Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Ta”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Study of gas tungsten arc welding procedures for tantalum alloy T-111 (Ta-8 W-2Hf) plate

Methods of eliminating or reducing underbread cracking in multipass GTA welds in thick T-111 plate were studied. Single V butt welds prepared using experimental filler metal compositions and standard weld procedures resulted in only moderate success in reducing underbread cracking. Subsequent procedural changes incorporating manual welding, slower weld speeds, and three or fewer fill passes resulted in crack-free single V welds only when the filler metal was free of hafnium. The double V joint design with successive fill passes on opposite sides of the joint produced excellent welds. The quality of each weld was determined metallographically since the cracking, when present, was very slight and undetectable using standard NDT techniques. Tensile and bend tests were performed on selected weldments. The inherent filler metal strength and the joint geometry determined the strength of the weldment. Hardness and electron beam microprobe traverses were made on selected specimens with the result that significant filler metal-base metal dilution as well as hafnium segregation was detected. A tentative explanation of T-111 plate underbread cracking is presented based on the intrinsic effects of hafnium in the weldment.

Gold, R. E.↗
NASA NTRS1991

Sputtered Ta-Si-N diffusion barriers in Cu metallizations for Si

Electrical measurements on shallow Si n+-p junction diodes with a 30-nm TiSi2 contacting layer demonstrate that an 80-nm-thick amorphous Ta36Si14N50 film prepared by reactive RF sputtering of a Ta5Si3 target in an Ar/N2 plasma very effectively prevents the interaction between the Si substrate with the TiSi2 contacting layer and a 500-nm Cu overlayer. The Ta36Si14N50 diffusion barrier maintains the integrity of the I-V characteristics up to 900 C for 30-min annealing in vacuum. It is concluded that the amorphous Ta36Si14N50 alloy is not only a material with a very low reactivity for copper, titanium, and silicon, but must have a small diffusivity for copper as well.

Kolawa, E.↗
NASA NTRS2015

TA-13: Ground and Launch Systems, 2015 NASA Technology Roadmaps

This presentation is a summary of new content contained in the 2015 update of Technology Area-13, Ground and Launch Systems technology roadmap beyond the content contained in the 2010 version. Also included are brief assessments of benefits, alignments, challenges, technical risk and reasonableness, sequencing and timing, and time and effort to achieve goals. This presentation is part of overall presentations of new content only for the 2015 update of the 15 NASA Technology Roadmaps that will be conducted in a public forum managed by the National Research Council on September 28-29, 2015. The 15 roadmaps have already been publically released via the STI process.

decision-making tools↗
NASA NTRS2009

Long-term reliability of hand-soldering M55365 Ta capacitors

This is a continuation of the report “Effects of Hand Soldering MIL-PRF-55365 Tantalum Capacitors,” which discusses the parametric effects of convection reflow soldering, JPL standard hand soldering, and optimized hand soldering on solid tantalum capacitors. The current focus is determining the long-term reliability effects of the various soldering techniques. Unfortunately, the 100-piece sample size chosen for the highly accelerated life tests was too small to reliably determine the effects of the different soldering techniques on the lifespan of the parts. In hindsight, this likely could have been predicted based on the large alphas and small betas of the Weibull failure distributions discovered during the scouting trials. Now that the effects of inadequate sample size are better understood, an opportunity exists to not only discover whether there are real differences in the reliability associated with the various soldering techniques, but also the potential to discover the voltage acceleration model and the temperature acceleration effect for these capacitors. It is recommended that the testing be repeated with a more appropriate sample size to capture this useful information.

Spence, Penelope↗
NASA NTRSDate not supplied

First-Principles Investigation of Phase Transitions in RuNb, RuTa, and Ru-Nb-Ta Ultrahigh Temperature Shape Memory Alloys

Ultrahigh temperature shape memory alloys (UHT-SMAs) have transition temperatures above 600 C, and they have found applications for sensing and actuating devices in aerospace industry. Among very few such UHT-SMAs currently known are Ru-based alloys such as RuNb and RuTa, whose martensite structures and phase transitions are totally different from those of NiTi-based SMAs and were poorly understood. In this work, we carried out a systematical study of RuNb using first-principles total energy calculations and molecular dynamics (MD) simulations. The transition paths and mechanisms in cubic → tetragonal →monoclinic transitions are revealed. and the transition sequence and martensitic transition temperatures are determined (MTTs) by evaluating the Gibbs free energies using thermodynamic integration. The calculated MTTs are in very good agreement with the experimental data. We found that the monoclinic phase at the second transition has the 𝑃21/m symmetry instead of experimentally identified 𝑃2/m. Our calculations demonstrate that RuTa has very similar phase transitions to those of RuTa. Furthermore, we studied the Ru0.5Nb0.25Ta0.25 ternary. Our results can explain the measured significant drop of MTT (~ 200 C) in the second transition for Ru0.5Nb0.25Ta0.25 compared with those of RuNb and RuTa, while in the first transition its MTT is between MTTs of RuNb and RuTa. The insights gained by this study and the verified ab initio methods for accurate MTT calculations can be applied to fast screen and quantitatively design novel UHT-SMAs having similar properties with desirable MTTs and much reduced cost.

Zhigang Wu↗
DOE OSTI2020

Materials Data on Ta27S50 by Materials Project

Ta27S50 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twenty-seven inequivalent Ta+3.70+ sites. In the first Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 45°. There are a spread of Ta–S bond distances ranging from 2.46–2.55 Å. In the second Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 45°. There are a spread of Ta–S bond distances ranging from 2.45–2.53 Å. In the third Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.47–2.50 Å. In the fourth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.47–2.54 Å. In the fifth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 13°. There are a spread of Ta–S bond distances ranging from 2.47–2.49 Å. In the sixth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 45°. There are a spread of Ta–S bond distances ranging from 2.46–2.54 Å. In the seventh Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted edge and face-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.46–2.51 Å. In the eighth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 44°. There are a spread of Ta–S bond distances ranging from 2.46–2.55 Å. In the ninth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 44°. There are a spread of Ta–S bond distances ranging from 2.46–2.53 Å. In the tenth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 13°. There are two shorter (2.47 Å) and four longer (2.48 Å) Ta–S bond lengths. In the eleventh Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.47–2.54 Å. In the twelfth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 12°. There are a spread of Ta–S bond distances ranging from 2.46–2.49 Å. In the thirteenth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.46–2.54 Å. In the fourteenth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.47–2.55 Å. In the fifteenth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 45°. There are a spread of Ta–S bond distances ranging from 2.46–2.55 Å. In the sixteenth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 14–44°. There are a spread of Ta–S bond distances ranging from 2.45–2.52 Å. In the seventeenth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted edge and face-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.46–2.51 Å. In the eighteenth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 44°. There are a spread of Ta–S bond distances ranging from 2.46–2.53 Å. In the nineteenth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.47–2.50 Å. In the twentieth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 13–45°. There are a spread of Ta–S bond distances ranging from 2.46–2.52 Å. In the twenty-first Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.47–2.55 Å. In the twenty-second Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 14°. There are a spread of Ta–S bond distances ranging from 2.46–2.49 Å. In the twenty-third Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing TaS6 octahedra. There are a spread of Ta–S bond distances ranging from 2.38–2.62 Å. In the twenty-fourth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 44°. There are a spread of Ta–S bond distances ranging from 2.47–2.55 Å. In the twenty-fifth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 46°. There are a spread of Ta–S bond distances ranging from 2.46–2.53 Å. In the twenty-sixth Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of distorted corner and edge-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 45°. There are a spread of Ta–S bond distances ranging from 2.46–2.54 Å. In the twenty-seventh Ta+3.70+ site, Ta+3.70+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing TaS6 octahedra. There are a spread of Ta–S bond distances ranging from 2.38–2.60 Å. There are fifty inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the third S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the fourth S2- site, S2- is bonded to four Ta+3.70+ atoms to form distorted edge-sharing STa4 trigonal pyramids. In the fifth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the sixth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the seventh S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the eighth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the ninth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the tenth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the eleventh S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the twelfth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to four Ta+3.70+ atoms. In the thirteenth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the fourteenth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the fifteenth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the sixteenth S2- site, S2- is bonded to four Ta+3.70+ atoms to form distorted edge-sharing STa4 trigonal pyramids. In the seventeenth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the eighteenth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to four Ta+3.70+ atoms. In the nineteenth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the twentieth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the twenty-first S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the twenty-second S2- site, S2- is bonded to four Ta+3.70+ atoms to form distorted edge-sharing STa4 trigonal pyramids. In the twenty-third S2- site, S2- is bonded to four Ta+3.70+ atoms to form distorted edge-sharing STa4 trigonal pyramids. In the twenty-fourth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the twenty-fifth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the twenty-sixth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the twenty-seventh S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the twenty-eighth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the twenty-ninth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the thirtieth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the thirty-first S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the thirty-second S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the thirty-third S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the thirty-fourth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the thirty-fifth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the thirty-sixth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to four Ta+3.70+ atoms. In the thirty-seventh S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to four Ta+3.70+ atoms. In the thirty-eighth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the thirty-ninth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the fortieth S2- site, S2- is bonded to four Ta+3.70+ atoms to form distorted edge-sharing STa4 trigonal pyramids. In the forty-first S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the forty-second S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to four Ta+3.70+ atoms. In the forty-third S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the forty-fourth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the forty-fifth S2- site, S2- is bonded to four Ta+3.70+ atoms to form distorted edge-sharing STa4 trigonal pyramids. In the forty-sixth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the forty-seventh S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the forty-eighth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.70+ atoms. In the forty-ninth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.70+ atoms. In the fiftieth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to four Ta+3.70+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta36B4C35 by Materials Project

Ta26C25Ta9C8TaBC(B)2BC1 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of two boron molecules; one BC1 sheet oriented in the (0, 0, 1) direction; one Ta26C25 sheet oriented in the (0, 0, 1) direction; one Ta9C8 sheet oriented in the (0, 0, 1) direction; and one TaBC sheet oriented in the (0, 0, 1) direction. In the BC1 sheet, B3+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. All B–C bond lengths are 1.83 Å. C4- is bonded in a distorted trigonal planar geometry to three equivalent B3+ atoms. In the Ta26C25 sheet, there are eighteen inequivalent Ta+3.56+ sites. In the first Ta+3.56+ site, Ta+3.56+ is bonded in a 3-coordinate geometry to three equivalent C4- atoms. There are one shorter (2.14 Å) and two longer (2.15 Å) Ta–C bond lengths. In the second Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 1°. All Ta–C bond lengths are 2.23 Å. In the third Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are five shorter (2.25 Å) and one longer (2.26 Å) Ta–C bond lengths. In the fourth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. All Ta–C bond lengths are 2.25 Å. In the fifth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.24 Å) and three longer (2.26 Å) Ta–C bond lengths. In the sixth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.24 Å) and three longer (2.25 Å) Ta–C bond lengths. In the seventh Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ta–C bond lengths are 2.24 Å. In the eighth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ta–C bond lengths are 2.24 Å. In the ninth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ta–C bond lengths are 2.24 Å. In the tenth Ta+3.56+ site, Ta+3.56+ is bonded to six equivalent C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ta–C bond lengths are 2.24 Å. In the eleventh Ta+3.56+ site, Ta+3.56+ is bonded to six equivalent C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.23 Å) and three longer (2.24 Å) Ta–C bond lengths. In the twelfth Ta+3.56+ site, Ta+3.56+ is bonded to six equivalent C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ta–C bond lengths are 2.23 Å. In the thirteenth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ta–C bond lengths are 2.23 Å. In the fourteenth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ta–C bond lengths are 2.23 Å. In the fifteenth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.23 Å) and three longer (2.24 Å) Ta–C bond lengths. In the sixteenth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ta–C bond lengths are 2.23 Å. In the seventeenth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.23 Å) and two longer (2.24 Å) Ta–C bond lengths. In the eighteenth Ta+3.56+ site, Ta+3.56+ is bonded in a distorted T-shaped geometry to three equivalent C4- atoms. All Ta–C bond lengths are 2.25 Å. There are fifteen inequivalent C4- sites. In the first C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the third C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the fifth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the sixth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the seventh C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the eighth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the ninth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the tenth C4- site, C4- is bonded to six equivalent Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.23 Å) and three longer (2.24 Å) C–Ta bond lengths. In the eleventh C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the twelfth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the thirteenth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourteenth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifteenth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. All C–Ta bond lengths are 2.25 Å. In the Ta9C8 sheet, there are nine inequivalent Ta+3.56+ sites. In the first Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are five shorter (2.24 Å) and one longer (2.25 Å) Ta–C bond lengths. In the second Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Ta–C bond distances ranging from 2.23–2.26 Å. In the third Ta+3.56+ site, Ta+3.56+ is bonded in a distorted T-shaped geometry to three equivalent C4- atoms. All Ta–C bond lengths are 2.26 Å. In the fourth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth Ta+3.56+ site, Ta+3.56+ is bonded in a distorted T-shaped geometry to three equivalent C4- atoms. In the sixth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.23 Å) and three longer (2.24 Å) Ta–C bond lengths. In the seventh Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.23 Å) and four longer (2.24 Å) Ta–C bond lengths. In the eighth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.24 Å) and two longer (2.25 Å) Ta–C bond lengths. In the ninth Ta+3.56+ site, Ta+3.56+ is bonded to six C4- atoms to form a mixture of corner and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ta–C bond lengths are 2.24 Å. There are eight inequivalent C4- sites. In the first C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the third C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. All C–Ta bond lengths are 2.24 Å. In the fourth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. All C–Ta bond lengths are 2.24 Å. In the fifth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the sixth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the seventh C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the eighth C4- site, C4- is bonded to six Ta+3.56+ atoms to form a mixture of corner and edge-sharing CTa6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the TaBC sheet, Ta+3.56+ is bonded in a single-bond geometry to one C4- atom. The Ta–C bond length is 2.08 Å. B3+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. There are a spread of B–C bond distances ranging from 1.81–1.85 Å. C4- is bonded to one Ta+3.56+ and three equivalent B3+ atoms to form corner-sharing CTaB3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta22(CuS12)3 by Materials Project

Ta22(CuS12)3 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are twenty-two inequivalent Ta+3.14+ sites. In the first Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 46°. There are three shorter (2.47 Å) and three longer (2.51 Å) Ta–S bond lengths. In the second Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.46–2.50 Å. In the third Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.46–2.51 Å. In the fourth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.44–2.53 Å. In the fifth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.45–2.50 Å. In the sixth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.46–2.52 Å. In the seventh Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 42°. There are a spread of Ta–S bond distances ranging from 2.47–2.55 Å. In the eighth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.46–2.52 Å. In the ninth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of edge, face, and corner-sharing TaS6 octahedra. There are a spread of Ta–S bond distances ranging from 2.47–2.58 Å. In the tenth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge, face, and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 49°. There are a spread of Ta–S bond distances ranging from 2.46–2.56 Å. In the eleventh Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 46°. There are a spread of Ta–S bond distances ranging from 2.47–2.51 Å. In the twelfth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of edge, face, and corner-sharing TaS6 octahedra. There are a spread of Ta–S bond distances ranging from 2.46–2.65 Å. In the thirteenth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge, face, and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 40–44°. There are a spread of Ta–S bond distances ranging from 2.46–2.58 Å. In the fourteenth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge, face, and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 40–44°. There are a spread of Ta–S bond distances ranging from 2.44–2.53 Å. In the fifteenth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge, face, and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 46–48°. There are a spread of Ta–S bond distances ranging from 2.47–2.57 Å. In the sixteenth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge, face, and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 46–48°. There are a spread of Ta–S bond distances ranging from 2.47–2.57 Å. In the seventeenth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of edge, face, and corner-sharing TaS6 octahedra. There are a spread of Ta–S bond distances ranging from 2.47–2.58 Å. In the eighteenth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of edge, face, and corner-sharing TaS6 octahedra. There are a spread of Ta–S bond distances ranging from 2.46–2.65 Å. In the nineteenth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge, face, and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 40–44°. There are a spread of Ta–S bond distances ranging from 2.45–2.53 Å. In the twentieth Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge, face, and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 40–44°. There are a spread of Ta–S bond distances ranging from 2.46–2.58 Å. In the twenty-first Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge, face, and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 49°. There are a spread of Ta–S bond distances ranging from 2.45–2.56 Å. In the twenty-second Ta+3.14+ site, Ta+3.14+ is bonded to six S2- atoms to form a mixture of distorted edge and corner-sharing TaS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 42°. There are a spread of Ta–S bond distances ranging from 2.47–2.54 Å. There are three inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in a rectangular see-saw-like geometry to four S2- atoms. There are a spread of Cu–S bond distances ranging from 2.23–2.35 Å. In the second Cu1+ site, Cu1+ is bonded in a rectangular see-saw-like geometry to four S2- atoms. There are one shorter (2.21 Å) and three longer (2.35 Å) Cu–S bond lengths. In the third Cu1+ site, Cu1+ is bonded in a rectangular see-saw-like geometry to four S2- atoms. There are a spread of Cu–S bond distances ranging from 2.22–2.36 Å. There are thirty-four inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Ta+3.14+ and one Cu1+ atom. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms. In the third S2- site, S2- is bonded in a 6-coordinate geometry to three Ta+3.14+ and three Cu1+ atoms. In the fourth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.14+ atoms. In the fifth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.14+ atoms. In the sixth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Ta+3.14+ and one Cu1+ atom. In the seventh S2- site, S2- is bonded in a 6-coordinate geometry to three Ta+3.14+ and three Cu1+ atoms. In the eighth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.14+ atoms. In the ninth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.14+ atoms. In the tenth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Ta+3.14+ and one Cu1+ atom. In the eleventh S2- site, S2- is bonded in a 5-coordinate geometry to three Ta+3.14+ and two equivalent Cu1+ atoms. In the twelfth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.14+ atoms. In the thirteenth S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.14+ atoms. In the fourteenth S2- site, S2- is bonded in a rectangular see-saw-like geometry to three Ta+3.14+ and one Cu1+ atom. In the fifteenth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms. In the sixteenth S2- site, S2- is bonded to four Ta+3.14+ atoms to form distorted STa4 trigonal pyramids that share a cornercorner with one STa6 pentagonal pyramid, corners with two equivalent STa4 trigonal pyramids, and edges with two equivalent STa6 pentagonal pyramids. In the seventeenth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms. In the eighteenth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms. In the nineteenth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms. In the twentieth S2- site, S2- is bonded to six Ta+3.14+ atoms to form distorted STa6 pentagonal pyramids that share a cornercorner with one STa6 pentagonal pyramid, edges with six STa6 pentagonal pyramids, and edges with two equivalent STa4 trigonal pyramids. In the twenty-first S2- site, S2- is bonded in a 5-coordinate geometry to five Ta+3.14+ atoms. In the twenty-second S2- site, S2- is bonded in a distorted T-shaped geometry to three Ta+3.14+ atoms. In the twenty-third S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms. In the twenty-fourth S2- site, S2- is bonded to six Ta+3.14+ atoms to form a mixture of distorted edge and corner-sharing STa6 pentagonal pyramids. In the twenty-fifth S2- site, S2- is bonded to six Ta+3.14+ atoms to form distorted STa6 pentagonal pyramids that share corners with two equivalent STa6 pentagonal pyramids, a cornercorner with one STa4 trigonal pyramid, and edges with seven STa6 pentagonal pyramids. In the twenty-sixth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms. In the twenty-seventh S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms. In the twenty-eighth S2- site, S2- is bonded to six Ta+3.14+ atoms to form distorted STa6 pentagonal pyramids that share corners with two equivalent STa6 pentagonal pyramids, a cornercorner with one STa4 trigonal pyramid, and edges with seven STa6 pentagonal pyramids. In the twenty-ninth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms. In the thirtieth S2- site, S2- is bonded in a 5-coordinate geometry to five Ta+3.14+ atoms. In the thirty-first S2- site, S2- is bonded to six Ta+3.14+ atoms to form distorted STa6 pentagonal pyramids that share a cornercorner with one STa6 pentagonal pyramid, edges with six STa6 pentagonal pyramids, and edges with two equivalent STa4 trigonal pyramids. In the thirty-second S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms. In the thirty-third S2- site, S2- is bonded to four Ta+3.14+ atoms to form distorted STa4 trigonal pyramids that share a cornercorner with one STa6 pentagonal pyramid, corners with two equivalent STa4 trigonal pyramids, and edges with two equivalent STa6 pentagonal pyramids. In the thirty-fourth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+3.14+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta13Al23 by Materials Project

Ta13Al23 is Bergman Structure: Mg32(Al,Zn)49 Bergman-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are fifteen inequivalent Ta sites. In the first Ta site, Ta is bonded in a 12-coordinate geometry to three Ta and nine Al atoms. There are one shorter (2.86 Å) and two longer (3.16 Å) Ta–Ta bond lengths. There are a spread of Ta–Al bond distances ranging from 2.77–3.03 Å. In the second Ta site, Ta is bonded in a 12-coordinate geometry to three Ta and nine Al atoms. There are one shorter (2.82 Å) and two longer (3.05 Å) Ta–Ta bond lengths. There are a spread of Ta–Al bond distances ranging from 2.67–3.06 Å. In the third Ta site, Ta is bonded in a 11-coordinate geometry to one Ta and ten Al atoms. The Ta–Ta bond length is 2.88 Å. There are a spread of Ta–Al bond distances ranging from 2.76–3.07 Å. In the fourth Ta site, Ta is bonded in a 1-coordinate geometry to four Ta and ten Al atoms. There are one shorter (2.92 Å) and three longer (3.19 Å) Ta–Ta bond lengths. There are a spread of Ta–Al bond distances ranging from 2.63–2.91 Å. In the fifth Ta site, Ta is bonded in a 11-coordinate geometry to four Ta and ten Al atoms. There are one shorter (2.96 Å) and three longer (3.25 Å) Ta–Ta bond lengths. There are a spread of Ta–Al bond distances ranging from 2.76–2.92 Å. In the sixth Ta site, Ta is bonded in a 6-coordinate geometry to three equivalent Ta and twelve Al atoms. There are a spread of Ta–Al bond distances ranging from 2.78–3.06 Å. In the seventh Ta site, Ta is bonded in a 6-coordinate geometry to three Ta and twelve Al atoms. There are a spread of Ta–Al bond distances ranging from 2.78–3.06 Å. In the eighth Ta site, Ta is bonded in a 12-coordinate geometry to four Ta and twelve Al atoms. There are three shorter (2.99 Å) and nine longer (3.00 Å) Ta–Al bond lengths. In the ninth Ta site, Ta is bonded in a 9-coordinate geometry to two Ta and nine Al atoms. The Ta–Ta bond length is 2.95 Å. There are a spread of Ta–Al bond distances ranging from 2.69–2.89 Å. In the tenth Ta site, Ta is bonded in a 9-coordinate geometry to two Ta and nine Al atoms. The Ta–Ta bond length is 2.98 Å. There are a spread of Ta–Al bond distances ranging from 2.74–2.92 Å. In the eleventh Ta site, Ta is bonded in a 2-coordinate geometry to five Ta and nine Al atoms. There are one shorter (3.07 Å) and one longer (3.29 Å) Ta–Ta bond lengths. There are a spread of Ta–Al bond distances ranging from 2.80–3.32 Å. In the twelfth Ta site, Ta is bonded in a 12-coordinate geometry to four Ta and twelve Al atoms. The Ta–Ta bond length is 3.09 Å. There are a spread of Ta–Al bond distances ranging from 2.97–3.05 Å. In the thirteenth Ta site, Ta is bonded in a 12-coordinate geometry to four Ta and twelve Al atoms. The Ta–Ta bond length is 3.11 Å. There are a spread of Ta–Al bond distances ranging from 2.98–3.00 Å. In the fourteenth Ta site, Ta is bonded in a 11-coordinate geometry to eleven Al atoms. There are a spread of Ta–Al bond distances ranging from 2.63–2.82 Å. In the fifteenth Ta site, Ta is bonded in a 12-coordinate geometry to four Ta and twelve Al atoms. There are nine shorter (3.02 Å) and three longer (3.03 Å) Ta–Al bond lengths. There are twenty-one inequivalent Al sites. In the first Al site, Al is bonded to six Ta and six Al atoms to form distorted AlTa6Al6 cuboctahedra that share corners with two AlTa7Al5 cuboctahedra, edges with two equivalent AlTa6Al6 cuboctahedra, and faces with eight AlTa6Al6 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.53–2.95 Å. In the second Al site, Al is bonded in a 7-coordinate geometry to four Ta and three equivalent Al atoms. All Al–Al bond lengths are 2.75 Å. In the third Al site, Al is bonded in a 10-coordinate geometry to four Ta and six Al atoms. There are a spread of Al–Al bond distances ranging from 2.69–3.04 Å. In the fourth Al site, Al is bonded to seven Ta and five Al atoms to form distorted AlTa7Al5 cuboctahedra that share corners with five AlTa6Al6 cuboctahedra, edges with two equivalent AlTa7Al5 cuboctahedra, and faces with eleven AlTa6Al6 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.46–2.65 Å. In the fifth Al site, Al is bonded to seven Ta and five Al atoms to form distorted AlTa7Al5 cuboctahedra that share corners with five AlTa6Al6 cuboctahedra, edges with two equivalent AlTa7Al5 cuboctahedra, and faces with eleven AlTa7Al5 cuboctahedra. There are two shorter (2.56 Å) and two longer (2.70 Å) Al–Al bond lengths. In the sixth Al site, Al is bonded to seven Ta and five Al atoms to form distorted AlTa7Al5 cuboctahedra that share corners with three AlTa7Al5 cuboctahedra, edges with two AlTa7Al5 cuboctahedra, and faces with twelve AlTa6Al6 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.45–2.68 Å. In the seventh Al site, Al is bonded in a 12-coordinate geometry to six Ta and six Al atoms. There are a spread of Al–Al bond distances ranging from 2.53–3.05 Å. In the eighth Al site, Al is bonded in a 12-coordinate geometry to six Ta and four Al atoms. There are one shorter (2.49 Å) and two longer (2.55 Å) Al–Al bond lengths. In the ninth Al site, Al is bonded in a 12-coordinate geometry to six Ta and six Al atoms. There are a spread of Al–Al bond distances ranging from 2.52–3.07 Å. In the tenth Al site, Al is bonded in a 5-coordinate geometry to five Ta and six Al atoms. There are a spread of Al–Al bond distances ranging from 2.74–3.03 Å. In the eleventh Al site, Al is bonded in a 6-coordinate geometry to five Ta and six Al atoms. There are a spread of Al–Al bond distances ranging from 2.69–3.01 Å. In the twelfth Al site, Al is bonded in a 5-coordinate geometry to five Ta and four Al atoms. The Al–Al bond length is 2.88 Å. In the thirteenth Al site, Al is bonded in a 9-coordinate geometry to five Ta and four Al atoms. There are one shorter (2.66 Å) and one longer (2.77 Å) Al–Al bond lengths. In the fourteenth Al site, Al is bonded in a 10-coordinate geometry to six Ta and four Al atoms. In the fifteenth Al site, Al is bonded in a 12-coordinate geometry to six Ta and four Al atoms. In the sixteenth Al site, Al is bonded to six Ta and six Al atoms to form distorted AlTa6Al6 cuboctahedra that share corners with two AlTa7Al5 cuboctahedra, edges with three AlTa6Al6 cuboctahedra, and faces with eight AlTa7Al5 cuboctahedra. The Al–Al bond length is 2.54 Å. In the seventeenth Al site, Al is bonded in a 8-coordinate geometry to two Ta and six Al atoms. In the eighteenth Al site, Al is bonded in a 11-coordinate geometry to four Ta and seven Al atoms. In the nineteenth Al site, Al is bonded in a 12-coordinate geometry to six Ta and six Al atoms. There are three shorter (2.55 Å) and three longer (2.86 Å) Al–Al bond lengths. In the twentieth Al site, Al is bonded in a 12-coordinate geometry to six Ta and six Al atoms. There are one shorter (2.54 Å) and two longer (2.85 Å) Al–Al bond lengths. In the twenty-first Al site, Al is bonded to six Ta and six Al atoms to form distorted AlTa6Al6 cuboctahedra that share corners with two equivalent AlTa7Al5 cuboctahedra, edges with two equivalent AlTa6Al6 cuboctahedra, and faces with ten AlTa6Al6 cuboctahedra.

36 MATERIALS SCIENCE↗