Materials Data on HfNiO3 by Materials Project
HfNiO3 is Orthorhombic Perovskite structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Hf4+ is bonded to six O2- atoms to form distorted HfO6 pentagonal pyramids that share corners with four NiO6 octahedra, corners with two equivalent HfO6 pentagonal pyramids, edges with four NiO6 octahedra, and edges with two equivalent HfO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 52–75°. There are a spread of Hf–O bond distances ranging from 2.03–2.25 Å. There are two inequivalent Ni2+ sites. In the first Ni2+ site, Ni2+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six equivalent NiO6 octahedra, corners with four equivalent HfO6 pentagonal pyramids, and edges with four equivalent HfO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 49–50°. There are a spread of Ni–O bond distances ranging from 2.00–2.19 Å. In the second Ni2+ site, Ni2+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six equivalent NiO6 octahedra, corners with four equivalent HfO6 pentagonal pyramids, and edges with four equivalent HfO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 49–50°. There are a spread of Ni–O bond distances ranging from 1.96–2.30 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted see-saw-like geometry to two equivalent Hf4+ and two Ni2+ atoms. In the second O2- site, O2- is bonded to two equivalent Hf4+ and two Ni2+ atoms to form a mixture of edge and corner-sharing OHf2Ni2 trigonal pyramids. In the third O2- site, O2- is bonded to two equivalent Hf4+ and two Ni2+ atoms to form a mixture of edge and corner-sharing OHf2Ni2 trigonal pyramids.