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5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on K4Hf5O12 by Materials Project

K4Hf5O12 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are three shorter (2.69 Å) and six longer (2.97 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share corners with six equivalent KO12 cuboctahedra, faces with three equivalent KO12 cuboctahedra, and faces with seven HfO6 octahedra. There are a spread of K–O bond distances ranging from 2.91–3.27 Å. There are three inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. There are three shorter (2.05 Å) and three longer (2.20 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to six equivalent O2- atoms to form HfO6 octahedra that share corners with six equivalent HfO6 octahedra and faces with six equivalent KO12 cuboctahedra. The corner-sharing octahedral tilt angles are 7°. All Hf–O bond lengths are 2.09 Å. In the third Hf4+ site, Hf4+ is bonded to six O2- atoms to form distorted HfO6 octahedra that share corners with three equivalent HfO6 octahedra and faces with four equivalent KO12 cuboctahedra. The corner-sharing octahedral tilt angles are 7°. There are three shorter (1.97 Å) and three longer (2.31 Å) Hf–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to four K1+ and two Hf4+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three K1+ and three Hf4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHfO3 by Materials Project

KHfO3 is (Cubic) Perovskite structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. K is bonded to twelve O atoms to form KO12 cuboctahedra that share corners with twelve equivalent KO12 cuboctahedra, faces with six equivalent KO12 cuboctahedra, and faces with eight equivalent HfO6 octahedra. There are a spread of K–O bond distances ranging from 2.94–2.98 Å. Hf is bonded to six O atoms to form HfO6 octahedra that share corners with six equivalent HfO6 octahedra and faces with eight equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–1°. All Hf–O bond lengths are 2.09 Å. There are three inequivalent O sites. In the first O site, O is bonded in a distorted linear geometry to four equivalent K and two equivalent Hf atoms. In the second O site, O is bonded in a distorted linear geometry to four equivalent K and two equivalent Hf atoms. In the third O site, O is bonded in a distorted linear geometry to four equivalent K and two equivalent Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2Hf2O5 by Materials Project

K2Hf2O5 crystallizes in the orthorhombic Pnna space group. The structure is three-dimensional. K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.58–3.23 Å. Hf4+ is bonded to six O2- atoms to form a mixture of edge, face, and corner-sharing HfO6 octahedra. The corner-sharing octahedra tilt angles range from 12–48°. There are a spread of Hf–O bond distances ranging from 2.02–2.25 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four equivalent K1+ and two equivalent Hf4+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+ and three equivalent Hf4+ atoms. In the third O2- site, O2- is bonded in a distorted tetrahedral geometry to two equivalent K1+ and two equivalent Hf4+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to four equivalent K1+ and two equivalent Hf4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2HfO6 by Materials Project

K2HfO6 crystallizes in the orthorhombic Cmme 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 O atoms. There are a spread of K–O bond distances ranging from 2.79–3.21 Å. In the second K site, K is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.72–3.25 Å. There are two inequivalent Hf sites. In the first Hf site, Hf is bonded in an octahedral geometry to six O atoms. There are a spread of Hf–O bond distances ranging from 2.01–2.09 Å. In the second Hf site, Hf is bonded in an octahedral geometry to six O atoms. All Hf–O bond lengths are 2.05 Å. There are five inequivalent O sites. In the first O site, O is bonded in a distorted T-shaped geometry to two equivalent K and one Hf atom. In the second O site, O is bonded in a 1-coordinate geometry to three K and one Hf atom. In the third O site, O is bonded in a distorted T-shaped geometry to two equivalent K and one Hf atom. In the fourth O site, O is bonded in a single-bond geometry to two equivalent K and one Hf atom. In the fifth O site, O is bonded in a 1-coordinate geometry to four K and one Hf atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2HfO6 by Materials Project

K2HfO6 crystallizes in the orthorhombic Cmme space group. The structure is two-dimensional and consists of two K2HfO6 sheets oriented in the (0, 1, 0) direction. there are two inequivalent K sites. In the first K site, K is bonded in a 10-coordinate geometry to ten O atoms. There are a spread of K–O bond distances ranging from 2.75–3.09 Å. In the second K site, K is bonded in a 10-coordinate geometry to ten O atoms. There are a spread of K–O bond distances ranging from 2.76–3.14 Å. There are two inequivalent Hf sites. In the first Hf site, Hf is bonded to six O atoms to form corner-sharing HfO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are two shorter (2.06 Å) and four longer (2.08 Å) Hf–O bond lengths. In the second Hf site, Hf is bonded to six O atoms to form corner-sharing HfO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of Hf–O bond distances ranging from 2.01–2.09 Å. There are five inequivalent O sites. In the first O site, O is bonded in a linear geometry to four K and two Hf atoms. In the second O site, O is bonded in a linear geometry to four K and two Hf atoms. In the third O site, O is bonded in a distorted single-bond geometry to four K and one Hf atom. In the fourth O site, O is bonded in a distorted single-bond geometry to four K and one Hf atom. In the fifth O site, O is bonded in a water-like geometry to two K atoms.

36 MATERIALS SCIENCE↗