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DOE OSTI2020

Materials Data on TaVCu by Materials Project

TaVCu crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Ta is bonded in a 12-coordinate geometry to four equivalent Ta, six equivalent V, and six equivalent Cu atoms. There are two shorter (3.04 Å) and two longer (3.07 Å) Ta–Ta bond lengths. There are two shorter (2.93 Å) and four longer (2.95 Å) Ta–V bond lengths. There are four shorter (2.84 Å) and two longer (3.01 Å) Ta–Cu bond lengths. V is bonded to six equivalent Ta, two equivalent V, and four equivalent Cu atoms to form distorted VTa6V2Cu4 cuboctahedra that share corners with eight equivalent CuTa6V4Cu2 cuboctahedra, corners with ten equivalent VTa6V2Cu4 cuboctahedra, edges with six equivalent VTa6V2Cu4 cuboctahedra, faces with six equivalent VTa6V2Cu4 cuboctahedra, and faces with twelve equivalent CuTa6V4Cu2 cuboctahedra. Both V–V bond lengths are 2.40 Å. All V–Cu bond lengths are 2.51 Å. Cu is bonded to six equivalent Ta, four equivalent V, and two equivalent Cu atoms to form CuTa6V4Cu2 cuboctahedra that share corners with eight equivalent VTa6V2Cu4 cuboctahedra, corners with ten equivalent CuTa6V4Cu2 cuboctahedra, edges with six equivalent CuTa6V4Cu2 cuboctahedra, faces with six equivalent CuTa6V4Cu2 cuboctahedra, and faces with twelve equivalent VTa6V2Cu4 cuboctahedra. Both Cu–Cu bond lengths are 2.53 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta3(InS3)2 by Materials Project

Ta3(InS3)2 crystallizes in the trigonal R32 space group. The structure is three-dimensional. there are two inequivalent Ta+3.33+ sites. In the first Ta+3.33+ site, Ta+3.33+ is bonded to six equivalent S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. All Ta–S bond lengths are 2.49 Å. In the second Ta+3.33+ site, Ta+3.33+ is bonded to six equivalent S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. All Ta–S bond lengths are 2.49 Å. In1+ is bonded in a 6-coordinate geometry to six equivalent S2- atoms. All In–S bond lengths are 3.15 Å. S2- is bonded in a 5-coordinate geometry to three Ta+3.33+ and two equivalent In1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2(PdRu)3 by Materials Project

Ta2(RuPd)3 is Uranium Silicide-derived structured and crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. Ta is bonded to six Ru and six Pd atoms to form TaPd6Ru6 cuboctahedra that share corners with four equivalent RuTa4Pd4 cuboctahedra, corners with twelve equivalent TaPd6Ru6 cuboctahedra, edges with two equivalent RuTa4Pd4 cuboctahedra, edges with twelve PdTa4Pd2Ru6 cuboctahedra, faces with six equivalent TaPd6Ru6 cuboctahedra, and faces with six PdTa4Pd2Ru6 cuboctahedra. There are a spread of Ta–Ru bond distances ranging from 2.71–2.78 Å. All Ta–Pd bond lengths are 2.81 Å. There are three inequivalent Ru sites. In the first Ru site, Ru is bonded to four equivalent Ta and four equivalent Pd atoms to form distorted RuTa4Pd4 cuboctahedra that share corners with eight equivalent TaPd6Ru6 cuboctahedra, corners with sixteen PdTa4Pd2Ru6 cuboctahedra, edges with four equivalent TaPd6Ru6 cuboctahedra, edges with four equivalent RuTa4Pd4 cuboctahedra, edges with four equivalent PdTa4Pd2Ru6 cuboctahedra, and faces with two equivalent PdTa4Pd4Ru4 cuboctahedra. All Ru–Pd bond lengths are 2.74 Å. In the second Ru site, Ru is bonded in a distorted square co-planar geometry to four equivalent Ta and eight Pd atoms. There are four shorter (2.78 Å) and four longer (2.81 Å) Ru–Pd bond lengths. In the third Ru site, Ru is bonded in a distorted square co-planar geometry to four equivalent Ta and four equivalent Pd atoms. All Ru–Pd bond lengths are 2.78 Å. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded to four equivalent Ta, six Ru, and two equivalent Pd atoms to form distorted PdTa4Pd2Ru6 cuboctahedra that share corners with four equivalent RuTa4Pd4 cuboctahedra, corners with twelve equivalent PdTa4Pd2Ru6 cuboctahedra, edges with two equivalent RuTa4Pd4 cuboctahedra, edges with four equivalent PdTa4Pd4Ru4 cuboctahedra, edges with eight equivalent TaPd6Ru6 cuboctahedra, faces with four equivalent TaPd6Ru6 cuboctahedra, and faces with eight PdTa4Pd2Ru6 cuboctahedra. Both Pd–Pd bond lengths are 2.75 Å. In the second Pd site, Pd is bonded to four equivalent Ta, four equivalent Ru, and four equivalent Pd atoms to form distorted PdTa4Pd4Ru4 cuboctahedra that share corners with four equivalent PdTa4Pd4Ru4 cuboctahedra, corners with eight equivalent RuTa4Pd4 cuboctahedra, edges with eight equivalent TaPd6Ru6 cuboctahedra, edges with eight equivalent PdTa4Pd2Ru6 cuboctahedra, faces with two equivalent RuTa4Pd4 cuboctahedra, faces with four equivalent TaPd6Ru6 cuboctahedra, and faces with eight PdTa4Pd2Ru6 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2Cr3Si by Materials Project

Ta2Cr3Si crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ta is bonded in a 12-coordinate geometry to four equivalent Ta, nine equivalent Cr, and three equivalent Si atoms. All Ta–Ta bond lengths are 3.00 Å. There are six shorter (2.86 Å) and three longer (2.89 Å) Ta–Cr bond lengths. All Ta–Si bond lengths are 2.86 Å. Cr is bonded to six equivalent Ta, four equivalent Cr, and two equivalent Si atoms to form distorted CrTa6Cr4Si2 cuboctahedra that share corners with four equivalent SiTa6Cr6 cuboctahedra, corners with fourteen equivalent CrTa6Cr4Si2 cuboctahedra, edges with six equivalent CrTa6Cr4Si2 cuboctahedra, faces with six equivalent SiTa6Cr6 cuboctahedra, and faces with twelve equivalent CrTa6Cr4Si2 cuboctahedra. There are two shorter (2.36 Å) and two longer (2.51 Å) Cr–Cr bond lengths. Both Cr–Si bond lengths are 2.49 Å. Si is bonded to six equivalent Ta and six equivalent Cr atoms to form SiTa6Cr6 cuboctahedra that share corners with twelve equivalent CrTa6Cr4Si2 cuboctahedra, edges with six equivalent SiTa6Cr6 cuboctahedra, faces with two equivalent SiTa6Cr6 cuboctahedra, and faces with eighteen equivalent CrTa6Cr4Si2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2GaCo3 by Materials Project

Ta2Co3Ga crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ta is bonded in a 12-coordinate geometry to four equivalent Ta, nine equivalent Co, and three equivalent Ga atoms. There are one shorter (2.89 Å) and three longer (2.98 Å) Ta–Ta bond lengths. There are three shorter (2.73 Å) and six longer (2.85 Å) Ta–Co bond lengths. All Ta–Ga bond lengths are 2.87 Å. Co is bonded to six equivalent Ta, four equivalent Co, and two equivalent Ga atoms to form CoTa6Ga2Co4 cuboctahedra that share corners with four equivalent GaTa6Co6 cuboctahedra, corners with fourteen equivalent CoTa6Ga2Co4 cuboctahedra, edges with six equivalent CoTa6Ga2Co4 cuboctahedra, faces with six equivalent GaTa6Co6 cuboctahedra, and faces with twelve equivalent CoTa6Ga2Co4 cuboctahedra. There are two shorter (2.36 Å) and two longer (2.54 Å) Co–Co bond lengths. Both Co–Ga bond lengths are 2.41 Å. Ga is bonded to six equivalent Ta and six equivalent Co atoms to form GaTa6Co6 cuboctahedra that share corners with twelve equivalent CoTa6Ga2Co4 cuboctahedra, edges with six equivalent GaTa6Co6 cuboctahedra, faces with two equivalent GaTa6Co6 cuboctahedra, and faces with eighteen equivalent CoTa6Ga2Co4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2Co4O9 by Materials Project

Ta2Co4O9 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ta–O bond distances ranging from 1.87–2.27 Å. In the second Ta5+ site, Ta5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ta–O bond distances ranging from 1.87–2.28 Å. In the third Ta5+ site, Ta5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ta–O bond distances ranging from 1.87–2.28 Å. In the fourth Ta5+ site, Ta5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ta–O bond distances ranging from 1.87–2.27 Å. In the fifth Ta5+ site, Ta5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ta–O bond distances ranging from 1.86–2.28 Å. In the sixth Ta5+ site, Ta5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ta–O bond distances ranging from 1.87–2.27 Å. In the seventh Ta5+ site, Ta5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ta–O bond distances ranging from 1.87–2.28 Å. In the eighth Ta5+ site, Ta5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ta–O bond distances ranging from 1.87–2.28 Å. There are sixteen inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of distorted edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 47–67°. There are a spread of Co–O bond distances ranging from 2.03–2.29 Å. In the second Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of distorted edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–67°. There are a spread of Co–O bond distances ranging from 2.03–2.29 Å. In the third Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 47–48°. There are a spread of Co–O bond distances ranging from 2.02–2.32 Å. In the fourth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–48°. There are a spread of Co–O bond distances ranging from 2.01–2.32 Å. In the fifth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 47–48°. There are a spread of Co–O bond distances ranging from 2.02–2.32 Å. In the sixth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–48°. There are a spread of Co–O bond distances ranging from 2.01–2.32 Å. In the seventh Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 47–66°. There are a spread of Co–O bond distances ranging from 2.03–2.27 Å. In the eighth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–66°. There are a spread of Co–O bond distances ranging from 2.03–2.27 Å. In the ninth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of distorted edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–67°. There are a spread of Co–O bond distances ranging from 2.03–2.29 Å. In the tenth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of distorted edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–67°. There are a spread of Co–O bond distances ranging from 2.03–2.30 Å. In the eleventh Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 47–48°. There are a spread of Co–O bond distances ranging from 2.01–2.32 Å. In the twelfth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–48°. There are a spread of Co–O bond distances ranging from 2.01–2.32 Å. In the thirteenth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–48°. There are a spread of Co–O bond distances ranging from 2.02–2.31 Å. In the fourteenth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–48°. There are a spread of Co–O bond distances ranging from 2.01–2.31 Å. In the fifteenth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–66°. There are a spread of Co–O bond distances ranging from 2.03–2.27 Å. In the sixteenth Co2+ site, Co2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 47–66°. There are a spread of Co–O bond distances ranging from 2.04–2.27 Å. There are thirty-six inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the second O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ta5+ and two Co2+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ta5+ and two Co2+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Co2+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Co2+ atoms. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to one Ta5+ and four Co2+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to one Ta5+ and four Co2+ atoms. In the ninth O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the tenth O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the eleventh O2- site, O2- is bonded in a 5-coordinate geometry to one Ta5+ and four Co2+ atoms. In the twelfth O2- site, O2- is bonded in a 5-coordinate geometry to one Ta5+ and four Co2+ atoms. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Co2+ atoms. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Co2+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ta5+ and two Co2+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ta5+ and two Co2+ atoms. In the seventeenth O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the eighteenth O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the nineteenth O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the twentieth O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the twenty-first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ta5+ and two Co2+ atoms. In the twenty-second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ta5+ and two Co2+ atoms. In the twenty-third O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Co2+ atoms. In the twenty-fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Co2+ atoms. In the twenty-fifth O2- site, O2- is bonded in a 5-coordinate geometry to one Ta5+ and four Co2+ atoms. In the twenty-sixth O2- site, O2- is bonded in a 5-coordinate geometry to one Ta5+ and four Co2+ atoms. In the twenty-seventh O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the twenty-eighth O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the twenty-ninth O2- site, O2- is bonded in a 5-coordinate geometry to one Ta5+ and four Co2+ atoms. In the thirtieth O2- site, O2- is bonded in a 5-coordinate geometry to one Ta5+ and four Co2+ atoms. In the thirty-first O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Co2+ atoms. In the thirty-second O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Co2+ atoms. In the thirty-third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ta5+ and two Co2+ atoms. In the thirty-fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ta5+ and two Co2+ atoms. In the thirty-fifth O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids. In the thirty-sixth O2- site, O2- is bonded to two Ta5+ and two Co2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Co2 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3TaO2F7 by Materials Project

K3TaO2F7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 4-coordinate geometry to four equivalent F atoms. There are two shorter (2.63 Å) and two longer (2.71 Å) K–F bond lengths. In the second K site, K is bonded in a 8-coordinate geometry to one O and seven F atoms. The K–O bond length is 3.00 Å. There are a spread of K–F bond distances ranging from 2.51–3.19 Å. Ta is bonded in a distorted pentagonal bipyramidal geometry to two equivalent O and five F atoms. Both Ta–O bond lengths are 2.12 Å. There are a spread of Ta–F bond distances ranging from 1.92–1.95 Å. O is bonded in a 3-coordinate geometry to one K, one Ta, and one O atom. The O–O bond length is 1.35 Å. There are five inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to two equivalent K and one Ta atom. In the second F site, F is bonded in a distorted single-bond geometry to two equivalent K and one Ta atom. In the third F site, F is bonded to four K atoms to form a mixture of distorted edge and corner-sharing FK4 trigonal pyramids. In the fourth F site, F is bonded in a distorted trigonal planar geometry to two equivalent K and one Ta atom. In the fifth F site, F is bonded in a distorted single-bond geometry to two equivalent K and one Ta atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2FeO6 by Materials Project

FeTa2O6 is zeta iron carbide-derived structured and crystallizes in the monoclinic P2 space group. The structure is three-dimensional. there are eight inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with six TaO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 36–54°. There are a spread of Ta–O bond distances ranging from 1.95–2.10 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four TaO6 octahedra, corners with four FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 36–59°. There are a spread of Ta–O bond distances ranging from 1.87–2.14 Å. In the third Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four equivalent TaO6 octahedra, corners with four equivalent FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 40–55°. There are two shorter (1.99 Å) and four longer (2.01 Å) Ta–O bond lengths. In the fourth Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four equivalent TaO6 octahedra, corners with four equivalent FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 40–52°. There are a spread of Ta–O bond distances ranging from 1.95–2.06 Å. In the fifth Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four equivalent TaO6 octahedra, corners with four equivalent FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 41–55°. There are two shorter (1.99 Å) and four longer (2.01 Å) Ta–O bond lengths. In the sixth Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four TaO6 octahedra, corners with four FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 36–59°. There are a spread of Ta–O bond distances ranging from 1.87–2.13 Å. In the seventh Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with six TaO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 36–54°. There are a spread of Ta–O bond distances ranging from 1.95–2.11 Å. In the eighth Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four equivalent TaO6 octahedra, corners with four equivalent FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 40–52°. There are a spread of Ta–O bond distances ranging from 1.95–2.07 Å. There are four inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with six TaO6 octahedra, and edges with two TaO6 octahedra. The corner-sharing octahedra tilt angles range from 40–59°. There are a spread of Fe–O bond distances ranging from 2.05–2.23 Å. In the second Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with eight TaO6 octahedra and edges with two TaO6 octahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Fe–O bond distances ranging from 2.16–2.19 Å. In the third Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with six TaO6 octahedra, and edges with two TaO6 octahedra. The corner-sharing octahedra tilt angles range from 40–59°. There are a spread of Fe–O bond distances ranging from 2.05–2.24 Å. In the fourth Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with eight TaO6 octahedra and edges with two TaO6 octahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Fe–O bond distances ranging from 2.16–2.19 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ta5+ and one Fe2+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ta5+ and two Fe2+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ta5+ and one Fe2+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ta5+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ta5+ and one Fe2+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Ta5+ and two Fe2+ atoms. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the sixteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the seventeenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ta5+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ta5+ and one Fe2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr3NdTaAl3O12 by Materials Project

Sr3NdTaAl3O12 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are four inequivalent Sr sites. In the first Sr site, Sr is bonded to twelve O atoms to form distorted SrO12 cuboctahedra that share corners with four equivalent SrO12 cuboctahedra, a faceface with one NdO12 cuboctahedra, faces with five SrO12 cuboctahedra, faces with two equivalent TaO6 octahedra, and faces with six AlO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.56–3.06 Å. In the second Sr site, Sr is bonded in a 12-coordinate geometry to eleven O atoms. There are a spread of Sr–O bond distances ranging from 2.56–2.83 Å. In the third Sr site, Sr is bonded to twelve O atoms to form distorted SrO12 cuboctahedra that share corners with four equivalent NdO12 cuboctahedra, corners with eight SrO12 cuboctahedra, faces with four equivalent SrO12 cuboctahedra, faces with two equivalent TaO6 octahedra, and faces with six AlO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.59–2.99 Å. In the fourth Sr site, Sr is bonded to twelve O atoms to form distorted SrO12 cuboctahedra that share corners with two equivalent NdO12 cuboctahedra, corners with ten SrO12 cuboctahedra, faces with two equivalent SrO12 cuboctahedra, and faces with eight AlO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.62–3.05 Å. There are two inequivalent Nd sites. In the first Nd site, Nd is bonded in a 12-coordinate geometry to twelve O atoms. There are a spread of Nd–O bond distances ranging from 2.46–3.05 Å. In the second Nd site, Nd is bonded to twelve O atoms to form distorted NdO12 cuboctahedra that share corners with two equivalent NdO12 cuboctahedra, corners with ten SrO12 cuboctahedra, faces with two equivalent SrO12 cuboctahedra, faces with four equivalent TaO6 octahedra, and faces with four AlO6 octahedra. There are a spread of Nd–O bond distances ranging from 2.45–2.90 Å. Ta is bonded to six O atoms to form TaO6 octahedra that share a cornercorner with one TaO6 octahedra, corners with five AlO6 octahedra, faces with two equivalent NdO12 cuboctahedra, and faces with four SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 8–17°. There are a spread of Ta–O bond distances ranging from 1.94–2.04 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four AlO6 octahedra, a faceface with one NdO12 cuboctahedra, and faces with five SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 3–16°. There are a spread of Al–O bond distances ranging from 1.92–1.98 Å. In the second Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four AlO6 octahedra, a faceface with one NdO12 cuboctahedra, and faces with five SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 8–18°. There are a spread of Al–O bond distances ranging from 1.90–1.98 Å. In the third Al site, Al is bonded to six O atoms to form AlO6 octahedra that share a cornercorner with one TaO6 octahedra, corners with five AlO6 octahedra, and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 2–11°. There are a spread of Al–O bond distances ranging from 1.89–1.96 Å. There are fourteen inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to two Sr, two Nd, one Ta, and one Al atom. In the second O site, O is bonded in a 2-coordinate geometry to three Sr, one Nd, one Ta, and one Al atom. In the third O site, O is bonded in a 6-coordinate geometry to three Sr, one Nd, and two Al atoms. In the fourth O site, O is bonded to four Sr and two Al atoms to form distorted OSr4Al2 octahedra that share corners with three OSr4Al2 octahedra and a faceface with one OSr3NdAl2 octahedra. The corner-sharing octahedra tilt angles range from 55–61°. In the fifth O site, O is bonded in a 5-coordinate geometry to three Nd and two equivalent Ta atoms. In the sixth O site, O is bonded in a 2-coordinate geometry to four Sr and two Al atoms. In the seventh O site, O is bonded to three Sr, one Nd, and two equivalent Al atoms to form a mixture of distorted corner and face-sharing OSr3NdAl2 octahedra. The corner-sharing octahedra tilt angles range from 0–61°. In the eighth O site, O is bonded in a 6-coordinate geometry to three Sr, one Nd, one Ta, and one Al atom. In the ninth O site, O is bonded in a distorted linear geometry to four Sr and two Al atoms. In the tenth O site, O is bonded in a 2-coordinate geometry to two Sr, two Nd, one Ta, and one Al atom. In the eleventh O site, O is bonded in a 2-coordinate geometry to three Sr, one Nd, and two Al atoms. In the twelfth O site, O is bonded in a 2-coordinate geometry to four Sr, one Ta, and one Al atom. In the thirteenth O site, O is bonded in a distorted linear geometry to three Sr, one Nd, and two equivalent Al atoms. In the fourteenth O site, O is bonded in a 3-coordinate geometry to one Sr, three Nd, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta3MnS6 by Materials Project

Ta3MnS6 is Ilmenite-like structured and crystallizes in the hexagonal P6_322 space group. The structure is three-dimensional. there are two inequivalent Ta+3.33+ sites. In the first Ta+3.33+ site, Ta+3.33+ is bonded to six equivalent S2- atoms to form distorted TaS6 pentagonal pyramids that share corners with six equivalent MnS6 octahedra and edges with six equivalent TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 46°. All Ta–S bond lengths are 2.49 Å. In the second Ta+3.33+ site, Ta+3.33+ is bonded to six equivalent S2- atoms to form distorted TaS6 pentagonal pyramids that share corners with three equivalent MnS6 octahedra, edges with six TaS6 pentagonal pyramids, and a faceface with one MnS6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are three shorter (2.47 Å) and three longer (2.51 Å) Ta–S bond lengths. Mn2+ is bonded to six equivalent S2- atoms to form MnS6 octahedra that share corners with twelve TaS6 pentagonal pyramids and faces with two equivalent TaS6 pentagonal pyramids. All Mn–S bond lengths are 2.35 Å. S2- is bonded to three Ta+3.33+ and one Mn2+ atom to form a mixture of distorted edge, face, and corner-sharing STa3Mn trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2FeO6 by Materials Project

FeTa2O6 is zeta iron carbide-derived structured and crystallizes in the monoclinic P2 space group. The structure is three-dimensional. there are eight inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with eight TaO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 36–52°. There are a spread of Ta–O bond distances ranging from 1.94–2.05 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four TaO6 octahedra, corners with four FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 39–53°. There are a spread of Ta–O bond distances ranging from 1.97–2.04 Å. In the third Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with six TaO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 32–56°. There are a spread of Ta–O bond distances ranging from 1.94–2.11 Å. In the fourth Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four equivalent TaO6 octahedra, corners with four equivalent FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 41–54°. There are four shorter (2.00 Å) and two longer (2.02 Å) Ta–O bond lengths. In the fifth Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four TaO6 octahedra, corners with four FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 36–59°. There are a spread of Ta–O bond distances ranging from 1.87–2.12 Å. In the sixth Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four equivalent TaO6 octahedra, corners with four equivalent FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 41–54°. There are a spread of Ta–O bond distances ranging from 1.99–2.03 Å. In the seventh Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with four TaO6 octahedra, corners with four FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 41–53°. There are a spread of Ta–O bond distances ranging from 1.98–2.03 Å. In the eighth Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with four equivalent TaO6 octahedra, corners with four equivalent FeO6 octahedra, an edgeedge with one TaO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 32–62°. There are a spread of Ta–O bond distances ranging from 1.86–2.22 Å. There are four inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent TaO6 octahedra, corners with four equivalent FeO6 octahedra, and edges with two TaO6 octahedra. The corner-sharing octahedra tilt angles range from 40–59°. There are a spread of Fe–O bond distances ranging from 2.04–2.24 Å. In the second Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with eight TaO6 octahedra and edges with two TaO6 octahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Fe–O bond distances ranging from 2.12–2.21 Å. In the third Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with six TaO6 octahedra, and edges with two TaO6 octahedra. The corner-sharing octahedra tilt angles range from 38–62°. There are a spread of Fe–O bond distances ranging from 2.03–2.24 Å. In the fourth Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with eight TaO6 octahedra and edges with two TaO6 octahedra. The corner-sharing octahedra tilt angles range from 51–53°. There are two shorter (2.14 Å) and four longer (2.19 Å) Fe–O bond lengths. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ta5+ and one Fe2+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ta5+ and one Fe2+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ta5+ and two Fe2+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ta5+ atoms. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ta5+ and two Fe2+ atoms. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ta5+ atoms. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ta5+ and one Fe2+ atom. In the sixteenth O2- site, O2- is bonded in a trigonal planar geometry to two Ta5+ and one Fe2+ atom. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom. In the eighteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ta5+ and one Fe2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2GaNi3 by Materials Project

Ta2Ni3Ga crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ta is bonded in a 12-coordinate geometry to four equivalent Ta, nine equivalent Ni, and three equivalent Ga atoms. There are one shorter (2.96 Å) and three longer (2.98 Å) Ta–Ta bond lengths. There are three shorter (2.77 Å) and six longer (2.87 Å) Ta–Ni bond lengths. All Ta–Ga bond lengths are 2.87 Å. Ni is bonded to six equivalent Ta, four equivalent Ni, and two equivalent Ga atoms to form NiTa6Ga2Ni4 cuboctahedra that share corners with four equivalent GaTa6Ni6 cuboctahedra, corners with fourteen equivalent NiTa6Ga2Ni4 cuboctahedra, edges with six equivalent NiTa6Ga2Ni4 cuboctahedra, faces with six equivalent GaTa6Ni6 cuboctahedra, and faces with twelve equivalent NiTa6Ga2Ni4 cuboctahedra. There are two shorter (2.38 Å) and two longer (2.53 Å) Ni–Ni bond lengths. Both Ni–Ga bond lengths are 2.43 Å. Ga is bonded to six equivalent Ta and six equivalent Ni atoms to form GaTa6Ni6 cuboctahedra that share corners with twelve equivalent NiTa6Ga2Ni4 cuboctahedra, edges with six equivalent GaTa6Ni6 cuboctahedra, faces with two equivalent GaTa6Ni6 cuboctahedra, and faces with eighteen equivalent NiTa6Ga2Ni4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Two-Dimensional Tantalum Carbo-Selenide for Hydrogen Evolution

Herein, we report the synthesis of two-dimensional Ta 2 Se 2 C (2D-Ta 2 Se 2 C) nanosheets using electrochemical lithiation in multilayer Ta 2 Se 2 C followed by sonication in deionized water. Multilayer Ta 2 Se 2 C was obtained via solid-state synthesis of Fe x Ta 2 Se 2 C followed by chemical etching of Fe. 2D-Ta 2 Se 2 C exhibited promising electrocatalytic activity for the hydrogen evolution reaction from water compared to multilayer Ta 2 Se 2 C and 2D-TaSe 2 . 2D-Ta 2 Se 2 C showed an overpotential at 10 mA·cm -2 (η 10 ) of 264 mV, a Tafel slope of 91 mV·dec -1 , and an electrochemically active surface area of 17.61 m ECSA 2 ·g catalyst -1 . The high performance could be attributed to the large surface area of single sheets which hence maximizes the number of exposed catalytic sites and increased density of vacancies, observed with transmission electron microscopy, during synthesis and processing.

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

Two-level systems in nucleated and non-nucleated epitaxial alpha-tantalum films

Building usefully coherent superconducting quantum processors depends on reducing losses in their constituent materials. Tantalum, like niobium, has proven utility as the primary superconducting layer within highly coherent qubits. However, unlike Nb, high temperatures are typically used to stabilize the desirable body-centered-cubic phase, α-Ta, during thin film deposition. It has long been known that a thin Nb layer permits the room-temperature nucleation of α-Ta, but here we observe the epitaxial process and present few-photon microwave loss measurements in Nb-nucleated Ta films. We compare resonators patterned from Ta films grown at high temperature (500 °C) and films nucleated at room temperature, in order to understand the impact of the crystalline order on quantum coherence. In both cases, films grew with Al 2 O 3 (001) ∥ Ta (110), indicating that the epitaxial orientation is independent of temperature and is preserved across the Nb/Ta interface. We use conventional low-power spectroscopy to measure two level system (TLS) loss as well as an electric-field bias technique to measure the effective dipole moments of TLS in the surfaces of resonators. In our measurements, Nb-nucleated Ta resonators had greater loss tangent (1.5 ± 0.1 × 10 -5 ) than non-nucleated (5 ± 1× 10 -6 ) in approximate proportion to defect densities as characterized by x-ray diffraction (0.27° vs 0.18° [110] reflection width) and electron microscopy (30 vs 70 nm domain size). Furthermore, the dependence of the loss tangent on domain size indicates that the development of more ordered Ta films is likely to lead to improvements in qubit coherence times. Moreover, low-temperature α-Ta epitaxy may enable the growth of microstate-free heterostructures, which would not withstand high temperature processing.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Interface-sensitive microwave loss in superconducting tantalum films sputtered on c-plane sapphire

Quantum coherence in superconducting circuits has increased steadily over the last decades because of a growing understanding of the various loss mechanisms. Recently, tantalum (Ta) emerged as a promising material to address microscopic sources of loss found on niobium (Nb) or aluminum (Al) surfaces. However, the effects of film and interface microstructure on low-temperature microwave loss are still not well understood. Here, in this study, we present a systematic study of the structural and electrical properties of Ta and Nb films sputtered on c-plane sapphire at varying growth temperatures. As growth temperature was increased, our results show that the onset of epitaxial growth of α -phase Ta correlates with lower Ta surface roughness, higher critical temperature, and higher residual resistivity ratio, but surprisingly also correlates with a significant increase in loss at microwave frequency. Notably, this high level of loss is not observed in Nb films prepared in the same way and having very similar structure. By experimentally controlling the surface on which the Ta film is nucleated, we determine that the source of loss was only present in samples having an epitaxial Ta/sapphire interface and show that it was apparently mitigated by either growing a thin, epitaxial Nb interlayer between the Ta film and the substrate or by intentionally treating, and effectively damaging, the sapphire surface with an in situ argon plasma before Ta growth. In addition to elucidating this interfacial microwave loss, this work provides adequate process details to aid reproducible growth of low-loss Ta films across fabrication facilities.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

2022 Results for Avian Monitoring of Inorganic Elements and Organic Chemical Concentrations in Passerine Eggs and Nestlings Collected from Technical Area 16 Burn Grounds, Technical Area 36 Minie, and Technical Area 39 Point 6 at Los Alamos National Laboratory

In 2022, nonviable avian eggs and one nestling were opportunistically collected at Los Alamos National Laboratory (LANL) near open detonation sites located at Technical Area (TA) 16 burn grounds, TA-36 Minie, and TA-39 Point 6. Samples were evaluated for inorganic elements (mostly metals) or per- and polyfluoroalkyl substances (PFAS). Three western bluebird (Sialia mexicana) egg samples were collected from TA-16 burn grounds. One deceased mountain bluebird (Sialia currucoides) nestling sample was collected from TA-36 Minie. One ash-throated flycatcher (Myiarchus cinerascens) egg sample was collected from TA-39 Point 6. Concentrations of inorganic elements (i.e., mostly metals) observed in this study were compared with the regional statistical reference level (RSRL), which is the upper-level bounds of background concentrations (mean + three standard deviations = 99% confidence interval). Several inorganic elements were not detected in avian eggs. All of the inorganic elements that were detected were below the RSRL and the lowest observable adverse effect level (LOAEL), when available. No PFAS compounds were detected in the mountain bluebird nestling sample collected from TA-36, and the majority of PFAS compounds were not detected in the western bluebird egg sample from TA-16. These data suggest that inorganic element and PFAS concentrations in eggs and nestlings are not of ecological concern. More data are needed to make a robust assessment and to evaluate trends over time.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

2024 Results for Avian Monitoring at the Technical Area 36 Minie Site, Technical Area 39 Point 6, Technical Area 16 Burn Ground, and DARHT at Los Alamos National Laboratory

Los Alamos National Laboratory (LANL) biological subject matter experts in the Environmental Protection and Compliance Division initiated a multi-year program in 2013 to monitor avifauna (birds) at two open detonation sites and one open burn site on LANL property. Additional monitoring began in 2017 at a third firing site, the Dual-Axis Radiographic Hydrodynamic Test (DARHT) Facility. In this annual report, we compare monitoring results from these efforts among years to identify and evaluate firing and open burn site impacts on the local bird community. The objectives of this study are • to determine whether LANL operations impact bird abundance, species richness, or diversity; • to examine occupancy and nest success of secondary-cavity nesting birds that use nest boxes; and • to examine chemical concentrations (such as radionuclides, inorganic elements, and/or organic compounds) in nonviable eggs and deceased nestlings that are collected opportunistically with the upper-level bounds of background concentrations, when available. During May through July 2024, LANL biologists completed multiple avian point count surveys at each of the following treatment sites: • Technical Area (TA) 36 Minie Site, • TA-39 Point 6, • TA-16 Burn Ground, and • DARHT. We recorded a total of 1,088 birds that represented 65 species at the four treatment sites and compared these results with data from their associated control sites. In 2024, abundance and species richness at treatment and control sites continued to trend similarly from year to year, with minor random deviations expected from bird communities. Species richness at firing sites differed little from the previous year’s values. Two new bird species were observed at the firing sites—cedar waxwing (Bombycilla cedrorum) and pinyon jay (Gymnorhinus cyanocephalus). Shannon diversity values at TA-36 Minie Site, TA-39, and DARHT were statistically higher than one or more of their associated controls. Annual species diversity at treatment sites was high in 2024 across all firing sites relative to similar habitat control sites. We also monitored avian nest boxes to compare occupancy and nest success data from nest boxes at treatment sites with the overall avian nest box monitoring network and against a subset of relevant control sites. Nest box success has decreased at both treatment and control sites since monitoring began, suggesting that overlapping climatic factors are responsible for patterns of declining nest success. In 2024, nonviable avian eggs and one nestling were opportunistically collected at Bandelier National Monument, TA-16 Burn Ground, TA-36 Minie, TA-39 Point 6, and DARHT. All egg samples and the one nestling sample were evaluated for per- and polyfluoroalkyl substances, which were detected from all locations, including the control site at Bandelier National Monument. Overall results from 2024 continue to suggest that operations at the four treatment sites are not negatively impacting bird populations. This long-term project will continue to monitor for any changes over time.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2022

An Analysis of Spatio-Temporal Relationship between Satellite-Based Land Surface Temperature and Station-Based Near-Surface Air Temperature over Brazil

A better understanding of the relationship between land surface temperature (Ts) and near-surface air temperature (Ta) is crucial for improving the simulation accuracy of climate models, developing retrieval schemes for soil and vegetation moisture, and estimating large-scale Ta from satellite-based Ts observations. In this study, we investigated the relationship between multiple satellite-based Ts products, derived from the Atmospheric Infrared Sounder (AIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua satellite, and Ta from 204 meteorological stations over Brazil during 2003–2016. Monthly satellite-based Ts products used in this study include: (1) AIRS Version 6 with 1° spatial resolution, (2) AIRS Version 7 with 1° spatial resolution, (3) MODIS Collection 6 with 0.05° spatial resolution, and (4) MODIS Collection 6 with 1° spatial resolution re-sampled from (3) for a direct comparison with AIRS products. We found that satellite-based Ts is lower than Ta over the forest area, but higher than Ta over the non-forest area. Nevertheless, the correlation coefficients (R) between monthly Ta and four Ts products during 2003–2016 are greater than 0.8 over most stations. The long-term trend analysis shows a general warming trend in temperatures, particularly over the central and eastern parts of Brazil. The satellite products could also observe the increasing Ts over the deforestation region. Furthermore, we examined the temperature anomalies during three drought events in the dry season of 2005, 2010, and 2015. All products show similar spatio-temporal patterns, with positive temperature anomalies expanding in areal coverage and magnitude from the 2005 to 2015 event. The above results show that satellite-based Ts is sensitive in reflecting environmental changes such as deforestation and extreme climatic events, and can be used as an alternative to Ta for climatological studies. Moreover, the observed differences between Ts and Ta may inform how thermal assumptions can be improved in satellite-based retrievals of soil and vegetation moisture or evapotranspiration.

land surface temperature↗