Materials Data on TmMgSe3 by Materials Project
MgTmSe3 is Ilmenite-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Mg2+ is bonded in a 6-coordinate geometry to six Se+1.67- atoms. There are a spread of Mg–Se bond distances ranging from 2.63–3.33 Å. Tm3+ is bonded to six Se+1.67- atoms to form a mixture of distorted edge and face-sharing TmSe6 pentagonal pyramids. There are a spread of Tm–Se bond distances ranging from 2.71–3.06 Å. There are two inequivalent Se+1.67- sites. In the first Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two equivalent Mg2+ and two equivalent Tm3+ atoms. In the second Se+1.67- site, Se+1.67- is bonded to two equivalent Mg2+ and two equivalent Tm3+ atoms to form edge-sharing SeTm2Mg2 trigonal pyramids.