Materials Data on Na2TiSiO5 by Materials Project

Abstract

Na2TiSiO5 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with four equivalent SiO4 tetrahedra, corners with two equivalent TiO5 trigonal bipyramids, edges with four equivalent NaO6 octahedra, and edges with two equivalent TiO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 55°. There are four shorter (2.33 Å) and two longer (2.60 Å) Na–O bond lengths. Ti4+ is bonded to five O2- atoms to form distorted TiO5 trigonal bipyramids that share corners with four equivalent NaO6 octahedra, corners with four equivalent SiO4 tetrahedra, and edges with four equivalent NaO6 octahedra. The corner-sharing octahedral tilt angles are 63°. There is one shorter (1.72 Å) and four longer (2.01 Å) Ti–O bond length. Si4+ is bonded to four equivalent O2- atoms to form SiO4 tetrahedra that share corners with eight equivalent NaO6 octahedra and corners with four equivalent TiO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 60°. All Si–O bond lengths are 1.65 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to four equivalent Na1+ and one Ti4+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na1+, one Ti4+, and one Si4+ atom.