DOE OSTI2020
Rb4Hg5Te13 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to ten Te+1.08- atoms. There are a spread of Rb–Te bond distances ranging from 3.77–4.44 Å. In the second Rb1+ site, Rb1+ is bonded in a 7-coordinate geometry to seven Te+1.08- atoms. There are a spread of Rb–Te bond distances ranging from 3.71–3.97 Å. In the third Rb1+ site, Rb1+ is bonded in a 7-coordinate geometry to seven Te+1.08- atoms. There are a spread of Rb–Te bond distances ranging from 3.86–4.12 Å. There are three inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded to four Te+1.08- atoms to form distorted corner-sharing HgTe4 tetrahedra. There are a spread of Hg–Te bond distances ranging from 2.82–3.45 Å. In the second Hg2+ site, Hg2+ is bonded to four Te+1.08- atoms to form HgTe4 tetrahedra that share a cornercorner with one TeRbTe5 octahedra, a cornercorner with one TeRb2Hg2Te square pyramid, and corners with four HgTe4 tetrahedra. The corner-sharing octahedral tilt angles are 90°. There are a spread of Hg–Te bond distances ranging from 2.85–3.03 Å. In the third Hg2+ site, Hg2+ is bonded to four Te+1.08- atoms to form HgTe4 tetrahedra that share corners with four HgTe4 tetrahedra, a cornercorner with one TeRbHg2Te2 trigonal bipyramid, and an edgeedge with one TeRbTe5 octahedra. There are a spread of Hg–Te bond distances ranging from 2.84–2.97 Å. There are ten inequivalent Te+1.08- sites. In the first Te+1.08- site, Te+1.08- is bonded to one Rb1+, two equivalent Hg2+, and two equivalent Te+1.08- atoms to form distorted TeRbHg2Te2 trigonal bipyramids that share corners with two equivalent TeRbTe5 octahedra, corners with two equivalent HgTe4 tetrahedra, and corners with two equivalent TeRbHg2Te2 trigonal bipyramids. The corner-sharing octahedral tilt angles are 10°. Both Te–Te bond lengths are 2.96 Å. In the second Te+1.08- site, Te+1.08- is bonded in a 5-coordinate geometry to two Rb1+ and three Hg2+ atoms. In the third Te+1.08- site, Te+1.08- is bonded in a 6-coordinate geometry to three Rb1+, one Hg2+, and two Te+1.08- atoms. The Te–Te bond length is 3.25 Å. In the fourth Te+1.08- site, Te+1.08- is bonded in a 7-coordinate geometry to four equivalent Rb1+, two equivalent Hg2+, and one Te+1.08- atom. The Te–Te bond length is 3.17 Å. In the fifth Te+1.08- site, Te+1.08- is bonded to one Rb1+ and five Te+1.08- atoms to form distorted TeRbTe5 octahedra that share corners with two equivalent HgTe4 tetrahedra, corners with two equivalent TeRbHg2Te2 trigonal bipyramids, and edges with two equivalent HgTe4 tetrahedra. There are one shorter (2.96 Å) and two longer (3.42 Å) Te–Te bond lengths. In the sixth Te+1.08- site, Te+1.08- is bonded in a 6-coordinate geometry to four equivalent Rb1+ and two equivalent Te+1.08- atoms. Both Te–Te bond lengths are 2.85 Å. In the seventh Te+1.08- site, Te+1.08- is bonded to two equivalent Rb1+, two equivalent Hg2+, and one Te+1.08- atom to form distorted TeRb2Hg2Te square pyramids that share corners with two equivalent HgTe4 tetrahedra. The Te–Te bond length is 2.79 Å. In the eighth Te+1.08- site, Te+1.08- is bonded in a 4-coordinate geometry to three Rb1+, one Hg2+, and two Te+1.08- atoms. In the ninth Te+1.08- site, Te+1.08- is bonded in a 5-coordinate geometry to four equivalent Rb1+, two equivalent Hg2+, and one Te+1.08- atom. In the tenth Te+1.08- site, Te+1.08- is bonded in a 6-coordinate geometry to two equivalent Rb1+, two equivalent Hg2+, and two Te+1.08- atoms.