SEARCH · Engineering Papers
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
SrF2 is Fluorite structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Sr2+ is bonded in a body-centered cubic geometry to eight equivalent F1- atoms. All Sr–F bond lengths are 2.54 Å. F1- is bonded to four equivalent Sr2+ atoms to form a mixture of edge and corner-sharing FSr4 tetrahedra.
SrF2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Sr2+ is bonded in a 3-coordinate geometry to eleven F1- atoms. There are a spread of Sr–F bond distances ranging from 2.40–2.94 Å. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded to six equivalent Sr2+ atoms to form distorted FSr6 octahedra that share corners with twelve equivalent FSr6 octahedra, corners with twelve equivalent FSr5 trigonal bipyramids, edges with six equivalent FSr6 octahedra, faces with two equivalent FSr6 octahedra, and faces with six equivalent FSr5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 50°. In the second F1- site, F1- is bonded to five equivalent Sr2+ atoms to form distorted FSr5 trigonal bipyramids that share corners with twelve equivalent FSr6 octahedra, corners with eight equivalent FSr5 trigonal bipyramids, edges with six equivalent FSr5 trigonal bipyramids, and faces with six equivalent FSr6 octahedra. The corner-sharing octahedra tilt angles range from 31–59°.
SrF3 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Sr is bonded in a 9-coordinate geometry to nine F atoms. There are a spread of Sr–F bond distances ranging from 2.51–2.66 Å. There are three inequivalent F sites. In the first F site, F is bonded to four equivalent Sr atoms to form a mixture of corner and edge-sharing FSr4 tetrahedra. In the second F site, F is bonded in a trigonal non-coplanar geometry to three equivalent Sr atoms. In the third F site, F is bonded in a water-like geometry to two equivalent Sr atoms.
SrF is Wurtzite structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Sr is bonded to four equivalent F atoms to form corner-sharing SrF4 tetrahedra. There are one shorter (2.58 Å) and three longer (2.59 Å) Sr–F bond lengths. F is bonded to four equivalent Sr atoms to form corner-sharing FSr4 tetrahedra.