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6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Thermally induced structural evolution and nanoscale interfacial dynamics in Bi-Sb-Te layered nanostructures

Layered chalcogenides, including Bi-Sb-Te ternary alloys and heterostructures, are renowned as thermoelectric and topological insulators and have recently been highlighted as plasmonic building blocks beyond noble metals. Here, we conduct joint in situ transmission electron microscopy and density functional theory calculations to investigate the temperature-dependent nanoscale dynamics and interfacial properties, identifying the role of native defects and edge configurations in the anisotropic sublimation of Bi 2 Te 3 -Sb 2 Te 3 heterostructures and Sb 2-x Bi x Te 3 alloys. We report structural dynamics, including edge evolution, layer-by-layer sublimation, and the formation and coalescence of thermally induced polygonal nanopores. These nanopores are initiated by preferential dissociation of tellurium, reducing thermal stability in heterostructures. Triangular and quasi-hexagonal configurations dominate nanopore structures in heterostructures. Our calculations reveal antisite defects (Te Sb and Te Bi ) as key players in defect-assisted sublimation. These findings enhance our understanding of nanoscale dynamics and assist in designing tunable low-dimensional chalcogenides.

Bi2Te3-Sb2Te3 heterostructure↗
DOE OSTI2020

Materials Data on Bi(SbTe2)3 by Materials Project

Bi(SbTe2)3 is MAX Phase-like structured and crystallizes in the monoclinic Cm space group. The structure is two-dimensional and consists of two Bi(SbTe2)3 sheets oriented in the (1, 0, 0) direction. Bi3+ is bonded to six Te2- atoms to form BiTe6 octahedra that share corners with three equivalent SbTe6 octahedra, edges with two equivalent BiTe6 octahedra, and edges with seven SbTe6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of Bi–Te bond distances ranging from 3.11–3.26 Å. There are three inequivalent Sb3+ sites. In the first Sb3+ site, Sb3+ is bonded to six Te2- atoms to form SbTe6 octahedra that share corners with three equivalent SbTe6 octahedra, edges with four equivalent BiTe6 octahedra, and edges with five SbTe6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are a spread of Sb–Te bond distances ranging from 3.01–3.25 Å. In the second Sb3+ site, Sb3+ is bonded to six Te2- atoms to form SbTe6 octahedra that share corners with three equivalent SbTe6 octahedra, edges with two equivalent BiTe6 octahedra, and edges with seven SbTe6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are a spread of Sb–Te bond distances ranging from 3.04–3.22 Å. In the third Sb3+ site, Sb3+ is bonded to six Te2- atoms to form SbTe6 octahedra that share corners with three equivalent BiTe6 octahedra, an edgeedge with one BiTe6 octahedra, and edges with eight SbTe6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of Sb–Te bond distances ranging from 3.03–3.21 Å. There are six inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to one Bi3+ and five Sb3+ atoms to form edge-sharing TeBiSb5 octahedra. In the second Te2- site, Te2- is bonded to two equivalent Bi3+ and four Sb3+ atoms to form edge-sharing TeBi2Sb4 octahedra. In the third Te2- site, Te2- is bonded in a 6-coordinate geometry to two equivalent Bi3+ and one Sb3+ atom. In the fourth Te2- site, Te2- is bonded in a 6-coordinate geometry to one Bi3+ and two equivalent Sb3+ atoms. In the fifth Te2- site, Te2- is bonded in a 6-coordinate geometry to three Sb3+ atoms. In the sixth Te2- site, Te2- is bonded in a 6-coordinate geometry to three Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BiSbTe2 by Materials Project

SbBiSbTe3Bi2SbTe3 is MAX Phase-like structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one antimony molecule; one Bi2SbTe3 sheet oriented in the (0, 0, 1) direction; and one BiSbTe3 sheet oriented in the (0, 0, 1) direction. In the Bi2SbTe3 sheet, there are two inequivalent Bi1+ sites. In the first Bi1+ site, Bi1+ is bonded to six Te2- atoms to form BiTe6 octahedra that share corners with six equivalent SbTe6 octahedra, edges with six equivalent BiTe6 octahedra, and a faceface with one SbTe6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are three shorter (3.07 Å) and three longer (3.33 Å) Bi–Te bond lengths. In the second Bi1+ site, Bi1+ is bonded in a 3-coordinate geometry to three equivalent Te2- atoms. All Bi–Te bond lengths are 3.75 Å. Sb3+ is bonded to six Te2- atoms to form SbTe6 octahedra that share corners with six equivalent BiTe6 octahedra, edges with six equivalent SbTe6 octahedra, and a faceface with one BiTe6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are three shorter (3.04 Å) and three longer (3.22 Å) Sb–Te bond lengths. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to three equivalent Bi1+ and three equivalent Sb3+ atoms to form distorted edge-sharing TeBi3Sb3 pentagonal pyramids. In the second Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Bi1+ atoms. In the third Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Bi1+ and three equivalent Sb3+ atoms. In the BiSbTe3 sheet, Bi1+ is bonded to six Te2- atoms to form BiTe6 octahedra that share corners with six equivalent SbTe6 octahedra, edges with six equivalent BiTe6 octahedra, and a faceface with one SbTe6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are three shorter (3.08 Å) and three longer (3.30 Å) Bi–Te bond lengths. Sb3+ is bonded to six Te2- atoms to form SbTe6 octahedra that share corners with six equivalent BiTe6 octahedra, edges with six equivalent SbTe6 octahedra, and a faceface with one BiTe6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are three shorter (3.04 Å) and three longer (3.25 Å) Sb–Te bond lengths. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to three equivalent Bi1+ and three equivalent Sb3+ atoms to form distorted edge-sharing TeBi3Sb3 pentagonal pyramids. In the second Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Bi1+ atoms. In the third Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BiSbTe3 by Materials Project

BiSbTe3 is MAX Phase-like structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three BiSbTe3 sheets oriented in the (0, 0, 1) direction. Bi3+ is bonded to six Te2- atoms to form BiTe6 octahedra that share corners with three equivalent SbTe6 octahedra, edges with three equivalent SbTe6 octahedra, and edges with six equivalent BiTe6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are three shorter (3.08 Å) and three longer (3.28 Å) Bi–Te bond lengths. Sb3+ is bonded to six Te2- atoms to form SbTe6 octahedra that share corners with three equivalent BiTe6 octahedra, edges with three equivalent BiTe6 octahedra, and edges with six equivalent SbTe6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are three shorter (3.03 Å) and three longer (3.21 Å) Sb–Te bond lengths. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to three equivalent Bi3+ and three equivalent Sb3+ atoms to form edge-sharing TeBi3Sb3 octahedra. In the second Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Bi3+ atoms. In the third Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi2Sb2Te3 by Materials Project

(BiSb)2Te3 is Caswellsilverite-like structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Bi3+ is bonded to three equivalent Bi3+ and three equivalent Te2- atoms to form distorted BiBi3Te3 octahedra that share corners with three equivalent SbTe6 octahedra, corners with three equivalent TeBi3Sb3 octahedra, edges with three equivalent SbTe6 octahedra, edges with three equivalent TeBi3Sb3 octahedra, and edges with six equivalent BiBi3Te3 octahedra. The corner-sharing octahedral tilt angles are 10°. All Bi–Bi bond lengths are 3.08 Å. All Bi–Te bond lengths are 3.52 Å. Sb is bonded to six Te2- atoms to form SbTe6 octahedra that share corners with three equivalent BiBi3Te3 octahedra, corners with three equivalent SbTe6 octahedra, edges with three equivalent BiBi3Te3 octahedra, and edges with nine equivalent SbTe6 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. There are three shorter (3.06 Å) and three longer (3.21 Å) Sb–Te bond lengths. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to three equivalent Bi3+ and three equivalent Sb atoms to form TeBi3Sb3 octahedra that share corners with three equivalent BiBi3Te3 octahedra, corners with three equivalent TeSb6 octahedra, edges with three equivalent BiBi3Te3 octahedra, and edges with nine TeBi3Sb3 octahedra. The corner-sharing octahedra tilt angles range from 4–10°. In the second Te2- site, Te2- is bonded to six equivalent Sb atoms to form a mixture of edge and corner-sharing TeSb6 octahedra. The corner-sharing octahedral tilt angles are 4°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi(SbTe2)3 by Materials Project

BiSbTe3Sb2Te3 is MAX Phase-like structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three BiSbTe3 sheets oriented in the (0, 0, 1) direction and three Sb2Te3 sheets oriented in the (0, 0, 1) direction. In each BiSbTe3 sheet, Bi3+ is bonded to six Te2- atoms to form BiTe6 octahedra that share corners with three equivalent SbTe6 octahedra, edges with three equivalent SbTe6 octahedra, and edges with six equivalent BiTe6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are three shorter (3.08 Å) and three longer (3.26 Å) Bi–Te bond lengths. Sb3+ is bonded to six Te2- atoms to form SbTe6 octahedra that share corners with three equivalent BiTe6 octahedra, edges with three equivalent BiTe6 octahedra, and edges with six equivalent SbTe6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are three shorter (3.03 Å) and three longer (3.19 Å) Sb–Te bond lengths. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Sb3+ atoms. In the second Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Bi3+ atoms. In the third Te2- site, Te2- is bonded to three equivalent Bi3+ and three equivalent Sb3+ atoms to form edge-sharing TeBi3Sb3 octahedra. In each Sb2Te3 sheet, there are two inequivalent Sb3+ sites. In the first Sb3+ site, Sb3+ is bonded to six Te2- atoms to form a mixture of edge and corner-sharing SbTe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (3.04 Å) and three longer (3.21 Å) Sb–Te bond lengths. In the second Sb3+ site, Sb3+ is bonded to six Te2- atoms to form a mixture of edge and corner-sharing SbTe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (3.04 Å) and three longer (3.21 Å) Sb–Te bond lengths. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to six Sb3+ atoms to form edge-sharing TeSb6 octahedra. In the second Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Sb3+ atoms.

36 MATERIALS SCIENCE↗