Materials Data on Tm2Be2SiO7 by Materials Project

Abstract

Be2Tm2SiO7 crystallizes in the tetragonal P-42_1m space group. The structure is three-dimensional. Be2+ is bonded to four O2- atoms to form BeO4 tetrahedra that share a cornercorner with one BeO4 tetrahedra and corners with two equivalent SiO4 tetrahedra. There are a spread of Be–O bond distances ranging from 1.57–1.69 Å. Tm3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Tm–O bond distances ranging from 2.23–2.63 Å. Si4+ is bonded to four equivalent O2- atoms to form SiO4 tetrahedra that share corners with four equivalent BeO4 tetrahedra. All Si–O bond lengths are 1.64 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Be2+ and two equivalent Tm3+ atoms to form a mixture of distorted edge and corner-sharing OTm2Be2 tetrahedra. In the second O2- site, O2- is bonded to one Be2+ and three equivalent Tm3+ atoms to form a mixture of distorted edge and corner-sharing OTm3Be tetrahedra. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Be2+, two equivalent Tm3+, and one Si4+ atom.