of Sc atoms, and transforms to monoclinic (P2 1 /a) structure at similar to ~133 K (45 K lower than that of Sc 2 Mo 3 O 12 ). It exhibits excellent NTE in a broader range. Most of the phonon modes below 350 cm -1 have negative Grüneisen parameters, of which the lowest and next-lowest frequency (38.5 and 45.8 cm -1 ) optical phonon modes arising from the translational vibrations of the Sc/Zr and Mo/V atoms in the plane of the nonlinear linkage Sc/Zr-O-Mo/V have the largest and next-largest negative Grüneisen parameters and positive total anharmonicity, and contribute most to the NTE.
The continuous demand for efficient, nontoxic, and thermally stable materials for room-temperature energy conversion motivates the exploration of novel thermoelectric systems beyond the traditional magnetic Heusler alloys. While full and half-Heusler compounds, especially Co-, Ni-, and Mn-based systems, have demonstrated promising thermoelectric properties, their typically high operating temperatures and magnetic complexities limit their applicability in ambient thermal management. In this context, we investigate whether Sc-based inverse Heusler alloys can offer a viable nonmagnetic alternative with competitive thermoelectric performance. In this work, we perform a systematic first-principles study of the inverse Heusler compounds Sc 2 RuZ (Z = Si, Ge, Sn), focusing on their structural, electronic, mechanical, and thermodynamic-thermoelectric properties. Density Functional Theory (DFT) was employed to compute optimized lattice structures and band dispersion, while dynamical stability was assessed via phonon calculations. Thermoelectric transport coefficients, including Seebeck coefficient, electrical conductivity, and thermal conductivity, were estimated using the semiclassical Boltzmann transport theory within the constant relaxation time approximation. Our results show that all Sc 2 RuZ compounds are thermodynamically stable semiconductors with indirect band gaps of 0.12–0.16 eV and exhibit high elastic moduli, especially Sc 2 RuSn, which demonstrates superior stiffness and incompressibility. Importantly, all compounds display promising room-temperature thermoelectric characteristics, including high Seebeck coefficients and power factors. These findings reveal that Sc 2 RuZ alloys represent a rare class of stable, nonmagnetic inverse Heusler semiconductors with intrinsic thermoelectric potential at room temperature, unlike many existing Heusler systems optimized for spintronics or high-temperature operation. This work expands the known design space for Heusler-based thermoelectrics and offers a theoretical basis for experimental realization of efficient, low-temperature, nonmagnetic thermoelectric materials.
Resonant oscillators with stable frequencies and large quality factors help us to keep track of time with high precision. Examples range from quartz crystal oscillators in wristwatches to atomic oscillators in atomic clocks, which are, at present, our most precise time measurement devices. The search for more stable and convenient reference oscillators is continuing. Nuclear oscillators are better than atomic oscillators because of their naturally higher quality factors and higher resilience against external perturbations. One of the most promising cases is an ultra-narrow nuclear resonance transition in 45 Sc between the ground state and the 12.4-keV isomeric state with a long lifetime of 0.47 s (ref. 10 ). The scientific potential of 45 Sc was realized long ago, but applications require 45 Sc resonant excitation, which in turn requires accelerator-driven, high-brightness X-ray sources that have become available only recently. Here we report on resonant X-ray excitation of the 45 Sc isomeric state by irradiation of Sc-metal foil with 12.4-keV photon pulses from a state-of-the-art X-ray free-electron laser and subsequent detection of nuclear decay products. Simultaneously, the transition energy was determined as ${\mathrm{12,389.59}}_{+0.12\left({\rm{syst}}\right)}^{\pm 0.15\left({\rm{stat}}\right)}\,{\rm{eV}}$ with an uncertainty that is two orders of magnitude smaller than the previously known values. These advancements enable the application of this isomer in extreme metrology, nuclear clock technology, ultra-high-precision spectroscopy and similar applications.
Herein, we have performed first-principles calculations to investigate the electronic structure, configurations, formation, and binding energies of native and radiation induced point defects in pristine and Sc-doped wurtzite AlN. For the native defects, the nitrogen vacancy has the lowest formation energy in p-type material while the aluminum vacancy has the lowest formation energy in n-type material which is consistent with the previous studies. Several interstitial defect structures were modeled for Al, N, and Sc atoms. The effects of charge state on their relative stability were investigated. The binding energy of Sc with point defects was calculated and found to be dependent strongly on the defect type and charge state. The results obtained are discussed in light of the possible Sc effects on the radiation damage evolution in AlN. Thus the attraction of Sc atom to N vacancy and both Al and N interstitials reduces their mobility and increases Frenkel pair recombination distance.
ScMn6Sn6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Sc is bonded to eight Sn atoms to form distorted edge-sharing ScSn8 hexagonal bipyramids. There are two shorter (2.93 Å) and six longer (3.12 Å) Sc–Sn bond lengths. Mn is bonded in a 12-coordinate geometry to six Sn atoms. There are a spread of Mn–Sn bond distances ranging from 2.72–2.80 Å. There are three inequivalent Sn sites. In the first Sn site, Sn is bonded in a 7-coordinate geometry to one Sc and six equivalent Mn atoms. In the second Sn site, Sn is bonded in a 6-coordinate geometry to six equivalent Mn atoms. In the third Sn site, Sn is bonded in a 12-coordinate geometry to three equivalent Sc and six equivalent Mn atoms.
ScMn6Ge6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Sc is bonded to eight Ge atoms to form distorted edge-sharing ScGe8 hexagonal bipyramids. There are two shorter (2.74 Å) and six longer (2.96 Å) Sc–Ge bond lengths. Mn is bonded in a 12-coordinate geometry to six Ge atoms. There are a spread of Mn–Ge bond distances ranging from 2.50–2.67 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to one Sc, six equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.61 Å. In the second Ge site, Ge is bonded in a 12-coordinate geometry to three equivalent Sc and six equivalent Mn atoms. In the third Ge site, Ge is bonded in a 6-coordinate geometry to six equivalent Mn atoms.
Sc(Fe2P)2 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Sc is bonded to six equivalent P atoms to form a mixture of distorted edge and corner-sharing ScP6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are two shorter (2.73 Å) and four longer (2.78 Å) Sc–P bond lengths. Fe is bonded in a 3-coordinate geometry to three equivalent P atoms. There are one shorter (2.24 Å) and two longer (2.29 Å) Fe–P bond lengths. P is bonded in a 9-coordinate geometry to three equivalent Sc and six equivalent Fe atoms.
Sc(PO3)3 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are three inequivalent Sc3+ sites. In the first Sc3+ site, Sc3+ is bonded to six O2- atoms to form ScO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Sc–O bond distances ranging from 2.08–2.13 Å. In the second Sc3+ site, Sc3+ is bonded to six O2- atoms to form ScO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Sc–O bond distances ranging from 2.10–2.12 Å. In the third Sc3+ site, Sc3+ is bonded to six O2- atoms to form ScO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Sc–O bond distances ranging from 2.09–2.12 Å. There are nine inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two ScO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 28–32°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent ScO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 39–40°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent ScO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 29°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two ScO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 28–32°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two ScO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–38°. There is two shorter (1.50 Å) and two longer (1.60 Å) P–O bond length. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two ScO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 27–37°. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two ScO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 36–43°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two ScO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–30°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the ninth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent ScO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 25–28°. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. There are twenty-seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fifteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the seventeenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the eighteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the twentieth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-third O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the twenty-fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the twenty-sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom. In the twenty-seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom.
Scandium-47 ( 47 Sc) production via bremsstrahlung irradiation of natural vanadium targets offers significant advantages for producing high purity 47 Sc; this work evaluates several rapid dissolution and chemical separation techniques for recovering high purity 47 Sc from irradiated vanadium. Here, techniques developed are combined into a simple, gram-scale, semi-automated target processing system that enables 47 Sc recovery from irradiated vanadium targets with chemical yields as high as 93 ± 3% and 47 Sc/V separation factors of 6 ± 3 ·10 11 within 90 min total processing times. Future research into H 2 O 2 resistant separation techniques and their applicability for direct process coupling to chelation are recommended.
We report Scandium-47 ( 47 Sc) is of high value for targeted radiotherapy and theranostics; we report a novel, cost-effective approach to produce extremely high-purity 47 Sc via photonuclear irradiation of natural vanadium. Irradiations at bremsstrahlung end-point energies below 26 and at 38 MeV produce > 99.99% and 98.8 ± 3.1% pure 47 Sc (respectively). Linear scaling of experimental data suggests producing 100+ mCi quantities of 47 Sc may be feasible via this approach. Future research into refinement and scale-up to support pre-clinical and clinical research with this production pathway is recommended.
In this work, the frequency-dependent ferroelectric properties of 45 nm (Al,Sc)N films sputter deposited on complementary metal–oxide–semiconductor (CMOS)-compatible Al metal electrodes are measured and compared. Low in-plane compressive stress (-10 ± 20 MPa) is observed in (Al,Sc)N thin films deposited on Al electrodes. The (Al,Sc)N films exhibit an imprint in the measured coercive fields (E c ) of -4.3/+5.3 MV cm -1 at 10 kHz. Using positive-up negative-down (PUND) measurements, ferroelectric switching is observed within ≈200 ns of an applied voltage pulse, which demonstrates the ability of ferroelectric (Al,Sc)N to achieve the fast read/write speeds desired in memory devices.
Epitaxial Sc x Al 1- x N thin films of ~100 nm thickness grown on metal polar GaN substrates are found to exhibit significantly enhanced relative dielectric permittivity (ε r ) values relative to AlN. ε r values of ~17–21 for Sc mole fractions of 17%–25% ( x = 0.17–0.25) measured electrically by capacitance–voltage measurements indicate that Sc x Al 1- x N has the largest relative dielectric permittivity of any existing nitride material. Since epitaxial Sc x Al 1- x N layers deposited on GaN also exhibit large polarization discontinuity, the heterojunction can exploit the in situ high-K dielectric property to extend transistor operation for power electronics and high-speed microwave applications.