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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Autotrophic biofilms sustained by deeply sourced groundwater host diverse bacteria implicated in sulfur and hydrogen metabolism

Abstract Background Biofilms in sulfide-rich springs present intricate microbial communities that play pivotal roles in biogeochemical cycling. We studied chemoautotrophically based biofilms that host diverse CPR bacteria and grow in sulfide-rich springs to investigate microbial controls on biogeochemical cycling. Results Sulfide springs biofilms were investigated using bulk geochemical analysis, genome-resolved metagenomics, and scanning transmission X-ray microscopy (STXM) at room temperature and 87 K. Chemolithotrophic sulfur-oxidizing bacteria, including Thiothrix and Beggiatoa , dominate the biofilms, which also contain CPR Gracilibacteria, Absconditabacteria, Saccharibacteria, Peregrinibacteria, Berkelbacteria, Microgenomates, and Parcubacteria. STXM imaging revealed ultra-small cells near the surfaces of filamentous bacteria that may be CPR bacterial episymbionts. STXM and NEXAFS spectroscopy at carbon K and sulfur L 2,3 edges show that filamentous bacteria contain protein-encapsulated spherical elemental sulfur granules, indicating that they are sulfur oxidizers, likely Thiothrix . Berkelbacteria and Moranbacteria in the same biofilm sample are predicted to have a novel electron bifurcating group 3b [NiFe]-hydrogenase, putatively a sulfhydrogenase, potentially linked to sulfur metabolism via redox cofactors. This complex could potentially contribute to symbioses, for example, with sulfur-oxidizing bacteria such as Thiothrix that is based on cryptic sulfur cycling. One Doudnabacteria genome encodes adjacent sulfur dioxygenase and rhodanese genes that may convert thiosulfate to sulfite. We find similar conserved genomic architecture associated with CPR bacteria from other sulfur-rich subsurface ecosystems. Conclusions Our combined metagenomic, geochemical, spectromicroscopic, and structural bioinformatics analyses of biofilms growing in sulfide-rich springs revealed consortia that contain CPR bacteria and sulfur-oxidizing Proteobacteria, including Thiothrix , and bacteria from a new family within Beggiatoales. We infer roles for CPR bacteria in sulfur and hydrogen cycling.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Materials Data on KAg(CN)2 by Materials Project

KAg(CN)2 is Potassium Silver Cyanide structured and crystallizes in the trigonal P-31c space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six equivalent N3- atoms to form edge-sharing KN6 octahedra. There are three shorter (2.86 Å) and three longer (2.98 Å) K–N bond lengths. In the second K1+ site, K1+ is bonded to six equivalent N3- atoms to form edge-sharing KN6 octahedra. All K–N bond lengths are 2.92 Å. Ag1+ is bonded in a linear geometry to two equivalent C2+ atoms. Both Ag–C bond lengths are 2.05 Å. C2+ is bonded in a linear geometry to one Ag1+ and one N3- atom. The C–N bond length is 1.17 Å. N3- is bonded in a 4-coordinate geometry to three K1+ and one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KY(CuO2)2 by Materials Project

KY(CuO2)2 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. K1+ is bonded to eight equivalent O2- atoms to form distorted edge-sharing KO8 hexagonal bipyramids. All K–O bond lengths are 2.90 Å. Y3+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Y–O bond lengths are 2.41 Å. Cu2+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Cu–O bond lengths are 1.95 Å. O2- is bonded in a 6-coordinate geometry to two equivalent K1+, two equivalent Y3+, and two equivalent Cu2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KYbF4 by Materials Project

KYbF4 crystallizes in the trigonal P3_2 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of K–F bond distances ranging from 2.66–3.23 Å. In the second K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YbF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YbF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.59–3.20 Å. In the third K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.65–3.14 Å. In the fourth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YbF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YbF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.63–3.02 Å. In the fifth K1+ site, K1+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.63–2.90 Å. In the sixth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YbF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YbF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.62–3.10 Å. There are six inequivalent Yb3+ sites. In the first Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.24–2.30 Å. In the second Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share corners with five YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.21–2.29 Å. In the third Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.24–2.30 Å. In the fourth Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share corners with five YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.25–2.27 Å. In the fifth Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.21–2.33 Å. In the sixth Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share corners with five YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.22–2.32 Å. There are twenty-four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the second F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two K1+ and two Yb3+ atoms. In the third F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two equivalent Yb3+ atoms. In the fourth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Yb3+ atoms. In the fifth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the sixth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Yb3+ atoms. In the seventh F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Yb3+ atoms. In the eighth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two K1+ and two equivalent Yb3+ atoms. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Yb3+ atoms. In the tenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the eleventh F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two equivalent Yb3+ atoms. In the twelfth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Yb3+ atoms. In the thirteenth F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of edge and corner-sharing FK3Yb tetrahedra. In the fourteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the fifteenth F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of distorted edge and corner-sharing FK3Yb tetrahedra. In the sixteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the seventeenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the eighteenth F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of distorted edge and corner-sharing FK3Yb tetrahedra. In the nineteenth F1- site, F1- is bonded in a 3-coordinate geometry to two K1+ and two Yb3+ atoms. In the twentieth F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of distorted edge and corner-sharing FK3Yb tetrahedra. In the twenty-first F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of distorted edge and corner-sharing FK3Yb tetrahedra. In the twenty-second F1- site, F1- is bonded in a 3-coordinate geometry to two K1+, two Yb3+, and one F1- atom. The F–F bond length is 2.00 Å. In the twenty-third F1- site, F1- is bonded in a 3-coordinate geometry to two K1+, two Yb3+, and one F1- atom. In the twenty-fourth F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of distorted edge and corner-sharing FK3Yb tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KTmF4 by Materials Project

KTmF4 crystallizes in the trigonal P3_2 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 4-coordinate geometry to nine F1- atoms. There are a spread of K–F bond distances ranging from 2.61–3.29 Å. In the second K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one TmF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six TmF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.54–3.05 Å. In the third K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.58–3.05 Å. In the fourth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one TmF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six TmF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.58–3.01 Å. In the fifth K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.58–2.93 Å. In the sixth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one TmF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six TmF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.60–3.05 Å. There are six inequivalent Tm3+ sites. In the first Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.12–2.28 Å. In the second Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share corners with five TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.18–2.25 Å. In the third Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.12–2.27 Å. In the fourth Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share corners with five TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.18–2.25 Å. In the fifth Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.12–2.27 Å. In the sixth Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share corners with five TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.17–2.25 Å. There are twenty-four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the second F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Tm3+ atoms. In the third F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two equivalent Tm3+ atoms. In the fourth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Tm3+ atoms. In the fifth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Tm3+ atoms. In the sixth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Tm3+ atoms. In the seventh F1- site, F1- is bonded in a distorted linear geometry to one K1+ and two Tm3+ atoms. In the eighth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two equivalent Tm3+ atoms. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Tm3+ atoms. In the tenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the eleventh F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Tm3+ atoms. In the twelfth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Tm3+ atoms. In the thirteenth F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of edge and corner-sharing FK3Tm tetrahedra. In the fourteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the fifteenth F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of distorted edge and corner-sharing FK3Tm tetrahedra. In the sixteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the seventeenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the eighteenth F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of distorted edge and corner-sharing FK3Tm tetrahedra. In the nineteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the twentieth F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of distorted edge and corner-sharing FK3Tm tetrahedra. In the twenty-first F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of distorted edge and corner-sharing FK3Tm tetrahedra. In the twenty-second F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the twenty-third F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the twenty-fourth F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of distorted edge and corner-sharing FK3Tm tetrahedra.

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 KLaCO4 by Materials Project

LaKOCO3 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one K2O2 sheet oriented in the (0, 0, 1) direction and one LaCO3 sheet oriented in the (0, 0, 1) direction. In the K2O2 sheet, there are four inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing KO5 square pyramids. There are a spread of K–O bond distances ranging from 2.57–2.98 Å. In the second K1+ site, K1+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing KO5 square pyramids. There are a spread of K–O bond distances ranging from 2.56–2.98 Å. In the third K1+ site, K1+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing KO5 square pyramids. There are a spread of K–O bond distances ranging from 2.56–2.98 Å. In the fourth K1+ site, K1+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing KO5 square pyramids. There are a spread of K–O bond distances ranging from 2.57–2.98 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to five K1+ atoms to form a mixture of edge and corner-sharing OK5 square pyramids. In the second O2- site, O2- is bonded to five K1+ atoms to form a mixture of edge and corner-sharing OK5 square pyramids. In the third O2- site, O2- is bonded to five K1+ atoms to form a mixture of edge and corner-sharing OK5 square pyramids. In the fourth O2- site, O2- is bonded to five K1+ atoms to form a mixture of edge and corner-sharing OK5 square pyramids. In the LaCO3 sheet, there are four inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.38–2.49 Å. In the second La3+ site, La3+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.38–2.49 Å. In the third La3+ site, La3+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.38–2.49 Å. In the fourth La3+ site, La3+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.38–2.49 Å. There are four inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.27 Å. In the second C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.27 Å) C–O bond length. In the third C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.26 Å. In the fourth C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.26 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the second O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the third O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the fourth O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the fifth O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the sixth O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the seventh O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the eighth O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the ninth O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the tenth O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the eleventh O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the twelfth O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2Cd3Te4 by Materials Project

K2Cd3Te4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six Te2- atoms to form distorted KTe6 octahedra that share corners with twelve CdTe4 tetrahedra, edges with six KTe6 octahedra, and edges with three CdTe4 tetrahedra. There are a spread of K–Te bond distances ranging from 3.67–3.80 Å. In the second K1+ site, K1+ is bonded to six Te2- atoms to form distorted KTe6 octahedra that share corners with ten CdTe4 tetrahedra, edges with six KTe6 octahedra, and edges with four CdTe4 tetrahedra. There are a spread of K–Te bond distances ranging from 3.56–3.80 Å. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to four Te2- atoms to form CdTe4 tetrahedra that share corners with eight KTe6 octahedra, corners with four CdTe4 tetrahedra, edges with two KTe6 octahedra, and edges with two CdTe4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–97°. There are a spread of Cd–Te bond distances ranging from 2.83–2.99 Å. In the second Cd2+ site, Cd2+ is bonded to four Te2- atoms to form CdTe4 tetrahedra that share corners with six KTe6 octahedra, corners with four equivalent CdTe4 tetrahedra, edges with three KTe6 octahedra, and edges with two equivalent CdTe4 tetrahedra. The corner-sharing octahedra tilt angles range from 12–95°. There are a spread of Cd–Te bond distances ranging from 2.83–2.97 Å. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 6-coordinate geometry to three K1+ and three Cd2+ atoms. In the second Te2- site, Te2- is bonded in a 6-coordinate geometry to three K1+ and three Cd2+ atoms. In the third Te2- site, Te2- is bonded to three K1+ and three Cd2+ atoms to form a mixture of distorted edge and corner-sharing TeK3Cd3 octahedra. The corner-sharing octahedra tilt angles range from 0–54°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KZn2BCl2O3 by Materials Project

KZn2BO3Cl2 crystallizes in the trigonal R32 space group. The structure is three-dimensional. K1+ is bonded to six equivalent Cl1- atoms to form KCl6 octahedra that share corners with six equivalent ZnClO3 tetrahedra and edges with six equivalent KCl6 octahedra. All K–Cl bond lengths are 3.26 Å. Zn2+ is bonded to three equivalent O2- and one Cl1- atom to form ZnClO3 tetrahedra that share corners with three equivalent KCl6 octahedra and corners with three equivalent ZnClO3 tetrahedra. The corner-sharing octahedral tilt angles are 63°. All Zn–O bond lengths are 1.97 Å. The Zn–Cl bond length is 2.28 Å. B3+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All B–O bond lengths are 1.38 Å. O2- is bonded in a trigonal planar geometry to two equivalent Zn2+ and one B3+ atom. Cl1- is bonded to three equivalent K1+ and one Zn2+ atom to form a mixture of distorted edge and corner-sharing ClK3Zn tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHoF4 by Materials Project

KHoF4 crystallizes in the trigonal P3_1 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one HoF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six HoF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.55–3.08 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.61–3.01 Å. In the third K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one HoF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six HoF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.61–3.03 Å. In the fourth K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.59–3.06 Å. In the fifth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one HoF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six HoF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.62–3.09 Å. In the sixth K1+ site, K1+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.60–2.90 Å. There are six inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to seven F1- atoms to form HoF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent HoF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one HoF7 pentagonal bipyramid. There are a spread of Ho–F bond distances ranging from 2.16–2.30 Å. In the second Ho3+ site, Ho3+ is bonded to seven F1- atoms to form HoF7 pentagonal bipyramids that share corners with five HoF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one HoF7 pentagonal bipyramid. There are a spread of Ho–F bond distances ranging from 2.21–2.28 Å. In the third Ho3+ site, Ho3+ is bonded to seven F1- atoms to form HoF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent HoF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one HoF7 pentagonal bipyramid. There are a spread of Ho–F bond distances ranging from 2.16–2.29 Å. In the fourth Ho3+ site, Ho3+ is bonded to seven F1- atoms to form HoF7 pentagonal bipyramids that share corners with five HoF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one HoF7 pentagonal bipyramid. There are a spread of Ho–F bond distances ranging from 2.21–2.28 Å. In the fifth Ho3+ site, Ho3+ is bonded to seven F1- atoms to form HoF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent HoF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one HoF7 pentagonal bipyramid. There are a spread of Ho–F bond distances ranging from 2.16–2.29 Å. In the sixth Ho3+ site, Ho3+ is bonded to seven F1- atoms to form HoF7 pentagonal bipyramids that share corners with five HoF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one HoF7 pentagonal bipyramid. There are a spread of Ho–F bond distances ranging from 2.21–2.28 Å. There are twenty-four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Ho3+ atoms. In the second F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Ho3+ atoms. In the third F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Ho3+ atoms. In the fourth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Ho3+ atoms. In the fifth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Ho3+ atoms. In the sixth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Ho3+ atoms. In the seventh F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Ho3+ atoms. In the eighth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two equivalent Ho3+ atoms. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Ho3+ atoms. In the tenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Ho3+ atoms. In the eleventh F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Ho3+ atoms. In the twelfth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Ho3+ atoms. In the thirteenth F1- site, F1- is bonded to three K1+ and one Ho3+ atom to form a mixture of corner and edge-sharing FK3Ho tetrahedra. In the fourteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Ho3+ atoms. In the fifteenth F1- site, F1- is bonded to three K1+ and one Ho3+ atom to form a mixture of distorted corner and edge-sharing FK3Ho tetrahedra. In the sixteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Ho3+ atoms. In the seventeenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Ho3+ atoms. In the eighteenth F1- site, F1- is bonded to three K1+ and one Ho3+ atom to form a mixture of distorted corner and edge-sharing FK3Ho tetrahedra. In the nineteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Ho3+ atoms. In the twentieth F1- site, F1- is bonded to three K1+ and one Ho3+ atom to form a mixture of distorted corner and edge-sharing FK3Ho tetrahedra. In the twenty-first F1- site, F1- is bonded to three K1+ and one Ho3+ atom to form a mixture of distorted corner and edge-sharing FK3Ho tetrahedra. In the twenty-second F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Ho3+ atoms. In the twenty-third F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Ho3+ atoms. In the twenty-fourth F1- site, F1- is bonded to three K1+ and one Ho3+ atom to form a mixture of distorted corner and edge-sharing FK3Ho tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2Cd3Se4 by Materials Project

K2Cd3Se4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 octahedra that share corners with ten CdSe4 tetrahedra, edges with six KSe6 octahedra, and edges with four CdSe4 tetrahedra. There are a spread of K–Se bond distances ranging from 3.35–3.57 Å. In the second K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 octahedra that share corners with twelve CdSe4 tetrahedra, edges with six KSe6 octahedra, and edges with three CdSe4 tetrahedra. There are a spread of K–Se bond distances ranging from 3.47–3.58 Å. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to four Se2- atoms to form CdSe4 tetrahedra that share corners with six KSe6 octahedra, corners with four equivalent CdSe4 tetrahedra, edges with three KSe6 octahedra, and edges with two equivalent CdSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 13–95°. There are a spread of Cd–Se bond distances ranging from 2.64–2.79 Å. In the second Cd2+ site, Cd2+ is bonded to four Se2- atoms to form CdSe4 tetrahedra that share corners with eight KSe6 octahedra, corners with four CdSe4 tetrahedra, edges with two KSe6 octahedra, and edges with two CdSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 10–95°. There are a spread of Cd–Se bond distances ranging from 2.65–2.81 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to three K1+ and three Cd2+ atoms. In the second Se2- site, Se2- is bonded in a 6-coordinate geometry to three K1+ and three Cd2+ atoms. In the third Se2- site, Se2- is bonded to three K1+ and three Cd2+ atoms to form a mixture of distorted edge and corner-sharing SeK3Cd3 octahedra. The corner-sharing octahedra tilt angles range from 0–55°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KYF4 by Materials Project

KYF4 crystallizes in the trigonal P3_1 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.57–3.07 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.63–3.06 Å. In the third K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.63–3.06 Å. In the fourth K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.60–3.01 Å. In the fifth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.64–3.08 Å. In the sixth K1+ site, K1+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.62–2.93 Å. There are six inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.18–2.32 Å. In the second Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share corners with five YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.23–2.29 Å. In the third Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.18–2.31 Å. In the fourth Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share corners with five YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.23–2.30 Å. In the fifth Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.18–2.31 Å. In the sixth Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share corners with five YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.23–2.30 Å. There are twenty-four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the second F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Y3+ atoms. In the third F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Y3+ atoms. In the fourth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Y3+ atoms. In the fifth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the sixth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Y3+ atoms. In the seventh F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Y3+ atoms. In the eighth F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Y3+ atoms. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Y3+ atoms. In the tenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the eleventh F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Y3+ atoms. In the twelfth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Y3+ atoms. In the thirteenth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form a mixture of edge and corner-sharing FK3Y tetrahedra. In the fourteenth F1- site, F1- is bonded to two K1+ and two Y3+ atoms to form a mixture of distorted edge and corner-sharing FK2Y2 tetrahedra. In the fifteenth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form distorted FK3Y tetrahedra that share corners with seven FK3Y tetrahedra and edges with two FK2Y2 tetrahedra. In the sixteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the seventeenth F1- site, F1- is bonded to two K1+ and two Y3+ atoms to form a mixture of distorted edge and corner-sharing FK2Y2 tetrahedra. In the eighteenth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form distorted FK3Y tetrahedra that share corners with seven FK3Y tetrahedra and edges with two FK2Y2 tetrahedra. In the nineteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the twentieth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form distorted FK3Y tetrahedra that share corners with seven FK3Y tetrahedra and edges with two FK2Y2 tetrahedra. In the twenty-first F1- site, F1- is bonded to three K1+ and one Y3+ atom to form distorted FK3Y tetrahedra that share corners with eight FK2Y2 tetrahedra and an edgeedge with one FK3Y tetrahedra. In the twenty-second F1- site, F1- is bonded to two K1+ and two Y3+ atoms to form a mixture of distorted edge and corner-sharing FK2Y2 tetrahedra. In the twenty-third F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the twenty-fourth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form a mixture of distorted edge and corner-sharing FK3Y tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Role of deep levels and barrier height lowering in current-flow mechanism in 150 μ m thick epitaxial n-type 4H–SiC Schottky barrier radiation detectors

Schottky barrier detectors (SBDs) require larger surface areas than conventional electronics to increase the detection efficiency although such SBDs manifest large diode ideality factors due to inhomogeneous areal distribution of surface barrier height (SBH). Inhomogeneous SBH distributions lead to various current flow mechanisms in SBDs, which need to be identified to optimize detector performance. In this Letter, we identify the current flow mechanism in large area Schottky barrier diodes for radiation detection fabricated on 150 μm thick n-4H–SiC epitaxial layers. The analysis of temperature-dependent forward current–voltage (I–V–T) characteristics of SBDs revealed two linear regions in current–voltage curves up to 450 K, one corresponding to the current flow through a low barrier patch, while the other corresponds to that of average barrier distribution. Applying a SBH distribution model to the reverse I–V–T characteristics, an activation energy of 0.76 eV for the current flow over the Schottky barrier was calculated. Additionally, the activation energy did not directly correspond to any of the defect levels observed from the deep level transient spectroscopy (DLTS). Above 450 K, a Schottky type barrier lowering suggested a current flow through a low barrier patch of ≈ 0.8 eV. The absence of any SBH lowering below 450 K indicated that the current corresponded to a neutrally charged trap level at ≈ 0.6 eV below the conduction band edge, which was consistent with DLTS measurements revealing the presence of an electron trap level Z1/2 at 0.59 eV below the conduction band edge.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Materials Data on K by Materials Project

K crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 8-coordinate geometry to eight equivalent K atoms. All K–K bond lengths are 4.61 Å. In the second K site, K is bonded to seven K atoms to form a mixture of distorted corner, edge, and face-sharing KK7 pentagonal bipyramids. There are four shorter (4.29 Å) and one longer (4.46 Å) K–K bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K4Al2O by Materials Project

K4Al2O crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. K is bonded in a distorted single-bond geometry to three equivalent Al and one O atom. All K–Al bond lengths are 3.27 Å. The K–O bond length is 2.86 Å. Al is bonded to six equivalent K atoms to form distorted AlK6 octahedra that share edges with six equivalent AlK6 octahedra and faces with two equivalent OK4 tetrahedra. O is bonded to four equivalent K atoms to form OK4 tetrahedra that share faces with four equivalent AlK6 octahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2MoO2F5 by Materials Project

K2MoO2F5 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 8-coordinate geometry to three O and five F atoms. There are one shorter (2.94 Å) and two longer (3.04 Å) K–O bond lengths. There are a spread of K–F bond distances ranging from 2.66–3.04 Å. In the second K site, K is bonded in a 10-coordinate geometry to ten F atoms. There are a spread of K–F bond distances ranging from 2.91–3.07 Å. Mo is bonded in an octahedral geometry to one O and five F atoms. The Mo–O bond length is 1.72 Å. There are a spread of Mo–F bond distances ranging from 1.99–2.08 Å. There are two inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to one K and one Mo atom. In the second O site, O is bonded in a water-like geometry to two equivalent K atoms. There are four inequivalent F sites. In the first F site, F is bonded in a 4-coordinate geometry to three K and one Mo atom. In the second F site, F is bonded in a distorted single-bond geometry to three K and one Mo atom. In the third F site, F is bonded to three K and one Mo atom to form distorted edge-sharing FK3Mo tetrahedra. In the fourth F site, F is bonded in a 4-coordinate geometry to three K and one Mo atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KErF4 by Materials Project

KErF4 crystallizes in the trigonal P3_1 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one ErF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six ErF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.56–3.05 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.63–3.06 Å. In the third K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one ErF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six ErF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.62–3.02 Å. In the fourth K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.59–3.07 Å. In the fifth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one ErF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six ErF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.62–3.08 Å. In the sixth K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.61–2.90 Å. There are six inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to seven F1- atoms to form ErF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent ErF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one ErF7 pentagonal bipyramid. There are a spread of Er–F bond distances ranging from 2.15–2.31 Å. In the second Er3+ site, Er3+ is bonded to seven F1- atoms to form ErF7 pentagonal bipyramids that share corners with five ErF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one ErF7 pentagonal bipyramid. There are a spread of Er–F bond distances ranging from 2.21–2.28 Å. In the third Er3+ site, Er3+ is bonded to seven F1- atoms to form ErF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent ErF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one ErF7 pentagonal bipyramid. There are a spread of Er–F bond distances ranging from 2.13–2.31 Å. In the fourth Er3+ site, Er3+ is bonded to seven F1- atoms to form ErF7 pentagonal bipyramids that share corners with five ErF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one ErF7 pentagonal bipyramid. There are a spread of Er–F bond distances ranging from 2.21–2.28 Å. In the fifth Er3+ site, Er3+ is bonded to seven F1- atoms to form ErF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent ErF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one ErF7 pentagonal bipyramid. There are a spread of Er–F bond distances ranging from 2.15–2.31 Å. In the sixth Er3+ site, Er3+ is bonded to seven F1- atoms to form ErF7 pentagonal bipyramids that share corners with five ErF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one ErF7 pentagonal bipyramid. There are a spread of Er–F bond distances ranging from 2.21–2.28 Å. There are twenty-four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Er3+ atoms. In the second F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Er3+ atoms. In the third F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Er3+ atoms. In the fourth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Er3+ atoms. In the fifth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Er3+ atoms. In the sixth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Er3+ atoms. In the seventh F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Er3+ atoms. In the eighth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two equivalent Er3+ atoms. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Er3+ atoms. In the tenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Er3+ atoms. In the eleventh F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Er3+ atoms. In the twelfth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Er3+ atoms. In the thirteenth F1- site, F1- is bonded to three K1+ and one Er3+ atom to form a mixture of edge and corner-sharing FK3Er tetrahedra. In the fourteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Er3+ atoms. In the fifteenth F1- site, F1- is bonded to three K1+ and one Er3+ atom to form a mixture of distorted edge and corner-sharing FK3Er tetrahedra. In the sixteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Er3+ atoms. In the seventeenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Er3+ atoms. In the eighteenth F1- site, F1- is bonded to three K1+ and one Er3+ atom to form a mixture of distorted edge and corner-sharing FK3Er tetrahedra. In the nineteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Er3+ atoms. In the twentieth F1- site, F1- is bonded to three K1+ and one Er3+ atom to form a mixture of distorted edge and corner-sharing FK3Er tetrahedra. In the twenty-first F1- site, F1- is bonded to three K1+ and one Er3+ atom to form a mixture of distorted edge and corner-sharing FK3Er tetrahedra. In the twenty-second F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Er3+ atoms. In the twenty-third F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Er3+ atoms. In the twenty-fourth F1- site, F1- is bonded to three K1+ and one Er3+ atom to form a mixture of distorted edge and corner-sharing FK3Er tetrahedra.

36 MATERIALS SCIENCE↗