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8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on HfTe5 by Materials Project

HfTe5 crystallizes in the orthorhombic Cmcm space group. The structure is one-dimensional and consists of four HfTe5 ribbons oriented in the (1, 0, 0) direction. Hf4+ is bonded in a 8-coordinate geometry to eight Te+0.80- atoms. There are a spread of Hf–Te bond distances ranging from 2.96–3.00 Å. There are three inequivalent Te+0.80- sites. In the first Te+0.80- site, Te+0.80- is bonded in a distorted L-shaped geometry to two equivalent Hf4+ atoms. In the second Te+0.80- site, Te+0.80- is bonded in a distorted single-bond geometry to one Hf4+ atom. In the third Te+0.80- site, Te+0.80- is bonded in a distorted L-shaped geometry to two equivalent Hf4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Controllable strain-driven topological phase transition and dominant surface-state transport in HfTe5

Abstract The fine-tuning of topologically protected states in quantum materials holds great promise for novel electronic devices. However, there are limited methods that allow for the controlled and efficient modulation of the crystal lattice while simultaneously monitoring the changes in the electronic structure within a single sample. Here, we apply significant and controllable strain to high-quality HfTe 5 samples and perform electrical transport measurements to reveal the topological phase transition from a weak topological insulator phase to a strong topological insulator phase. After applying high strain to HfTe 5 and converting it into a strong topological insulator, we found that the resistivity of the sample increased by 190,500% and that the electronic transport was dominated by the topological surface states at cryogenic temperatures. Our results demonstrate the suitability of HfTe 5 as a material for engineering topological properties, with the potential to generalize this approach to study topological phase transitions in van der Waals materials and heterostructures.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf3TiTe20 by Materials Project

(HfTe5)3TiTe5 crystallizes in the orthorhombic Amm2 space group. The structure is one-dimensional and consists of six HfTe5 ribbons oriented in the (1, 0, 0) direction and two TiTe5 ribbons oriented in the (1, 0, 0) direction. In each HfTe5 ribbon, Hf4+ is bonded in a 8-coordinate geometry to eight Te+0.80- atoms. There are a spread of Hf–Te bond distances ranging from 2.95–3.00 Å. There are three inequivalent Te+0.80- sites. In the first Te+0.80- site, Te+0.80- is bonded in a distorted L-shaped geometry to two equivalent Hf4+ atoms. In the second Te+0.80- site, Te+0.80- is bonded in a distorted L-shaped geometry to two equivalent Hf4+ atoms. In the third Te+0.80- site, Te+0.80- is bonded in a distorted single-bond geometry to one Hf4+ atom. In each TiTe5 ribbon, Ti4+ is bonded in a 8-coordinate geometry to eight Te+0.80- atoms. There are six shorter (2.89 Å) and two longer (2.94 Å) Ti–Te bond lengths. There are three inequivalent Te+0.80- sites. In the first Te+0.80- site, Te+0.80- is bonded in a distorted L-shaped geometry to two equivalent Ti4+ atoms. In the second Te+0.80- site, Te+0.80- is bonded in a distorted L-shaped geometry to two equivalent Ti4+ atoms. In the third Te+0.80- site, Te+0.80- is bonded in a distorted single-bond geometry to one Ti4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2Te by Materials Project

Hf2Te crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one Hf2Te sheet oriented in the (0, 0, 1) direction. there are four inequivalent Hf sites. In the first Hf site, Hf is bonded in a 2-coordinate geometry to two Te atoms. There are one shorter (3.13 Å) and one longer (3.16 Å) Hf–Te bond lengths. In the second Hf site, Hf is bonded to five Te atoms to form distorted edge-sharing HfTe5 trigonal bipyramids. All Hf–Te bond lengths are 2.92 Å. In the third Hf site, Hf is bonded in a 3-coordinate geometry to three Te atoms. There are two shorter (2.94 Å) and one longer (3.04 Å) Hf–Te bond lengths. In the fourth Hf site, Hf is bonded in a 2-coordinate geometry to two equivalent Te atoms. Both Hf–Te bond lengths are 2.95 Å. There are two inequivalent Te sites. In the first Te site, Te is bonded in a 6-coordinate geometry to six Hf atoms. In the second Te site, Te is bonded in a distorted hexagonal planar geometry to six Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf8FeTe6 by Materials Project

Hf8FeTe6 crystallizes in the orthorhombic Pmmn space group. The structure is three-dimensional. there are five inequivalent Hf sites. In the first Hf site, Hf is bonded in a 5-coordinate geometry to two equivalent Fe and three Te atoms. Both Hf–Fe bond lengths are 2.61 Å. There are two shorter (3.01 Å) and one longer (3.02 Å) Hf–Te bond lengths. In the second Hf site, Hf is bonded in a 4-coordinate geometry to two equivalent Fe and two equivalent Te atoms. Both Hf–Fe bond lengths are 2.72 Å. Both Hf–Te bond lengths are 3.02 Å. In the third Hf site, Hf is bonded to five Te atoms to form distorted edge-sharing HfTe5 trigonal bipyramids. There are four shorter (2.87 Å) and one longer (2.88 Å) Hf–Te bond lengths. In the fourth Hf site, Hf is bonded in a 4-coordinate geometry to one Fe and four Te atoms. The Hf–Fe bond length is 3.18 Å. There are a spread of Hf–Te bond distances ranging from 2.97–3.11 Å. In the fifth Hf site, Hf is bonded in a 5-coordinate geometry to one Fe and four equivalent Te atoms. The Hf–Fe bond length is 2.75 Å. All Hf–Te bond lengths are 2.96 Å. Fe is bonded in a 7-coordinate geometry to nine Hf atoms. There are three inequivalent Te sites. In the first Te site, Te is bonded in a 5-coordinate geometry to five Hf atoms. In the second Te site, Te is bonded to six Hf atoms to form a mixture of distorted corner, edge, and face-sharing TeHf6 pentagonal pyramids. In the third Te site, Te is bonded in a 4-coordinate geometry to four Hf atoms.

36 MATERIALS SCIENCE↗