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11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on ReSe2 by Materials Project

ReSe2 is Molybdenite-like structured and crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one ReSe2 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Re4+ sites. In the first Re4+ site, Re4+ is bonded to six Se2- atoms to form distorted edge-sharing ReSe6 octahedra. There are a spread of Re–Se bond distances ranging from 2.45–2.66 Å. In the second Re4+ site, Re4+ is bonded to six Se2- atoms to form distorted edge-sharing ReSe6 octahedra. There are a spread of Re–Se bond distances ranging from 2.49–2.62 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three Re4+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three Re4+ atoms. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to three Re4+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to three Re4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ReSe2 by Materials Project

ReSe2 is Molybdenite-like structured and crystallizes in the hexagonal P-6m2 space group. The structure is two-dimensional and consists of four ReSe2 sheets oriented in the (0, 0, 1) direction. Re4+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing ReSe6 pentagonal pyramids. All Re–Se bond lengths are 2.53 Å. Se2- is bonded in a distorted T-shaped geometry to three equivalent Re4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2(ReSe2)3 by Materials Project

Na2(ReSe2)3 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of Na–Se bond distances ranging from 2.94–3.52 Å. In the second Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Na–Se bond distances ranging from 3.08–3.47 Å. In the third Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Na–Se bond distances ranging from 3.04–3.57 Å. There are three inequivalent Re+3.33+ sites. In the first Re+3.33+ site, Re+3.33+ is bonded to five Se2- atoms to form edge-sharing ReSe5 square pyramids. There are a spread of Re–Se bond distances ranging from 2.53–2.58 Å. In the second Re+3.33+ site, Re+3.33+ is bonded to five Se2- atoms to form a mixture of edge and corner-sharing ReSe5 square pyramids. There are a spread of Re–Se bond distances ranging from 2.54–2.67 Å. In the third Re+3.33+ site, Re+3.33+ is bonded to five Se2- atoms to form a mixture of edge and corner-sharing ReSe5 square pyramids. There are a spread of Re–Se bond distances ranging from 2.53–2.69 Å. There are six inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 4-coordinate geometry to one Na1+ and three Re+3.33+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to two equivalent Na1+ and three Re+3.33+ atoms. In the third Se2- site, Se2- is bonded in a 5-coordinate geometry to two Na1+ and three Re+3.33+ atoms. In the fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to three Na1+ and three Re+3.33+ atoms. In the fifth Se2- site, Se2- is bonded in a 3-coordinate geometry to three Na1+ and one Re+3.33+ atom. In the sixth Se2- site, Se2- is bonded to three Na1+ and two Re+3.33+ atoms to form distorted edge-sharing SeNa3Re2 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2In(ReSe4)2 by Materials Project

TaSe2TaInSe2(ReSe2)2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of two ReSe2 sheets oriented in the (0, 0, 1) direction; one TaInSe2 sheet oriented in the (0, 0, 1) direction; and one TaSe2 sheet oriented in the (0, 0, 1) direction. In each ReSe2 sheet, Re3+ is bonded to six Se2- atoms to form distorted edge-sharing ReSe6 pentagonal pyramids. There are three shorter (2.53 Å) and three longer (2.54 Å) Re–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted T-shaped geometry to three equivalent Re3+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Re3+ atoms. In the TaInSe2 sheet, Ta+4.50+ is bonded to six Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. There are three shorter (2.61 Å) and three longer (2.62 Å) Ta–Se bond lengths. In1+ is bonded in a 6-coordinate geometry to three equivalent Se2- atoms. All In–Se bond lengths are 3.16 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta+4.50+ atoms. In the second Se2- site, Se2- is bonded in a 6-coordinate geometry to three equivalent Ta+4.50+ and three equivalent In1+ atoms. In the TaSe2 sheet, Ta+4.50+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. All Ta–Se bond lengths are 2.61 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Ta+4.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2Ga(ReSe4)2 by Materials Project

TaSe2TaGaSe2(ReSe2)2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of two ReSe2 sheets oriented in the (0, 0, 1) direction; one TaGaSe2 sheet oriented in the (0, 0, 1) direction; and one TaSe2 sheet oriented in the (0, 0, 1) direction. In each ReSe2 sheet, Re3+ is bonded to six Se2- atoms to form distorted edge-sharing ReSe6 pentagonal pyramids. All Re–Se bond lengths are 2.53 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted T-shaped geometry to three equivalent Re3+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Re3+ atoms. In the TaGaSe2 sheet, Ta+3.50+ is bonded to six Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. There are three shorter (2.62 Å) and three longer (2.64 Å) Ta–Se bond lengths. Ga3+ is bonded in a 6-coordinate geometry to three equivalent Se2- atoms. All Ga–Se bond lengths are 2.83 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta+3.50+ atoms. In the second Se2- site, Se2- is bonded in a 6-coordinate geometry to three equivalent Ta+3.50+ and three equivalent Ga3+ atoms. In the TaSe2 sheet, Ta+3.50+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. All Ta–Se bond lengths are 2.62 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Ta+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2Re2SnSe8 by Materials Project

TaSe2TaSnSe2(ReSe2)2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of two ReSe2 sheets oriented in the (0, 0, 1) direction; one TaSe2 sheet oriented in the (0, 0, 1) direction; and one TaSnSe2 sheet oriented in the (0, 0, 1) direction. In each ReSe2 sheet, Re3+ is bonded to six Se2- atoms to form distorted edge-sharing ReSe6 pentagonal pyramids. There are three shorter (2.52 Å) and three longer (2.58 Å) Re–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted T-shaped geometry to three equivalent Re3+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Re3+ atoms. In the TaSe2 sheet, Ta4+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. There are three shorter (2.60 Å) and three longer (2.61 Å) Ta–Se bond lengths. Se2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ atoms. In the TaSnSe2 sheet, Ta4+ is bonded to six Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. There are three shorter (2.60 Å) and three longer (2.61 Å) Ta–Se bond lengths. Sn2+ is bonded in a 6-coordinate geometry to three equivalent Se2- atoms. All Sn–Se bond lengths are 3.29 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ and three equivalent Sn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Machine-learning-assisted analysis of transition metal dichalcogenide thin-film growth

In situ reflective high-energy electron diffraction (RHEED) is widely used to monitor the surface crystalline state during thin-film growth by molecular beam epitaxy (MBE) and pulsed laser deposition. With the recent development of machine learning (ML), ML-assisted analysis of RHEED videos aids in interpreting the complete RHEED data of oxide thin films. The quantitative analysis of RHEED data allows us to characterize and categorize the growth modes step by step, and extract hidden knowledge of the epitaxial film growth process. In this study, we employed the ML-assisted RHEED analysis method to investigate the growth of 2D thin films of transition metal dichalcogenides (ReSe2) on graphene substrates by MBE. Principal component analysis (PCA) and K-means clustering were used to separate statistically important patterns and visualize the trend of pattern evolution without any notable loss of information. Using the modified PCA, we could monitor the diffraction intensity of solely the ReSe2 layers by filtering out the substrate contribution. These findings demonstrate that ML analysis can be successfully employed to examine and understand the film-growth dynamics of 2D materials. Further, the ML-based method can pave the way for the development of advanced real-time monitoring and autonomous material synthesis techniques.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaReSe4 by Materials Project

TaReSe4 is Molybdenite-derived structured and crystallizes in the hexagonal P-6m2 space group. The structure is two-dimensional and consists of one ReSe2 sheet oriented in the (0, 0, 1) direction and one TaSe2 sheet oriented in the (0, 0, 1) direction. In the ReSe2 sheet, Re3+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing ReSe6 pentagonal pyramids. All Re–Se bond lengths are 2.54 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Re3+ atoms. In the TaSe2 sheet, Ta5+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. All Ta–Se bond lengths are 2.61 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2Fe(ReSe4)2 by Materials Project

TaReFeSe4TaSe2ReSe2 crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one ReSe2 sheet oriented in the (0, 0, 1) direction; one TaReFeSe4 sheet oriented in the (0, 0, 1) direction; and one TaSe2 sheet oriented in the (0, 0, 1) direction. In the ReSe2 sheet, Re3+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing ReSe6 pentagonal pyramids. All Re–Se bond lengths are 2.54 Å. Se2- is bonded in a distorted T-shaped geometry to three equivalent Re3+ atoms. In the TaReFeSe4 sheet, Ta4+ is bonded to six Se2- atoms to form distorted TaSe6 pentagonal pyramids that share corners with six equivalent FeSe6 octahedra, edges with six equivalent TaSe6 pentagonal pyramids, and a faceface with one FeSe6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are three shorter (2.61 Å) and three longer (2.63 Å) Ta–Se bond lengths. Re3+ is bonded to six Se2- atoms to form distorted ReSe6 pentagonal pyramids that share corners with six equivalent FeSe6 octahedra, edges with six equivalent ReSe6 pentagonal pyramids, and a faceface with one FeSe6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are three shorter (2.51 Å) and three longer (2.65 Å) Re–Se bond lengths. Fe2+ is bonded to six Se2- atoms to form FeSe6 octahedra that share corners with six equivalent TaSe6 pentagonal pyramids, corners with six equivalent ReSe6 pentagonal pyramids, edges with six equivalent FeSe6 octahedra, a faceface with one TaSe6 pentagonal pyramid, and a faceface with one ReSe6 pentagonal pyramid. There are three shorter (2.55 Å) and three longer (2.57 Å) Fe–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent Re3+ and three equivalent Fe2+ atoms to form distorted SeFe3Re3 pentagonal pyramids that share corners with three equivalent SeTa3Fe3 pentagonal pyramids and edges with nine SeFe3Re3 pentagonal pyramids. In the second Se2- site, Se2- is bonded to three equivalent Ta4+ and three equivalent Fe2+ atoms to form a mixture of distorted corner and edge-sharing SeTa3Fe3 pentagonal pyramids. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted T-shaped geometry to three equivalent Re3+ atoms. In the TaSe2 sheet, Ta4+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. All Ta–Se bond lengths are 2.61 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2Co(ReSe4)2 by Materials Project

TaReCoSe4TaSe2ReSe2 crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one ReSe2 sheet oriented in the (0, 0, 1) direction; one TaReCoSe4 sheet oriented in the (0, 0, 1) direction; and one TaSe2 sheet oriented in the (0, 0, 1) direction. In the ReSe2 sheet, Re3+ is bonded to six Se2- atoms to form distorted edge-sharing ReSe6 pentagonal pyramids. All Re–Se bond lengths are 2.54 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Re3+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Re3+ atoms. In the TaReCoSe4 sheet, Ta4+ is bonded to six Se2- atoms to form distorted TaSe6 pentagonal pyramids that share corners with six equivalent CoSe6 octahedra, edges with six equivalent TaSe6 pentagonal pyramids, and a faceface with one CoSe6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are three shorter (2.61 Å) and three longer (2.63 Å) Ta–Se bond lengths. Re3+ is bonded to six Se2- atoms to form distorted ReSe6 pentagonal pyramids that share corners with six equivalent CoSe6 octahedra, edges with six equivalent ReSe6 pentagonal pyramids, and a faceface with one CoSe6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are three shorter (2.52 Å) and three longer (2.59 Å) Re–Se bond lengths. Co2+ is bonded to six Se2- atoms to form CoSe6 octahedra that share corners with six equivalent TaSe6 pentagonal pyramids, corners with six equivalent ReSe6 pentagonal pyramids, edges with six equivalent CoSe6 octahedra, a faceface with one TaSe6 pentagonal pyramid, and a faceface with one ReSe6 pentagonal pyramid. There are three shorter (2.37 Å) and three longer (2.49 Å) Co–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to three equivalent Re3+ and three equivalent Co2+ atoms. In the second Se2- site, Se2- is bonded to three equivalent Ta4+ and three equivalent Co2+ atoms to form distorted edge-sharing SeTa3Co3 pentagonal pyramids. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted T-shaped geometry to three equivalent Re3+ atoms. In the TaSe2 sheet, Ta4+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. All Ta–Se bond lengths are 2.61 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

In Situ Atomic Tracking on the Interfacial Etching and Reconfiguration of Cu-ReSe 2 Contact during Thermal Annealing

The Schottky barrier height can be greatly affected by the metal diffusion, reaction, and covalent bonding formation at the contact. Exploring novel methods and revealing the fundamental mechanisms for contact engineering are of vital importance for microelectronic devices. Here, in this study, the annealing induced interfacial reactions at Cu-ReSe 2 contact are dynamically revealed from the atomic scale. Accompanied by the diffusion of Se to Cu, ReSe 2 is gradually decomposed to a thin Re interlayer through a “chain-by-chain” manner. Theoretical calculations show that the Cu atoms can facilitate the chemical bond breaking of ReSe 2 , significantly lowering the Se diffusion energy barrier toward Cu. The formed Re/ReSe 2 heterostructure presents a metal-like band structure, which underscores the critical role of Cu in altering the interfacial chemistry and promoting carrier transport across the interface. Our results can provide vital insights into the contact properties of ReSe 2 and provide a possible method for fabricating high-performance ReSe 2 -based devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗