Materials Data on HfTl2PbSe4 by Materials Project

Abstract

HfTl2PbSe4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Hf4+ is bonded to six Se2- atoms to form HfSe6 octahedra that share corners with six equivalent TlSe6 octahedra, edges with two equivalent HfSe6 octahedra, edges with four equivalent PbSe6 octahedra, and edges with six equivalent TlSe6 octahedra. The corner-sharing octahedra tilt angles range from 2–16°. There are a spread of Hf–Se bond distances ranging from 2.66–2.76 Å. Tl1+ is bonded to six Se2- atoms to form distorted TlSe6 octahedra that share corners with three equivalent HfSe6 octahedra, corners with three equivalent PbSe6 octahedra, edges with three equivalent HfSe6 octahedra, edges with three equivalent PbSe6 octahedra, and edges with six equivalent TlSe6 octahedra. The corner-sharing octahedra tilt angles range from 2–18°. There are a spread of Tl–Se bond distances ranging from 3.20–3.46 Å. Pb2+ is bonded to six Se2- atoms to form PbSe6 octahedra that share corners with six equivalent TlSe6 octahedra, edges with two equivalent PbSe6 octahedra, edges with four equivalent HfSe6 octahedra, and edges with six equivalent TlSe6 octahedra. The corner-sharing octahedra tilt angles range from 14–18°. There are four shorter (3.08 Å) and two longer (3.09 Å) Pb–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to two equivalent Hf4+, three equivalent Tl1+, and one Pb2+ atom. In the second Se2- site, Se2- is bonded to one Hf4+, three equivalent Tl1+, and two equivalent Pb2+ atoms to form a mixture of distorted edge and corner-sharing SeHfTl3Pb2 octahedra. The corner-sharing octahedra tilt angles range from 11–12°.