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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Y(III) Sorption at the Orthoclase (001) Surface Measured by X-ray Reflectivity

Interactions of heavy metals with charged mineral surfaces control their mobility in the environment. Here, we investigate the adsorption of Y(III) onto the orthoclase (001) basal plane, the former as a representative of rare earth elements and an analogue of trivalent actinides and the latter as a representative of naturally abundant K-feldspar minerals. In this study, we apply in situ high-resolution X-ray reflectivity to determine the sorption capacity and molecular distribution of adsorbed Y species as a function of the Y 3+ concentration, [Y 3+ ], at pH 7 and 5. With [Y 3+ ] ≥ 1 mM at pH 7, we observe an inner-sphere (IS) sorption complex at a distance of ~1.5 Å from the surface and an outer-sphere (OS) complex at 3–4 Å. Based on the adsorption height of the IS complex, a bidentate, binuclear binding mode, in which Y 3+ binds to two terminal oxygens, is proposed. In contrast, mostly OS sorption is observed at pH 5. The observed maximum Y coverage is ~1.3 Y 3+ /A UC (A UC : area of the unit cell = 111.4 Å 2 ) for all the investigated pH values and Y concentrations, which is in the expected range based on the estimated surface charge of orthoclase (001).

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

Restructuring of the Lewis Acid Sites in Y-Modified Dealuminated Beta-Zeolite by Hydrothermal Treatment

Yttrium-modified dealuminated Betazeolite (Y-BEA) represents a type of Lewis acid zeolite that has gained attention for its potential to efficiently catalyze the conversion of biomass-derived oxygenates. The structure of the Y active sites and their dynamics during biomass conversion reactions, which normally involve substantial amounts of water, necessitate thorough investigation for the rational design of more active and stable catalysts. Here, we conducted a study where a series of Y-BEA catalysts with different yttrium loadings (1–7 wt.%) were subjected to hydrothermal treatment (450 °C, 20% water) and investigated for their structural and catalytic activity changes through a combination of multiple characterizations and kinetic measurements. The number of acid sites of Y-BEA decreased without a change in acid strength following the hydrothermal treatment, which was confirmed by the results of acid site titration, infrared spectroscopy of probe molecules, and kinetic measurements for probe reactions (acetone aldol condensation). Structural analysis using X-ray diffraction (XRD), specific surface area measurement, X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS) demonstrated that both the zeolite structure and the isolation status of the Y site remain intact after hydrothermal treatment. Further, the Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) spectra, thermogravimetric analysis (TGA), and operando 1 H and 29 Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR) revealed the dehydroxylation of Y-BEA induced by hydration-rearrangement-condensation restructuring during the high-temperature steam treatment. Dehydroxylation affects the structure of Y sites by reducing their vicinal silanol sites. In conclusion, this conversion of Lewis acidic Y sites into nonacidic sites is the primary factor behind the change in acid site quantity and catalytic activity on Y-BEA.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Estudio de Resiliencia de la Red Electrica de Puerto Rico y Transiciones a Energia 100% Renovable (PR100): Actualizacion de Progreso de Seis Meses [Slides]

Puerto Rico se ha comprometido a satisfacer sus necesidades de electricidad con un 100% de energia renovable para 2050, junto con el cumplimiento de objetivos intermedios del 40% para 2025, el 60% para 2040, la eliminacion gradual de la generacion a base de carbon para 2028, y una mejora del 30% en la eficiencia energetica para 2040, segun lo establecido en la Ley de Politica Publica Energetica de Puerto Rico (Ley 17). Desde los huracanes Irma y Maria en septiembre de 2017, DOE y sus laboratorios nacionales han proporcionado a las partes interesadas del sistema energetico de Puerto Rico herramientas, adiestramiento y apoyo de modelaje para permitir la planificacion y el funcionamiento de la red electrica con mas resiliencia frente a nuevas interrupciones. El 2 de febrero de 2022, DOE, FEMA y seis laboratorios nacionales lanzaron el Estudio de Resiliencia de la Red Electrica de Puerto Rico y Transicion a la Energia 100% Renovable (PR100), de dos anos de duracion, para llevar a cabo un analisis exhaustivo de las vias impulsadas por las partes interesadas para el futuro energetico de Puerto Rico. El analisis energetico, solido y objetivo, comprende cinco actividades, con enfasis en la confiabilidad del sistema electrico, la resiliencia y la planificacion de la generacion. Esta presentacion se realizo en un seminario web publico el 21 de julio del 2022, proporcionando un resumen general del progreso en los primeros seis meses del Estudio, incluyendo la presentacion de cuatro escenarios iniciales definidos mediante un rol activo de las partes interesadas. This is the Spanish translation of NREL/PR-6A20-83431.

14 SOLAR ENERGY↗
DOE OSTI2022

Estudio de Resiliencia de la Red Electrica de Puerto Rico y Transicion a Energia 100% Renovable (PR100): Actualizacion de Progreso de Seis Meses [Slides]

Puerto Rico se ha comprometido a satisfacer sus necesidades de electricidad con un 100% de energia renovable para 2050, junto con el cumplimiento de objetivos intermedios del 40% para 2025, el 60% para 2040, la eliminacion gradual de la generacion a base de carbon para 2028, y una mejora del 30% en la eficiencia energetica para 2040, segun lo establecido en la Ley de Politica Publica Energetica de Puerto Rico (Ley 17). Desde los huracanes Irma y Maria en septiembre de 2017, DOE y sus laboratorios nacionales han proporcionado a las partes interesadas del sistema energetico de Puerto Rico herramientas, adiestramiento y apoyo de modelaje para permitir la planificacion y el funcionamiento de la red electrica con mas resiliencia frente a nuevas interrupciones. El 2 de febrero de 2022, DOE, FEMA y seis laboratorios nacionales lanzaron el Estudio de Resiliencia de la Red Electrica de Puerto Rico y Transicion a la Energia 100% Renovable (PR100), de dos anos de duracion, para llevar a cabo un analisis exhaustivo de las vias impulsadas por las partes interesadas para el futuro energetico de Puerto Rico. El analisis energetico, solido y objetivo, comprende cinco actividades, con enfasis en la confiabilidad del sistema electrico, la resiliencia y la planificacion de la generacion. Esta presentacion provee una actualizacion de progreso del trabajo de seis meses sobre el Estudio, incluyendo la presentacion de cuatro escenarios iniciales definidos mediante un rol activo de las partes interesadas. This is the Spanish translation of NREL/PR-6A20-83432.

14 SOLAR ENERGY↗
DOE OSTI2020

Materials Data on Y(Fe5Si)2 by Materials Project

YFe10Si2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Y is bonded in a 12-coordinate geometry to sixteen Fe and four equivalent Si atoms. There are a spread of Y–Fe bond distances ranging from 2.95–3.18 Å. All Y–Si bond lengths are 3.09 Å. There are four inequivalent Fe sites. In the first Fe site, Fe is bonded in a 10-coordinate geometry to one Y, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.31–2.90 Å. Both Fe–Si bond lengths are 2.60 Å. In the second Fe site, Fe is bonded in a 10-coordinate geometry to one Y, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.41–2.66 Å. Both Fe–Si bond lengths are 2.52 Å. In the third Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Y, eight Fe, and two equivalent Si atoms. All Fe–Fe bond lengths are 2.43 Å. Both Fe–Si bond lengths are 2.63 Å. In the fourth Fe site, Fe is bonded to two equivalent Y, eight Fe, and two equivalent Si atoms to form distorted FeY2Fe8Si2 cuboctahedra that share corners with four equivalent SiY2Fe10 cuboctahedra, corners with ten equivalent FeY2Fe8Si2 cuboctahedra, edges with two equivalent SiY2Fe10 cuboctahedra, edges with four equivalent FeY2Fe8Si2 cuboctahedra, faces with four equivalent SiY2Fe10 cuboctahedra, and faces with six equivalent FeY2Fe8Si2 cuboctahedra. Both Fe–Fe bond lengths are 2.38 Å. Both Fe–Si bond lengths are 2.39 Å. Si is bonded to two equivalent Y and ten Fe atoms to form distorted SiY2Fe10 cuboctahedra that share corners with six equivalent SiY2Fe10 cuboctahedra, corners with eight equivalent FeY2Fe8Si2 cuboctahedra, edges with three equivalent SiY2Fe10 cuboctahedra, edges with four equivalent FeY2Fe8Si2 cuboctahedra, a faceface with one SiY2Fe10 cuboctahedra, and faces with eight equivalent FeY2Fe8Si2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(GePt)2 by Materials Project

Y(PtGe)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Y is bonded in a 5-coordinate geometry to eight Pt and eight Ge atoms. There are a spread of Y–Pt bond distances ranging from 3.24–3.41 Å. There are a spread of Y–Ge bond distances ranging from 3.20–3.39 Å. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded in a 9-coordinate geometry to four equivalent Y and five Ge atoms. There are one shorter (2.43 Å) and four longer (2.52 Å) Pt–Ge bond lengths. In the second Pt site, Pt is bonded in a 4-coordinate geometry to four equivalent Y and four equivalent Ge atoms. There are one shorter (2.55 Å) and three longer (2.56 Å) Pt–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Y and five Pt atoms. In the second Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Y and four equivalent Pt atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(SiPt)2 by Materials Project

Y(PtSi)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Y is bonded in a 12-coordinate geometry to eight Pt and eight Si atoms. There are four shorter (3.21 Å) and four longer (3.27 Å) Y–Pt bond lengths. There are four shorter (3.17 Å) and four longer (3.24 Å) Y–Si bond lengths. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded to four equivalent Y and four equivalent Si atoms to form distorted PtY4Si4 tetrahedra that share corners with twelve equivalent SiY4Pt4 tetrahedra, edges with two equivalent SiY4Pt4 tetrahedra, edges with four equivalent PtY4Si4 tetrahedra, and faces with four equivalent PtY4Si4 tetrahedra. All Pt–Si bond lengths are 2.50 Å. In the second Pt site, Pt is bonded in a 9-coordinate geometry to four equivalent Y and five Si atoms. There are one shorter (2.38 Å) and four longer (2.43 Å) Pt–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded to four equivalent Y and four equivalent Pt atoms to form distorted SiY4Pt4 tetrahedra that share corners with twelve equivalent PtY4Si4 tetrahedra, edges with two equivalent PtY4Si4 tetrahedra, edges with four equivalent SiY4Pt4 tetrahedra, and faces with four equivalent SiY4Pt4 tetrahedra. In the second Si site, Si is bonded in a 9-coordinate geometry to four equivalent Y and five Pt atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(InCu)6 by Materials Project

YCu6In6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Y is bonded to twelve Cu and eight In atoms to form distorted YIn8Cu12 hexagonal bipyramids that share corners with eight equivalent YIn8Cu12 hexagonal bipyramids, faces with sixteen equivalent CuY2In6Cu4 cuboctahedra, and faces with two equivalent YIn8Cu12 hexagonal bipyramids. There are eight shorter (3.52 Å) and four longer (3.53 Å) Y–Cu bond lengths. There are a spread of Y–In bond distances ranging from 3.08–3.24 Å. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded to two equivalent Y, four Cu, and six In atoms to form distorted CuY2In6Cu4 cuboctahedra that share corners with ten equivalent CuY2In6Cu4 cuboctahedra, edges with four equivalent CuY2In6Cu4 cuboctahedra, faces with six equivalent CuY2In6Cu4 cuboctahedra, and faces with four equivalent YIn8Cu12 hexagonal bipyramids. There are two shorter (2.69 Å) and two longer (2.78 Å) Cu–Cu bond lengths. There are two shorter (2.74 Å) and four longer (2.80 Å) Cu–In bond lengths. In the second Cu site, Cu is bonded in a 12-coordinate geometry to two equivalent Y, four equivalent Cu, and six In atoms. There are a spread of Cu–In bond distances ranging from 2.74–2.92 Å. There are three inequivalent In sites. In the first In site, In is bonded in a 8-coordinate geometry to one Y, six Cu, and one In atom. The In–In bond length is 2.96 Å. In the second In site, In is bonded in a 10-coordinate geometry to one Y and six Cu atoms. In the third In site, In is bonded in a 8-coordinate geometry to two equivalent Y and six Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(BrO6)3 by Materials Project

YO11Br2(O2)2BrO3 crystallizes in the monoclinic P2_1 space group. The structure is one-dimensional and consists of two hypobromous acid;dihydrate molecules; four oxygen molecules; and one YO11Br2 ribbon oriented in the (0, 1, 0) direction. In the YO11Br2 ribbon, Y is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Y–O bond distances ranging from 2.11–2.61 Å. There are eleven inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Br atom. The O–Br bond length is 1.65 Å. In the second O site, O is bonded in a single-bond geometry to one Br atom. The O–Br bond length is 1.65 Å. In the third O site, O is bonded in an L-shaped geometry to one Y and one O atom. The O–O bond length is 1.30 Å. In the fourth O site, O is bonded in a 3-coordinate geometry to two equivalent Y and one O atom. The O–O bond length is 1.33 Å. In the fifth O site, O is bonded in a water-like geometry to one Y and one O atom. The O–O bond length is 1.33 Å. In the sixth O site, O is bonded in a 2-coordinate geometry to one Y and one O atom. In the seventh O site, O is bonded in a bent 120 degrees geometry to two O atoms. In the eighth O site, O is bonded in a bent 150 degrees geometry to one Y and one Br atom. The O–Br bond length is 1.80 Å. In the ninth O site, O is bonded in a single-bond geometry to one Br atom. The O–Br bond length is 1.65 Å. In the tenth O site, O is bonded in a bent 150 degrees geometry to one Y and one Br atom. The O–Br bond length is 1.80 Å. In the eleventh O site, O is bonded in a single-bond geometry to one Br atom. The O–Br bond length is 1.65 Å. There are two inequivalent Br sites. In the first Br site, Br is bonded in a trigonal non-coplanar geometry to three O atoms. In the second Br site, Br is bonded in a trigonal non-coplanar geometry to three O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(CuSn)2 by Materials Project

Y(CuSn)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Y is bonded in a 12-coordinate geometry to eight Cu and eight Sn atoms. There are four shorter (3.36 Å) and four longer (3.37 Å) Y–Cu bond lengths. There are four shorter (3.30 Å) and four longer (3.57 Å) Y–Sn bond lengths. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to four equivalent Y and four equivalent Sn atoms. All Cu–Sn bond lengths are 2.60 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to four equivalent Y and five Sn atoms. There are one shorter (2.48 Å) and four longer (2.65 Å) Cu–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded to four equivalent Y and four equivalent Cu atoms to form a mixture of distorted face and edge-sharing SnY4Cu4 tetrahedra. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Y and five Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Superconductivity in Y 4 RuGe 8 with a Vacancy-Ordered CeNiSi 2 -Type Superstructure

In this work, we report a new compound, Y 4 RuGe 8 , with a transition metal vacancy-ordered CeNiSi 2 -type superstructure, which has a superconducting transition at 1.3 K. Y 4 RuGe 8 crystals were grown by indium flux at relatively low temperatures (below 1273 K), which makes it possible to stabilize such a vacancy-ordered phase. The crystal structure of Y 4 RuGe 8 was solved by single-crystal X-ray diffraction and confirmed by transmission electron microscopy. The as-grown Y 4 RuGe 8 crystals are always twinned, crystallizing in the space group $P\bar{1}$(no. 2) with the lattice parameters a = 5.7680(1) Å, b = 8.2042(2) Å, c = 11.5093(3) Å, α = 79.696(1)degrees, β = 88.491(1)degrees, and γ = 79.637(2)degrees; this structure is a superstructure deriving from the higher symmetry CeNiSi 2 -type structure (Cmcm, no. 63) due to the ordering of Ru vacancies. The ordering of Ru sites breaks slightly distorted Ge planes in the CeNiSi 2 prototype into infinite cis-trans Ge chains in Y 4 RuGe 8 . The presence of bulk superconductivity in Y 4 RuGe 8 is well supported by zero resistance and a jump in specific heat at the critical transition temperature. The Sommerfeld coefficient (19 mJ K -2 mol -1 ) of the specific heat is greater than that (11 mJ K -2 mol -1 ) estimated using the bare density of states (4.7 states/eV/f.u.) from first-principles calculations. The ab initio calculations indicate that 4d electrons of both Y and Ru and 4p electrons of Ge are the main contributors to the total density of states at the Fermi level in Y 4 RuGe 8 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Structural Phase Transitions in the van der Waals Ferromagnets Fe x Pd y Te 2

Two-dimensional van der Waals (vdW) magnets are attracting significant attention, both as platforms for studying fundamental magnetic interactions and for the exciting possibility of utilizing them as building blocks in devices and heterostructures, which may lead to new physical phenomena and functionalities. Here, we provide a detailed study of the crystal structure and physical properties of the recently discovered vdW ferromagnet FePd 2 Te 2 . We find this compound has a relatively wide width of formation, and grow single crystals with compositions Fe x Pd y Te 2 where x ranges from 0.9 to 1.1 and y from 1.8 to 2.5, respectively. Temperature-dependent X-ray diffraction and transport measurements reveal that a first-order structural transition occurs in the range of T = 360–420 K, where the critical temperature, modulation wave vector, and corresponding room-temperature crystal structures all depend on chemical composition. Above the transition, the compounds with Pd fraction y > 2 adopt a disordered derivative of the tetragonal FeTe structure, with the Fe layer showing mixed Fe/Pd occupancy and the extra Pd atoms partially occupying interstitial sites. Below 370 K, the structure is incommensurately modulated, likely associated with the complex ordering of Pd/Fe atoms in the metal layers or the interstitial Pd in the vdW gaps. For y < 2, the composition Fe 1.1 Pd 1.8 Te 2 has monoclinic symmetry at room temperature that is consistent with the reported structure of FePd 2 Te 2 . This phase undergoes a structural transition at 420 K for which the high temperature structure is yet to be determined; however, based on the similarities with the y > 2 compounds, we speculate that its T > 420 K structure is also tetragonal. Importantly, the high temperature, symmetry-breaking structural transition observed here provides a likely explanation for the origin of the structural domains previously observed in FePd 2 Te 2 . All compounds investigated in the Fe x Pd y Te 2 series show metallic behavior, with magnetic characterization indicating that they are easy-plane, hard, ferromagnets with T C spanning 98–180 K. Both the critical temperature for the structural transition and the Curie temperature are moderately suppressed with increasing Pd fraction y and corresponding decreasing Fe fraction x, indicating that synthetic control over x and y paves way for the further exploration of these compounds.

crystal structure↗
DOE OSTI2024

Unveiling and Mapping Polymorphs in Fluorite Y2TiO5 Using 4D-STEM and Unsupervised Machine Learning

Y2TiO5 belongs to the Ln2TiO5 (Ln = lanthanide or Y) family of ceramic materials and exhibits a range of desirable material properties such as radiation tolerance, frustrated magnetism, and large dielectric constant. However, understanding the complex crystal structure of Y2TiO5 remains elusive, given that Y2TiO5 can adopt multiple polymorphs such as cubic, orthorhombic, and hexagonal phases within the lattice. In this work, we report a detailed structural analysis of Y2TiO5 using four-dimensional scanning transmission electron microscopy coupled with unsupervised machine learning. The pyrochlore nanodomains, characterized by the ordered arrangement of yttrium cations on the A site of their A2BO5 structure, are present within the matrix of a predominantly fluorite-structured Y2TiO5 along with a third polymorph, the hexagonal phase. The pyrochlore phase is found to form 2 nm boundary regions around hexagonal phase stacking faults, highlighting the potential influence of the hexagonal phase on the occurrence and distribution of the pyrochlore phase. Lastly, we identify a unique pyrochlore phase with asymmetric arrangement of cation ordering along a single planar direction. Our findings provide invaluable insights into the possible mechanisms stabilizing pyrochlore nanodomains within the fluorite lattice of Y2TiO5.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Accurate determination of production data of the non-standard positron emitter 86 Y via the 86 Sr(p,n)-reaction

In view of several significant discrepancies in the excitation function of the 86 Sr(p,n) 86g+xm Y reaction which is the method of choice for the production of the non-standard positron emitter 86 Y for theranostic application, we carried out a careful measurement of the cross sections of this reaction from its threshold up to 16.2 MeV at Forschungszentrum Jülich (FZJ) and from 14.3 to 24.5 MeV at LBNL. Thin samples of 96.4% enriched 86 SrCO 3 were prepared by sedimentation and, after irradiation with protons in a stacked-form, the induced radioactivity was measured by high-resolution γ -ray spectrometry. The projectile flux was determined by using the monitor reactions nat Cu(p,xn) 62,63,65 Zn and nat Ti(p,x) 48 V, and the calculated proton energy for each sample was verified by considering the ratios of two reaction products of different thresholds. Additionally, the experimental cross section data obtained agreed well with the results of a nuclear model calculation based on the code TALYS. From the cross section data, the integral yield of 86 Y was calculated. Over the optimum production energy range E p = 14 → 7 MeV the yield of 86 Y amounts to 291 MBq/μA for 1 h irradiation time. This value is appreciably lower than the previous literature values calculated from measured and evaluated excitation functions. It is, however, more compatible with the experimental yields of 86 Y obtained in clinical scale production runs. The levels of the isotopic impurities 87m Y, 87g Y, and 88 Y were also estimated and found to be <2% in sum.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
NASA NTRS1995

Penetration of the Interplanetary Magnetic Field B(sub y) into Earth's Plasma Sheet

There has been considerable recent interest in the relationship between the cross-tail magnetic field component B(sub y) and tail dynamics. The purpose of this paper is to give an overall description of the penetration of the interplanetary magnetic field (IMF) B(sub y) into the near-Earth plasma sheet. We show that plasma sheet B(sub y) may be generated by the differential shear motion of field lines and enhanced by flux tube compression. The latter mechanism leads to a B(sub y) analogue of the pressure-balance inconsistency as flux tubes move from the far tail toward the Earth. The growth of B(sub y), however, may be limited by the dawn-dusk asymmetry in the shear velocity as a result of plasma sheet tilting. B(sub y) penetration into the plasma sheet implies field-aligned currents flowing between hemispheres. These currents together with the IMF B(sub y) related mantle field-aligned currents effectively shield the lobe from the IMF B(sub y).

Hau, L.-N.↗
NASA NTRS2007

Unleashing Gen Y: Marketing Mars to Millennials

Space advocates need to engage Generation Y (born 1977-1999).This outreach is necessary to recruit the next generation of scientists and engineers to explore Mars. Space advocates in the non-profit, private, and government sectors need to use a combination of technical communication, marketing, and politics, to develop messages that resonate with Gen Y. Until now, space messages have been generated by and for college-educated white males; Gen Y is much more diverse, including as much as one third minorities. Young women, too, need to be reached. My research has shown that messages emphasizing technology, fun, humor, and opportunity are the best means of reaching the Gen Y audience of 60 million (US population is 300 million). The important things space advocates must avoid are talking down to this generation, making false promises, or expecting them to "wait their turn" before they can participate. This is the MTV generation! We need to find ways of engaging Gen Y now to build a future where human beings can live and work on the planet Mars. In addition to the messages themselves, advocates need to keep up with Gen Y' s social networking and use of iPods, cell phones, and the Internet. NASA and space advocacy groups can use these tools for "viral marketing," where young people share targeted space-related information via cell phones or the Internet because they like it. Overall, Gen Y is a socially dynamic and media-savvy group; advocates' space messages need to be sincere, creative, and placed in locations where Gen Y lives. Mars messages must be memorable!

Leahy, Bart D.↗
DOE OSTI2020

Materials Data on Y(SiIr)2 by Materials Project

YIr2Si2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Y is bonded in a 8-coordinate geometry to eight Ir and eight Si atoms. There are four shorter (3.15 Å) and four longer (3.26 Å) Y–Ir bond lengths. There are four shorter (3.17 Å) and four longer (3.18 Å) Y–Si bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Y and five Si atoms. There are one shorter (2.37 Å) and four longer (2.43 Å) Ir–Si bond lengths. In the second Ir site, Ir is bonded to four equivalent Y and four equivalent Si atoms to form distorted IrY4Si4 tetrahedra that share corners with twelve equivalent SiY4Ir4 tetrahedra, edges with two equivalent SiY4Ir4 tetrahedra, edges with four equivalent IrY4Si4 tetrahedra, and faces with four equivalent IrY4Si4 tetrahedra. All Ir–Si bond lengths are 2.44 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded to four equivalent Y and four equivalent Ir atoms to form distorted SiY4Ir4 tetrahedra that share corners with twelve equivalent IrY4Si4 tetrahedra, edges with two equivalent IrY4Si4 tetrahedra, edges with four equivalent SiY4Ir4 tetrahedra, and faces with four equivalent SiY4Ir4 tetrahedra. In the second Si site, Si is bonded in a 9-coordinate geometry to four equivalent Y and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(Mn2Fe)4 by Materials Project

Y(Mn2Fe)4 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Y is bonded in a 12-coordinate geometry to twelve Mn and eight equivalent Fe atoms. There are four shorter (3.00 Å) and eight longer (3.05 Å) Y–Mn bond lengths. All Y–Fe bond lengths are 3.18 Å. There are two inequivalent Mn sites. In the first Mn site, Mn is bonded in a 10-coordinate geometry to one Y, nine Mn, and four equivalent Fe atoms. There are a spread of Mn–Mn bond distances ranging from 2.37–2.89 Å. All Mn–Fe bond lengths are 2.57 Å. In the second Mn site, Mn is bonded in a 12-coordinate geometry to two equivalent Y, four equivalent Mn, and four equivalent Fe atoms. All Mn–Fe bond lengths are 2.40 Å. Fe is bonded to two equivalent Y, eight Mn, and two equivalent Fe atoms to form a mixture of distorted edge, face, and corner-sharing FeY2Mn8Fe2 cuboctahedra. Both Fe–Fe bond lengths are 2.36 Å.

36 MATERIALS SCIENCE↗