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DOE OSTI2020

Materials Data on Yb2Pt by Materials Project

Yb2Pt is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Yb sites. In the first Yb site, Yb is bonded to four equivalent Pt atoms to form a mixture of corner and edge-sharing YbPt4 tetrahedra. There are a spread of Yb–Pt bond distances ranging from 2.87–2.97 Å. In the second Yb site, Yb is bonded in a 5-coordinate geometry to five equivalent Pt atoms. There are a spread of Yb–Pt bond distances ranging from 3.08–3.36 Å. Pt is bonded in a 9-coordinate geometry to nine Yb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Synthesis, Structure, and Electric Conductivity of Higher Hydrides of Ytterbium at High Pressure

While most of the rare-earth metals readily form trihydrides, due to increased stability of the filled 4f electronic shell for Yb(II), only YbH 2.67 , formally corresponding to Yb II (Yb III H 4 ) 2 (or Yb 3 H 8 ), remains the highest hydride of ytterbium. Utilizing the diamond anvil cell methodology and synchrotron powder X-ray diffraction, we have attempted to push this limit further via hydrogenation of metallic Yb and Yb 3 H 8 . Compression of the latter has also been investigated in a neutral pressure-transmitting medium (PTM). While the in situ heating of Yb facilitates the formation of YbH 2+x hydrides, we have not observed clear qualitative differences between the systems compressed in H 2 and He or Ne PTM. In all of these cases, a sequence of phase transitions occurred within ca. 13–18 GPa (P$\bar{31}$m–I4/m phase) and around 27 GPa (to the I4/mmm phase). The molecular volume of the systems compressed in H 2 PTM is ca. 1.5% larger than of those compressed in inert gases, suggesting a small hydrogen uptake. Nevertheless, hydrogenation toward YbH 3 is incomplete, and polyhydrides do not form up to the highest pressure studied here (ca. 75 GPa). As pointed out by electronic transport measurements, the mixed-valence Yb 3 H 8 retains its semiconducting character up to >50 GPa, although the very low remnant activation energy of conduction (<5 meV) suggests that metallization under further compression should be achievable. Finally, we provide a theoretical description of a hypothetical stoichiometric YbH 3 .

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

Chemical bonding dictates drastic critical temperature difference in two seemingly identical superconductors

Though YB 6 and LaB 6 share the same crystal structure, atomic valence electron configuration, and phonon modes, they exhibit drastically different phonon-mediated superconductivity. YB 6 superconducts below 8.4 K, giving it the second-highest critical temperature of known borides, second only to MgB 2 . LaB 6 does not superconduct until near-absolute zero temperatures (below 0.45 K), however. Though previous studies have quantified the canonical superconductivity descriptors of YB 6 ’s greater Fermi-level (E f ) density of states and higher electron–phonon coupling (EPC), the root of this difference has not been assessed with full detail of the electronic structure. Through chemical bonding, we determine low-lying, unoccupied 4f atomic orbitals in lanthanum to be the key difference between these superconductors. These orbitals, which are not accessible in YB 6 , hybridize with π B–B bonds and bring this π-system lower in energy than the σ B–B bonds otherwise at E f . This inversion of bands is crucial: the optical phonon modes we show responsible for superconductivity cause the σ-orbitals of YB 6 to change drastically in overlap, but couple weakly to the π-orbitals of LaB 6 . These phonons in YB 6 even access a crossing of electronic states, indicating strong EPC. No such crossing in LaB 6 is observed. Finally, a supercell (the M k-point) is shown to undergo Peierls-like effects in YB 6 , introducing additional EPC from both softened acoustic phonons and the same electron-coupled optical modes as in the unit cell. Overall, we find that LaB 6 and YB 6 have fundamentally different mechanisms of superconductivity, despite their otherwise near-identity.

Science & Technology - Other Topics↗
DOE OSTI2020

Materials Data on YbGa4Ni by Materials Project

YbNiGa4 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Yb is bonded in a 5-coordinate geometry to two equivalent Ni and thirteen Ga atoms. Both Yb–Ni bond lengths are 3.09 Å. There are a spread of Yb–Ga bond distances ranging from 2.94–3.40 Å. Ni is bonded in a 9-coordinate geometry to two equivalent Yb and seven Ga atoms. There are a spread of Ni–Ga bond distances ranging from 2.36–2.51 Å. There are three inequivalent Ga sites. In the first Ga site, Ga is bonded in a distorted q6 geometry to four equivalent Yb and six Ga atoms. All Ga–Ga bond lengths are 2.84 Å. In the second Ga site, Ga is bonded in a distorted linear geometry to three equivalent Yb, one Ni, and four equivalent Ga atoms. In the third Ga site, Ga is bonded in a 12-coordinate geometry to three equivalent Yb, three equivalent Ni, and one Ga atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbGa5Co by Materials Project

YbCoGa5 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Yb is bonded to twelve Ga atoms to form YbGa12 cuboctahedra that share corners with four equivalent YbGa12 cuboctahedra, faces with four equivalent YbGa12 cuboctahedra, and faces with four equivalent GaYb4Ga8 cuboctahedra. There are eight shorter (2.96 Å) and four longer (2.99 Å) Yb–Ga bond lengths. Co is bonded in a body-centered cubic geometry to eight Ga atoms. All Co–Ga bond lengths are 2.48 Å. There are five inequivalent Ga sites. In the first Ga site, Ga is bonded to four equivalent Yb and eight Ga atoms to form distorted GaYb4Ga8 cuboctahedra that share corners with four equivalent GaYb4Ga8 cuboctahedra, faces with four equivalent YbGa12 cuboctahedra, and faces with four equivalent GaYb4Ga8 cuboctahedra. All Ga–Ga bond lengths are 2.96 Å. In the second Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Yb, two equivalent Co, and seven Ga atoms. There are one shorter (2.62 Å) and four longer (2.99 Å) Ga–Ga bond lengths. In the third Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Yb, two equivalent Co, and seven Ga atoms. There are one shorter (2.62 Å) and four longer (2.99 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Yb, two equivalent Co, and seven Ga atoms. In the fifth Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Yb, two equivalent Co, and seven Ga atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbIn4Pt by Materials Project

YbPtIn4 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Yb is bonded in a 7-coordinate geometry to two equivalent Pt and eleven In atoms. Both Yb–Pt bond lengths are 3.26 Å. There are a spread of Yb–In bond distances ranging from 3.26–3.69 Å. Pt is bonded in a 9-coordinate geometry to two equivalent Yb and seven In atoms. There are a spread of Pt–In bond distances ranging from 2.75–2.83 Å. There are three inequivalent In sites. In the first In site, In is bonded in a distorted q6 geometry to four equivalent Yb and six In atoms. There are two shorter (3.07 Å) and four longer (3.14 Å) In–In bond lengths. In the second In site, In is bonded in a 2-coordinate geometry to one Yb, one Pt, and four equivalent In atoms. In the third In site, In is bonded in a 3-coordinate geometry to three equivalent Yb, three equivalent Pt, and one In atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbIn4Pd by Materials Project

YbPdIn4 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Yb is bonded in a 7-coordinate geometry to two equivalent Pd and eleven In atoms. Both Yb–Pd bond lengths are 3.31 Å. There are a spread of Yb–In bond distances ranging from 3.26–3.66 Å. Pd is bonded in a 9-coordinate geometry to two equivalent Yb and seven In atoms. There are a spread of Pd–In bond distances ranging from 2.73–2.83 Å. There are three inequivalent In sites. In the first In site, In is bonded in a 3-coordinate geometry to three equivalent Yb, three equivalent Pd, and one In atom. The In–In bond length is 3.09 Å. In the second In site, In is bonded in a 2-coordinate geometry to one Yb, one Pd, and four equivalent In atoms. All In–In bond lengths are 3.15 Å. In the third In site, In is bonded in a distorted q6 geometry to four equivalent Yb and six In atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbIn4Rh by Materials Project

YbRhIn4 crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. Yb is bonded in a 1-coordinate geometry to one Rh and twelve In atoms. The Yb–Rh bond length is 3.02 Å. There are a spread of Yb–In bond distances ranging from 3.29–3.72 Å. Rh is bonded in a 9-coordinate geometry to one Yb and eight In atoms. There are a spread of Rh–In bond distances ranging from 2.64–2.92 Å. There are three inequivalent In sites. In the first In site, In is bonded in a 2-coordinate geometry to four equivalent Yb and two equivalent Rh atoms. In the second In site, In is bonded in a linear geometry to two equivalent Yb and two equivalent Rh atoms. In the third In site, In is bonded in a distorted rectangular see-saw-like geometry to two equivalent Yb and two equivalent Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Yb3In3Ge2Au by Materials Project

Yb3AuIn3Ge2 crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Yb is bonded in a 5-coordinate geometry to one Au, six equivalent In, and four equivalent Ge atoms. The Yb–Au bond length is 3.09 Å. There are two shorter (3.31 Å) and four longer (3.50 Å) Yb–In bond lengths. All Yb–Ge bond lengths are 3.15 Å. Au is bonded in a distorted q6 geometry to three equivalent Yb and six equivalent In atoms. All Au–In bond lengths are 2.90 Å. In is bonded in a 12-coordinate geometry to six equivalent Yb, two equivalent Au, two equivalent In, and two equivalent Ge atoms. Both In–In bond lengths are 3.22 Å. Both In–Ge bond lengths are 2.82 Å. Ge is bonded in a 9-coordinate geometry to six equivalent Yb and three equivalent In atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Yb7Bi17O36 by Materials Project

Bi17Yb7O36 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are seven inequivalent Yb3+ sites. In the first Yb3+ site, Yb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Yb–O bond distances ranging from 2.25–2.60 Å. In the second Yb3+ site, Yb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Yb–O bond distances ranging from 2.31–2.50 Å. In the third Yb3+ site, Yb3+ is bonded to five O2- atoms to form distorted YbO5 trigonal bipyramids that share corners with two BiO6 octahedra, a cornercorner with one BiO4 trigonal pyramid, and an edgeedge with one BiO6 octahedra. The corner-sharing octahedra tilt angles range from 41–43°. There are a spread of Yb–O bond distances ranging from 2.26–2.33 Å. In the fourth Yb3+ site, Yb3+ is bonded to six O2- atoms to form distorted YbO6 pentagonal pyramids that share a cornercorner with one BiO6 octahedra and a cornercorner with one BiO4 trigonal pyramid. The corner-sharing octahedral tilt angles are 52°. There are a spread of Yb–O bond distances ranging from 2.23–2.49 Å. In the fifth Yb3+ site, Yb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Yb–O bond distances ranging from 2.20–2.48 Å. In the sixth Yb3+ site, Yb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Yb–O bond distances ranging from 2.26–2.45 Å. In the seventh Yb3+ site, Yb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Yb–O bond distances ranging from 2.29–2.48 Å. There are seventeen inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Bi–O bond distances ranging from 2.18–2.31 Å. In the second Bi3+ site, Bi3+ is bonded to four O2- atoms to form distorted BiO4 trigonal pyramids that share a cornercorner with one YbO6 pentagonal pyramid and a cornercorner with one YbO5 trigonal bipyramid. There are a spread of Bi–O bond distances ranging from 2.15–2.24 Å. In the third Bi3+ site, Bi3+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Bi–O bond distances ranging from 2.16–2.26 Å. In the fourth Bi3+ site, Bi3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Bi–O bond distances ranging from 2.11–2.95 Å. In the fifth Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.15–2.84 Å. In the sixth Bi3+ site, Bi3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Bi–O bond distances ranging from 2.26–2.80 Å. In the seventh Bi3+ site, Bi3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Bi–O bond distances ranging from 2.16–2.64 Å. In the eighth Bi3+ site, Bi3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Bi–O bond distances ranging from 2.13–2.96 Å. In the ninth Bi3+ site, Bi3+ is bonded to six O2- atoms to form distorted BiO6 octahedra that share a cornercorner with one BiO6 octahedra, a cornercorner with one YbO5 trigonal bipyramid, and an edgeedge with one YbO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 42°. There are a spread of Bi–O bond distances ranging from 2.08–2.27 Å. In the tenth Bi3+ site, Bi3+ is bonded to six O2- atoms to form distorted corner-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles are 42°. There are a spread of Bi–O bond distances ranging from 2.08–2.30 Å. In the eleventh Bi3+ site, Bi3+ is bonded in a distorted pentagonal planar geometry to five O2- atoms. There are a spread of Bi–O bond distances ranging from 2.18–2.45 Å. In the twelfth Bi3+ site, Bi3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Bi–O bond distances ranging from 2.20–2.79 Å. In the thirteenth Bi3+ site, Bi3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Bi–O bond distances ranging from 2.21–2.67 Å. In the fourteenth Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.21–2.73 Å. In the fifteenth Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share a cornercorner with one YbO6 pentagonal pyramid and a cornercorner with one YbO5 trigonal bipyramid. There are a spread of Bi–O bond distances ranging from 2.09–2.23 Å. In the sixteenth Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.22–2.46 Å. In the seventeenth Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.20–2.79 Å. There are thirty-six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Yb3+ and three Bi3+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Yb3+ and two Bi3+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Yb3+ and one Bi3+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Yb3+ and two Bi3+ atoms. In the fifth O2- site, O2- is bonded to two Yb3+ and two Bi3+ atoms to form distorted OYb2Bi2 trigonal pyramids that share corners with nine OYbBi3 tetrahedra and edges with two equivalent OYb2Bi2 tetrahedra. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Yb3+ and two Bi3+ atoms. In the seventh O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of corner and edge-sharing OYbBi3 tetrahedra. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Yb3+ and two Bi3+ atoms. In the ninth O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form distorted OYbBi3 tetrahedra that share corners with eight OYbBi3 tetrahedra and a cornercorner with one OYb2Bi2 trigonal pyramid. In the tenth O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of distorted corner and edge-sharing OYbBi3 tetrahedra. In the eleventh O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of corner and edge-sharing OYbBi3 tetrahedra. In the twelfth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Yb3+ and one Bi3+ atom. In the thirteenth O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of corner and edge-sharing OYbBi3 tetrahedra. In the fourteenth O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of corner and edge-sharing OYbBi3 tetrahedra. In the fifteenth O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of distorted corner and edge-sharing OYbBi3 tetrahedra. In the sixteenth O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of distorted corner and edge-sharing OYbBi3 trigonal pyramids. In the seventeenth O2- site, O2- is bonded in a 4-coordinate geometry to one Yb3+ and three Bi3+ atoms. In the eighteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Yb3+ and three Bi3+ atoms. In the nineteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Yb3+ and three Bi3+ atoms. In the twentieth O2- site, O2- is bonded in a 4-coordinate geometry to one Yb3+ and three Bi3+ atoms. In the twenty-first O2- site, O2- is bonded in a 4-coordinate geometry to one Yb3+ and three Bi3+ atoms. In the twenty-second O2- site, O2- is bonded to two Yb3+ and two Bi3+ atoms to form distorted OYb2Bi2 tetrahedra that share corners with three OYbBi3 tetrahedra, edges with three OYb2Bi2 tetrahedra, and edges with two equivalent OYb2Bi2 trigonal pyramids. In the twenty-third O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of distorted corner and edge-sharing OYbBi3 tetrahedra. In the twenty-fourth O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form OYbBi3 tetrahedra that share corners with four OYbBi3 tetrahedra and edges with four OYb2Bi2 tetrahedra. In the twenty-fifth O2- site, O2- is bonded to two Yb3+ and two Bi3+ atoms to form distorted OYb2Bi2 tetrahedra that share corners with five OYbBi3 tetrahedra, corners with two equivalent OYb2Bi2 trigonal pyramids, and edges with three OYb2Bi2 tetrahedra. In the twenty-sixth O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form distorted OYbBi3 tetrahedra that share corners with five OYbBi3 tetrahedra, corners with two equivalent OYb2Bi2 trigonal pyramids, and edges with three OYbBi3 tetrahedra. In the twenty-seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three Bi3+ atoms. In the twenty-eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Yb3+ and two Bi3+ atoms. In the twenty-ninth O2- site, O2- is bonded to two Yb3+ and two Bi3+ atoms to form OYb2Bi2 tetrahedra that share corners with four OYbBi3 tetrahedra, a cornercorner with one OYb2Bi2 trigonal pyramid, and edges with three OYb2Bi2 tetrahedra. In the thirtieth O2- site, O2- is bonded to two Yb3+ and two Bi3+ atoms to form distorted OYb2Bi2 tetrahedra that share corners with four OYbBi3 tetrahedra, corners with two equivalent OYb2Bi2 trigonal pyramids, and edges with three OYb2Bi2 tetrahedra. In the thirty-first O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of distorted corner and edge-sharing OYbBi3 tetrahedra. In the thirty-second O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of corner and edge-sharing OYbBi3 tetrahedra. In the thirty-third O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of distorted corner and edge-sharing OYbBi3 tetrahedra. In the thirty-fourth O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of distorted corner and edge-sharing OYbBi3 tetrahedra. In the thirty-fifth O2- site, O2- is bonded in a trigonal non-coplanar geometry to one Yb3+ and two Bi3+ atoms. In the thirty-sixth O2- site, O2- is bonded to one Yb3+ and three Bi3+ atoms to form a mixture of corner and edge-sharing OYbBi3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbWO5 by Materials Project

YbWO5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Yb is bonded to eight O atoms to form distorted edge-sharing YbO8 hexagonal bipyramids. There are a spread of Yb–O bond distances ranging from 2.31–2.66 Å. W is bonded in a 5-coordinate geometry to five O atoms. There are a spread of W–O bond distances ranging from 1.79–2.19 Å. There are five inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to two equivalent Yb and one W atom. In the second O site, O is bonded in a distorted trigonal planar geometry to two equivalent Yb and one W atom. In the third O site, O is bonded in a distorted trigonal planar geometry to two equivalent Yb and one W atom. In the fourth O site, O is bonded in a linear geometry to one Yb and one W atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to one Yb and one W atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb3Yb7Se12 by Materials Project

Rb3Yb7Se12 is Orthorhombic Perovskite-like structured and crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. there are three inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of Rb–Se bond distances ranging from 3.51–3.97 Å. In the second Rb1+ site, Rb1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Rb–Se bond distances ranging from 3.52–4.17 Å. In the third Rb1+ site, Rb1+ is bonded to six Se2- atoms to form distorted RbSe6 octahedra that share edges with two equivalent RbSe6 octahedra and edges with four YbSe6 octahedra. There are a spread of Rb–Se bond distances ranging from 3.41–3.90 Å. There are seven inequivalent Yb3+ sites. In the first Yb3+ site, Yb3+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Yb–Se bond distances ranging from 2.81–2.96 Å. In the second Yb3+ site, Yb3+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of Yb–Se bond distances ranging from 2.80–3.47 Å. In the third Yb3+ site, Yb3+ is bonded in a 4-coordinate geometry to six Se2- atoms. There are a spread of Yb–Se bond distances ranging from 2.78–3.41 Å. In the fourth Yb3+ site, Yb3+ is bonded in a 4-coordinate geometry to six Se2- atoms. There are a spread of Yb–Se bond distances ranging from 2.77–3.47 Å. In the fifth Yb3+ site, Yb3+ is bonded to six Se2- atoms to form edge-sharing YbSe6 octahedra. There are a spread of Yb–Se bond distances ranging from 2.82–3.06 Å. In the sixth Yb3+ site, Yb3+ is bonded to six Se2- atoms to form distorted YbSe6 octahedra that share edges with two equivalent RbSe6 octahedra and edges with two equivalent YbSe6 octahedra. There are a spread of Yb–Se bond distances ranging from 2.88–3.52 Å. In the seventh Yb3+ site, Yb3+ is bonded to six Se2- atoms to form distorted YbSe6 octahedra that share edges with two equivalent RbSe6 octahedra and edges with two equivalent YbSe6 octahedra. There are a spread of Yb–Se bond distances ranging from 2.86–3.44 Å. There are twelve inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to three Rb1+ and three Yb3+ atoms. In the second Se2- site, Se2- is bonded to two equivalent Rb1+ and three Yb3+ atoms to form distorted SeRb2Yb3 square pyramids that share corners with two equivalent SeRb3Yb3 octahedra and edges with two equivalent SeRb2Yb3 square pyramids. The corner-sharing octahedral tilt angles are 72°. In the third Se2- site, Se2- is bonded to one Rb1+ and five Yb3+ atoms to form distorted SeRbYb5 square pyramids that share corners with two equivalent SeRb3Yb3 octahedra, an edgeedge with one SeRb3Yb3 octahedra, and edges with two equivalent SeRbYb5 square pyramids. The corner-sharing octahedral tilt angles are 11°. In the fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to one Rb1+ and five Yb3+ atoms. In the fifth Se2- site, Se2- is bonded in a 3-coordinate geometry to two equivalent Rb1+ and three Yb3+ atoms. In the sixth Se2- site, Se2- is bonded in a 5-coordinate geometry to two equivalent Rb1+ and three Yb3+ atoms. In the seventh Se2- site, Se2- is bonded in a 6-coordinate geometry to three Rb1+ and three Yb3+ atoms. In the eighth Se2- site, Se2- is bonded to three Rb1+ and three Yb3+ atoms to form distorted SeRb3Yb3 octahedra that share corners with four SeRb2Yb3 square pyramids, edges with two equivalent SeRb3Yb3 octahedra, and an edgeedge with one SeRbYb5 square pyramid. In the ninth Se2- site, Se2- is bonded in a 2-coordinate geometry to one Rb1+, two Yb3+, and two equivalent Se2- atoms. Both Se–Se bond lengths are 2.53 Å. In the tenth Se2- site, Se2- is bonded in a 2-coordinate geometry to one Rb1+, four Yb3+, and two equivalent Se2- atoms. Both Se–Se bond lengths are 2.52 Å. In the eleventh Se2- site, Se2- is bonded in a 5-coordinate geometry to three Yb3+ and two equivalent Se2- atoms. In the twelfth Se2- site, Se2- is bonded in a 5-coordinate geometry to three Yb3+ and two equivalent Se2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbMn2 by Materials Project

YbMn2 is Hexagonal Laves structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Yb is bonded in a 12-coordinate geometry to four equivalent Yb and twelve Mn atoms. There are one shorter (3.34 Å) and three longer (3.37 Å) Yb–Yb bond lengths. There are a spread of Yb–Mn bond distances ranging from 3.22–3.25 Å. There are two inequivalent Mn sites. In the first Mn site, Mn is bonded to six equivalent Yb and six equivalent Mn atoms to form a mixture of corner, edge, and face-sharing MnYb6Mn6 cuboctahedra. All Mn–Mn bond lengths are 2.68 Å. In the second Mn site, Mn is bonded to six equivalent Yb and six Mn atoms to form a mixture of corner, edge, and face-sharing MnYb6Mn6 cuboctahedra. There are two shorter (2.58 Å) and two longer (2.93 Å) Mn–Mn bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Yb2Mg by Materials Project

MgYb2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one MgYb2 sheet oriented in the (0, 0, 1) direction. Mg is bonded in a distorted q6 geometry to two equivalent Mg and seven Yb atoms. Both Mg–Mg bond lengths are 3.22 Å. There are a spread of Mg–Yb bond distances ranging from 3.39–3.52 Å. There are two inequivalent Yb sites. In the first Yb site, Yb is bonded in a 12-coordinate geometry to four equivalent Mg atoms. In the second Yb site, Yb is bonded in a 12-coordinate geometry to three equivalent Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbPu3 by Materials Project

Pu3Yb is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are three inequivalent Pu sites. In the first Pu site, Pu is bonded to eight Pu and four equivalent Yb atoms to form PuYb4Pu8 cuboctahedra that share corners with four equivalent YbPu12 cuboctahedra, corners with fourteen PuYb4Pu8 cuboctahedra, edges with six equivalent YbPu12 cuboctahedra, edges with twelve PuYb4Pu8 cuboctahedra, faces with four equivalent YbPu12 cuboctahedra, and faces with sixteen PuYb4Pu8 cuboctahedra. There are a spread of Pu–Pu bond distances ranging from 3.35–3.52 Å. There are two shorter (3.40 Å) and two longer (3.44 Å) Pu–Yb bond lengths. In the second Pu site, Pu is bonded to eight Pu and four equivalent Yb atoms to form PuYb4Pu8 cuboctahedra that share corners with four equivalent YbPu12 cuboctahedra, corners with fourteen PuYb4Pu8 cuboctahedra, edges with six equivalent YbPu12 cuboctahedra, edges with twelve PuYb4Pu8 cuboctahedra, faces with four equivalent YbPu12 cuboctahedra, and faces with sixteen PuYb4Pu8 cuboctahedra. All Pu–Pu bond lengths are 3.35 Å. There are two shorter (3.40 Å) and two longer (3.44 Å) Pu–Yb bond lengths. In the third Pu site, Pu is bonded to eight Pu and four equivalent Yb atoms to form PuYb4Pu8 cuboctahedra that share corners with four equivalent YbPu12 cuboctahedra, corners with fourteen PuYb4Pu8 cuboctahedra, edges with six equivalent YbPu12 cuboctahedra, edges with twelve PuYb4Pu8 cuboctahedra, faces with four equivalent YbPu12 cuboctahedra, and faces with sixteen PuYb4Pu8 cuboctahedra. There are one shorter (3.36 Å) and one longer (3.52 Å) Pu–Pu bond lengths. There are two shorter (3.40 Å) and two longer (3.44 Å) Pu–Yb bond lengths. Yb is bonded to twelve Pu atoms to form YbPu12 cuboctahedra that share corners with six equivalent YbPu12 cuboctahedra, corners with twelve PuYb4Pu8 cuboctahedra, edges with eighteen PuYb4Pu8 cuboctahedra, faces with eight equivalent YbPu12 cuboctahedra, and faces with twelve PuYb4Pu8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbMoO5 by Materials Project

YbMoO5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Yb is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Yb–O bond distances ranging from 2.29–2.56 Å. Mo is bonded in a distorted tetrahedral geometry to five O atoms. There are a spread of Mo–O bond distances ranging from 1.76–2.38 Å. There are five inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to two equivalent Yb, one Mo, and one O atom. The O–O bond length is 2.00 Å. In the second O site, O is bonded in a distorted trigonal planar geometry to two equivalent Yb and one Mo atom. In the third O site, O is bonded in a distorted trigonal planar geometry to two equivalent Yb and one Mo atom. In the fourth O site, O is bonded in a linear geometry to one Yb and one Mo atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to one Yb and one Mo atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Electrochemistry of PUREX: R is for Reduction and Ion Transfer

The PUREX (Plutonium, Uranium, Reduction, EXtraction) process is the foundation of all industrial activities that involve the recycling of plutonium and uranium from used nuclear fuel. With over 70 years of research, engineering, and operations, it can be argued that little opportunity is left for further discovery and new fundamental understandings regarding PUREX, in general, and tri-n-butyl phosphate (TBP), in particular. Through use of an advanced electroanalytical approach, molecular-level insights regarding the back-extraction of Pu(IV) by reductive separation is reported. Studies of model PUREX systems, with lanthanide ions extracted into 20 % TBP in n-dodecane, are used to demonstrate the approach. These studies reveal knowledge pertinent to mass transfer aspects of the biphasic reductive stripping reaction central to the separation of U and Pu in PUREX. Two lanthanide ions—Ce(IV) and Yb(III)—were extracted from their concentrated solutions in aqueous 3 M HNO 3 to expressly provide electrically conducting third phases to facilitate electrochemical data acquisition. To simplify the diabolically-complicated reductive separation aspects of PUREX, the controlled polarization of electrode surfaces was used to reduce Ce(IV) and Yb(III) in place of chemical reductants. Electroanalyses of the biphasic systems with Ce(IV) and Yb(III) using three-phase electrode differential pulse voltammetry demonstrate the effects of mass transfer across water-oil interfaces on the electrode potentials for the reduction to Ce(III) and Yb(II). These reductions trigger nitrate transfer out of the oil phase for Ce and proton transfer into the organic phase for Yb. This is in correlation with the transfer of the charge-neutral ion pairs Ce·3NO 3 and Yb·2NO 3 out of the oil phases. Here, the differences in ion transfer steps reflect significant variations in the equilibrium speciation of multinuclear Ce(IV) and mononuclear Yb(III) solvates of TBP in the oil phases and the loading of the organic phase.

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

Valence transition and termination-dependent surface states in the topological Kondo semimetal YbPtBi

Here, the Yb-terminated and Bi-terminated (111) surface electronic structure of topological Kondo semimetal YbPtBi is investigated using both density-functional-theory (DFT) -based calculations and angle-resolved photoemission spectroscopy (ARPES). The cleavage plane is found to be between Yb-layers and Bi-layers in both experiment and theory, and the broken inversion symmetry ensures the Yb-terminated surface does not mix with the Bi-terminated surface. The ARPES results at the Bi-terminated surface are similar to those reported for YPtBi or LuPtBi, and they can be well explained using DFT calculations assuming trivalent Yb atoms. In contrast, at the Yb-terminated surface, a trivalent to divalent transition and reduced hybridization with conduction electrons for the topmost Yb atoms are observed, as a result of reduced bonding with Bi-atoms. In addition, the Fermi arc features induced by the triply degenerate-points, which are missing at the Bi-terminated surface, can be identified at the Yb-terminated surface. Our study demonstrates unambiguously the reconstruction of surface electronic structure due to the valence transition of the lanthanide element in a Kondo lattice system.

36 MATERIALS SCIENCE↗