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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on BaNiO3 by Materials Project

BaNiO3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ba2+ is bonded to twelve equivalent O2- atoms to form BaO12 cuboctahedra that share corners with six equivalent BaO12 cuboctahedra, corners with six equivalent NiO6 octahedra, faces with eight equivalent BaO12 cuboctahedra, and faces with six equivalent NiO6 octahedra. The corner-sharing octahedral tilt angles are 13°. There are six shorter (2.87 Å) and six longer (3.04 Å) Ba–O bond lengths. Ni4+ is bonded to six equivalent O2- atoms to form NiO6 octahedra that share corners with six equivalent BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, and faces with two equivalent NiO6 octahedra. All Ni–O bond lengths are 1.89 Å. O2- is bonded in a 2-coordinate geometry to four equivalent Ba2+ and two equivalent Ni4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaNiO3 by Materials Project

BaNiO3 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Ba2+ is bonded to twelve equivalent O2- atoms to form BaO12 cuboctahedra that share corners with six equivalent BaO12 cuboctahedra, corners with six equivalent NiO6 octahedra, faces with eight equivalent BaO12 cuboctahedra, and faces with six equivalent NiO6 octahedra. The corner-sharing octahedra tilt angles range from 12–13°. There are a spread of Ba–O bond distances ranging from 2.87–3.09 Å. Ni4+ is bonded to six equivalent O2- atoms to form NiO6 octahedra that share corners with six equivalent BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, and faces with two equivalent NiO6 octahedra. All Ni–O bond lengths are 1.89 Å. O2- is bonded in a 2-coordinate geometry to four equivalent Ba2+ and two equivalent Ni4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaNiO3 by Materials Project

BaNiO3 is (Cubic) Perovskite structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with twelve equivalent BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, and faces with eight equivalent NiO6 octahedra. There are four shorter (2.84 Å) and eight longer (2.85 Å) Ba–O bond lengths. Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six equivalent NiO6 octahedra and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.01 Å) and two longer (2.02 Å) Ni–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four equivalent Ba2+ and two equivalent Ni4+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to four equivalent Ba2+ and two equivalent Ni4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Epitaxial growth of hexagonal BaNi O 3–δ thin films on SrTi O 3 (111) substrates

Transition metal oxides containing nickel species in oxidation states higher than 3+ often exhibit high catalytic activity, which makes them promising for applications as advanced electrocatalysts for water splitting and fuel cells. Here, we examine the structure and properties of BaNiO 3 (BNO) thin films, containing formally Ni 4+ , grown on SrTiO 3 (111) substrates using oxygen-plasma–assisted molecular beam epitaxy. X-ray diffraction and scanning transmission electron microscopy measurements reveal that BNO films have a hexagonal structure with $c$- and $a$-axes of mixed textures showing epitaxial relationships BNO (0001) ∥ SrTiO 3 (111) and BNO (10$\overline{1}$0) ∥ SrTi O 3 (111), respectively. The formation of the $a$-axis texture is dominant due to the smaller lattice mismatch with the substrate. Here, density functional theory calculations confirm that the hexagonal BNO film with the $a$-axis texture is energetically more favorable than the competing $c$-axis texture. Detailed spectroscopy data analysis indicates that hexagonal BNO films contain mixtures of Ni 2+ , Ni 3+ , and Ni 4+ species, with Ni 4+ being dominant. Our study provides insights into stabilizing Ni 4+ in complex oxides, which is important for further exploration of the potential of materials containing Ni 4+ .

36 MATERIALS SCIENCE↗