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At least 1,207 records · Page 67
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Understanding metal propagation in solid electrolytes due to mixed ionic-electronic conduction

Metal penetration into a solid electrolyte (SE) is one of the critical problems impeding the practical application of solid-state batteries. In this study, we investigate the conditions under which electronic conductivity of the SE can lead to metal deposition and fracture within the SE. Three different stages for void filling (metal plating initiation, metal growth, and metal compression) in the SE are identified. We show that a micron-size isolated void in the SE near the anode can be quickly filled in by metal and fractured when the developed pressure in the void grows larger than the maximum pressure the SE material can sustain. We find that the anode voltage and applied current density play a significant role in determining the vulnerability to metal deposition. We discuss several strategies to prevent electronic conductivity-driven metal propagation in electrolytes that are not fully dense, including the densified layers between the anode and SE.

25 ENERGY STORAGE↗
DOE OSTI2020

Crystal Structure and Atomic Vacancy Optimized Thermoelectric Properties in Gadolinium Selenides

Thermoelectric materials enable the energy conversion of waste heat into electricity, helpful to relieve global energy crisis. Here, we report a systematic investigation on high-temperature thermoelectric gadolinium selenides, cubic Gd 3-x Se 4 (x = 0.16, 0.21 and 0.25) and orthorhombic Gd 2 Se 3-y (y = 0.02, 0.06 and 0.08). High energy synchrotron x-ray diffraction and total scattering have been used to investigate the crystallographic and local structures. Atomic-scale clusters of Gd vacancy in the cubic phase are observed by employing the reverse Monte Carlo simulation. For cubic Gd 3-x Se 4 , adjusting Gd vacancy triggers the effect of multiple conduction bands, confirmed by the increase in effective masses and theoretical calculations. A reasonable peak zT value of 0.27 is achieved at 850 K for Gd 3-x Se 4 (x = 0.16). On the other hand, tuning Se vacancy enables the optimization of electron concentration for the orthorhombic Gd 2 Se 3-y . More significantly, its low deformation potential (Ξ = 12eV) gives rise to enhanced electron mobility and higher peak zT value of 0.54 at 850 K for Gd 2 Se 3-y (y = 0.02). Intriguingly, a higher zT of 1.2 at 1200 K is reasonably predicted by quality factor analysis. Finally, this work extends the scope of high-temperature thermoelectric materials and facilitates the exploration of novel high-temperature thermoelectric materials

36 MATERIALS SCIENCE↗
DOE OSTI2020

Ultrafine Interwoven Dendritic Cu 2 Se/CuFeSe 2 Composites with Enhanced Thermoelectric Performance

As an effort to develop high-performance and stable copper chalcogenide thermoelectrics, several (1-x)Cu 2 Se/(x)CuFeSe 2 composites were successfully synthesized via a one-step solid-state transformation of CuSe 2 template. Uniform ultrafine dendritic structures consisting of interweaving Cu 2 Se and CuFeSe 2 nanofibers were observed in samples with low Fe content (0.05 ≤ x ≤ 0.1). Increasing the Fe content to x = 0.5 led to phase segregation into Cu 2 Se-rich region with embedded CuFeSe 2 fine structures interwoven with CuFeSe 2 -rich region containing Cu 2 Se nanofibers. The formation of such an entwined dendritic structure is believed to arise from the temperature-dependent solubility of CuFeSe 2 in the Cu 2 Se matrix. The dynamic dissolution of CuFeSe 2 into the Cu 2 Se at high temperatures leads to temperature-dependent doping of the Cu 2 Se matrix, enabling drastic enhancements of thermoelectric power factor at high temperatures. As a result, such a strategy is expected to be a powerful tool for properties modulation in thermoelectric materials.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Strong spin-dephasing in a topological insulator-paramagnet heterostructure

The interface between magnetic materials and topological insulators can drive the formation of exotic phases of matter and enable functionality through the manipulation of the strong spin polarized transport. Here, we report that the transport processes that rely on strong spin-momentum locking in the topological insulator Bi 2 Se 3 are completely suppressed by scattering at a heterointerface with the kagome-lattice paramagnet, Co 7 Se 8 . Bi 2 Se 3 –Co 7 Se 8 –Bi 2 Se 3 trilayer heterostructures were grown using molecular beam epitaxy, where magnetotransport measurements revealed a substantial suppression of the weak antilocalization effect for Co 7 Se 8 at thicknesses as thin as a monolayer, indicating a strong dephasing mechanism. Bi 2- x Co x Se 3 films, in which Co is in a non-magnetic 3 + state, show weak antilocalization that survives to higher than x = 0.4, which, in comparison with the heterostructures, suggests that the unordered moments of Co 2+ act as a far stronger dephasing element. This work highlights several important points regarding coherent transport processes involving spin-momentum locking in topological insulator interfaces and how magnetic materials can be integrated with topological materials to realize both exotic phases and novel device functionality.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Early crystallization of amorphous selenium under high pressure studied by synchrotron XRD method

Abstract The amorphous selenium (a-Se) was studied via x-ray diffraction (XRD) under pressures ranging from ambient pressure up to 30 GPa at room temperature to study its high-pressure behavior. Two compressional experiments on a-Se samples, with and without heat treatment, respectively, were conducted. Contrary to the previous reports that a-Se crystallized abruptly at around 12 GPa, in this work we report an early partially crystallized state at 4.9 GPa before completing the crystallization at around 9.5 GPa based on in-situ high pressure XRD measurements on the a-Se with 70 °C heat treatment. In comparison, crystallization pressure on another a-Se sample without thermal treatment history was observed to be 12.7 GPa, consistent with the previously reported crystallization pressure. Thus, it is proposed in this work that prior heat treatment of a-Se can result in an earlier crystallization under high pressure, which helps to understand the possible mechanism caused by the previous controversial reports on pressure induced crystallization behavior in a-Se.

Physics↗
DOE OSTI2020

Ion irradiation of iron chalcogenide superconducting films

Iron-chalcogenide FeSe x Te 1-x (Fe(Se,Te)) superconductors have attracted a great deal of interests in both fundamental physics and potential applications. While Majorana zero-modes hosted by the Fe(Se,Te) superconductors hold great promise for topological quantum computing, low-anisotropy and very high upper critical fields make Fe(Se,Te) an excellent candidate for high magnetic field and energy applications. Recently, we demonstrated a route for creating structural defects by ion irradiation in the FST films, leading to strong flux pinning. Ion irradiation into Fe(Se,Te) films significantly improved the critical current density J c over a wide field range and for all orientations with respect to magnetic field. In particular, a robust enhancement of critical temperature T c and J c was realized simultaneously in the Fe(Se,Te) film irradiated with proton. Here, we provide a review of the ion irradiated Fe(Se,Te) films, including the film growth and characteristics before and after irradiations, design of irradiation process for different ion energy and species with irradiation simulations and experimental setups that are scalable for long length Fe(Se,Te) coated conductors.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on Cu8SiSe6 by Materials Project

Cu8SiSe6 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. there are five inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Cu–Se bond distances ranging from 2.37–3.05 Å. In the second Cu1+ site, Cu1+ is bonded in a distorted T-shaped geometry to three Se2- atoms. There are a spread of Cu–Se bond distances ranging from 2.42–2.60 Å. In the third Cu1+ site, Cu1+ is bonded to four Se2- atoms to form distorted CuSe4 tetrahedra that share corners with two equivalent SiSe4 tetrahedra and corners with six equivalent CuSe4 trigonal pyramids. There are a spread of Cu–Se bond distances ranging from 2.41–2.57 Å. In the fourth Cu1+ site, Cu1+ is bonded in a distorted trigonal planar geometry to three Se2- atoms. There are a spread of Cu–Se bond distances ranging from 2.45–2.55 Å. In the fifth Cu1+ site, Cu1+ is bonded to four Se2- atoms to form distorted CuSe4 trigonal pyramids that share corners with two equivalent SiSe4 tetrahedra, corners with three equivalent CuSe4 tetrahedra, a cornercorner with one CuSe4 trigonal pyramid, and an edgeedge with one CuSe4 trigonal pyramid. There are a spread of Cu–Se bond distances ranging from 2.43–2.73 Å. Si4+ is bonded to four Se2- atoms to form SiSe4 tetrahedra that share corners with two equivalent CuSe4 tetrahedra and corners with four equivalent CuSe4 trigonal pyramids. There are a spread of Si–Se bond distances ranging from 2.26–2.28 Å. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to four Cu1+ and one Si4+ atom. In the second Se2- site, Se2- is bonded in a distorted trigonal bipyramidal geometry to five Cu1+ atoms. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to eight Cu1+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted tetrahedral geometry to three Cu1+ and one Si4+ atom. In the fifth Se2- site, Se2- is bonded in a 6-coordinate geometry to five Cu1+ and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag2PSe3 by Materials Project

Ag2PSe3 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. there are four inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to one Ag1+ and four Se2- atoms. The Ag–Ag bond length is 3.10 Å. There are a spread of Ag–Se bond distances ranging from 2.70–2.78 Å. In the second Ag1+ site, Ag1+ is bonded in a 5-coordinate geometry to five Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.71–3.16 Å. In the third Ag1+ site, Ag1+ is bonded in a 8-coordinate geometry to two Ag1+ and six Se2- atoms. The Ag–Ag bond length is 3.00 Å. There are a spread of Ag–Se bond distances ranging from 2.66–3.58 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 5-coordinate geometry to one Ag1+ and five Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.68–3.29 Å. There are two inequivalent P4+ sites. In the first P4+ site, P4+ is bonded in a trigonal non-coplanar geometry to three Se2- atoms. There are a spread of P–Se bond distances ranging from 2.21–2.26 Å. In the second P4+ site, P4+ is bonded in a trigonal non-coplanar geometry to three Se2- atoms. There are a spread of P–Se bond distances ranging from 2.21–2.26 Å. There are six inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 1-coordinate geometry to three Ag1+ and one P4+ atom. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to four Ag1+ and one P4+ atom. In the third Se2- site, Se2- is bonded in a 4-coordinate geometry to four Ag1+ and one P4+ atom. In the fourth Se2- site, Se2- is bonded in a 4-coordinate geometry to three Ag1+ and one P4+ atom. In the fifth Se2- site, Se2- is bonded in a 4-coordinate geometry to three Ag1+ and one P4+ atom. In the sixth Se2- site, Se2- is bonded in a 4-coordinate geometry to three Ag1+ and one P4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag8SnSe6 by Materials Project

Ag8SnSe6 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. there are five inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.68–2.76 Å. In the second Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to two Se2- atoms. There are one shorter (2.59 Å) and one longer (2.61 Å) Ag–Se bond lengths. In the third Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to four Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.57–3.66 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.71–2.79 Å. In the fifth Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.69–2.94 Å. Sn4+ is bonded in a tetrahedral geometry to four Se2- atoms. There are a spread of Sn–Se bond distances ranging from 2.55–2.57 Å. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to five Ag1+ atoms. In the second Se2- site, Se2- is bonded in a 6-coordinate geometry to eight Ag1+ atoms. In the third Se2- site, Se2- is bonded in a distorted trigonal pyramidal geometry to three Ag1+ and one Sn4+ atom. In the fourth Se2- site, Se2- is bonded in a 5-coordinate geometry to four Ag1+ and one Sn4+ atom. In the fifth Se2- site, Se2- is bonded in a 5-coordinate geometry to four Ag1+ and one Sn4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag8GeSe6 by Materials Project

Ag8GeSe6 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. there are five inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.62–2.88 Å. In the second Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.59–3.30 Å. In the third Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.69–2.76 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.65–2.99 Å. In the fifth Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.67–2.77 Å. Ge4+ is bonded in a tetrahedral geometry to four Se2- atoms. There are a spread of Ge–Se bond distances ranging from 2.38–2.41 Å. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to four Ag1+ and one Ge4+ atom. In the second Se2- site, Se2- is bonded in a distorted tetrahedral geometry to three Ag1+ and one Ge4+ atom. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to five Ag1+ and one Ge4+ atom. In the fourth Se2- site, Se2- is bonded in a 8-coordinate geometry to eight Ag1+ atoms. In the fifth Se2- site, Se2- is bonded in a 5-coordinate geometry to five Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KPSe6 by Materials Project

KPSe6 crystallizes in the orthorhombic Pca2_1 space group. The structure is two-dimensional and consists of one KPSe6 sheet oriented in the (1, 0, 0) direction. K1+ is bonded in a 8-coordinate geometry to eight Se1- atoms. There are a spread of K–Se bond distances ranging from 3.43–3.80 Å. P5+ is bonded in a tetrahedral geometry to four Se1- atoms. There are a spread of P–Se bond distances ranging from 2.18–2.33 Å. There are six inequivalent Se1- sites. In the first Se1- site, Se1- is bonded in a 1-coordinate geometry to two equivalent K1+ and one P5+ atom. In the second Se1- site, Se1- is bonded in a 4-coordinate geometry to two equivalent K1+ and two Se1- atoms. There are one shorter (2.42 Å) and one longer (2.46 Å) Se–Se bond lengths. In the third Se1- site, Se1- is bonded in a distorted single-bond geometry to one K1+ and one P5+ atom. In the fourth Se1- site, Se1- is bonded in a distorted single-bond geometry to one K1+, one P5+, and one Se1- atom. In the fifth Se1- site, Se1- is bonded in a distorted trigonal non-coplanar geometry to one K1+ and two Se1- atoms. The Se–Se bond length is 2.37 Å. In the sixth Se1- site, Se1- is bonded in a distorted single-bond geometry to one K1+, one P5+, and one Se1- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuSe2 by Materials Project

CuSe2 is Marcasite structured and crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. Cu3+ is bonded to six equivalent Se+1.50- atoms to form CuSe6 octahedra that share corners with eight equivalent CuSe6 octahedra, corners with six equivalent SeCu3Se tetrahedra, and edges with two equivalent CuSe6 octahedra. The corner-sharing octahedral tilt angles are 61°. There are four shorter (2.57 Å) and two longer (2.58 Å) Cu–Se bond lengths. Se+1.50- is bonded to three equivalent Cu3+ and one Se+1.50- atom to form distorted SeCu3Se tetrahedra that share corners with three equivalent CuSe6 octahedra, corners with thirteen equivalent SeCu3Se tetrahedra, and an edgeedge with one SeCu3Se tetrahedra. The corner-sharing octahedra tilt angles range from 71–75°. The Se–Se bond length is 2.37 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2In12Se19 by Materials Project

K2In12Se19 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are three shorter (3.51 Å) and three longer (3.60 Å) K–Se bond lengths. In the second K1+ site, K1+ is bonded in a 3-coordinate geometry to six Se2- atoms. There are three shorter (3.36 Å) and three longer (3.77 Å) K–Se bond lengths. There are four inequivalent In3+ sites. In the first In3+ site, In3+ is bonded to four Se2- atoms to form corner-sharing InSe4 tetrahedra. There are a spread of In–Se bond distances ranging from 2.59–2.75 Å. In the second In3+ site, In3+ is bonded to four Se2- atoms to form corner-sharing InSe4 tetrahedra. There are a spread of In–Se bond distances ranging from 2.58–2.74 Å. In the third In3+ site, In3+ is bonded to four Se2- atoms to form corner-sharing InSe4 tetrahedra. There are a spread of In–Se bond distances ranging from 2.56–2.70 Å. In the fourth In3+ site, In3+ is bonded to four Se2- atoms to form a mixture of edge and corner-sharing InSe4 tetrahedra. There are a spread of In–Se bond distances ranging from 2.62–2.69 Å. There are seven inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted trigonal planar geometry to one K1+ and two In3+ atoms. In the second Se2- site, Se2- is bonded to one K1+ and three In3+ atoms to form a mixture of distorted edge and corner-sharing SeKIn3 trigonal pyramids. In the third Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to three In3+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent In3+ atoms. In the fifth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three In3+ atoms. In the sixth Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to one K1+ and two equivalent In3+ atoms. In the seventh Se2- site, Se2- is bonded in a 3-coordinate geometry to one K1+ and two equivalent In3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuSe2 by Materials Project

CuSe2 is Pyrite structured and crystallizes in the cubic Pa-3 space group. The structure is three-dimensional. Cu3+ is bonded to six equivalent Se+1.50- atoms to form CuSe6 octahedra that share corners with twelve equivalent CuSe6 octahedra and corners with six equivalent SeCu3Se tetrahedra. The corner-sharing octahedral tilt angles are 65°. All Cu–Se bond lengths are 2.58 Å. Se+1.50- is bonded to three equivalent Cu3+ and one Se+1.50- atom to form distorted SeCu3Se tetrahedra that share corners with three equivalent CuSe6 octahedra and corners with fifteen equivalent SeCu3Se tetrahedra. The corner-sharing octahedral tilt angles are 77°. The Se–Se bond length is 2.38 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb3Se12I by Materials Project

(NbSe4)3I crystallizes in the tetragonal P4/mnc space group. The structure is three-dimensional. there are two inequivalent Nb+4.33+ sites. In the first Nb+4.33+ site, Nb+4.33+ is bonded in a 8-coordinate geometry to eight Se1- atoms. There are four shorter (2.60 Å) and four longer (2.77 Å) Nb–Se bond lengths. In the second Nb+4.33+ site, Nb+4.33+ is bonded to eight Se1- atoms to form distorted face-sharing NbSe8 hexagonal bipyramids. There are a spread of Nb–Se bond distances ranging from 2.66–2.75 Å. There are four inequivalent Se1- sites. In the first Se1- site, Se1- is bonded in a 2-coordinate geometry to two Nb+4.33+ atoms. In the second Se1- site, Se1- is bonded in a 2-coordinate geometry to two equivalent Nb+4.33+ and one Se1- atom. The Se–Se bond length is 2.36 Å. In the third Se1- site, Se1- is bonded in a 2-coordinate geometry to two equivalent Nb+4.33+, one Se1-, and two equivalent I1- atoms. Both Se–I bond lengths are 4.06 Å. In the fourth Se1- site, Se1- is bonded in a 2-coordinate geometry to two Nb+4.33+ and one I1- atom. The Se–I bond length is 3.39 Å. I1- is bonded in a 4-coordinate geometry to eight Se1- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlRe6Se8Cl3 by Materials Project

Re6TlSe8Cl3 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are six inequivalent Re3+ sites. In the first Re3+ site, Re3+ is bonded to four Se2- and one Cl1- atom to form a mixture of corner and edge-sharing ReSe4Cl square pyramids. There are a spread of Re–Se bond distances ranging from 2.52–2.56 Å. The Re–Cl bond length is 2.44 Å. In the second Re3+ site, Re3+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing ReSe5 square pyramids. There are a spread of Re–Se bond distances ranging from 2.54–2.67 Å. In the third Re3+ site, Re3+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing ReSe5 square pyramids. There are a spread of Re–Se bond distances ranging from 2.54–2.66 Å. In the fourth Re3+ site, Re3+ is bonded to five Se2- atoms to form ReSe5 square pyramids that share corners with three ReSe4Cl square pyramids and edges with five ReSe5 square pyramids. There are a spread of Re–Se bond distances ranging from 2.53–2.66 Å. In the fifth Re3+ site, Re3+ is bonded to four Se2- and one Cl1- atom to form ReSe4Cl square pyramids that share corners with two ReSe5 square pyramids and edges with four ReSe4Cl square pyramids. There are one shorter (2.54 Å) and three longer (2.55 Å) Re–Se bond lengths. The Re–Cl bond length is 2.43 Å. In the sixth Re3+ site, Re3+ is bonded to four Se2- and one Cl1- atom to form ReSe4Cl square pyramids that share corners with two ReSe5 square pyramids and edges with four ReSe4Cl square pyramids. There are a spread of Re–Se bond distances ranging from 2.53–2.57 Å. The Re–Cl bond length is 2.41 Å. Tl1+ is bonded in a 9-coordinate geometry to five Cl1- atoms. There are a spread of Tl–Cl bond distances ranging from 3.11–3.41 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 4-coordinate geometry to four Re3+ atoms. In the second Se2- site, Se2- is bonded in a 4-coordinate geometry to four Re3+ atoms. In the third Se2- site, Se2- is bonded in a 4-coordinate geometry to three Re3+ atoms. In the fourth Se2- site, Se2- is bonded in a 5-coordinate geometry to three Re3+ atoms. In the fifth Se2- site, Se2- is bonded in a 9-coordinate geometry to three Re3+ atoms. In the sixth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Re3+ atoms. In the seventh Se2- site, Se2- is bonded in a 5-coordinate geometry to three Re3+ atoms. In the eighth Se2- site, Se2- is bonded in a 7-coordinate geometry to three Re3+ atoms. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 2-coordinate geometry to one Re3+ and one Tl1+ atom. In the second Cl1- site, Cl1- is bonded in a 1-coordinate geometry to one Re3+ and two equivalent Tl1+ atoms. In the third Cl1- site, Cl1- is bonded in a 1-coordinate geometry to one Re3+ and two equivalent Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tl4SiSe4 by Materials Project

Tl4SiSe4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are five inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are two shorter (3.05 Å) and two longer (3.34 Å) Tl–Se bond lengths. In the second Tl1+ site, Tl1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.30–3.70 Å. In the third Tl1+ site, Tl1+ is bonded to five Se2- atoms to form distorted TlSe5 square pyramids that share corners with two equivalent TlSe5 square pyramids, corners with three equivalent SiSe4 tetrahedra, and an edgeedge with one SiSe4 tetrahedra. There are a spread of Tl–Se bond distances ranging from 3.21–3.54 Å. In the fourth Tl1+ site, Tl1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.07–3.43 Å. In the fifth Tl1+ site, Tl1+ is bonded in a 4-coordinate geometry to six Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.14–3.88 Å. Si4+ is bonded to four Se2- atoms to form SiSe4 tetrahedra that share corners with three equivalent TlSe5 square pyramids and an edgeedge with one TlSe5 square pyramid. There are a spread of Si–Se bond distances ranging from 2.30–2.32 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 1-coordinate geometry to four Tl1+ and one Si4+ atom. In the second Se2- site, Se2- is bonded in a 1-coordinate geometry to six Tl1+ and one Si4+ atom. In the third Se2- site, Se2- is bonded to five Tl1+ and one Si4+ atom to form a mixture of distorted edge and corner-sharing SeTl5Si octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to five Tl1+ and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tl2PSe3 by Materials Project

Tl2PSe3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.13–3.95 Å. In the second Tl1+ site, Tl1+ is bonded in a 4-coordinate geometry to seven Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.27–3.90 Å. In the third Tl1+ site, Tl1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.19–3.79 Å. In the fourth Tl1+ site, Tl1+ is bonded to six Se2- atoms to form distorted edge-sharing TlSe6 pentagonal pyramids. There are a spread of Tl–Se bond distances ranging from 3.23–3.49 Å. There are two inequivalent P4+ sites. In the first P4+ site, P4+ is bonded in a trigonal non-coplanar geometry to three Se2- atoms. There are one shorter (2.21 Å) and two longer (2.22 Å) P–Se bond lengths. In the second P4+ site, P4+ is bonded in a trigonal non-coplanar geometry to three Se2- atoms. There are a spread of P–Se bond distances ranging from 2.20–2.23 Å. There are six inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 1-coordinate geometry to three Tl1+ and one P4+ atom. In the second Se2- site, Se2- is bonded in a 1-coordinate geometry to five Tl1+ and one P4+ atom. In the third Se2- site, Se2- is bonded in a 1-coordinate geometry to five Tl1+ and one P4+ atom. In the fourth Se2- site, Se2- is bonded in a 1-coordinate geometry to six Tl1+ and one P4+ atom. In the fifth Se2- site, Se2- is bonded in a 1-coordinate geometry to four Tl1+ and one P4+ atom. In the sixth Se2- site, Se2- is bonded in a 1-coordinate geometry to four Tl1+ and one P4+ atom.

36 MATERIALS SCIENCE↗