Materials Data on TmAsS by Materials Project
TmAsS is Matlockite structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Tm3+ is bonded in a 9-coordinate geometry to four equivalent As1- and five equivalent S2- atoms. There are a spread of Tm–As bond distances ranging from 3.08–3.13 Å. There are four shorter (2.77 Å) and one longer (2.81 Å) Tm–S bond lengths. As1- is bonded in a 8-coordinate geometry to four equivalent Tm3+ and four equivalent As1- atoms. There are a spread of As–As bond distances ranging from 2.54–2.83 Å. S2- is bonded to five equivalent Tm3+ atoms to form a mixture of distorted edge and corner-sharing STm5 trigonal bipyramids.