Materials Data on Bi4Te7Pb by Materials Project
PbBi4Te7 is MAX Phase-like structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one Bi2Te3 sheet oriented in the (0, 0, 1) direction and one PbBi2Te4 sheet oriented in the (0, 0, 1) direction. In the Bi2Te3 sheet, Bi3+ is bonded to six Te2- atoms to form a mixture of corner and edge-sharing BiTe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (3.10 Å) and three longer (3.29 Å) Bi–Te bond lengths. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Bi3+ atoms. In the second Te2- site, Te2- is bonded to six equivalent Bi3+ atoms to form edge-sharing TeBi6 octahedra. In the PbBi2Te4 sheet, Pb2+ is bonded to six equivalent Te2- atoms to form PbTe6 octahedra that share corners with six equivalent BiTe6 octahedra, edges with six equivalent PbTe6 octahedra, and edges with six equivalent BiTe6 octahedra. The corner-sharing octahedral tilt angles are 1°. All Pb–Te bond lengths are 3.26 Å. Bi3+ is bonded to six Te2- atoms to form BiTe6 octahedra that share corners with three equivalent PbTe6 octahedra, edges with three equivalent PbTe6 octahedra, and edges with six equivalent BiTe6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are three shorter (3.09 Å) and three longer (3.30 Å) Bi–Te bond lengths. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to three equivalent Pb2+ and three equivalent Bi3+ atoms to form a mixture of corner and edge-sharing TeBi3Pb3 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Bi3+ atoms.