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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Hf3TaCo8 by Materials Project

Hf3TaCo8 is Hexagonal Laves-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are three inequivalent Hf sites. In the first Hf site, Hf is bonded in a 12-coordinate geometry to four Hf and twelve Co atoms. There are three shorter (2.97 Å) and one longer (3.00 Å) Hf–Hf bond lengths. There are a spread of Hf–Co bond distances ranging from 2.84–2.86 Å. In the second Hf site, Hf is bonded in a 12-coordinate geometry to three equivalent Hf, one Ta, and twelve Co atoms. The Hf–Ta bond length is 2.93 Å. There are a spread of Hf–Co bond distances ranging from 2.83–2.89 Å. In the third Hf site, Hf is bonded in a 12-coordinate geometry to one Hf, three equivalent Ta, and twelve Co atoms. All Hf–Ta bond lengths are 2.96 Å. There are a spread of Hf–Co bond distances ranging from 2.79–2.84 Å. Ta is bonded in a 12-coordinate geometry to four Hf and twelve Co atoms. There are nine shorter (2.82 Å) and three longer (2.84 Å) Ta–Co bond lengths. There are four inequivalent Co sites. In the first Co site, Co is bonded to four Hf, two equivalent Ta, and six Co atoms to form a mixture of face, edge, and corner-sharing CoHf4Ta2Co6 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.40–2.43 Å. In the second Co site, Co is bonded to five Hf, one Ta, and six Co atoms to form a mixture of face, edge, and corner-sharing CoHf5TaCo6 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.40–2.44 Å. In the third Co site, Co is bonded to three equivalent Hf, three equivalent Ta, and six Co atoms to form CoHf3Ta3Co6 cuboctahedra that share corners with eighteen CoHf4Ta2Co6 cuboctahedra, edges with six equivalent CoHf3Ta3Co6 cuboctahedra, and faces with eighteen CoHf4Ta2Co6 cuboctahedra. In the fourth Co site, Co is bonded to six Hf and six Co atoms to form CoHf6Co6 cuboctahedra that share corners with eighteen CoHf4Ta2Co6 cuboctahedra, edges with six equivalent CoHf6Co6 cuboctahedra, and faces with eighteen CoHf4Ta2Co6 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaFe4W by Materials Project

TaWFe4 is Hexagonal Laves-derived structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ta is bonded in a 1-coordinate geometry to three equivalent Ta, one W, and twelve Fe atoms. All Ta–Ta bond lengths are 2.96 Å. The Ta–W bond length is 2.89 Å. There are a spread of Ta–Fe bond distances ranging from 2.76–2.87 Å. W is bonded in a 7-coordinate geometry to one Ta and twelve Fe atoms. There are a spread of W–Fe bond distances ranging from 2.76–2.80 Å. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded to six equivalent Ta and six equivalent Fe atoms to form FeTa6Fe6 cuboctahedra that share corners with twelve equivalent FeTa3Fe6W3 cuboctahedra, edges with six equivalent FeTa6Fe6 cuboctahedra, and faces with twenty FeFe6W6 cuboctahedra. All Fe–Fe bond lengths are 2.42 Å. In the second Fe site, Fe is bonded to six equivalent W and six equivalent Fe atoms to form FeFe6W6 cuboctahedra that share corners with twelve equivalent FeTa3Fe6W3 cuboctahedra, edges with six equivalent FeFe6W6 cuboctahedra, and faces with twenty FeTa6Fe6 cuboctahedra. All Fe–Fe bond lengths are 2.39 Å. In the third Fe site, Fe is bonded to three equivalent Ta, three equivalent W, and six Fe atoms to form FeTa3Fe6W3 cuboctahedra that share corners with eighteen FeTa6Fe6 cuboctahedra, edges with six equivalent FeTa3Fe6W3 cuboctahedra, and faces with eighteen FeTa6Fe6 cuboctahedra. There are two shorter (2.33 Å) and two longer (2.42 Å) Fe–Fe bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaTa4O14 by Materials Project

BaTa4O14 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ba is bonded to eight O atoms to form BaO8 hexagonal bipyramids that share edges with six equivalent TaO6 octahedra. There are six shorter (2.75 Å) and two longer (3.02 Å) Ba–O bond lengths. There are two inequivalent Ta sites. In the first Ta site, Ta is bonded to six equivalent O atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles are 38°. All Ta–O bond lengths are 1.99 Å. In the second Ta site, Ta is bonded to six O atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and edges with two equivalent BaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 37–38°. There is two shorter (1.99 Å) and four longer (2.00 Å) Ta–O bond length. There are three inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to one Ba and two equivalent Ta atoms. In the second O site, O is bonded in a bent 150 degrees geometry to two Ta atoms. In the third O site, O is bonded in a single-bond geometry to one Ba atom.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

Open-source Numerical Modeling of Solidification Cracking Susceptibility: Application to Refractory Alloy Systems

Introduction. Alloys such as aluminum, nickel-base, and austenitic stainless steels are susceptible to solidification cracking during welding and 3D printing. Compositional optimization is one method used to effectively mitigate solidification cracking of those alloy systems. With the surge in hypersonic and in-space propulsion activities, refractory metals (Nb, Mo, Ta, W, and Re) and their alloy derivatives are increasing in importance due to their extreme high melting point and retention of high-temperature strength; however, their chemistry was most typically optimized to promote ductility during mechanical operations such as drawing and forming. Welding of such alloys has been a challenge due to a number of issues including solidification cracking, atmospheric contamination (O, C, and N), as well as a shift in ductile-to-brittle transition to higher temperature following grain growth induced by welding. Compositional optimization of refractory alloys for solidification cracking resistance in particular is desirable as their usage increases with the advent of advanced manufacturing methods such as 3D printing. This work evaluates the effect of compositional variation in refractory metal systems on the solidification cracking susceptibility with the goals of optimizing existing alloys and joining process techniques, and formulating new alloys with increased solidification cracking resistance. Experimental Procedures. A python code was developed in a Jupyter notebook environment (Michael and Sowards, 2023) to facilitate the calculation of crack susceptibility index proposed by Kou (2015). Composition is entered as a single point, or as a 1-D or 2-D array. The notebook calls pycalphad (Otis and Liu, 2017 and Bocklund et al, 2020) to calculate the evolution of fraction solid as a function of temperature (under either Scheil or equilibrium assumptions) and then evaluates steepness of the fraction solid curve near the terminal stage of solidification to predict solidification cracking resistance. Open source thermodynamic databases available at online repositories are used (van de Walle). The process is setup in an automated fashion to generate plots that show variation in solidification cracking susceptibility according to composition on 1-D line plots or 2-D contour plots. The Jupyter notebook and crack susceptibility algorithm was also integrated with a widely used commercial CALPHAD code for validation and alloy exploration. Results and Discussion. The crack susceptibility model was first validated against a series of refractory alloy compositions evaluated in past work which utilized a specialized Varestraint test built inside a vacuum chamber environment (Lessman and Gold, 1971). The alloys tested in the Varestraint apparatus included T-111 (Ta-8W-2Hf), ASTAR-811C (Ta-8W-1Re-0.7Hf-0.025C), FS-85 (Nb-27Ta-10W-1Zr), T-222 (Ta-9.6W-2.4Hf-0.01C), Ta-10W, B-66 (Nb-5Mo-5V-1Zr), and SCb-291 (Nb-10W-10Ta). The initial test of the model showed a strong correlation with empirical Varestraint data, i.e., a Spearman rank correlation between model predictions and hot cracking measurements was observed to be greater than 0.8. Following the validation, a set of refractory metal binary mixtures was investigated to evaluate sensitivity of Nb, Mo, W, and Ta to C, N, and O content. A series of plots were produced that suggest ppmw ranges of C, N, and O where solidification cracking increases significantly and reaches a maximum. Also comparative ranking of each primary refractory metal to each interstitial was produced. For example C produces greater cracking response in Mo whereas O produces greater cracking response in Ta and Nb. Such compositional values have utility in setting limits on pickup of these interstitial elements during welding and printing rather than using a one-size-fits-all approach. Furthermore, the results have use in determining additive powder recycling requirements, which is especially pertinent for refractory metal powders due to their high cost compared to conventional alloys. Another application created thousands of hypothetical alloys within the nominal specified composition range of two widely used refractory alloys C103 (Nb-10Hf-1Ti) and TZM (Mo-0.5Ti-0.1Zr). The cracking index was calculated for the alloys and results were fed into machine learning regression techniques including Multiple Linear Regression, Ridge Regression, and Lasso Regression to determine relative potency each alloying element had on computed solidification cracking index. A series of linear equations were produced that relate composition of C103 and TZM to solidification cracking index. The crack susceptibility of C103 for example is described by an equation of the form: cracking index ~ O + 0.667*C + 0.635*N + 0.00037*Ta – 0.0008*Hf (in wt.%) From that equation, it is clear that O has strong propensity to induce solidification cracking. Interestingly, Hf is shown to reduce calculated cracking response. Finally, realizing the potential of this method to discover new refractory alloy formulations across the period table that have low solidification cracking sensitivity, the code was applied to new untested alloy systems including W-Zr-C, W-Ta-C, and others. Conclusions. In summary, an open source numerical method has been developed using Python code to calculate Kou’s crack susceptibility index. The method was applied to refractory metals which are inherently difficult to study from a weldability testing standpoint since inert shielding gas is not sufficient and welding is typically done in vacuum, especially in light of findings presented here where oxygen has profound influence on solidification cracking. This work revealed the effect of compositional variations on a series of refractory metals and showed the framework defined here will be useful in 1) the development of new alloys that have improved weldability and 3D printability, 2) placing compositional limits on existing alloys, and 3) ensuring adequate controls of manufacturing processes such as 3D printing where powder reuse is critical. Keywords. pycalphad; Python; refractory metals; solidification cracking. References. B. Bocklund et. al. (2020) http://doi.org/10.5281/zenodo.3630657. S. Kou. (2015) https://doi.org/10.1016/j.actamat.2015.01.034. G.G. Lessmann and R.E. Gold. Welding Journal, issue 1, pp. 1-s – 8-s (1971). F.N. Michael and J.W. Sowards. NASA/TM-20230002218 (2023). R. Otis and Z.-K. Liu. (2017) http://doi.org/10.5334/jors.140. A. Van de Wallle et. al. (2018) https://doi.org/10.1016/j.calphad.2018.04.003.

pycalphad↗
DOE OSTI2020

Materials Data on Ta5Si3 by Materials Project

Ta5Si3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Ta sites. In the first Ta site, Ta is bonded in a 5-coordinate geometry to five equivalent Si atoms. There are a spread of Ta–Si bond distances ranging from 2.60–2.87 Å. In the second Ta site, Ta is bonded in a 6-coordinate geometry to six equivalent Si atoms. All Ta–Si bond lengths are 2.66 Å. Si is bonded in a 9-coordinate geometry to nine Ta atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta3B2 by Materials Project

Ta3B2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are two inequivalent Ta sites. In the first Ta site, Ta is bonded in a square co-planar geometry to four equivalent B atoms. All Ta–B bond lengths are 2.53 Å. In the second Ta site, Ta is bonded in a distorted hexagonal planar geometry to six equivalent B atoms. There are four shorter (2.46 Å) and two longer (2.51 Å) Ta–B bond lengths. B is bonded in a 9-coordinate geometry to eight Ta and one B atom. The B–B bond length is 1.90 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta5N6 by Materials Project

Ta5N6 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Ta+3.60+ sites. In the first Ta+3.60+ site, Ta+3.60+ is bonded to six equivalent N3- atoms to form a mixture of distorted edge and corner-sharing TaN6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 3°. There are four shorter (2.19 Å) and two longer (2.21 Å) Ta–N bond lengths. In the second Ta+3.60+ site, Ta+3.60+ is bonded to six equivalent N3- atoms to form a mixture of edge and corner-sharing TaN6 octahedra. All Ta–N bond lengths are 2.15 Å. N3- is bonded to five Ta+3.60+ atoms to form a mixture of edge, face, and corner-sharing NTa5 square pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta3Ga2 by Materials Project

Ta3Ga2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are two inequivalent Ta sites. In the first Ta site, Ta is bonded in a 6-coordinate geometry to six equivalent Ga atoms. There are two shorter (2.62 Å) and four longer (2.75 Å) Ta–Ga bond lengths. In the second Ta site, Ta is bonded in a square co-planar geometry to four equivalent Ga atoms. All Ta–Ga bond lengths are 2.73 Å. Ga is bonded in a 9-coordinate geometry to eight Ta and one Ga atom. The Ga–Ga bond length is 2.47 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta5Ge3 by Materials Project

Ta5Ge3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Ta sites. In the first Ta site, Ta is bonded in a 5-coordinate geometry to five equivalent Ge atoms. There are a spread of Ta–Ge bond distances ranging from 2.65–2.94 Å. In the second Ta site, Ta is bonded in a 6-coordinate geometry to six equivalent Ge atoms. All Ta–Ge bond lengths are 2.70 Å. Ge is bonded in a 9-coordinate geometry to nine Ta atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta3PbS6 by Materials Project

Ta3PbS6 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Ta+3.33+ sites. In the first Ta+3.33+ site, Ta+3.33+ is bonded to six equivalent S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. All Ta–S bond lengths are 2.50 Å. In the second Ta+3.33+ site, Ta+3.33+ is bonded to six equivalent S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. All Ta–S bond lengths are 2.48 Å. Pb2+ is bonded in a 6-coordinate geometry to six equivalent S2- atoms. All Pb–S bond lengths are 2.95 Å. S2- is bonded in a 4-coordinate geometry to three Ta+3.33+ and one Pb2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2O by Materials Project

Ta2O is alpha Po structured and crystallizes in the cubic I-43m space group. The structure is zero-dimensional and consists of six tantalum molecules and two Ta5O4 clusters. In each Ta5O4 cluster, there are two inequivalent Ta sites. In the first Ta site, Ta is bonded in a distorted single-bond geometry to one O atom. The Ta–O bond length is 1.84 Å. In the second Ta site, Ta is bonded in a tetrahedral geometry to four equivalent O atoms. All Ta–O bond lengths are 1.88 Å. O is bonded in a distorted linear geometry to two Ta atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta5N6 by Materials Project

Ta5N6 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Ta+3.60+ sites. In the first Ta+3.60+ site, Ta+3.60+ is bonded in a hexagonal planar geometry to six equivalent N3- atoms. All Ta–N bond lengths are 2.25 Å. In the second Ta+3.60+ site, Ta+3.60+ is bonded in a hexagonal planar geometry to six equivalent N3- atoms. There are two shorter (2.17 Å) and four longer (2.27 Å) Ta–N bond lengths. N3- is bonded in a 5-coordinate geometry to five Ta+3.60+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgTa2N3 by Materials Project

MgTa2N3 is Caswellsilverite-like structured and crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. Mg2+ is bonded to six equivalent N3- atoms to form MgN6 octahedra that share corners with six equivalent TaN6 pentagonal pyramids, edges with three equivalent MgN6 octahedra, edges with three equivalent TaN6 octahedra, and edges with six equivalent TaN6 pentagonal pyramids. All Mg–N bond lengths are 2.16 Å. There are two inequivalent Ta+3.50+ sites. In the first Ta+3.50+ site, Ta+3.50+ is bonded to six equivalent N3- atoms to form distorted TaN6 pentagonal pyramids that share corners with two equivalent TaN6 octahedra, corners with four equivalent MgN6 octahedra, edges with two equivalent TaN6 octahedra, edges with four equivalent MgN6 octahedra, and edges with six equivalent TaN6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 2–3°. There are four shorter (2.21 Å) and two longer (2.22 Å) Ta–N bond lengths. In the second Ta+3.50+ site, Ta+3.50+ is bonded to six equivalent N3- atoms to form TaN6 octahedra that share corners with six equivalent TaN6 pentagonal pyramids, edges with six equivalent MgN6 octahedra, and edges with six equivalent TaN6 pentagonal pyramids. All Ta–N bond lengths are 2.14 Å. N3- is bonded to two equivalent Mg2+ and four Ta+3.50+ atoms to form a mixture of face, edge, and corner-sharing NMg2Ta4 octahedra. The corner-sharing octahedra tilt angles range from 0–48°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta4Se9I8 by Materials Project

Ta4Se9I8 crystallizes in the orthorhombic Pna2_1 space group. The structure is zero-dimensional and consists of four Ta4Se9I8 clusters. there are four inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to five Se+1.33- and two I1- atoms to form a mixture of face and corner-sharing TaSe5I2 pentagonal bipyramids. There are a spread of Ta–Se bond distances ranging from 2.61–2.69 Å. There are one shorter (2.74 Å) and one longer (2.77 Å) Ta–I bond lengths. In the second Ta5+ site, Ta5+ is bonded to five Se+1.33- and two I1- atoms to form a mixture of face and corner-sharing TaSe5I2 pentagonal bipyramids. There are a spread of Ta–Se bond distances ranging from 2.62–2.69 Å. Both Ta–I bond lengths are 2.75 Å. In the third Ta5+ site, Ta5+ is bonded to five Se+1.33- and two I1- atoms to form a mixture of face and corner-sharing TaSe5I2 pentagonal bipyramids. There are a spread of Ta–Se bond distances ranging from 2.61–2.68 Å. There are one shorter (2.75 Å) and one longer (2.76 Å) Ta–I bond lengths. In the fourth Ta5+ site, Ta5+ is bonded to five Se+1.33- and two I1- atoms to form a mixture of face and corner-sharing TaSe5I2 pentagonal bipyramids. There are a spread of Ta–Se bond distances ranging from 2.59–2.68 Å. There are one shorter (2.77 Å) and one longer (2.83 Å) Ta–I bond lengths. There are nine inequivalent Se+1.33- sites. In the first Se+1.33- site, Se+1.33- is bonded in a 2-coordinate geometry to two Ta5+ atoms. In the second Se+1.33- site, Se+1.33- is bonded in a 2-coordinate geometry to two Ta5+ atoms. In the third Se+1.33- site, Se+1.33- is bonded in a 2-coordinate geometry to two Ta5+ atoms. In the fourth Se+1.33- site, Se+1.33- is bonded in a 2-coordinate geometry to two Ta5+ atoms. In the fifth Se+1.33- site, Se+1.33- is bonded in a 2-coordinate geometry to two Ta5+ atoms. In the sixth Se+1.33- site, Se+1.33- is bonded in a 2-coordinate geometry to two Ta5+ atoms. In the seventh Se+1.33- site, Se+1.33- is bonded in a 4-coordinate geometry to four Ta5+ atoms. In the eighth Se+1.33- site, Se+1.33- is bonded in a 2-coordinate geometry to two Ta5+ atoms. In the ninth Se+1.33- site, Se+1.33- is bonded in a 2-coordinate geometry to two Ta5+ atoms. There are eight inequivalent I1- sites. In the first I1- site, I1- is bonded in a single-bond geometry to one Ta5+ atom. In the second I1- site, I1- is bonded in a single-bond geometry to one Ta5+ atom. In the third I1- site, I1- is bonded in a single-bond geometry to one Ta5+ atom. In the fourth I1- site, I1- is bonded in a single-bond geometry to one Ta5+ atom. In the fifth I1- site, I1- is bonded in a distorted single-bond geometry to one Ta5+ atom. In the sixth I1- site, I1- is bonded in a single-bond geometry to one Ta5+ atom. In the seventh I1- site, I1- is bonded in a single-bond geometry to one Ta5+ atom. In the eighth I1- site, I1- is bonded in a single-bond geometry to one Ta5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaNi2TeSe by Materials Project

TaNi2TeSe crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of two TaNi2TeSe sheets oriented in the (0, 0, 1) direction. Ta is bonded in a 2-coordinate geometry to eight Ni, one Te, and two equivalent Se atoms. There are a spread of Ta–Ni bond distances ranging from 2.71–2.74 Å. The Ta–Te bond length is 3.01 Å. Both Ta–Se bond lengths are 2.67 Å. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 1-coordinate geometry to four equivalent Ta, two equivalent Ni, two equivalent Te, and one Se atom. There are one shorter (2.43 Å) and one longer (2.53 Å) Ni–Ni bond lengths. Both Ni–Te bond lengths are 2.56 Å. The Ni–Se bond length is 2.39 Å. In the second Ni site, Ni is bonded in a 1-coordinate geometry to four equivalent Ta, two equivalent Ni, two equivalent Te, and one Se atom. Both Ni–Te bond lengths are 2.56 Å. The Ni–Se bond length is 2.38 Å. Te is bonded in a 4-coordinate geometry to one Ta and four Ni atoms. Se is bonded in a 4-coordinate geometry to two equivalent Ta and two Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb6Ta4S25 by Materials Project

Rb6Ta4S25 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twelve inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.44–3.86 Å. In the second Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.56–3.99 Å. In the third Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.55–3.97 Å. In the fourth Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.44–3.69 Å. In the fifth Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to ten S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.44–4.02 Å. In the sixth Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.44–3.74 Å. In the seventh Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.45–3.70 Å. In the eighth Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.57–3.95 Å. In the ninth Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.44–3.90 Å. In the tenth Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.43–3.71 Å. In the eleventh Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.57–3.97 Å. In the twelfth Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine S+1.04- atoms. There are a spread of Rb–S bond distances ranging from 3.44–3.86 Å. There are eight inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.04- atoms. There are a spread of Ta–S bond distances ranging from 2.25–2.88 Å. In the second Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.04- atoms. There are a spread of Ta–S bond distances ranging from 2.23–2.96 Å. In the third Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.04- atoms. There are a spread of Ta–S bond distances ranging from 2.23–2.97 Å. In the fourth Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.04- atoms. There are a spread of Ta–S bond distances ranging from 2.23–2.97 Å. In the fifth Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.04- atoms. There are a spread of Ta–S bond distances ranging from 2.23–2.95 Å. In the sixth Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.04- atoms. There are a spread of Ta–S bond distances ranging from 2.26–2.88 Å. In the seventh Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.04- atoms. There are a spread of Ta–S bond distances ranging from 2.25–2.88 Å. In the eighth Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.04- atoms. There are a spread of Ta–S bond distances ranging from 2.25–2.88 Å. There are fifty inequivalent S+1.04- sites. In the first S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.08 Å. In the second S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.10 Å. In the third S+1.04- site, S+1.04- is bonded in a distorted single-bond geometry to three Rb1+ and one Ta5+ atom. In the fourth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+ and two Ta5+ atoms. In the fifth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to one Rb1+, two Ta5+, and one S+1.04- atom. The S–S bond length is 2.11 Å. In the sixth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.10 Å. In the seventh S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to three Rb1+ and one Ta5+ atom. In the eighth S+1.04- site, S+1.04- is bonded in a distorted single-bond geometry to three Rb1+ and one Ta5+ atom. In the ninth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.10 Å. In the tenth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to one Rb1+, two Ta5+, and one S+1.04- atom. The S–S bond length is 2.10 Å. In the eleventh S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to three Rb1+, one Ta5+, and one S+1.04- atom. In the twelfth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+ and two Ta5+ atoms. In the thirteenth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to three Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.11 Å. In the fourteenth S+1.04- site, S+1.04- is bonded in a 2-coordinate geometry to one Rb1+, two Ta5+, and one S+1.04- atom. The S–S bond length is 2.09 Å. In the fifteenth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, two Ta5+, and one S+1.04- atom. In the sixteenth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.08 Å. In the seventeenth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.10 Å. In the eighteenth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+ and two Ta5+ atoms. In the nineteenth S+1.04- site, S+1.04- is bonded in a 4-coordinate geometry to two Rb1+ and two S+1.04- atoms. The S–S bond length is 2.06 Å. In the twentieth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. In the twenty-first S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.09 Å. In the twenty-second S+1.04- site, S+1.04- is bonded in a 2-coordinate geometry to one Rb1+, two Ta5+, and one S+1.04- atom. In the twenty-third S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.08 Å. In the twenty-fourth S+1.04- site, S+1.04- is bonded in a 4-coordinate geometry to two Rb1+ and two S+1.04- atoms. The S–S bond length is 2.06 Å. In the twenty-fifth S+1.04- site, S+1.04- is bonded in a distorted single-bond geometry to four Rb1+ and one Ta5+ atom. In the twenty-sixth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.09 Å. In the twenty-seventh S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to three Rb1+ and one Ta5+ atom. In the twenty-eighth S+1.04- site, S+1.04- is bonded in a 4-coordinate geometry to two Rb1+ and two S+1.04- atoms. There are one shorter (2.06 Å) and one longer (2.10 Å) S–S bond lengths. In the twenty-ninth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to three Rb1+ and one Ta5+ atom. In the thirtieth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. In the thirty-first S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to one Rb1+, two Ta5+, and one S+1.04- atom. The S–S bond length is 2.11 Å. In the thirty-second S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. In the thirty-third S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+ and two Ta5+ atoms. In the thirty-fourth S+1.04- site, S+1.04- is bonded in a distorted single-bond geometry to four Rb1+ and one Ta5+ atom. In the thirty-fifth S+1.04- site, S+1.04- is bonded in a distorted single-bond geometry to four Rb1+ and one Ta5+ atom. In the thirty-sixth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to three Rb1+, one Ta5+, and one S+1.04- atom. In the thirty-seventh S+1.04- site, S+1.04- is bonded in a 2-coordinate geometry to one Rb1+, two Ta5+, and one S+1.04- atom. In the thirty-eighth S+1.04- site, S+1.04- is bonded in a water-like geometry to two S+1.04- atoms. In the thirty-ninth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. In the fortieth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. The S–S bond length is 2.08 Å. In the forty-first S+1.04- site, S+1.04- is bonded in a distorted single-bond geometry to four Rb1+ and one Ta5+ atom. In the forty-second S+1.04- site, S+1.04- is bonded in a water-like geometry to two S+1.04- atoms. The S–S bond length is 2.06 Å. In the forty-third S+1.04- site, S+1.04- is bonded in a 2-coordinate geometry to one Rb1+, two Ta5+, and one S+1.04- atom. In the forty-fourth S+1.04- site, S+1.04- is bonded in a 4-coordinate geometry to two Rb1+ and two S+1.04- atoms. In the forty-fifth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. In the forty-sixth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to three Rb1+, one Ta5+, and one S+1.04- atom. In the forty-seventh S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to three Rb1+ and one Ta5+ atom. In the forty-eighth S+1.04- site, S+1.04- is bonded in a distorted single-bond geometry to three Rb1+ and one Ta5+ atom. In the forty-ninth S+1.04- site, S+1.04- is bonded in a 1-coordinate geometry to two Rb1+, one Ta5+, and one S+1.04- atom. In the fiftieth S+1.04- site, S+1.04- is bonded in a distorted single-bond geometry to three Rb1+ and one Ta5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Ta4F15 by Materials Project

K3Ta4F15 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of K–F bond distances ranging from 2.68–3.15 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of K–F bond distances ranging from 2.74–3.14 Å. In the third K1+ site, K1+ is bonded in a 3-coordinate geometry to three F1- atoms. There are one shorter (2.59 Å) and two longer (2.77 Å) K–F bond lengths. In the fourth K1+ site, K1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of K–F bond distances ranging from 2.67–3.21 Å. In the fifth K1+ site, K1+ is bonded in a distorted trigonal non-coplanar geometry to three F1- atoms. There are two shorter (2.50 Å) and one longer (2.66 Å) K–F bond lengths. In the sixth K1+ site, K1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of K–F bond distances ranging from 2.57–3.22 Å. There are eight inequivalent Ta3+ sites. In the first Ta3+ site, Ta3+ is bonded to six F1- atoms to form corner-sharing TaF6 octahedra. The corner-sharing octahedral tilt angles are 3°. There are a spread of Ta–F bond distances ranging from 1.96–2.07 Å. In the second Ta3+ site, Ta3+ is bonded to six F1- atoms to form corner-sharing TaF6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 17°. There are a spread of Ta–F bond distances ranging from 2.05–2.18 Å. In the third Ta3+ site, Ta3+ is bonded to six F1- atoms to form TaF6 pentagonal pyramids that share corners with two equivalent TaF6 pentagonal pyramids, a cornercorner with one TaF5 square pyramid, and a cornercorner with one TaF5 trigonal bipyramid. There are a spread of Ta–F bond distances ranging from 2.04–2.23 Å. In the fourth Ta3+ site, Ta3+ is bonded to five F1- atoms to form distorted TaF5 trigonal bipyramids that share a cornercorner with one TaF6 pentagonal pyramid, a cornercorner with one TaF5 square pyramid, and corners with two equivalent TaF5 trigonal bipyramids. There are a spread of Ta–F bond distances ranging from 2.01–2.21 Å. In the fifth Ta3+ site, Ta3+ is bonded to six F1- atoms to form corner-sharing TaF6 pentagonal pyramids. There are a spread of Ta–F bond distances ranging from 2.02–2.10 Å. In the sixth Ta3+ site, Ta3+ is bonded to five F1- atoms to form distorted TaF5 square pyramids that share a cornercorner with one TaF6 pentagonal pyramid, corners with two equivalent TaF5 square pyramids, and a cornercorner with one TaF5 trigonal bipyramid. There are a spread of Ta–F bond distances ranging from 2.06–2.19 Å. In the seventh Ta3+ site, Ta3+ is bonded to six F1- atoms to form corner-sharing TaF6 octahedra. The corner-sharing octahedral tilt angles are 3°. There are a spread of Ta–F bond distances ranging from 1.92–2.08 Å. In the eighth Ta3+ site, Ta3+ is bonded to six F1- atoms to form corner-sharing TaF6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 12°. There are a spread of Ta–F bond distances ranging from 2.03–2.18 Å. There are thirty inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted linear geometry to two Ta3+ atoms. In the second F1- site, F1- is bonded to three K1+ and one Ta3+ atom to form distorted corner-sharing FK3Ta tetrahedra. In the third F1- site, F1- is bonded in a linear geometry to two equivalent Ta3+ atoms. In the fourth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two equivalent Ta3+ atoms. In the fifth F1- site, F1- is bonded in an L-shaped geometry to two Ta3+ atoms. In the sixth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one K1+ and two equivalent Ta3+ atoms. In the seventh F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one K1+ and two equivalent Ta3+ atoms. In the eighth F1- site, F1- is bonded in a linear geometry to two equivalent Ta3+ atoms. In the ninth F1- site, F1- is bonded in a distorted trigonal planar geometry to two equivalent K1+ and one Ta3+ atom. In the tenth F1- site, F1- is bonded in a distorted L-shaped geometry to two equivalent K1+ and two Ta3+ atoms. In the eleventh F1- site, F1- is bonded in a water-like geometry to two Ta3+ atoms. In the twelfth F1- site, F1- is bonded to three K1+ and one Ta3+ atom to form distorted corner-sharing FK3Ta tetrahedra. In the thirteenth F1- site, F1- is bonded in a 3-coordinate geometry to two K1+ and one Ta3+ atom. In the fourteenth F1- site, F1- is bonded in a linear geometry to one K1+ and two equivalent Ta3+ atoms. In the fifteenth F1- site, F1- is bonded in a distorted linear geometry to one K1+ and two equivalent Ta3+ atoms. In the sixteenth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two equivalent Ta3+ atoms. In the seventeenth F1- site, F1- is bonded in a distorted water-like geometry to two equivalent K1+ and two Ta3+ atoms. In the eighteenth F1- site, F1- is bonded in a distorted trigonal non-coplanar geometry to two equivalent K1+ and one Ta3+ atom. In the nineteenth F1- site, F1- is bonded in a 1-coordinate geometry to three K1+ and one Ta3+ atom. In the twentieth F1- site, F1- is bonded in a 4-coordinate geometry to three K1+ and one Ta3+ atom. In the twenty-first F1- site, F1- is bonded in a distorted trigonal non-coplanar geometry to two equivalent K1+ and one Ta3+ atom. In the twenty-second F1- site, F1- is bonded in a single-bond geometry to one Ta3+ atom. In the twenty-third F1- site, F1- is bonded in a 3-coordinate geometry to two equivalent K1+ and one Ta3+ atom. In the twenty-fourth F1- site, F1- is bonded in a 1-coordinate geometry to three K1+ and one Ta3+ atom. In the twenty-fifth F1- site, F1- is bonded in a 1-coordinate geometry to three K1+ and one Ta3+ atom. In the twenty-sixth F1- site, F1- is bonded in a 4-coordinate geometry to two equivalent K1+ and two Ta3+ atoms. In the twenty-seventh F1- site, F1- is bonded in a distorted linear geometry to two Ta3+ atoms. In the twenty-eighth F1- site, F1- is bonded in a 3-coordinate geometry to two K1+ and one Ta3+ atom. In the twenty-ninth F1- site, F1- is bonded in a distorted L-shaped geometry to two equivalent K1+ and two Ta3+ atoms. In the thirtieth F1- site, F1- is bonded in a single-bond geometry to one Ta3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Ta2S11 by Materials Project

K3Ta2S11 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twelve inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to eight S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.28–3.78 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.32–3.63 Å. In the third K1+ site, K1+ is bonded in a 8-coordinate geometry to ten S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.28–3.84 Å. In the fourth K1+ site, K1+ is bonded in a 8-coordinate geometry to eight S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.28–3.71 Å. In the fifth K1+ site, K1+ is bonded in a 8-coordinate geometry to eight S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.27–3.74 Å. In the sixth K1+ site, K1+ is bonded in a 9-coordinate geometry to nine S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.30–3.61 Å. In the seventh K1+ site, K1+ is bonded in a 8-coordinate geometry to eight S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.28–3.72 Å. In the eighth K1+ site, K1+ is bonded in a 9-coordinate geometry to nine S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.31–3.62 Å. In the ninth K1+ site, K1+ is bonded in a 8-coordinate geometry to ten S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.29–3.82 Å. In the tenth K1+ site, K1+ is bonded in a 8-coordinate geometry to ten S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.28–3.84 Å. In the eleventh K1+ site, K1+ is bonded in a 9-coordinate geometry to nine S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.34–3.67 Å. In the twelfth K1+ site, K1+ is bonded in a 8-coordinate geometry to ten S+1.18- atoms. There are a spread of K–S bond distances ranging from 3.29–3.83 Å. There are eight inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.18- atoms. There are a spread of Ta–S bond distances ranging from 2.26–2.90 Å. In the second Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.18- atoms. There are a spread of Ta–S bond distances ranging from 2.24–2.93 Å. In the third Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.18- atoms. There are a spread of Ta–S bond distances ranging from 2.24–2.94 Å. In the fourth Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.18- atoms. There are a spread of Ta–S bond distances ranging from 2.26–2.89 Å. In the fifth Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.18- atoms. There are a spread of Ta–S bond distances ranging from 2.24–2.94 Å. In the sixth Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.18- atoms. There are a spread of Ta–S bond distances ranging from 2.26–2.90 Å. In the seventh Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.18- atoms. There are a spread of Ta–S bond distances ranging from 2.26–2.91 Å. In the eighth Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven S+1.18- atoms. There are a spread of Ta–S bond distances ranging from 2.24–2.93 Å. There are forty-four inequivalent S+1.18- sites. In the first S+1.18- site, S+1.18- is bonded in a distorted single-bond geometry to four K1+ and one Ta5+ atom. In the second S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to three K1+, one Ta5+, and one S+1.18- atom. The S–S bond length is 2.10 Å. In the third S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to three K1+ and one Ta5+ atom. In the fourth S+1.18- site, S+1.18- is bonded in a 4-coordinate geometry to three K1+ and one Ta5+ atom. In the fifth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. The S–S bond length is 2.09 Å. In the sixth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. The S–S bond length is 2.09 Å. In the seventh S+1.18- site, S+1.18- is bonded in a 4-coordinate geometry to three K1+ and one Ta5+ atom. In the eighth S+1.18- site, S+1.18- is bonded in a 2-coordinate geometry to two K1+, two Ta5+, and one S+1.18- atom. The S–S bond length is 2.09 Å. In the ninth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. The S–S bond length is 2.09 Å. In the tenth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to three K1+, one Ta5+, and one S+1.18- atom. The S–S bond length is 2.10 Å. In the eleventh S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to three K1+ and one Ta5+ atom. In the twelfth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, two Ta5+, and one S+1.18- atom. In the thirteenth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+ and one Ta5+ atom. In the fourteenth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, two Ta5+, and one S+1.18- atom. The S–S bond length is 2.10 Å. In the fifteenth S+1.18- site, S+1.18- is bonded in a distorted single-bond geometry to four K1+ and one Ta5+ atom. In the sixteenth S+1.18- site, S+1.18- is bonded in a 4-coordinate geometry to three K1+ and one Ta5+ atom. In the seventeenth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. The S–S bond length is 2.09 Å. In the eighteenth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. In the nineteenth S+1.18- site, S+1.18- is bonded in a 2-coordinate geometry to two K1+, two Ta5+, and one S+1.18- atom. The S–S bond length is 2.09 Å. In the twentieth S+1.18- site, S+1.18- is bonded in a distorted single-bond geometry to four K1+ and one Ta5+ atom. In the twenty-first S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. In the twenty-second S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+ and one Ta5+ atom. In the twenty-third S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, two Ta5+, and one S+1.18- atom. The S–S bond length is 2.10 Å. In the twenty-fourth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. The S–S bond length is 2.09 Å. In the twenty-fifth S+1.18- site, S+1.18- is bonded in a 2-coordinate geometry to two K1+, two Ta5+, and one S+1.18- atom. The S–S bond length is 2.09 Å. In the twenty-sixth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+ and two Ta5+ atoms. In the twenty-seventh S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+ and two Ta5+ atoms. In the twenty-eighth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to three K1+, one Ta5+, and one S+1.18- atom. In the twenty-ninth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, two Ta5+, and one S+1.18- atom. The S–S bond length is 2.10 Å. In the thirtieth S+1.18- site, S+1.18- is bonded in a 4-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. In the thirty-first S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, two Ta5+, and one S+1.18- atom. In the thirty-second S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. In the thirty-third S+1.18- site, S+1.18- is bonded in a distorted single-bond geometry to four K1+ and one Ta5+ atom. In the thirty-fourth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. In the thirty-fifth S+1.18- site, S+1.18- is bonded in a 4-coordinate geometry to three K1+ and one Ta5+ atom. In the thirty-sixth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to three K1+, one Ta5+, and one S+1.18- atom. In the thirty-seventh S+1.18- site, S+1.18- is bonded in a 2-coordinate geometry to two K1+, two Ta5+, and one S+1.18- atom. In the thirty-eighth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+ and one Ta5+ atom. In the thirty-ninth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, two Ta5+, and one S+1.18- atom. The S–S bond length is 2.10 Å. In the fortieth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. In the forty-first S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+ and one Ta5+ atom. In the forty-second S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to three K1+, one Ta5+, and one S+1.18- atom. In the forty-third S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to two K1+, one Ta5+, and one S+1.18- atom. In the forty-fourth S+1.18- site, S+1.18- is bonded in a 1-coordinate geometry to three K1+, one Ta5+, and one S+1.18- atom.

36 MATERIALS SCIENCE↗