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DOE OSTI2020

Materials Data on Sr3Sn4Bi by Materials Project

Sr3Sn4Bi crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. there are two inequivalent Sr sites. In the first Sr site, Sr is bonded in a 2-coordinate geometry to eight equivalent Sn and two equivalent Bi atoms. All Sr–Sn bond lengths are 3.56 Å. Both Sr–Bi bond lengths are 3.24 Å. In the second Sr site, Sr is bonded in a 8-coordinate geometry to six equivalent Sn and two equivalent Bi atoms. There are two shorter (3.46 Å) and four longer (3.67 Å) Sr–Sn bond lengths. Both Sr–Bi bond lengths are 3.36 Å. Sn is bonded in a 5-coordinate geometry to five Sr and three equivalent Sn atoms. There are two shorter (3.03 Å) and one longer (3.20 Å) Sn–Sn bond lengths. Bi is bonded to six Sr atoms to form corner-sharing BiSr6 octahedra. The corner-sharing octahedra tilt angles range from 0–38°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on EuCuSn by Materials Project

EuCuSn crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Eu is bonded in a 11-coordinate geometry to six equivalent Cu and six equivalent Sn atoms. There are a spread of Eu–Cu bond distances ranging from 3.14–3.63 Å. There are a spread of Eu–Sn bond distances ranging from 3.27–3.49 Å. Cu is bonded in a 10-coordinate geometry to six equivalent Eu, one Cu, and three equivalent Sn atoms. The Cu–Cu bond length is 2.66 Å. There are two shorter (2.69 Å) and one longer (2.92 Å) Cu–Sn bond lengths. Sn is bonded in a 10-coordinate geometry to six equivalent Eu, three equivalent Cu, and one Sn atom. The Sn–Sn bond length is 2.98 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaSr2(SnAs)6 by Materials Project

NaSr2(SnAs)6 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one NaSr2(SnAs)6 sheet oriented in the (0, 0, 1) direction. Na1+ is bonded to six equivalent As3- atoms to form NaAs6 octahedra that share edges with six equivalent SrAs6 octahedra. All Na–As bond lengths are 3.16 Å. Sr2+ is bonded to six equivalent As3- atoms to form SrAs6 octahedra that share edges with three equivalent NaAs6 octahedra and edges with three equivalent SrAs6 octahedra. All Sr–As bond lengths are 3.17 Å. There are two inequivalent Sn+2.17+ sites. In the first Sn+2.17+ site, Sn+2.17+ is bonded in a distorted T-shaped geometry to three equivalent As3- atoms. There are two shorter (2.78 Å) and one longer (2.79 Å) Sn–As bond lengths. In the second Sn+2.17+ site, Sn+2.17+ is bonded in a distorted T-shaped geometry to three equivalent As3- atoms. All Sn–As bond lengths are 2.78 Å. As3- is bonded to one Na1+, two equivalent Sr2+, and three Sn+2.17+ atoms to form a mixture of corner and edge-sharing AsNaSr2Sn3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnCl3O4 by Materials Project

SnO4Cl3 is alpha structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two SnO4Cl3 clusters. Sn is bonded in a 6-coordinate geometry to three O and three Cl atoms. There are a spread of Sn–O bond distances ranging from 2.10–2.14 Å. There are a spread of Sn–Cl bond distances ranging from 2.34–2.46 Å. There are four inequivalent O sites. In the first O site, O is bonded in a distorted water-like geometry to two equivalent Sn and one O atom. The O–O bond length is 1.79 Å. In the second O site, O is bonded in a single-bond geometry to one Sn atom. In the third O site, O is bonded in a bent 120 degrees geometry to two O atoms. The O–O bond length is 1.22 Å. In the fourth O site, O is bonded in a single-bond geometry to one O atom. There are three inequivalent Cl sites. In the first Cl site, Cl is bonded in a single-bond geometry to one Sn atom. In the second Cl site, Cl is bonded in a single-bond geometry to one Sn atom. In the third Cl site, Cl is bonded in a single-bond geometry to one Sn atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K8Zr3Si12SnO40 by Materials Project

K8Zr3SnSi12O40 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent K sites. In the first K site, K is bonded in a 6-coordinate geometry to six O atoms. There are a spread of K–O bond distances ranging from 2.81–3.28 Å. In the second K site, K is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of K–O bond distances ranging from 2.81–3.39 Å. In the third K site, K is bonded in a 5-coordinate geometry to five O atoms. There are a spread of K–O bond distances ranging from 2.81–3.00 Å. In the fourth K site, K is bonded in a 6-coordinate geometry to five O atoms. There are a spread of K–O bond distances ranging from 2.77–2.93 Å. In the fifth K site, K is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of K–O bond distances ranging from 2.85–3.09 Å. In the sixth K site, K is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of K–O bond distances ranging from 2.87–3.11 Å. In the seventh K site, K is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of K–O bond distances ranging from 2.86–3.12 Å. In the eighth K site, K is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of K–O bond distances ranging from 2.87–3.15 Å. There are three inequivalent Zr sites. In the first Zr site, Zr is bonded to six O atoms to form ZrO6 octahedra that share corners with six SiO4 tetrahedra. There are a spread of Zr–O bond distances ranging from 2.06–2.20 Å. In the second Zr site, Zr is bonded to six O atoms to form ZrO6 octahedra that share corners with six SiO4 tetrahedra. There are a spread of Zr–O bond distances ranging from 2.07–2.18 Å. In the third Zr site, Zr is bonded to six O atoms to form ZrO6 octahedra that share corners with six SiO4 tetrahedra. There are a spread of Zr–O bond distances ranging from 2.07–2.21 Å. Sn is bonded to six O atoms to form SnO6 octahedra that share corners with six SiO4 tetrahedra. There are a spread of Sn–O bond distances ranging from 2.04–2.16 Å. There are twelve inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two ZrO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–55°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one ZrO6 octahedra, a cornercorner with one SnO6 octahedra, and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–54°. There is one shorter (1.61 Å) and three longer (1.66 Å) Si–O bond length. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one ZrO6 octahedra, a cornercorner with one SnO6 octahedra, and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–57°. There is one shorter (1.61 Å) and three longer (1.66 Å) Si–O bond length. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two ZrO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–55°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. In the fifth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one ZrO6 octahedra, a cornercorner with one SnO6 octahedra, and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–45°. There are a spread of Si–O bond distances ranging from 1.63–1.67 Å. In the sixth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two ZrO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–44°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the seventh Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one ZrO6 octahedra, a cornercorner with one SnO6 octahedra, and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 42–46°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the eighth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two ZrO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–45°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the ninth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one ZrO6 octahedra, a cornercorner with one SnO6 octahedra, and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 45–48°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. In the tenth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two ZrO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 45–46°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. In the eleventh Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one ZrO6 octahedra, a cornercorner with one SnO6 octahedra, and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–48°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. In the twelfth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two ZrO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–45°. There is two shorter (1.62 Å) and two longer (1.66 Å) Si–O bond length. There are forty inequivalent O sites. In the first O site, O is bonded in an L-shaped geometry to two K atoms. In the second O site, O is bonded in an L-shaped geometry to two K atoms. In the third O site, O is bonded in an L-shaped geometry to two K atoms. In the fourth O site, O is bonded in an L-shaped geometry to two K atoms. In the fifth O site, O is bonded in a 2-coordinate geometry to one K, one Sn, and one Si atom. In the sixth O site, O is bonded in a distorted bent 150 degrees geometry to one K, one Zr, and one Si atom. In the seventh O site, O is bonded in a distorted bent 150 degrees geometry to one K, one Zr, and one Si atom. In the eighth O site, O is bonded in a distorted bent 150 degrees geometry to one K, one Zr, and one Si atom. In the ninth O site, O is bonded in a distorted bent 120 degrees geometry to one K, one Sn, and one Si atom. In the tenth O site, O is bonded in a distorted bent 120 degrees geometry to one K, one Zr, and one Si atom. In the eleventh O site, O is bonded in a distorted bent 120 degrees geometry to one Zr and one Si atom. In the twelfth O site, O is bonded in a distorted bent 120 degrees geometry to one Zr and one Si atom. In the thirteenth O site, O is bonded in a 4-coordinate geometry to two K, one Sn, and one Si atom. In the fourteenth O site, O is bonded in a 4-coordinate geometry to two K, one Zr, and one Si atom. In the fifteenth O site, O is bonded in a 4-coordinate geometry to two K, one Zr, and one Si atom. In the sixteenth O site, O is bonded in a 4-coordinate geometry to two K, one Zr, and one Si atom. In the seventeenth O site, O is bonded in a 4-coordinate geometry to two K, one Sn, and one Si atom. In the eighteenth O site, O is bonded in a 2-coordinate geometry to two K, one Zr, and one Si atom. In the nineteenth O site, O is bonded in a 2-coordinate geometry to two K, one Zr, and one Si atom. In the twentieth O site, O is bonded in a 2-coordinate geometry to two K, one Zr, and one Si atom. In the twenty-first O site, O is bonded in a 3-coordinate geometry to one K, one Sn, and one Si atom. In the twenty-second O site, O is bonded in a 3-coordinate geometry to one K, one Zr, and one Si atom. In the twenty-third O site, O is bonded in a 3-coordinate geometry to one K, one Zr, and one Si atom. In the twenty-fourth O site, O is bonded in a 3-coordinate geometry to one K, one Zr, and one Si atom. In the twenty-fifth O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the twenty-sixth O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the twenty-seventh O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the twenty-eighth O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the twenty-ninth O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the thirtieth O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the thirty-first O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the thirty-second O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the thirty-third O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the thirty-fourth O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the thirty-fifth O site, O is bonded in a distorted bent 120 degrees geometry to two K and two Si atoms. In the thirty-sixth O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Si atoms. In the thirty-seventh O site, O is bonded in a 3-coordinate geometry to one K, one Sn, and one Si atom. In the thirty-eighth O site, O is bonded in a 3-coordinate geometry to one K, one Zr, and one Si atom. In the thirty-ninth O site, O is bonded in a 2-coordinate geometry to one K, one Zr, and one Si atom. In the fortieth O site, O is bonded in a 3-coordinate geometry to one K, one Zr, and one Si atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na4Sn2Ge5O17 by Materials Project

Na4Sn2Ge5O17 crystallizes in the monoclinic P2/c space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 5-coordinate geometry to five O atoms. There are a spread of Na–O bond distances ranging from 2.30–2.55 Å. In the second Na site, Na is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Na–O bond distances ranging from 2.40–2.87 Å. Sn is bonded to six O atoms to form SnO6 octahedra that share corners with six GeO4 tetrahedra. There are a spread of Sn–O bond distances ranging from 2.07–2.12 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded to four O atoms to form GeO4 tetrahedra that share corners with two equivalent SnO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedral tilt angles are 42°. There is two shorter (1.75 Å) and two longer (1.79 Å) Ge–O bond length. In the second Ge site, Ge is bonded to four O atoms to form GeO4 tetrahedra that share corners with three equivalent SnO6 octahedra and a cornercorner with one GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–55°. There are a spread of Ge–O bond distances ranging from 1.76–1.82 Å. In the third Ge site, Ge is bonded to four O atoms to form GeO4 tetrahedra that share corners with two equivalent SnO6 octahedra and corners with two GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–54°. There are a spread of Ge–O bond distances ranging from 1.76–1.81 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a distorted trigonal planar geometry to one Na, one Sn, and one Ge atom. In the second O site, O is bonded to two equivalent Na, one Sn, and one Ge atom to form distorted edge-sharing ONa2SnGe trigonal pyramids. In the third O site, O is bonded in a 3-coordinate geometry to one Na and two Ge atoms. In the fourth O site, O is bonded in a trigonal planar geometry to one Na and two Ge atoms. In the fifth O site, O is bonded in a 3-coordinate geometry to two equivalent Na, one Sn, and one Ge atom. In the sixth O site, O is bonded in a distorted T-shaped geometry to one Na, one Sn, and one Ge atom. In the seventh O site, O is bonded in an L-shaped geometry to two equivalent Na atoms. In the eighth O site, O is bonded in a distorted trigonal planar geometry to one Na, one Sn, and one Ge atom. In the ninth O site, O is bonded in a distorted trigonal planar geometry to one Na, one Sn, and one Ge atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2Sn by Materials Project

Na2Sn crystallizes in the tetragonal I4_1/acd space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 3-coordinate geometry to four equivalent Sn atoms. There are a spread of Na–Sn bond distances ranging from 3.21–3.67 Å. In the second Na site, Na is bonded in a 4-coordinate geometry to four equivalent Sn atoms. There are a spread of Na–Sn bond distances ranging from 3.36–3.41 Å. Sn is bonded in a 9-coordinate geometry to eight Na and one Sn atom. The Sn–Sn bond length is 2.88 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(CuSn)2 by Materials Project

SrCu2Sn2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Sr is bonded in a 10-coordinate geometry to six equivalent Cu and eight equivalent Sn atoms. There are two shorter (3.22 Å) and four longer (3.38 Å) Sr–Cu bond lengths. There are four shorter (3.53 Å) and four longer (3.72 Å) Sr–Sn bond lengths. Cu is bonded in a 9-coordinate geometry to three equivalent Sr, two equivalent Cu, and four equivalent Sn atoms. Both Cu–Cu bond lengths are 2.59 Å. There are a spread of Cu–Sn bond distances ranging from 2.64–2.70 Å. Sn is bonded in a 9-coordinate geometry to four equivalent Sr, four equivalent Cu, and one Sn atom. The Sn–Sn bond length is 3.15 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Uncooled GeSn MWIR Photodetectors Using Fully Relaxed Thin Triple‐Step Buffer

GeSn photodetectors monolithically grown on Ge virtual substrates demonstrate mid-wave infrared (MWIR) detection at room temperature. The lattice mismatch between GeSn and Ge causes dislocations and compressive strain, creating leakage pathways and unwanted indirect band transitions. Designed thin Ge 0.91 Sn 0.09 triple-step buffer layers of ≈175 nm total thickness reduce dislocations and enable full relaxation, showing 100% lattice relaxation and smooth surface roughness of 0.83 nm with shorter auto-correlation length in surface morphology compared to single-step buffers. Ge 1-x Sn x photodetectors (x = 0.09, 0.12, and 0.15) on triple-step buffers with n-i-p configurations achieve lattice strain relaxations of 99%, 88%, and 80%, respectively. Ge 0.91 Sn 0.09 and Ge 0.88 Sn 0.12 show gradual variation in auto-correlation amplitude, while Ge 0.85 Sn 0.15 shows an increase due to lattice mismatch. Shockley–Read–Hall recombination current dominates at low reverse bias due to mismatch-induced dislocations, while band-to-band tunneling current dominates at higher reverse bias due to narrowing bandgap under strong electric fields. Here, the photodetectors show extended spectral response with increasing Sn composition of i-GeSn active layer sandwiched by barriers. Ge 0.88 Sn 0.12 and Ge 0.85 Sn 0.15 exhibit extended wavelength cut-offs of 3.12 and 3.27 µm at room temperature, demonstrating significant potential for silicon-based MWIR applications.

GeSn↗
DOE OSTI2025

Twisted Tin‐Chloride Perovskite Single‐Crystal Heterostructures

Self-assembly affords simpler synthetic routes to heterostructures compared with manual layer-by-layer stacking, yet controlling interlayer twist angles in a bulk solid remains an outstanding challenge. We report two new single-crystal heterostructures: (Sn 2 Cl 2 )(CYS) 2 SnCl 4 (CYS = + NH 3 (CH 2 ) 2 S – ; Sn_CYS) and (Sn 2 Cl 2 )(SeCYS) 2 SnCl 4 (SeCYS = + NH 3 (CH 2 ) 2 Se – ; Sn_SeCYS) synthesized in solution, with alternating perovskite and intergrowth layers. Notably, compared to the recently reported lead analog, (Pb 2 Cl 2 )(CYS) 2 PbCl 4 (Pb_CYS), the tin heterostructures feature a twist between the perovskite and intergrowth layers. We trace this twist to local distortions at the Sn centers, which change the interfacial lattice-matching requirements compared to those of the Pb analog. Electronic band structure calculations show that the striking differences in the relative energies of perovskite- and intergrowth-derived bands in Sn_CYS and Pb_CYS arise from structural and not compositional differences. The structural anisotropy of Sn_CYS is also reflected in a large in-plane photoluminescence linear anisotropy ratio. Interfacial strain further affords differential incorporation of Pb into the perovskite and intergrowth layers of the Sn heterostructures, resulting in redshifted optical absorption onsets. Thus, we posit that local structural distortions may be exploited to manipulate the twist angle and interfacial strain in bulk heterostructures, providing a new handle for tuning the band alignments of bulk quantum-well electronic structures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Semiconductor-compatible topological digital alloys

Recently, GeSn alloys have attracted much interest for direct-gap infrared photonics and as potential topological materials which are compatible with the semiconductor industry. However, for photonics, the high-Sn content required leads to low detectivity, associated with poor material quality, and the (>35 %) Sn required for topological properties have been out of reach experimentally. Here, we demonstrate that by patterning the Sn distribution within Ge, the electronic properties have a far greater tunability than is possible with the random alloy. For the GeSn δ-digital alloy (DA) formed by confining Sn atoms in atomic layer(s) along the [111] direction of Ge, we show that ∼ 10 % Sn can lead to a triple-point semimetal. These findings are understood in terms of Sn ordering causing spatial separation of Sn and Ge band edges, leading to band inversion. This mechanism can also lead to a weak topological insulator, Weyl semimetal, and enables tunable direct bandgaps down to 2 meV, covering the entire infrared range. This DA induced topological properties are also identified in compound semiconductors, such as InAs 1-x Sb x , showing the general applicability of the DA design for realizing topological properties on conventional semiconductor platforms. Furthermore, our findings not only point to a new class of currently unexplored topological systems accessible by epitaxy, but also establish the promise of low-Sn GeSn DAs for application as infrared laser diodes and photodetectors in Si photonic integrated circuits and infrared image sensors.

3D topological semimetal↗
DOE OSTI2022

Understanding the Surface Structure and Catalytic Activity of SnO x /Au(111) Inverse Catalysts for CO 2 and H 2 Activation

Carbon dioxide hydrogenation is a promising approach for the reduction of greenhouse gas pollution via the production of fuels and high-value chemicals utilizing C1 chemistry. In this process, the activation of nonpolar molecules, CO 2 and H 2 , at mild conditions is challenging. In this study, we report a well-defined inverse SnO x /Au(111) catalyst that shows the ability to activate both CO 2 and H 2 at room temperature. Scanning tunneling microscopy (STM) and ambient pressure X-ray photoemission spectroscopy (AP-XPS) are combined to understand the surface structure, growth mode, chemical state, and activity of SnO x /Au(111) surfaces. Nanostructures of SnO x at the sub-monolayer level were prepared by depositing Sn on Au(111) followed by O 2 oxidation. For the as-prepared SnO x /Au(111), two-dimensionally formed SnO x thin films on a Au(111) substrate were observed with STM of two different moieties, discernible based on their height: clusters (~0.4 Å) and nanoparticles (NPs, 1–2.5 Å), which are assigned to Sn–Au alloys and SnO x , respectively, in corroboration with XPS analysis. Furthermore, SnO x /Au(111) was annealed under UHV to test its thermal stability. Upon annealing at 400–600 K, a disappearance of SnO x NPs and reappearance of highly dispersed Sn clusters were clearly noticeable from the STM and XPS results, identifying the thermal decomposition of SnO x and subsequent formation of Sn–Au alloys on the surface due to the recombination of Sn clusters with Au. We investigated the reactivity of the SnO x /Au(111) surfaces toward CH 4 , CO 2 , and H 2 . The SnO x /Au(111) surfaces have excellent CO 2 and H 2 activation abilities even at room temperature with negligible reactivity for methane activation. Our AP-XPS results show that H 2 can be activated on the SnO x NPs by the reduction to Sn. For CO 2 , the activation and further dissociation are identified by a reoxidation of Sn with newly formed Sn–O bonds and the formation of surface carbon. Therefore, we propose that SnO x is a potential catalyst or additive to achieve CO 2 hydrogenation under mild conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Evaluation of Getter Metals in Na–Al–Si–O Aerogels and Xerogels for the Capture of Iodine Gas

In this paper, sodium aluminosilicate aerogels and xerogels were evaluated as scaffolds for a variety of different getters including: Ag + , Cs + , Cu 2+ , Fe 3+ , K + , Li + , Rb + , Sb 3+ , Sn 2+ , and Sn 4+ . The exchange capacities varied widely from a near complete exchange in the case of Ag + to much lower exchange levels for some of the Sn compounds [i.e., colloidal SnO 2 , Sn(II) acetate, Sn(IV) acetate]. Several of the additives showed great promise at allowing for high iodine loadings in the base materials including the following: AgNO 3 , colloidal SnO 2 , Sn(II) acetate, Sn(IV) acetate, Cu(NO 3 ) 2 , and CuSO 4 . From the standpoint of iodine uptake as a function of getter loading, the Sn4+ showed the most promise with a getter utilization (mass of iodine divided by mass of Sn, in atomic%) of 8.4, a chemical uptake of 60.7 mass% (oxygen excluded), and an mI $m_s^{-1}$ value of 0.881; these are some of the highest values reported to date for inorganic iodine sorbents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Electrochemical Corrosion and Catalysis Dynamics of Tin Oxide during Water Oxidation

Metal oxide corrosion severely limits anodic electrocatalysis, particularly at high potentials in acidic environments, where degradation pathways remain poorly defined. This study establishes explicit connections between corrosion and electrocatalysis on tin oxide during water oxidation by examining the roles of lattice defects, reactive oxygen species, interfacial pH variations, and speciation of corroded tin in acid. We first demonstrate the presence of structural defects such as oxygen vacancies and substoichiometric Sn(II) species by integrating electron paramagnetic resonance spectroscopy, ultraviolet photoelectron spectroscopy, and Mott–Schottky analysis. Kohn–Sham density functional theory calculations reveal that explicit water structures thermodynamically stabilize reaction intermediates and lower reaction overpotentials. Moreover, we propose that water dissociation leads to hydrogen-bonding networks formed by H* and OH* intermediates, which may span the entire catalyst surface and decrease the interfacial pH to drive corrosion. In contrast, the electrochemical generation of reactive oxygen species is shown to play a minor role in catalyst corrosion during water oxidation using inductively coupled plasma mass spectrometry coupled with selective chemical scavengers. Square-wave voltammetry combined with rotating ring-disk electrodes is used to reveal that under open-circuit conditions, only Sn(IV) cations chemically dissolve from tin oxide, while both Sn(IV) and Sn(II) species electrochemically corrode during water oxidation. Our results unveil a dynamic and complicated interplay between corrosive and catalytic pathways on metal oxide electrocatalysts: a decrease in interfacial pH due to water oxidation exacerbates Sn(II)/Sn(IV) corrosion. Subsequently, the electrochemical corrosion of Sn(II)/Sn(IV) facilitates product formation from lattice oxygen, while the redeposition of corroded Sn(II) as Sn(IV) can enable oxygen exchange with water. By elucidating the roles of defects and interfacial chemistry, this work provides a roadmap for engineering improved electrocatalysts that balance activity and stability, a critical step toward scalable and durable energy technologies.

36 MATERIALS SCIENCE↗
DOE OSTI2020

BSE versus StarTrack: Implementations of new wind, remnant-formation, and natal-kick schemes in NBODY7 and their astrophysical consequences

As a result of their formation via massive single and binary stellar evolution, the masses of stellar-remnant black holes (BH) are subjects of great interest in this era of gravitational-wave detection from binary black hole (BBH) and binary neutron star merger events. In this work, we present new developments in the stellar-remnant formation and related schemes of the current N-body evolution program NBODY7. We demonstrate that the newly implemented stellar-wind and remnant-formation schemes in the stellar-evolutionary sector or BSE of the NBODY7 code, such as the “rapid” and the “delayed” supernova (SN) schemes along with an implementation of pulsational-pair-instability and pair-instability supernova (PPSN/PSN), now produce neutron star (NS) and BH masses that agree nearly perfectly, over large ranges of zero-age-main-sequence (ZAMS) mass and metallicity, with those from the widely recognised StarTrack population-synthesis program. We also demonstrate the new, recipe-based implementations of various widely debated mechanisms of natal kicks on NSs and BHs, such as “convection-asymmetry-driven”, “collapse-asymmetry-driven”, and “neutrino-emission-driven” kicks, in addition to a fully consistent implementation of the standard, fallback-dependent, momentum-conserving natal kick. All the above newly implemented schemes are also shared with the standalone versions of SSE and BSE. Furthermore, all these demonstrations are performed with both the updated standalone BSE and the updated NBODY7/BSE. When convolved with stellar and primordial-binary populations as observed in young massive clusters, such remnant-formation and natal-kick mechanisms crucially determine the accumulated number, mass, and mass distribution of the BHs retained in young massive, open, and globular clusters (GCs); these BHs would eventually become available for long-term dynamical processing. Among other conclusions, we find that although the newer, delayed SN remnant formation model gives birth to the largest number (mass) of BHs, the older remnant-formation schemes cause the largest number (mass) of BHs to survive in clusters, when incorporating SN material fallback onto the BHs. The SN material fallback also causes the convection-asymmetry-driven SN kick to effectively retain similar numbers and masses of BHs in clusters as for the standard, momentum-conserving kick. The collapse-asymmetry-driven SN kick would cause nearly all BHs to be retained in clusters irrespective of their mass, remnant-formation model, and metallicity, whereas the inference of a large population of BHs in GCs would potentially rule out the neutrino-driven SN kick mechanism. Pre-SN mergers of massive primordial binaries would potentially cause BH masses to deviate from the theoretical, single-star ZAMS to mass-remnant mass relation unless a substantial of the total merging stellar mass of up to ≈40% is lost during a merger process. In particular, such mergers, at low metallicities, have the potential to produce low-spinning BHs within the PSN mass gap that can be retained in a stellar cluster and be available for subsequent dynamical interactions. As recent studies indicate, the new remnant-formation modelling reassures us that young massive and open clusters would potentially contribute to the dynamical BBH merger detection rate to a similar extent as their more massive GC counterparts.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

HOLISMOKES XIX

We present imaging and spectroscopic observations of supernova SN 2025wny, associated with the lens candidate PS1 J0716+3821. Photometric monitoring from the Lulin and Maidanak observatories confirms multiple point-like images, consistent with SN 2025wny being strongly lensed by two foreground galaxies. Optical spectroscopy of the brightest image with the Nordic Optical Telescope and the University of Hawaii 88-inch Telescope allowed us to determine the redshift to be z SN = 2.008 ± 0.001, based on narrow absorption lines originating in the interstellar medium of the supernova host galaxy. At this redshift, SN 2025wny shows a very high rest-frame UV flux and broad spectral features even weeks after the explosion, which is consistent with superluminous supernovae of Type I. We find a high ejecta temperature and depressed spectral lines compared to other similar objects. We also measured, for the first time, the redshift of the fainter of the two lens galaxies (the ‘perturber’) to be z p = 0.375 ± 0.001, which is fully consistent with the DESI spectroscopic redshift of the main deflector at z d = 0.3754. Thus, SN 2025wny represents the first confirmed galaxy-scale strongly lensed supernova with time delays likely in the range of days to weeks, as judged from the image separations. This makes SN 2025wny suitable for cosmography, offering a promising new system for independent measurements of the Hubble constant. Following a tradition in the field of strongly lensed supernovae, we give SN 2025wny the nickname SN Winny.

Taubenberger, Stefan↗
DOE OSTI2021

Rates and delay times of type Ia supernovae in the Dark Energy Survey

We use a sample of 809 photometrically classified Type Ia supernovae (SNe Ia) discovered by the Dark Energy Survey (DES) along with 40 415 field galaxies to calculate the rate of SNe Ia per galaxy in the redshift range 0.2 < z < 0.6. We recover the known correlation between SN Ia rate and galaxy stellar mass across a broad range of scales 8.5 ≤ log (M*/M ⊙ ) ≤ 11.25. We find that the SN Ia rate increases with stellar mass as a power law with index 0.63 ± 0.02, which is consistent with the previous work. We use an empirical model of stellar mass assembly to estimate the average star formation histories (SFHs) of galaxies across the stellar mass range of our measurement. Combining the modelled SFHs with the SN Ia rates to estimate constraints on the SN Ia delay time distribution (DTD), we find that the data are fit well by a power-law DTD with slope index β = –1.13 ± 0.05 and normalization A = 2.11 ± 0.05 × 10 –13 SNe M ⊙ –1 yr –1 , which corresponds to an overall SN Ia production efficiency N Ia /M * = 0.9 $^{+4.0}_{–0.7}$ × 10 –3 SNe M$^{–1}_{⊙}$. Upon splitting the SN sample by properties of the light curves, we find a strong dependence on DTD slope with the SN decline rate, with slower-declining SNe exhibiting a steeper DTD slope. We interpret this as a result of a relationship between intrinsic luminosity and progenitor age, and explore the implications of the result in the context of SN Ia progenitors.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

The Lick Observatory Supernova Search follow-up program: photometry data release of 70 SESNe

We present BVRI and unfiltered (Clear) light curves of 70 stripped-envelope supernovae (SESNe), observed between 2003 and 2020, from the Lick Observatory Supernova Search follow-up program. Our SESN sample consists of 19 spectroscopically normal SNe Ib, 2 peculiar SNe Ib, six SNe Ibn, 14 normal SNe Ic, 1 peculiar SN Ic, 10 SNe Ic-BL, 15 SNe IIb, 1 ambiguous SN IIb/Ib/c, and 2 superluminous SNe. Our follow-up photometry has (on a per-SN basis) a mean coverage of 81 photometric points (median of 58 points) and a mean cadence of 3.6 d (median of 1.2 d). From our full sample, a subset of 38 SNe have pre-maximum coverage in at least one passband, allowing for the peak brightness of each SN in this subset to be quantitatively determined. We describe our data collection and processing techniques, with emphasis toward our automated photometry pipeline, from which we derive publicly available data products to enable and encourage further study by the community. Using these data products, we derive host-galaxy extinction values through the empirical colour evolution relationship and, for the first time, produce accurate rise-time measurements for a large sample of SESNe in both optical and infrared passbands. By modelling multiband light curves, we find that SNe Ic tend to have lower ejecta masses and lower ejecta velocities than SNe Ib and IIb, but higher 56Ni masses.

Lick Observatory↗