DOE OSTI2020
Ti2Se crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are six inequivalent Ti sites. In the first Ti site, Ti is bonded in a distorted L-shaped geometry to two Se atoms. There are one shorter (2.62 Å) and one longer (2.69 Å) Ti–Se bond lengths. In the second Ti site, Ti is bonded in a 5-coordinate geometry to five Se atoms. There are a spread of Ti–Se bond distances ranging from 2.61–2.72 Å. In the third Ti site, Ti is bonded in a 4-coordinate geometry to four Se atoms. There are two shorter (2.60 Å) and two longer (2.63 Å) Ti–Se bond lengths. In the fourth Ti site, Ti is bonded to five Se atoms to form distorted edge-sharing TiSe5 trigonal bipyramids. There are a spread of Ti–Se bond distances ranging from 2.54–2.60 Å. In the fifth Ti site, Ti is bonded in a 5-coordinate geometry to five Se atoms. There are a spread of Ti–Se bond distances ranging from 2.58–2.91 Å. In the sixth Ti site, Ti is bonded in a 3-coordinate geometry to three Se atoms. There are two shorter (2.56 Å) and one longer (2.62 Å) Ti–Se bond lengths. There are three inequivalent Se sites. In the first Se site, Se is bonded in a 9-coordinate geometry to nine Ti atoms. In the second Se site, Se is bonded to seven Ti atoms to form distorted edge-sharing SeTi7 pentagonal bipyramids. In the third Se site, Se is bonded in a 8-coordinate geometry to eight Ti atoms.