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DOE OSTI2020

Materials Data on K16Zr12Se61 by Materials Project

K16Zr12Se61 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent K sites. In the first K site, K is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of K–Se bond distances ranging from 3.41–3.80 Å. In the second K site, K is bonded in a 8-coordinate geometry to seven Se atoms. There are a spread of K–Se bond distances ranging from 3.33–3.83 Å. In the third K site, K is bonded in a 10-coordinate geometry to ten Se atoms. There are a spread of K–Se bond distances ranging from 3.53–3.93 Å. In the fourth K site, K is bonded in a 7-coordinate geometry to seven Se atoms. There are a spread of K–Se bond distances ranging from 3.40–3.68 Å. In the fifth K site, K is bonded in a 6-coordinate geometry to nine Se atoms. There are a spread of K–Se bond distances ranging from 3.46–3.94 Å. In the sixth K site, K is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of K–Se bond distances ranging from 3.34–3.63 Å. In the seventh K site, K is bonded in a 9-coordinate geometry to nine Se atoms. There are a spread of K–Se bond distances ranging from 3.35–3.87 Å. In the eighth K site, K is bonded in a 9-coordinate geometry to nine Se atoms. There are a spread of K–Se bond distances ranging from 3.38–3.80 Å. In the ninth K site, K is bonded to eight Se atoms to form distorted KSe8 hexagonal bipyramids that share a cornercorner with one ZrSe8 hexagonal bipyramid, corners with two ZrSe7 pentagonal bipyramids, edges with two ZrSe8 hexagonal bipyramids, and an edgeedge with one ZrSe7 pentagonal bipyramid. There are a spread of K–Se bond distances ranging from 3.34–3.71 Å. In the tenth K site, K is bonded in a 10-coordinate geometry to ten Se atoms. There are a spread of K–Se bond distances ranging from 3.38–3.87 Å. In the eleventh K site, K is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of K–Se bond distances ranging from 3.36–3.62 Å. In the twelfth K site, K is bonded in a 7-coordinate geometry to seven Se atoms. There are a spread of K–Se bond distances ranging from 3.37–3.85 Å. In the thirteenth K site, K is bonded in a 7-coordinate geometry to eight Se atoms. There are a spread of K–Se bond distances ranging from 3.35–3.96 Å. In the fourteenth K site, K is bonded in a 11-coordinate geometry to eleven Se atoms. There are a spread of K–Se bond distances ranging from 3.55–4.00 Å. In the fifteenth K site, K is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of K–Se bond distances ranging from 3.29–3.77 Å. In the sixteenth K site, K is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of K–Se bond distances ranging from 3.42–3.79 Å. There are twelve inequivalent Zr sites. In the first Zr site, Zr is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of Zr–Se bond distances ranging from 2.72–2.96 Å. In the second Zr site, Zr is bonded to seven Se atoms to form distorted ZrSe7 pentagonal bipyramids that share a cornercorner with one KSe8 hexagonal bipyramid, an edgeedge with one ZrSe7 pentagonal bipyramid, and a faceface with one ZrSe8 hexagonal bipyramid. There are a spread of Zr–Se bond distances ranging from 2.60–2.87 Å. In the third Zr site, Zr is bonded to eight Se atoms to form distorted face-sharing ZrSe8 hexagonal bipyramids. There are a spread of Zr–Se bond distances ranging from 2.72–2.86 Å. In the fourth Zr site, Zr is bonded to eight Se atoms to form distorted ZrSe8 hexagonal bipyramids that share an edgeedge with one KSe8 hexagonal bipyramid and a faceface with one ZrSe7 pentagonal bipyramid. There are a spread of Zr–Se bond distances ranging from 2.70–2.89 Å. In the fifth Zr site, Zr is bonded to seven Se atoms to form distorted ZrSe7 pentagonal bipyramids that share a cornercorner with one KSe8 hexagonal bipyramid, an edgeedge with one ZrSe8 hexagonal bipyramid, and a faceface with one ZrSe8 hexagonal bipyramid. There are a spread of Zr–Se bond distances ranging from 2.58–2.93 Å. In the sixth Zr site, Zr is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of Zr–Se bond distances ranging from 2.73–2.98 Å. In the seventh Zr site, Zr is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of Zr–Se bond distances ranging from 2.72–2.98 Å. In the eighth Zr site, Zr is bonded to eight Se atoms to form distorted ZrSe8 hexagonal bipyramids that share a cornercorner with one KSe8 hexagonal bipyramid, an edgeedge with one ZrSe7 pentagonal bipyramid, and a faceface with one ZrSe8 hexagonal bipyramid. There are a spread of Zr–Se bond distances ranging from 2.74–2.88 Å. In the ninth Zr site, Zr is bonded to eight Se atoms to form distorted ZrSe8 hexagonal bipyramids that share an edgeedge with one KSe8 hexagonal bipyramid and a faceface with one ZrSe7 pentagonal bipyramid. There are a spread of Zr–Se bond distances ranging from 2.70–2.88 Å. In the tenth Zr site, Zr is bonded to eight Se atoms to form distorted face-sharing ZrSe8 hexagonal bipyramids. There are a spread of Zr–Se bond distances ranging from 2.72–2.88 Å. In the eleventh Zr site, Zr is bonded to seven Se atoms to form distorted ZrSe7 pentagonal bipyramids that share an edgeedge with one KSe8 hexagonal bipyramid, an edgeedge with one ZrSe7 pentagonal bipyramid, and a faceface with one ZrSe8 hexagonal bipyramid. There are a spread of Zr–Se bond distances ranging from 2.60–2.88 Å. In the twelfth Zr site, Zr is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of Zr–Se bond distances ranging from 2.71–2.94 Å. There are sixty-one inequivalent Se sites. In the first Se site, Se is bonded in a 6-coordinate geometry to two K, two Zr, and two Se atoms. There are one shorter (2.46 Å) and one longer (2.94 Å) Se–Se bond lengths. In the second Se site, Se is bonded in a 1-coordinate geometry to three K, one Zr, and one Se atom. The Se–Se bond length is 2.41 Å. In the third Se site, Se is bonded in a 5-coordinate geometry to three K, one Zr, and one Se atom. The Se–Se bond length is 2.48 Å. In the fourth Se site, Se is bonded in a 6-coordinate geometry to two K, two Zr, and two Se atoms. The Se–Se bond length is 2.86 Å. In the fifth Se site, Se is bonded in a 2-coordinate geometry to two K, two Zr, and one Se atom. The Se–Se bond length is 2.42 Å. In the sixth Se site, Se is bonded in a 1-coordinate geometry to two K, one Zr, and one Se atom. The Se–Se bond length is 2.40 Å. In the seventh Se site, Se is bonded in a 2-coordinate geometry to two K, one Zr, and two Se atoms. The Se–Se bond length is 2.42 Å. In the eighth Se site, Se is bonded in a 4-coordinate geometry to two K, one Zr, and one Se atom. In the ninth Se site, Se is bonded in a 5-coordinate geometry to three K, one Zr, and one Se atom. The Se–Se bond length is 2.42 Å. In the tenth Se site, Se is bonded in a 4-coordinate geometry to one K, two Zr, and one Se atom. In the eleventh Se site, Se is bonded in a 1-coordinate geometry to three K, one Zr, and two Se atoms. The Se–Se bond length is 2.42 Å. In the twelfth Se site, Se is bonded in a 4-coordinate geometry to one K, two Zr, and one Se atom. In the thirteenth Se site, Se is bonded in a 5-coordinate geometry to two K, two Zr, and one Se atom. In the fourteenth Se site, Se is bonded in a 4-coordinate geometry to one K, two Zr, and one Se atom. The Se–Se bond length is 2.40 Å. In the fifteenth Se site, Se is bonded in a 2-coordinate geometry to two K, one Zr, and two Se atoms. There are one shorter (2.45 Å) and one longer (2.95 Å) Se–Se bond lengths. In the sixteenth Se site, Se is bonded in a 2-coordinate geometry to two K, two Zr, and one Se atom. The Se–Se bond length is 2.45 Å. In the seventeenth Se site, Se is bonded in a 5-coordinate geometry to three K and two Zr atoms. In the eighteenth Se site, Se is bonded in a 4-coordinate geometry to one K, two Zr, and one Se atom. The Se–Se bond length is 2.43 Å. In the nineteenth Se site, Se is bonded in a 5-coordinate geometry to three K, one Zr, and one Se atom. The Se–Se bond length is 2.43 Å. In the twentieth Se site, Se is bonded in a 5-coordinate geometry to three K, one Zr, and one Se atom. In the twenty-first Se site, Se is bonded in a 4-coordinate geometry to two K, two Zr, and one Se atom. In the twenty-second Se site, Se is bonded in a 5-coordinate geometry to two K, two Zr, and one Se atom. The Se–Se bond length is 2.43 Å. In the twenty-third Se site, Se is bonded in a 1-coordinate geometry to four K, one Zr, and one Se atom. In the twenty-fourth Se site, Se is bonded in a 5-coordinate geometry to two K, two Zr, and one Se atom. In the twenty-fifth Se site, Se is bonded in a 5-coordinate geometry to three K and two Zr atoms. In the twenty-sixth Se site, Se is bonded in a 6-coordinate geometry to two K, two Zr, and two Se atoms. There are one shorter (2.47 Å) and one longer (2.96 Å) Se–Se bond lengths. In the twenty-seventh Se site, Se is bonded in a 5-coordinate geometry to three K, one Zr, and one Se atom. In the twenty-eighth Se site, Se is bonded in a 2-coordinate geometry to two K, two Zr, and one Se atom. In the twenty-ninth Se site, Se is bonded in a 2-coordinate geometry to two K, one Zr, and one Se atom. In the thirtieth Se site, Se is bonded in a 5-coordinate geometry to three K, one Zr, and one Se atom. The Se–Se bond length is 2.43 Å. In the thirty-first Se site, Se is bonded in a 5-coordinate geometry to three K, one Zr, and one Se atom. In the thirty-second Se site, Se is bonded in a 1-coordinate geometry to two K, one Zr, and two Se atoms. There are one shorter (2.41 Å) and one longer (2.89 Å) Se–Se bond lengths. In the thirty-third Se site, Se is bonded in a 2-coordinate geometry to two K, two Zr, and one Se atom. The Se–Se bond length is 2.45 Å. In the thirty-fourth Se site, Se is bonded in a 5-coordinate geometry to two K, two Zr, and one Se atom. The Se–Se bond length is 2.39 Å. In the thirty-fifth Se site, Se is bonded in a 5-coordinate geometry to three K, one Zr, and one Se atom. The Se–Se bond length is 2.47 Å. In the thirty-sixth Se site, Se is bonded in a 6-coordinate geometry to two K, two Zr, and two Se atoms. In the thirty-seventh Se site, Se is bonded in a 6-coordinate geometry to two K, two Zr, and two Se atoms. The Se–Se bond length is 2.47 Å. In the thirty-eighth Se site, Se is bonded in a 5-coordinate geometry to three K, one Zr, and one Se atom. The Se–Se bond length is 2.41 Å. In the thirty-ninth Se site, Se is bonded in a 5-coordinate geometry to two K, two Zr, and one Se atom. In the fortieth Se site, Se is bonded in a 2-coordinate geometry to three K, one Zr, and one Se atom. In the forty-first Se site, Se is bonded in a 5-coordinate geometry to two K, two Zr, and one Se atom. The Se–Se bond length is 2.42 Å. In the forty-second Se site, Se is bonded in a 2-coordinate geometry to three K, one Zr, and one Se atom. The Se–Se bond length is 2.39 Å. In the forty-third Se site, Se is bonded in a 5-coordinate geometry to three K, one Zr, and one Se atom. In the forty-fourth Se site, Se is bonded in a 2-coordinate geometry to two K, two Zr, and one Se atom. In the forty-fifth Se site, Se is bonded in a distorted trigonal bipyramidal geometry to three K and two Zr atoms. In the forty-sixth Se site, Se is bonded in a 2-coordinate geometry to two K, two Zr, and one Se atom. In the forty-seventh Se site, Se is bonded in a 2-coordinate geometry to two K, one Zr, and two Se atoms. In the forty-eighth Se site, Se is bonded in a 4-coordinate geometry to one K, two Zr, and one Se atom. In the forty-ninth Se site, Se is bonded in a 5-coordinate geometry to two K, two Zr, and one Se atom. The Se–Se bond length is 2.42 Å. In the fiftieth Se site, Se is bonded in a 4-coordinate geometry to one K, two Zr, and one Se atom. The Se–Se bond length is 2.40 Å. In the fifty-first Se site, Se is bonded in a 1-coordinate geometry to three K, one Zr, and two Se atoms. The Se–Se bond length is 2

36 MATERIALS SCIENCE↗
DOE OSTI2022

To grind or not to grind? The influence of mechanical and thermal treatments on the $\mathrm{Cu/Zn}$ disorder in $\mathrm{Cu}$ 2 $\mathrm{ZnSn}$($\mathrm{S}$ x $\mathrm{Se}$ 1-x ) 4 monograins

We report that Kesterite-type based thin film solar cell technologies are mainly based on polycrystalline absorber layers. A promising low cost alternative technology uses Cu 2 ZnSn(S x Se 1-x ) 4 (CZTSSe) monograins (single crystals of 20–100 μm size) which are fixed in a polymer matrix to form a flexible solar cell. The Cu/Zn disorder is discussed as a possible reason for band tailing causing voltage losses limiting the efficiency of CZTSSe-based devices. The experimental determination of the order parameter Q which is a quantitative measure of Cu/Zn disorder, requires a differentiation between the isoelectronic cations Cu + and Zn 2+ . An in-depth analysis of neutron diffraction data allows the determination of type and concentration of intrinsic point defects including a distinction between Cu and Zn. Neutron diffraction requires large sample volumes, thus monograins offer the unique possibility to correlate structural disorder in CZTSSe with device performance parameters. In this study we tackle the influence of grinding the monograins on stoichiometry deviations, the Cu/Zn disorder as well as intrinsic point defects and optoelectronic properties of CZTSSe monograins. Moreover, an easy methodology based on Raman scattering spectroscopy is proposed for the assessment of Cu/Zn disorder in the CZTSSe compounds.

14 SOLAR ENERGY↗
DOE OSTI2020

Materials Data on TeAs(SeF3)2 by Materials Project

AsTe2Se4F9AsF3 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is two-dimensional and consists of four trifluoroarsine molecules and two AsTe2Se4F9 sheets oriented in the (0, 0, 1) direction. In each AsTe2Se4F9 sheet, As5+ is bonded in an octahedral geometry to six F1- atoms. There are a spread of As–F bond distances ranging from 1.74–1.83 Å. There are two inequivalent Te4+ sites. In the first Te4+ site, Te4+ is bonded in a 2-coordinate geometry to one Se+1.50- and two F1- atoms. The Te–Se bond length is 2.65 Å. There are one shorter (1.97 Å) and one longer (2.54 Å) Te–F bond lengths. In the second Te4+ site, Te4+ is bonded in a distorted single-bond geometry to one Se+1.50- and one F1- atom. The Te–Se bond length is 2.76 Å. The Te–F bond length is 2.07 Å. There are four inequivalent Se+1.50- sites. In the first Se+1.50- site, Se+1.50- is bonded in a 1-coordinate geometry to one Se+1.50- and one F1- atom. The Se–Se bond length is 2.41 Å. The Se–F bond length is 2.87 Å. In the second Se+1.50- site, Se+1.50- is bonded in a 5-coordinate geometry to one Te4+, two Se+1.50-, and two F1- atoms. The Se–Se bond length is 2.45 Å. There are one shorter (2.89 Å) and one longer (3.21 Å) Se–F bond lengths. In the third Se+1.50- site, Se+1.50- is bonded in a 2-coordinate geometry to one Te4+ and one F1- atom. The Se–F bond length is 3.12 Å. In the fourth Se+1.50- site, Se+1.50- is bonded in a 2-coordinate geometry to one Se+1.50- and two F1- atoms. There are one shorter (1.80 Å) and one longer (2.47 Å) Se–F bond lengths. There are nine inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one As5+ and one Se+1.50- atom. In the third F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the fifth F1- site, F1- is bonded in a distorted single-bond geometry to one As5+ and one Se+1.50- atom. In the sixth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one As5+ and one Se+1.50- atom. In the seventh F1- site, F1- is bonded in a 1-coordinate geometry to one As5+, one Te4+, and one Se+1.50- atom. In the eighth F1- site, F1- is bonded in a single-bond geometry to two Se+1.50- atoms. In the ninth F1- site, F1- is bonded in a single-bond geometry to one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on IrSe3 by Materials Project

IrSe3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are seven inequivalent Ir5+ sites. In the first Ir5+ site, Ir5+ is bonded to six Se+1.67- atoms to form IrSe6 octahedra that share corners with four IrSe6 octahedra and corners with two equivalent IrSe5 square pyramids. The corner-sharing octahedra tilt angles range from 63–67°. There are a spread of Ir–Se bond distances ranging from 2.48–2.54 Å. In the second Ir5+ site, Ir5+ is bonded to six Se+1.67- atoms to form corner-sharing IrSe6 octahedra. The corner-sharing octahedra tilt angles range from 63–66°. There are a spread of Ir–Se bond distances ranging from 2.50–2.56 Å. In the third Ir5+ site, Ir5+ is bonded to six Se+1.67- atoms to form IrSe6 octahedra that share corners with four IrSe6 octahedra and corners with two equivalent IrSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 63–67°. There are a spread of Ir–Se bond distances ranging from 2.49–2.54 Å. In the fourth Ir5+ site, Ir5+ is bonded to five Se+1.67- atoms to form IrSe5 trigonal bipyramids that share corners with two equivalent IrSe6 octahedra and corners with two equivalent IrSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 60–63°. There are a spread of Ir–Se bond distances ranging from 2.43–2.49 Å. In the fifth Ir5+ site, Ir5+ is bonded to five Se+1.67- atoms to form corner-sharing IrSe5 trigonal bipyramids. There are a spread of Ir–Se bond distances ranging from 2.36–2.52 Å. In the sixth Ir5+ site, Ir5+ is bonded to five Se+1.67- atoms to form IrSe5 square pyramids that share corners with two equivalent IrSe6 octahedra and corners with two equivalent IrSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 60–63°. There are a spread of Ir–Se bond distances ranging from 2.42–2.49 Å. In the seventh Ir5+ site, Ir5+ is bonded to six Se+1.67- atoms to form corner-sharing IrSe6 octahedra. The corner-sharing octahedra tilt angles range from 63–67°. There are four shorter (2.51 Å) and two longer (2.55 Å) Ir–Se bond lengths. There are twenty-one inequivalent Se+1.67- sites. In the first Se+1.67- site, Se+1.67- is bonded in a 3-coordinate geometry to two Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.40 Å. In the second Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.50 Å. In the third Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to one Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.40 Å. In the fourth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.47 Å. In the fifth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.46 Å. In the sixth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.48 Å. In the seventh Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ atoms. In the eighth Se+1.67- site, Se+1.67- is bonded in a 4-coordinate geometry to three Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.53 Å. In the ninth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ atoms. In the tenth Se+1.67- site, Se+1.67- is bonded in a 4-coordinate geometry to three Ir5+ and one Se+1.67- atom. In the eleventh Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ atoms. In the twelfth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. In the thirteenth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. In the fourteenth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. In the fifteenth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ atoms. In the sixteenth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to one Ir5+ and one Se+1.67- atom. In the seventeenth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. In the eighteenth Se+1.67- site, Se+1.67- is bonded in a 3-coordinate geometry to two Ir5+ and one Se+1.67- atom. In the nineteenth Se+1.67- site, Se+1.67- is bonded in a distorted single-bond geometry to one Ir5+ atom. In the twentieth Se+1.67- site, Se+1.67- is bonded in a distorted single-bond geometry to one Ir5+ atom. In the twenty-first Se+1.67- site, Se+1.67- is bonded in a distorted single-bond geometry to one Ir5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Highly tunable band inversion in AB 2 X 4 (A=Ge, Sn, Pb; B=As, Sb, Bi; X=Se, Te) compounds

Topological materials have been discovered so far largely by searching for existing compounds in crystallographic databases, but there are potentially new topological materials with desirable features that have not been synthesized. One of the desirable features is high tunability resulting from the band inversion with a very small direct band gap, which can be tuned by changes in pressure or strain to induce a topological phase transition. Here, using density-functional theory (DFT) calculations, we have studied the septuple layered AB 2 X 4 series compounds, where A=(Ge, Sn and Pb), B=(As, Sb and Bi), and X=(Se and Te). With the DFT thermodynamic stability validated by the already-reported compounds in these series, we predict stable Se compounds, which are not found in crystallographic database. Among them, we find that GeBi 2 Se 4 and GeSb 2 Se 4 having a small direct band gap at the Z point are very close to a strong topological insulator, which can be tuned by a moderate pressure to induce the band inversion. Importantly, the topological features with the small direct band gap are well isolated in both momentum and energy windows, which offers high tunability for studying the topological phase transition.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaPb3Se4 by Materials Project

CaPb3Se4 crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Ca2+ is bonded to six Se2- atoms to form CaSe6 octahedra that share corners with six equivalent PbSe6 octahedra, edges with two equivalent CaSe6 octahedra, and edges with ten PbSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. All Ca–Se bond lengths are 3.03 Å. There are two inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded to six Se2- atoms to form PbSe6 octahedra that share corners with six equivalent PbSe6 octahedra, edges with four equivalent CaSe6 octahedra, and edges with eight PbSe6 octahedra. The corner-sharing octahedra tilt angles range from 2–3°. All Pb–Se bond lengths are 3.09 Å. In the second Pb2+ site, Pb2+ is bonded to six Se2- atoms to form PbSe6 octahedra that share corners with six equivalent CaSe6 octahedra, edges with two equivalent CaSe6 octahedra, and edges with ten PbSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. All Pb–Se bond lengths are 3.15 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to one Ca2+ and five Pb2+ atoms to form a mixture of edge and corner-sharing SeCaPb5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second Se2- site, Se2- is bonded to two equivalent Ca2+ and four Pb2+ atoms to form SeCa2Pb4 octahedra that share corners with six equivalent SeCa2Pb4 octahedra and edges with twelve SeCaPb5 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Superconducting Fourfold Fe(Te,Se) Film on Sixfold Magnetic MnTe via Hybrid Symmetry Epitaxy

Epitaxial Fe(Te,Se) thin films have been grown on various substrates but never been grown on magnetic layers. In this work, we report the epitaxial growth of fourfold Fe(Te,Se) film on a sixfold antiferromagnetic insulator, MnTe. The Fe(Te,Se)/MnTe heterostructure shows a clear superconducting transition at around 11 K, and the critical magnetic field measurement suggests the origin of the superconductivity to be bulk-like. Structural characterizations suggest that the uniaxial lattice match between Fe(Te,Se) and MnTe allows a hybrid symmetry epitaxy mode, which was recently discovered between Fe(Te,Se) and Bi 2 Te 3 . Furthermore, the Te/Fe flux ratio during deposition of the Fe(Te,Se) layer is found to be critical for its superconductivity. Now that superconducting Fe(Te,Se) can be grown on two related hexagonal platforms, Bi 2 Te 3 and MnTe, this result opens a new possibility of combining topological superconductivity of Fe(Te,Se) with the rich physics in the intrinsic magnetic topological materials (MnTe) n (Bi 2 Te 3 ) m family.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on Bi2Se4Cl7 by Materials Project

Bi2Se4Cl7 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Bi+3.50+ sites. In the first Bi+3.50+ site, Bi+3.50+ is bonded in a 7-coordinate geometry to seven Cl1- atoms. There are a spread of Bi–Cl bond distances ranging from 2.55–3.39 Å. In the second Bi+3.50+ site, Bi+3.50+ is bonded in a 6-coordinate geometry to seven Cl1- atoms. There are a spread of Bi–Cl bond distances ranging from 2.56–3.39 Å. In the third Bi+3.50+ site, Bi+3.50+ is bonded in a 7-coordinate geometry to seven Cl1- atoms. There are a spread of Bi–Cl bond distances ranging from 2.57–3.30 Å. In the fourth Bi+3.50+ site, Bi+3.50+ is bonded in a distorted octahedral geometry to six Cl1- atoms. There are a spread of Bi–Cl bond distances ranging from 2.57–3.13 Å. There are eight inequivalent Se sites. In the first Se site, Se is bonded in a 2-coordinate geometry to two Se and two Cl1- atoms. There are one shorter (2.35 Å) and one longer (2.37 Å) Se–Se bond lengths. There are one shorter (3.59 Å) and one longer (3.65 Å) Se–Cl bond lengths. In the second Se site, Se is bonded in a distorted T-shaped geometry to two Se and one Cl1- atom. There are one shorter (2.35 Å) and one longer (2.36 Å) Se–Se bond lengths. The Se–Cl bond length is 3.57 Å. In the third Se site, Se is bonded in a rectangular see-saw-like geometry to two Se and two Cl1- atoms. The Se–Se bond length is 2.35 Å. There are one shorter (3.13 Å) and one longer (3.32 Å) Se–Cl bond lengths. In the fourth Se site, Se is bonded in a distorted water-like geometry to two Se atoms. The Se–Se bond length is 2.36 Å. In the fifth Se site, Se is bonded in a 3-coordinate geometry to two Se and two Cl1- atoms. There are one shorter (3.54 Å) and one longer (3.66 Å) Se–Cl bond lengths. In the sixth Se site, Se is bonded in a 4-coordinate geometry to two Se and two Cl1- atoms. There are one shorter (2.36 Å) and one longer (2.37 Å) Se–Se bond lengths. There are one shorter (3.22 Å) and one longer (3.51 Å) Se–Cl bond lengths. In the seventh Se site, Se is bonded in a distorted L-shaped geometry to two Se atoms. In the eighth Se site, Se is bonded in a distorted T-shaped geometry to two Se and one Cl1- atom. The Se–Cl bond length is 3.45 Å. There are fourteen inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to two Bi+3.50+ and one Se atom. In the second Cl1- site, Cl1- is bonded in a distorted trigonal non-coplanar geometry to three Bi+3.50+ atoms. In the third Cl1- site, Cl1- is bonded in a 3-coordinate geometry to two Bi+3.50+ and one Se atom. In the fourth Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two Bi+3.50+ and one Se atom. In the fifth Cl1- site, Cl1- is bonded in a single-bond geometry to one Bi+3.50+ and two Se atoms. In the sixth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Bi+3.50+ atoms. In the seventh Cl1- site, Cl1- is bonded in a 2-coordinate geometry to three Bi+3.50+ atoms. In the eighth Cl1- site, Cl1- is bonded in a distorted water-like geometry to two Bi+3.50+ atoms. In the ninth Cl1- site, Cl1- is bonded in a bent 120 degrees geometry to two Bi+3.50+ atoms. In the tenth Cl1- site, Cl1- is bonded in a 1-coordinate geometry to two Bi+3.50+ and one Se atom. In the eleventh Cl1- site, Cl1- is bonded in a single-bond geometry to two Bi+3.50+ atoms. In the twelfth Cl1- site, Cl1- is bonded in a distorted water-like geometry to two Bi+3.50+ atoms. In the thirteenth Cl1- site, Cl1- is bonded in a single-bond geometry to one Bi+3.50+ and two Se atoms. In the fourteenth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Bi+3.50+ and two Se atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Revisiting Selenium Interactions with Pyrite: From Adsorption to Coprecipitation

Interactions of selenium (Se), a trace element bio-essential at low concentrations but highly toxic at high concentrations, with the most abundant sulfide mineral in the Earth's crust, namely pyrite, was investigated over a wide range of time scales. At the nanosecond scale, selenate Se(VI)O 4 2– adsorption onto the net pyrite surface is shown by ab-initio computations to proceed via the formation of a chemical bond between an oxyanion oxygen atom and a surface Fe atom, weakening the other Se-O bonds and reducing Se atom oxidation state. At the hour-to-day scale, adsorption and coprecipitation of selenate Se(VI)O 4 2– and selenite, Se(IV)O 3 2– , were investigated through wet chemical batch experiments at various pH values at different sulfide concentrations. Selenium removal from solution is slower and weaker for selenate than for selenite. After 24h, only 10% of selenate, against 60% of selenite (up to 100% in the presence of sulfide), is removed by the pyrite surface. Independently of its original oxidation state, adsorbed Se is completely reduced to elemental trigonal selenium via adsorption, precipitation or coprecipitation, as shown by XANES spectroscopy. Here, our EXAFS results, compared to published data on Se-rich pyrite, show a Se to S substitution within the pyrite structure. The reductive coprecipitation mechanism of selenium with pyrite represents valuable new insights for improving our understanding of modern and ancient biogeochemical cycles involving Se. In addition, several industries can benefit from direct applications of our findings, such as water treatment, green technologies and sustainable mining.

Adsorption↗
DOE OSTI2020

Materials Data on SmYSe2 by Materials Project

SmYSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Sm is bonded to six equivalent Se atoms to form SmSe6 octahedra that share corners with six equivalent YSe6 octahedra, edges with six equivalent SmSe6 octahedra, and edges with six equivalent YSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Sm–Se bond lengths are 2.96 Å. Y is bonded to six equivalent Se atoms to form YSe6 octahedra that share corners with six equivalent SmSe6 octahedra, edges with six equivalent SmSe6 octahedra, and edges with six equivalent YSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Y–Se bond lengths are 2.88 Å. Se is bonded to three equivalent Sm and three equivalent Y atoms to form a mixture of edge and corner-sharing SeSm3Y3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2024

The development of an augmented machine learning approach for the additive manufacturing of thermoelectric materials

Through the integration of machine learning (ML) techniques alongside additive manufacturing (AM) experimentation, we demonstrate an iterative process to rapidly predict laser-material interactions and melt pool geometries throughout the build parameter space for a bismuth telluride thermoelectric (TE) material. In doing so, we determined process parameters that created crack-free, highly dense (>99 %) n-type bismuth telluride (Bi 2 Te 2.7 Se 0.3 ) parts through laser powder bed fusion (LPBF). Furthermore, the ML-assisted understanding of the processing space allowed for the identification of build parameters that successfully yielded geometrically enhanced Bi 2 Te 2.7 Se 0.3 parts with reduced build times and no increase in experimental effort.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr4SeS3 by Materials Project

Sr4SeS3 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to one Se2- and five S2- atoms to form a mixture of edge and corner-sharing SrSeS5 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. The Sr–Se bond length is 3.11 Å. There are a spread of Sr–S bond distances ranging from 3.03–3.07 Å. In the second Sr2+ site, Sr2+ is bonded to two equivalent Se2- and four S2- atoms to form a mixture of edge and corner-sharing SrSe2S4 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. Both Sr–Se bond lengths are 3.11 Å. There are a spread of Sr–S bond distances ranging from 3.03–3.07 Å. Se2- is bonded to six Sr2+ atoms to form SeSr6 octahedra that share corners with six equivalent SSr6 octahedra, edges with two equivalent SeSr6 octahedra, and edges with ten SSr6 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to six Sr2+ atoms to form SSr6 octahedra that share corners with three equivalent SeSr6 octahedra, corners with three equivalent SSr6 octahedra, edges with three equivalent SeSr6 octahedra, and edges with nine SSr6 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. In the second S2- site, S2- is bonded to six Sr2+ atoms to form SSr6 octahedra that share corners with six equivalent SSr6 octahedra, edges with four equivalent SeSr6 octahedra, and edges with eight SSr6 octahedra. The corner-sharing octahedral tilt angles are 2°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrEuSeS by Materials Project

SrEuSeS is alpha Po-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. Sr2+ is bonded to three equivalent Se2- and three equivalent S2- atoms to form SrSe3S3 octahedra that share corners with six equivalent EuSe3S3 octahedra, edges with six equivalent SrSe3S3 octahedra, and edges with six equivalent EuSe3S3 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. All Sr–Se bond lengths are 3.13 Å. All Sr–S bond lengths are 3.05 Å. Eu2+ is bonded to three equivalent Se2- and three equivalent S2- atoms to form EuSe3S3 octahedra that share corners with six equivalent SrSe3S3 octahedra, edges with six equivalent SrSe3S3 octahedra, and edges with six equivalent EuSe3S3 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. All Eu–Se bond lengths are 3.08 Å. All Eu–S bond lengths are 3.00 Å. Se2- is bonded to three equivalent Sr2+ and three equivalent Eu2+ atoms to form SeSr3Eu3 octahedra that share corners with six equivalent SSr3Eu3 octahedra, edges with six equivalent SeSr3Eu3 octahedra, and edges with six equivalent SSr3Eu3 octahedra. The corner-sharing octahedral tilt angles are 2°. S2- is bonded to three equivalent Sr2+ and three equivalent Eu2+ atoms to form SSr3Eu3 octahedra that share corners with six equivalent SeSr3Eu3 octahedra, edges with six equivalent SeSr3Eu3 octahedra, and edges with six equivalent SSr3Eu3 octahedra. The corner-sharing octahedral tilt angles are 2°.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Cubic Crystal Structure Formation and Optical Properties within the Ag–B II –M IV –X (B II = Sr, Pb; M IV = Si, Ge, Sn; X = S, Se) Family of Semiconductors

Quaternary chalcogenide semiconductors are promising materials for energy conversion and nonlinear optical applications, with properties tunable primarily by varying the elemental composition and crystal structure. Here, we first analyze the connections among several cubic crystal structure types, as well as the orthorhombic Ag 2 PbGeS 4 -type structure, reported for select members within the Ag–B II –M IV –X (B II = Sr, Pb; M IV = Si, Ge, Sn; X = S, Se) compositional space. Focusing on the Ag–Pb–Si–S and Ag–Sr–Sn–S systems, we show that one structure type, with the formulas Ag 2 Pb 3 Si 2 S 8 and Ag 2 Sr 3 Sn 2 S 8 , is favored. We have prepared powder and single-crystal samples of Ag 2 Pb 3 Si 2 S 8 and Ag 2 Sr 3 Sn 2 S 8 , showing that each takes on the noncentrosymmetric cubic space group I$\bar{43}$d and is isostructural to the previously reported compound Ag 2 Sr 3 Ge 2 Se 8 . Through hybrid density functional theory calculations, these cubic compounds are demonstrated to be (quasi-)direct band gap semiconductors with high densities of states at the band maxima. Furthermore, the band-gap energies are measured by reflectance spectroscopy as 1.95(3) and 2.66(4) eV for Ag 2 Pb 3 Si 2 S 8 and Ag 2 Sr 3 Sn 2 S 8 , respectively. We further measure the optical properties and show the electronic band structures of three other isostructural A I –B II –M IV –X-type materials, i.e., Ag 2 Sr 3 Si 2 S 8 , Ag 2 Sr 3 Ge 2 S 8 , and Ag 2 Sr 3 Ge 2 Se 8 , showing that the band gaps can be predictably tuned by element substitution. Detailed visual analyses of the different structures and of their relationships with other members of the Ag–B II –M IV –X compositional family provide a basis for a broader understanding of the structure formation and optoelectronic properties within the quaternary chalcogenide semiconductor family.

14 SOLAR ENERGY↗
DOE OSTI2020

Materials Data on KNb2PSe10 by Materials Project

KNb2PSe10 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Se+1.40- atoms. There are a spread of K–Se bond distances ranging from 3.47–3.86 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight Se+1.40- atoms. There are a spread of K–Se bond distances ranging from 3.47–3.93 Å. There are four inequivalent Nb4+ sites. In the first Nb4+ site, Nb4+ is bonded to eight Se+1.40- atoms to form distorted NbSe8 hexagonal bipyramids that share an edgeedge with one PSe4 tetrahedra and faces with two equivalent NbSe8 hexagonal bipyramids. There are a spread of Nb–Se bond distances ranging from 2.64–2.80 Å. In the second Nb4+ site, Nb4+ is bonded to eight Se+1.40- atoms to form distorted NbSe8 hexagonal bipyramids that share an edgeedge with one PSe4 tetrahedra and faces with two equivalent NbSe8 hexagonal bipyramids. There are a spread of Nb–Se bond distances ranging from 2.64–2.81 Å. In the third Nb4+ site, Nb4+ is bonded to eight Se+1.40- atoms to form distorted NbSe8 hexagonal bipyramids that share an edgeedge with one PSe4 tetrahedra and faces with two equivalent NbSe8 hexagonal bipyramids. There are a spread of Nb–Se bond distances ranging from 2.64–2.81 Å. In the fourth Nb4+ site, Nb4+ is bonded to eight Se+1.40- atoms to form NbSe8 hexagonal bipyramids that share an edgeedge with one PSe4 tetrahedra and faces with two equivalent NbSe8 hexagonal bipyramids. There are a spread of Nb–Se bond distances ranging from 2.63–2.81 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four Se+1.40- atoms to form PSe4 tetrahedra that share edges with two NbSe8 hexagonal bipyramids. There are a spread of P–Se bond distances ranging from 2.17–2.27 Å. In the second P5+ site, P5+ is bonded to four Se+1.40- atoms to form PSe4 tetrahedra that share edges with two NbSe8 hexagonal bipyramids. There are a spread of P–Se bond distances ranging from 2.18–2.27 Å. There are twenty inequivalent Se+1.40- sites. In the first Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to two Nb4+ and one Se+1.40- atom. The Se–Se bond length is 2.33 Å. In the second Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to one K1+, two Nb4+, and one Se+1.40- atom. The Se–Se bond length is 2.36 Å. In the third Se+1.40- site, Se+1.40- is bonded in a 4-coordinate geometry to one K1+, two Nb4+, and one Se+1.40- atom. In the fourth Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to two Nb4+ and one Se+1.40- atom. The Se–Se bond length is 2.33 Å. In the fifth Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to one K1+, two Nb4+, and one Se+1.40- atom. The Se–Se bond length is 2.37 Å. In the sixth Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to two Nb4+ and one Se+1.40- atom. In the seventh Se+1.40- site, Se+1.40- is bonded in a distorted L-shaped geometry to one K1+, one Nb4+, and one P5+ atom. In the eighth Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to one K1+, two Nb4+, and one Se+1.40- atom. In the ninth Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to one K1+, one Nb4+, and one P5+ atom. In the tenth Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to two Nb4+ and one Se+1.40- atom. In the eleventh Se+1.40- site, Se+1.40- is bonded in a 3-coordinate geometry to one K1+, one Nb4+, and one P5+ atom. In the twelfth Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to one K1+, one Nb4+, and one P5+ atom. In the thirteenth Se+1.40- site, Se+1.40- is bonded in a 4-coordinate geometry to one K1+, two Nb4+, and one Se+1.40- atom. The Se–Se bond length is 2.35 Å. In the fourteenth Se+1.40- site, Se+1.40- is bonded in a 3-coordinate geometry to two Nb4+ and one P5+ atom. In the fifteenth Se+1.40- site, Se+1.40- is bonded in a 4-coordinate geometry to one K1+, two Nb4+, and one Se+1.40- atom. In the sixteenth Se+1.40- site, Se+1.40- is bonded in a 4-coordinate geometry to one K1+, two Nb4+, and one Se+1.40- atom. The Se–Se bond length is 2.35 Å. In the seventeenth Se+1.40- site, Se+1.40- is bonded in a 3-coordinate geometry to two Nb4+ and one P5+ atom. In the eighteenth Se+1.40- site, Se+1.40- is bonded in a 4-coordinate geometry to one K1+, two Nb4+, and one Se+1.40- atom. In the nineteenth Se+1.40- site, Se+1.40- is bonded in a distorted L-shaped geometry to one K1+ and one P5+ atom. In the twentieth Se+1.40- site, Se+1.40- is bonded in a 1-coordinate geometry to two K1+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on InAgSe2 by Materials Project

AgInSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ag1+ is bonded to six equivalent Se2- atoms to form AgSe6 octahedra that share corners with six equivalent InSe6 octahedra, edges with six equivalent AgSe6 octahedra, and edges with six equivalent InSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Ag–Se bond lengths are 2.88 Å. In3+ is bonded to six equivalent Se2- atoms to form InSe6 octahedra that share corners with six equivalent AgSe6 octahedra, edges with six equivalent AgSe6 octahedra, and edges with six equivalent InSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. All In–Se bond lengths are 2.82 Å. Se2- is bonded to three equivalent Ag1+ and three equivalent In3+ atoms to form a mixture of corner and edge-sharing SeIn3Ag3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaBiSe2 by Materials Project

NaBiSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Na1+ is bonded to six equivalent Se2- atoms to form NaSe6 octahedra that share corners with six equivalent BiSe6 octahedra, edges with six equivalent NaSe6 octahedra, and edges with six equivalent BiSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Na–Se bond lengths are 3.06 Å. Bi3+ is bonded to six equivalent Se2- atoms to form BiSe6 octahedra that share corners with six equivalent NaSe6 octahedra, edges with six equivalent NaSe6 octahedra, and edges with six equivalent BiSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Bi–Se bond lengths are 2.98 Å. Se2- is bonded to three equivalent Na1+ and three equivalent Bi3+ atoms to form a mixture of corner and edge-sharing SeNa3Bi3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnPbSe2 by Materials Project

PbSnSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Pb2+ is bonded to six equivalent Se2- atoms to form PbSe6 octahedra that share corners with six equivalent SnSe6 octahedra, edges with six equivalent PbSe6 octahedra, and edges with six equivalent SnSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Pb–Se bond lengths are 3.10 Å. Sn2+ is bonded to six equivalent Se2- atoms to form SnSe6 octahedra that share corners with six equivalent PbSe6 octahedra, edges with six equivalent PbSe6 octahedra, and edges with six equivalent SnSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Sn–Se bond lengths are 3.04 Å. Se2- is bonded to three equivalent Pb2+ and three equivalent Sn2+ atoms to form a mixture of edge and corner-sharing SeSn3Pb3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗