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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Tc2As3 by Materials Project

Tc2As3 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Tc+0.50+ sites. In the first Tc+0.50+ site, Tc+0.50+ is bonded to six As+0.33- atoms to form a mixture of distorted edge, face, and corner-sharing TcAs6 octahedra. The corner-sharing octahedra tilt angles range from 40–60°. There are a spread of Tc–As bond distances ranging from 2.47–2.71 Å. In the second Tc+0.50+ site, Tc+0.50+ is bonded to six As+0.33- atoms to form a mixture of distorted edge, face, and corner-sharing TcAs6 octahedra. The corner-sharing octahedra tilt angles range from 40–59°. There are a spread of Tc–As bond distances ranging from 2.48–2.60 Å. In the third Tc+0.50+ site, Tc+0.50+ is bonded to six As+0.33- atoms to form a mixture of edge, face, and corner-sharing TcAs6 octahedra. The corner-sharing octahedra tilt angles range from 40–60°. There are a spread of Tc–As bond distances ranging from 2.46–2.58 Å. In the fourth Tc+0.50+ site, Tc+0.50+ is bonded to six As+0.33- atoms to form a mixture of edge, face, and corner-sharing TcAs6 octahedra. The corner-sharing octahedra tilt angles range from 40–59°. There are a spread of Tc–As bond distances ranging from 2.45–2.58 Å. There are six inequivalent As+0.33- sites. In the first As+0.33- site, As+0.33- is bonded in a 5-coordinate geometry to four Tc+0.50+ and one As+0.33- atom. The As–As bond length is 2.49 Å. In the second As+0.33- site, As+0.33- is bonded in a 5-coordinate geometry to four Tc+0.50+ and one As+0.33- atom. In the third As+0.33- site, As+0.33- is bonded in a distorted rectangular see-saw-like geometry to four Tc+0.50+ atoms. In the fourth As+0.33- site, As+0.33- is bonded in a 4-coordinate geometry to four Tc+0.50+ atoms. In the fifth As+0.33- site, As+0.33- is bonded in a 5-coordinate geometry to four Tc+0.50+ and one As+0.33- atom. The As–As bond length is 2.82 Å. In the sixth As+0.33- site, As+0.33- is bonded in a 5-coordinate geometry to four Tc+0.50+ and one As+0.33- atom. The As–As bond length is 2.70 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tc3As by Materials Project

Tc3As is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Tc+1.67- sites. In the first Tc+1.67- site, Tc+1.67- is bonded to eight Tc+1.67- and four equivalent As5+ atoms to form TcTc8As4 cuboctahedra that share corners with twelve equivalent TcTc8As4 cuboctahedra, edges with eight equivalent TcTc8As4 cuboctahedra, edges with eight equivalent AsTc12 cuboctahedra, faces with four equivalent AsTc12 cuboctahedra, and faces with ten equivalent TcTc8As4 cuboctahedra. There are four shorter (2.66 Å) and four longer (2.80 Å) Tc–Tc bond lengths. All Tc–As bond lengths are 2.80 Å. In the second Tc+1.67- site, Tc+1.67- is bonded in a distorted square co-planar geometry to eight equivalent Tc+1.67- and four equivalent As5+ atoms. All Tc–As bond lengths are 2.66 Å. As5+ is bonded to twelve Tc+1.67- atoms to form AsTc12 cuboctahedra that share corners with four equivalent AsTc12 cuboctahedra, edges with eight equivalent AsTc12 cuboctahedra, edges with sixteen equivalent TcTc8As4 cuboctahedra, faces with four equivalent AsTc12 cuboctahedra, and faces with eight equivalent TcTc8As4 cuboctahedra.

36 MATERIALS SCIENCE↗