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At least 1,171 records · Page 65
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DOE OSTI2020

Materials Data on KCuO by Materials Project

KCuO is half-Heusler structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. K1+ is bonded to six equivalent Cu1+ and four equivalent O2- atoms to form distorted KCu6O4 tetrahedra that share corners with four equivalent CuK6O4 tetrahedra, corners with six equivalent KCu6O4 tetrahedra, edges with six equivalent CuK6O4 tetrahedra, and faces with twelve equivalent KCu6O4 tetrahedra. All K–Cu bond lengths are 2.94 Å. All K–O bond lengths are 2.54 Å. Cu1+ is bonded to six equivalent K1+ and four equivalent O2- atoms to form distorted CuK6O4 tetrahedra that share corners with four equivalent KCu6O4 tetrahedra, corners with six equivalent CuK6O4 tetrahedra, edges with six equivalent KCu6O4 tetrahedra, and faces with twelve equivalent CuK6O4 tetrahedra. All Cu–O bond lengths are 2.54 Å. O2- is bonded in a body-centered cubic geometry to four equivalent K1+ and four equivalent Cu1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3As by Materials Project

K3As is Sodium arsenide structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a distorted single-bond geometry to four equivalent As3- atoms. There are one shorter (3.42 Å) and three longer (3.82 Å) K–As bond lengths. In the second K1+ site, K1+ is bonded in a trigonal planar geometry to three equivalent As3- atoms. All K–As bond lengths are 3.38 Å. As3- is bonded to eleven K1+ atoms to form a mixture of distorted edge and face-sharing AsK11 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2UCl5 by Materials Project

K2UCl5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight Cl1- atoms. There are a spread of K–Cl bond distances ranging from 3.22–3.41 Å. U3+ is bonded to seven Cl1- atoms to form distorted edge-sharing UCl7 pentagonal bipyramids. There are two shorter (2.79 Å) and five longer (2.85 Å) U–Cl bond lengths. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 4-coordinate geometry to two equivalent K1+ and two equivalent U3+ atoms. In the second Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four equivalent K1+ and one U3+ atom. In the third Cl1- site, Cl1- is bonded to four equivalent K1+ and one U3+ atom to form a mixture of distorted corner, edge, and face-sharing ClK4U trigonal bipyramids. In the fourth Cl1- site, Cl1- is bonded to four equivalent K1+ and one U3+ atom to form a mixture of distorted corner, edge, and face-sharing ClK4U trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2TbCl5 by Materials Project

K2TbCl5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight Cl1- atoms. There are a spread of K–Cl bond distances ranging from 3.18–3.42 Å. Tb3+ is bonded to seven Cl1- atoms to form distorted edge-sharing TbCl7 pentagonal bipyramids. There are a spread of Tb–Cl bond distances ranging from 2.70–2.79 Å. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four equivalent K1+ and one Tb3+ atom. In the second Cl1- site, Cl1- is bonded in a 4-coordinate geometry to two equivalent K1+ and two equivalent Tb3+ atoms. In the third Cl1- site, Cl1- is bonded to four equivalent K1+ and one Tb3+ atom to form a mixture of distorted corner, edge, and face-sharing ClK4Tb trigonal bipyramids. In the fourth Cl1- site, Cl1- is bonded to four equivalent K1+ and one Tb3+ atom to form a mixture of distorted corner, edge, and face-sharing ClK4Tb trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2LaBr5 by Materials Project

K2LaBr5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of K–Br bond distances ranging from 3.39–3.62 Å. La3+ is bonded to seven Br1- atoms to form distorted edge-sharing LaBr7 pentagonal bipyramids. There are a spread of La–Br bond distances ranging from 2.98–3.07 Å. There are four inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 5-coordinate geometry to four equivalent K1+ and one La3+ atom. In the second Br1- site, Br1- is bonded in a 4-coordinate geometry to two equivalent K1+ and two equivalent La3+ atoms. In the third Br1- site, Br1- is bonded to four equivalent K1+ and one La3+ atom to form a mixture of distorted face, edge, and corner-sharing BrK4La trigonal bipyramids. In the fourth Br1- site, Br1- is bonded to four equivalent K1+ and one La3+ atom to form a mixture of distorted face, edge, and corner-sharing BrK4La trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2NdBr5 by Materials Project

K2NdBr5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of K–Br bond distances ranging from 3.36–3.59 Å. Nd3+ is bonded to seven Br1- atoms to form distorted edge-sharing NdBr7 pentagonal bipyramids. There are a spread of Nd–Br bond distances ranging from 2.96–3.05 Å. There are four inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 5-coordinate geometry to four equivalent K1+ and one Nd3+ atom. In the second Br1- site, Br1- is bonded in a 4-coordinate geometry to two equivalent K1+ and two equivalent Nd3+ atoms. In the third Br1- site, Br1- is bonded to four equivalent K1+ and one Nd3+ atom to form a mixture of distorted face, edge, and corner-sharing BrK4Nd trigonal bipyramids. In the fourth Br1- site, Br1- is bonded to four equivalent K1+ and one Nd3+ atom to form a mixture of distorted face, edge, and corner-sharing BrK4Nd trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The Pulsating Helium-atmosphere White Dwarfs. I. New DBVs from the Sloan Digital Sky Survey

Abstract We present a dedicated search for new pulsating helium-atmosphere (DBV) white dwarfs from the Sloan Digital Sky Survey using the McDonald 2.1 m Otto Struve Telescope. In total we observed 55 DB and DBA white dwarfs with spectroscopic temperatures between 19,000 and 35,000 K. We find 19 new DBVs and place upper limits on variability for the remaining 36 objects. In combination with previously known DBVs, we use these objects to provide an update to the empirical extent of the DB instability strip. With our sample of new DBVs, the red edge is better constrained, as we nearly double the number of DBVs known between 20,000 and 24,000 K. We do not find any new DBVs hotter than PG 0112+104, the current hottest DBV is at T eff ≈ 31,000 K, but do find pulsations in four DBVs with temperatures between 27,000 and 30,000 K, improving empirical constraints on the poorly defined blue edge. We investigate the ensemble pulsation properties of all currently known DBVs, finding that the weighted mean period and total pulsation power exhibit trends with effective temperature that are qualitatively similar to the pulsating hydrogen-atmosphere white dwarfs.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Materials Data on K3Nd by Materials Project

K3Nd is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. K is bonded to eight equivalent K and four equivalent Nd atoms to form distorted KK8Nd4 cuboctahedra that share corners with four equivalent NdK12 cuboctahedra, corners with fourteen equivalent KK8Nd4 cuboctahedra, edges with six equivalent NdK12 cuboctahedra, edges with twelve equivalent KK8Nd4 cuboctahedra, faces with four equivalent NdK12 cuboctahedra, and faces with sixteen equivalent KK8Nd4 cuboctahedra. There are a spread of K–K bond distances ranging from 4.22–4.44 Å. There are two shorter (4.33 Å) and two longer (4.34 Å) K–Nd bond lengths. Nd is bonded to twelve equivalent K atoms to form NdK12 cuboctahedra that share corners with six equivalent NdK12 cuboctahedra, corners with twelve equivalent KK8Nd4 cuboctahedra, edges with eighteen equivalent KK8Nd4 cuboctahedra, faces with eight equivalent NdK12 cuboctahedra, and faces with twelve equivalent KK8Nd4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Pr by Materials Project

K3Pr is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. K is bonded to eight equivalent K and four equivalent Pr atoms to form distorted KK8Pr4 cuboctahedra that share corners with four equivalent PrK12 cuboctahedra, corners with fourteen equivalent KK8Pr4 cuboctahedra, edges with six equivalent PrK12 cuboctahedra, edges with twelve equivalent KK8Pr4 cuboctahedra, faces with four equivalent PrK12 cuboctahedra, and faces with sixteen equivalent KK8Pr4 cuboctahedra. There are a spread of K–K bond distances ranging from 4.23–4.45 Å. All K–Pr bond lengths are 4.34 Å. Pr is bonded to twelve equivalent K atoms to form PrK12 cuboctahedra that share corners with six equivalent PrK12 cuboctahedra, corners with twelve equivalent KK8Pr4 cuboctahedra, edges with eighteen equivalent KK8Pr4 cuboctahedra, faces with eight equivalent PrK12 cuboctahedra, and faces with twelve equivalent KK8Pr4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Sm by Materials Project

K3Sm is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. K is bonded to eight equivalent K and four equivalent Sm atoms to form distorted KK8Sm4 cuboctahedra that share corners with four equivalent SmK12 cuboctahedra, corners with fourteen equivalent KK8Sm4 cuboctahedra, edges with six equivalent SmK12 cuboctahedra, edges with twelve equivalent KK8Sm4 cuboctahedra, faces with four equivalent SmK12 cuboctahedra, and faces with sixteen equivalent KK8Sm4 cuboctahedra. There are a spread of K–K bond distances ranging from 4.20–4.45 Å. There are two shorter (4.32 Å) and two longer (4.33 Å) K–Sm bond lengths. Sm is bonded to twelve equivalent K atoms to form SmK12 cuboctahedra that share corners with six equivalent SmK12 cuboctahedra, corners with twelve equivalent KK8Sm4 cuboctahedra, edges with eighteen equivalent KK8Sm4 cuboctahedra, faces with eight equivalent SmK12 cuboctahedra, and faces with twelve equivalent KK8Sm4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Tm by Materials Project

K3Tm is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. K is bonded to eight equivalent K and four equivalent Tm atoms to form distorted KK8Tm4 cuboctahedra that share corners with four equivalent TmK12 cuboctahedra, corners with fourteen equivalent KK8Tm4 cuboctahedra, edges with six equivalent TmK12 cuboctahedra, edges with twelve equivalent KK8Tm4 cuboctahedra, faces with four equivalent TmK12 cuboctahedra, and faces with sixteen equivalent KK8Tm4 cuboctahedra. There are a spread of K–K bond distances ranging from 4.17–4.42 Å. There are two shorter (4.28 Å) and two longer (4.29 Å) K–Tm bond lengths. Tm is bonded to twelve equivalent K atoms to form TmK12 cuboctahedra that share corners with six equivalent TmK12 cuboctahedra, corners with twelve equivalent KK8Tm4 cuboctahedra, edges with eighteen equivalent KK8Tm4 cuboctahedra, faces with eight equivalent TmK12 cuboctahedra, and faces with twelve equivalent KK8Tm4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Tb by Materials Project

K3Tb is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. K is bonded to eight equivalent K and four equivalent Tb atoms to form distorted KK8Tb4 cuboctahedra that share corners with four equivalent TbK12 cuboctahedra, corners with fourteen equivalent KK8Tb4 cuboctahedra, edges with six equivalent TbK12 cuboctahedra, edges with twelve equivalent KK8Tb4 cuboctahedra, faces with four equivalent TbK12 cuboctahedra, and faces with sixteen equivalent KK8Tb4 cuboctahedra. There are a spread of K–K bond distances ranging from 4.20–4.44 Å. There are two shorter (4.30 Å) and two longer (4.32 Å) K–Tb bond lengths. Tb is bonded to twelve equivalent K atoms to form TbK12 cuboctahedra that share corners with six equivalent TbK12 cuboctahedra, corners with twelve equivalent KK8Tb4 cuboctahedra, edges with eighteen equivalent KK8Tb4 cuboctahedra, faces with eight equivalent TbK12 cuboctahedra, and faces with twelve equivalent KK8Tb4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Ti by Materials Project

K3Ti is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. K is bonded to eight equivalent K and four equivalent Ti atoms to form distorted KK8Ti4 cuboctahedra that share corners with four equivalent TiK12 cuboctahedra, corners with fourteen equivalent KK8Ti4 cuboctahedra, edges with six equivalent TiK12 cuboctahedra, edges with twelve equivalent KK8Ti4 cuboctahedra, faces with four equivalent TiK12 cuboctahedra, and faces with sixteen equivalent KK8Ti4 cuboctahedra. There are a spread of K–K bond distances ranging from 3.97–4.42 Å. There are two shorter (4.10 Å) and two longer (4.19 Å) K–Ti bond lengths. Ti is bonded to twelve equivalent K atoms to form TiK12 cuboctahedra that share corners with six equivalent TiK12 cuboctahedra, corners with twelve equivalent KK8Ti4 cuboctahedra, edges with eighteen equivalent KK8Ti4 cuboctahedra, faces with eight equivalent TiK12 cuboctahedra, and faces with twelve equivalent KK8Ti4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2O by Materials Project

K2O is beta Vanadium nitride-like structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. There are one shorter (2.66 Å) and two longer (2.70 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. There are a spread of K–O bond distances ranging from 2.67–2.70 Å. O2- is bonded to six K1+ atoms to form a mixture of distorted corner and edge-sharing OK6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KMg6Nb by Materials Project

KMg6Nb crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to twelve Mg atoms to form KMg12 cuboctahedra that share corners with six equivalent KMg12 cuboctahedra, edges with four equivalent MgK2Mg8Nb2 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with two equivalent MgK2Mg8Nb2 cuboctahedra, and faces with six equivalent NbMg12 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.23–3.29 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a 4-coordinate geometry to two equivalent K, five Mg, and two equivalent Nb atoms. There are a spread of Mg–Mg bond distances ranging from 3.01–3.23 Å. Both Mg–Nb bond lengths are 3.08 Å. In the second Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent K, six Mg, and two equivalent Nb atoms. All Mg–Mg bond lengths are 3.18 Å. Both Mg–Nb bond lengths are 3.12 Å. In the third Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent K, eight Mg, and two equivalent Nb atoms. There are a spread of Mg–Mg bond distances ranging from 3.09–3.44 Å. There are one shorter (3.23 Å) and one longer (3.28 Å) Mg–Nb bond lengths. In the fourth Mg site, Mg is bonded to two equivalent K, eight Mg, and two equivalent Nb atoms to form distorted MgK2Mg8Nb2 cuboctahedra that share corners with four equivalent NbMg12 cuboctahedra, corners with six equivalent MgK2Mg8Nb2 cuboctahedra, edges with two equivalent NbMg12 cuboctahedra, edges with four equivalent KMg12 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with two equivalent MgK2Mg8Nb2 cuboctahedra, and faces with two equivalent NbMg12 cuboctahedra. Both Mg–Nb bond lengths are 3.29 Å. Nb is bonded to twelve Mg atoms to form NbMg12 cuboctahedra that share corners with four equivalent MgK2Mg8Nb2 cuboctahedra, corners with six equivalent NbMg12 cuboctahedra, edges with two equivalent MgK2Mg8Nb2 cuboctahedra, faces with two equivalent MgK2Mg8Nb2 cuboctahedra, faces with two equivalent NbMg12 cuboctahedra, and faces with six equivalent KMg12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Ho by Materials Project

K3Ho is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. K is bonded to eight equivalent K and four equivalent Ho atoms to form distorted KK8Ho4 cuboctahedra that share corners with four equivalent HoK12 cuboctahedra, corners with fourteen equivalent KK8Ho4 cuboctahedra, edges with six equivalent HoK12 cuboctahedra, edges with twelve equivalent KK8Ho4 cuboctahedra, faces with four equivalent HoK12 cuboctahedra, and faces with sixteen equivalent KK8Ho4 cuboctahedra. There are a spread of K–K bond distances ranging from 4.15–4.44 Å. There are two shorter (4.26 Å) and two longer (4.30 Å) K–Ho bond lengths. Ho is bonded to twelve equivalent K atoms to form HoK12 cuboctahedra that share corners with six equivalent HoK12 cuboctahedra, corners with twelve equivalent KK8Ho4 cuboctahedra, edges with eighteen equivalent KK8Ho4 cuboctahedra, faces with eight equivalent HoK12 cuboctahedra, and faces with twelve equivalent KK8Ho4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Eu by Materials Project

K3Eu is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. K is bonded to eight equivalent K and four equivalent Eu atoms to form distorted KK8Eu4 cuboctahedra that share corners with four equivalent EuK12 cuboctahedra, corners with fourteen equivalent KK8Eu4 cuboctahedra, edges with six equivalent EuK12 cuboctahedra, edges with twelve equivalent KK8Eu4 cuboctahedra, faces with four equivalent EuK12 cuboctahedra, and faces with sixteen equivalent KK8Eu4 cuboctahedra. There are a spread of K–K bond distances ranging from 4.54–4.63 Å. There are two shorter (4.55 Å) and two longer (4.58 Å) K–Eu bond lengths. Eu is bonded to twelve equivalent K atoms to form EuK12 cuboctahedra that share corners with six equivalent EuK12 cuboctahedra, corners with twelve equivalent KK8Eu4 cuboctahedra, edges with eighteen equivalent KK8Eu4 cuboctahedra, faces with eight equivalent EuK12 cuboctahedra, and faces with twelve equivalent KK8Eu4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Dy by Materials Project

K3Dy is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. K is bonded to eight equivalent K and four equivalent Dy atoms to form distorted KK8Dy4 cuboctahedra that share corners with four equivalent DyK12 cuboctahedra, corners with fourteen equivalent KK8Dy4 cuboctahedra, edges with six equivalent DyK12 cuboctahedra, edges with twelve equivalent KK8Dy4 cuboctahedra, faces with four equivalent DyK12 cuboctahedra, and faces with sixteen equivalent KK8Dy4 cuboctahedra. There are a spread of K–K bond distances ranging from 4.19–4.42 Å. There are two shorter (4.29 Å) and two longer (4.30 Å) K–Dy bond lengths. Dy is bonded to twelve equivalent K atoms to form DyK12 cuboctahedra that share corners with six equivalent DyK12 cuboctahedra, corners with twelve equivalent KK8Dy4 cuboctahedra, edges with eighteen equivalent KK8Dy4 cuboctahedra, faces with eight equivalent DyK12 cuboctahedra, and faces with twelve equivalent KK8Dy4 cuboctahedra.

36 MATERIALS SCIENCE↗