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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on TaTe2 by Materials Project

TaTe2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one TaTe2 sheet oriented in the (2, 0, -1) direction. there are four inequivalent Ta4+ sites. In the first Ta4+ site, Ta4+ is bonded to six Te2- atoms to form distorted edge-sharing TaTe6 octahedra. There are a spread of Ta–Te bond distances ranging from 2.70–2.94 Å. In the second Ta4+ site, Ta4+ is bonded to six Te2- atoms to form distorted edge-sharing TaTe6 octahedra. There are a spread of Ta–Te bond distances ranging from 2.65–2.93 Å. In the third Ta4+ site, Ta4+ is bonded to six Te2- atoms to form distorted edge-sharing TaTe6 octahedra. There are a spread of Ta–Te bond distances ranging from 2.77–2.94 Å. In the fourth Ta4+ site, Ta4+ is bonded to six Te2- atoms to form distorted edge-sharing TaTe6 octahedra. There are four shorter (2.89 Å) and two longer (2.91 Å) Ta–Te bond lengths. There are six inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to three Ta4+ atoms. In the second Te2- site, Te2- is bonded in a distorted trigonal non-coplanar geometry to three Ta4+ atoms. In the third Te2- site, Te2- is bonded in a distorted trigonal non-coplanar geometry to three Ta4+ atoms. In the fourth Te2- site, Te2- is bonded in a 3-coordinate geometry to three Ta4+ atoms. In the fifth Te2- site, Te2- is bonded in a 3-coordinate geometry to three Ta4+ atoms. In the sixth Te2- site, Te2- is bonded in a 3-coordinate geometry to three Ta4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaTe2 by Materials Project

TaTe2 is Molybdenite-like structured and crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one TaTe2 sheet oriented in the (2, 0, -1) direction. there are two inequivalent Ta4+ sites. In the first Ta4+ site, Ta4+ is bonded to six Te2- atoms to form distorted edge-sharing TaTe6 octahedra. There are four shorter (2.85 Å) and two longer (2.91 Å) Ta–Te bond lengths. In the second Ta4+ site, Ta4+ is bonded to six Te2- atoms to form distorted edge-sharing TaTe6 octahedra. There are a spread of Ta–Te bond distances ranging from 2.69–2.94 Å. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to three Ta4+ atoms. In the second Te2- site, Te2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Ta4+ atoms. In the third Te2- site, Te2- is bonded in a 3-coordinate geometry to three Ta4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Ultrafast optical melting of trimer superstructure in layered 1T′-TaTe2

Abstract Quasi-two-dimensional transition-metal dichalcogenides are a key platform for exploring emergent nanoscale phenomena arising from complex interactions. Access to the underlying degrees-of-freedom on their natural time scales motivates the use of advanced ultrafast probes sensitive to self-organised atomic-scale patterns. Here, we report the ultrafast investigation of TaTe 2 , which exhibits unique charge and lattice trimer order characterised by a transition upon cooling from stripe-like chains into a (3 × 3) superstructure of trimer clusters. Utilising MeV-scale ultrafast electron diffraction, we capture the photo-induced TaTe 2 structural dynamics – exposing a rapid ≈ 1.4 ps melting of its low-temperature ordered state followed by recovery via thermalisation into a hot cluster superstructure. Density-functional calculations indicate that the initial quench is triggered by intra-trimer Ta charge transfer which destabilises the clusters, unlike melting of charge density waves in other TaX 2 compounds. Our work paves the way for further exploration and ultimately rapid optical and electronic manipulation of trimer superstructures.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Exotic bonding interactions and coexistence of chemically distinct periodic lattice distortions in the charge density wave compound TaTe2

The superstructure of TaTe 2 is examined by total high-energy x-ray scattering and large-scale structure modeling over a broad temperature range. At room temperature, it features double zigzag chains of Ta atoms exhibiting metallic bonding. The chains are sandwiched between planes of weakly interacting Te atoms. Below 170 K, the chains appear broken to “butterflylike” clusters and single zigzag chains of covalently bonded Te atoms emerge while Ta-Te interactions remain largely ionic. This is a rare example of a charge density wave compound stabilized by bonding that is a mix of covalent, ionic, and metallic character giving rise to chemically distinct periodic lattice distortions. We argue that the formation of periodic lattice distortions in the Te sublattice in addition to those in the Ta sublattice favors charge delocalization, which may explain the unusually diminished resistivity and increased magnetic susceptibility exhibited by the low-temperature charge density wave phase of TaTe 2 . The effect may be common for 5d transition metal chalcogenides containing Te because of the extended electronic orbitals of the constituent atoms.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on Ta4BTe8 by Materials Project

Ta4BTe8 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional and consists of two boron molecules and one TaTe2 framework. In the TaTe2 framework, there are two inequivalent Ta+3.25+ sites. In the first Ta+3.25+ site, Ta+3.25+ is bonded in a distorted rectangular see-saw-like geometry to four Te2- atoms. There are a spread of Ta–Te bond distances ranging from 2.77–2.90 Å. In the second Ta+3.25+ site, Ta+3.25+ is bonded in a 5-coordinate geometry to five Te2- atoms. There are a spread of Ta–Te bond distances ranging from 2.79–2.98 Å. There are four inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to three Ta+3.25+ atoms. In the second Te2- site, Te2- is bonded in a 3-coordinate geometry to three Ta+3.25+ atoms. In the third Te2- site, Te2- is bonded in a 2-coordinate geometry to one Ta+3.25+ and one Te2- atom. The Te–Te bond length is 2.81 Å. In the fourth Te2- site, Te2- is bonded in a 3-coordinate geometry to two equivalent Ta+3.25+ and one Te2- atom.

36 MATERIALS SCIENCE↗