Materials Data on TmAgSe2 by Materials Project

Abstract

TmAgSe2 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. Tm3+ is bonded to six Se2- atoms to form TmSe6 octahedra that share corners with four equivalent TmSe6 octahedra, corners with six equivalent AgSe4 trigonal pyramids, edges with four equivalent TmSe6 octahedra, and edges with three equivalent AgSe4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 44–51°. There are a spread of Tm–Se bond distances ranging from 2.83–2.86 Å. Ag1+ is bonded to four Se2- atoms to form distorted AgSe4 trigonal pyramids that share corners with six equivalent TmSe6 octahedra, corners with four equivalent AgSe4 trigonal pyramids, and edges with three equivalent TmSe6 octahedra. The corner-sharing octahedra tilt angles range from 27–70°. There are a spread of Ag–Se bond distances ranging from 2.70–2.75 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent Tm3+ and two equivalent Ag1+ atoms to form a mixture of distorted edge and corner-sharing SeTm3Ag2 trigonal bipyramids. In the second Se2- site, Se2- is bonded to three equivalent Tm3+ and two equivalent Ag1+ atoms to form a mixture of distorted edge and corner-sharing SeTm3Ag2 trigonal bipyramids.