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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ca(SiNi)2 by Materials Project

Ca(NiSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ca2+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Ca–Si bond lengths are 3.08 Å. Ni3+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.31 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Ca2+, four equivalent Ni3+, and one Si4- atom. The Si–Si bond length is 2.50 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(SiNi)2 by Materials Project

Th(NiSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Th4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Th–Si bond lengths are 3.14 Å. Ni2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.34 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Th4+, four equivalent Ni2+, and one Si4- atom. The Si–Si bond length is 2.47 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La3(SiNi)4 by Materials Project

La3Ni4Si4 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are two shorter (3.12 Å) and four longer (3.17 Å) La–Si bond lengths. In the second La3+ site, La3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All La–Si bond lengths are 3.18 Å. There are two inequivalent Ni+1.75+ sites. In the first Ni+1.75+ site, Ni+1.75+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. There are two shorter (2.37 Å) and two longer (2.38 Å) Ni–Si bond lengths. In the second Ni+1.75+ site, Ni+1.75+ is bonded in a trigonal planar geometry to three Si4- atoms. There are two shorter (2.35 Å) and one longer (2.39 Å) Ni–Si bond lengths. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent La3+ and five Ni+1.75+ atoms. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to six La3+, two equivalent Ni+1.75+, and one Si4- atom. The Si–Si bond length is 2.45 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf(SiNi)2 by Materials Project

Hf(NiSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Hf4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Hf–Si bond lengths are 2.89 Å. Ni2+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.26 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Hf4+, four equivalent Ni2+, and one Si4- atom. The Si–Si bond length is 2.31 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(SiNi)2 by Materials Project

Np(NiSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Np–Si bond lengths are 3.00 Å. Ni2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.31 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Np4+, four equivalent Ni2+, and one Si4- atom. The Si–Si bond length is 2.33 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La(SiNi)2 by Materials Project

LaNi2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. La3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All La–Si bond lengths are 3.18 Å. Ni+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.35 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent La3+, four equivalent Ni+2.50+, and one Si4- atom. The Si–Si bond length is 2.56 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Yb(SiNi)2 by Materials Project

YbNi2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Yb3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Yb–Si bond lengths are 3.07 Å. Ni+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.30 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Yb3+, four equivalent Ni+2.50+, and one Si4- atom. The Si–Si bond length is 2.45 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zr(SiNi)2 by Materials Project

Zr(NiSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Zr4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Zr–Si bond lengths are 2.90 Å. Ni2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.27 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Zr4+, four equivalent Ni2+, and one Si4- atom. The Si–Si bond length is 2.33 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SiNi by Materials Project

NiSi is gamma CuTi structured and crystallizes in the orthorhombic Pmmn space group. The structure is three-dimensional. Ni4+ is bonded in a 6-coordinate geometry to six equivalent Si4- atoms. There are a spread of Ni–Si bond distances ranging from 2.34–2.39 Å. Si4- is bonded in a 10-coordinate geometry to six equivalent Ni4+ and four equivalent Si4- atoms. All Si–Si bond lengths are 2.67 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SiNi by Materials Project

NiSi crystallizes in the cubic P2_13 space group. The structure is three-dimensional. Ni4+ is bonded in a 7-coordinate geometry to seven equivalent Si4- atoms. There are a spread of Ni–Si bond distances ranging from 2.36–2.44 Å. Si4- is bonded in a 7-coordinate geometry to seven equivalent Ni4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce3(SiNi)4 by Materials Project

Ce3Ni4Si4 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Ce3+ sites. In the first Ce3+ site, Ce3+ is bonded to six Si4- atoms to form distorted CeSi6 pentagonal pyramids that share corners with four equivalent CeSi6 pentagonal pyramids, corners with eight equivalent NiSi4 tetrahedra, edges with two equivalent CeSi6 pentagonal pyramids, edges with four equivalent NiSi4 tetrahedra, and faces with two equivalent CeSi6 pentagonal pyramids. All Ce–Si bond lengths are 3.06 Å. In the second Ce3+ site, Ce3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Ce–Si bond lengths are 3.08 Å. There are two inequivalent Ni+1.75+ sites. In the first Ni+1.75+ site, Ni+1.75+ is bonded in a trigonal planar geometry to three Si4- atoms. There are two shorter (2.30 Å) and one longer (2.36 Å) Ni–Si bond lengths. In the second Ni+1.75+ site, Ni+1.75+ is bonded to four equivalent Si4- atoms to form NiSi4 tetrahedra that share corners with eight equivalent CeSi6 pentagonal pyramids, corners with four equivalent NiSi4 tetrahedra, edges with four equivalent CeSi6 pentagonal pyramids, and edges with four equivalent NiSi4 tetrahedra. There are two shorter (2.34 Å) and two longer (2.38 Å) Ni–Si bond lengths. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Ce3+ and five Ni+1.75+ atoms. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to six Ce3+, two equivalent Ni+1.75+, and one Si4- atom. The Si–Si bond length is 2.39 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y3(SiNi)2 by Materials Project

Y3(NiSi)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Y sites. In the first Y site, Y is bonded in a 7-coordinate geometry to two equivalent Ni and five equivalent Si atoms. Both Y–Ni bond lengths are 2.79 Å. There are four shorter (2.98 Å) and one longer (3.08 Å) Y–Si bond lengths. In the second Y site, Y is bonded to eight equivalent Ni and four equivalent Si atoms to form a mixture of edge and face-sharing YSi4Ni8 cuboctahedra. All Y–Ni bond lengths are 3.12 Å. All Y–Si bond lengths are 3.12 Å. Ni is bonded in a 9-coordinate geometry to six Y, one Ni, and two equivalent Si atoms. The Ni–Ni bond length is 2.36 Å. Both Ni–Si bond lengths are 2.34 Å. Si is bonded in a 9-coordinate geometry to seven Y and two equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

A New Family of Ternary Intermetallic Compounds with Dualistic Atomic Ordering – The ZIP Phases

A new family of nanostructured ternary intermetallic compounds − named the ZIP phases − is introduced in this work. The ZIP phases exhibit dualistic atomic ordering, i.e., they form two structural variants: one with the fcc diamond cubic structure (space group Fd$\bar{3}$m) and one with the hexagonal structure (space group P6 3 /mmc). They are also characterized by metallic behavior, ionic bonding, and atomic zigzagging. Powder metallurgical routes involving pressure-assisted densification are adopted to demonstrate ZIP phase synthesis in the Nb-Si-Ni, Nb-Si-Co, Ta-Si-Ni, V-Si-Ni, and Nb-Si-Fe ternary systems. Crucially, reactive hot pressing is capable of producing high-purity ZIP phase materials after the judicious, elemental system-specific optimization of the processing route. Synthesis of phase-pure materials – demonstrated in the Nb-Si-Ni ternary system by the synthesis of quasi phase-pure Nb 3 SiNi 2 and Ni 3 SiNb 2 ZIP phase-based materials – is a steppingstone to the prospective exploitation of the ZIP phases. Characterization of Nb 3 SiNi 2 and Ni 3 SiNb 2 involves crystal structure determination, spatially resolved chemical analysis, and determination of select thermal, electrical, magnetic, mechanical, and physical properties. Density functional theory is used to assess the stability of Nb 3 SiNi 2 & Ni 3 SiNb 2 and derivative binary compounds at different temperatures, also exploring the exfoliation of these two ZIP phases along specific surfaces to produce 2D derivatives.

Intermetallic compounds (IMCs)↗
DOE OSTI2025

Microwave Annealing for Fast and Effective Hydrogen Activation in Polycrystalline Silicon Passivating Contacts

Hydrogenation is a crucial step in the fabrication of high-efficiency silicon solar cells. In this study, the effectiveness of hydrogen activation is demonstrated via microwave annealing of hydrogen-rich dielectrics coated on poly-Si passivating contacts. This method is compared with conventional hydrogenation techniques, such as annealing in N2 in the presence of a hydrogen-rich source (such as hydrogenated aluminum oxide (AlOx:H), hydrogenated silicon nitride (SiNy:H), or a AlOx:H/SiNy:H stack). Key improvements observed include a reduction in J0 from 30 to <5 fA cm-2, an increase in iVoc from 690 to >730 mV, and an enhancement in effective lifetime (teff) from 0.6 to ~3.5 milliseconds on phosphorus-doped poly-Si/SiO2 passivating contact samples. With a very short annealing time of ~1-2 min, the samples passivated by AlOx:H, SiNy:H, or the stack show similar performance to samples subjected to 30 min of nitrogen annealing. Photoluminescence (PL) spectra corroborate the findings regarding the hydrogenation of the poly-Si layer and the c-Si substrate, with an increase in PL intensity after microwave annealing. Ultimately, this work suggests that microwave annealing could be a promising addition, offering flexibility to traditional firing hydrogenation processes.

hydrogenation↗
DOE OSTI2025

Poly-Si Passivating Contacts Hydrogenation by Microwave Annealing

Hydrogenation is a crucial step in the fabrication of high-efficiency silicon solar cells. In this study, we demonstrate the for the first time effectiveness of hydrogen activation via microwave annealing of hydrogen-rich dielectrics coated on poly-Si passivating contacts. This method is compared with conventional hydrogenation techniques, such as annealing in N2 in the presence of a hydrogen-rich source (such as hydrogenated aluminum oxide (AlOx:H), hydrogenated silicon nitride (SiNy:H), or a AlOx:H/SiNy:H stack). Key improvements observed include a reduction in J0 from 30 to <5 fA/cm2, an increase in iVoc from 690 to >730 mV, and an enhancement in effective lifetime (teff) from 0.6 to ~3.5 milliseconds on phosphorus-doped poly-Si/SiO2 passivating contact samples. With a very short annealing time of ~1-2 minutes, the samples passivated by AlOx:H, SiNy:H, or the stack show similar performance to samples subjected to 30 minutes of nitrogen annealing. Photoluminescence (PL) spectra corroborate our findings regarding the hydrogenation of the poly-Si layer and the c-Si substrate, with an increase in PL intensity after microwave annealing. Ultimately, our work suggests that microwave annealing could be a promising addition, offering flexibility to traditional firing hydrogenation processes.

14 SOLAR ENERGY↗
DOE OSTI2021

Two Planets Straddling the Habitable Zone of the Nearby K Dwarf Gl 414A

We present the discovery of two planets orbiting the nearby (D = 11.9 pc) K7 dwarf Gl 414A. Gl 414A b is a sub-Neptune mass planet with M{sub b}sini{sub b}=7.60{sub −2.19}{sup +2.44} M {sub ⊕} and a semimajor axis of 0.23 ± 0.01 au. Gl 414A c is a sub-Saturn mass planet with M{sub c}sini{sub c}=53.83{sub −8.58}{sup +9.18} M {sub ⊕} and a semimajor axis of 1.43 ± 0.06 au. We jointly analyzed radial velocity data from Keck/HIRES and the Automated Planet Finder at Lick Observatory, as well as photometric data from KELT, to detect the two planets and two additional signals related to the rotationally modulated activity and the long-term magnetic activity cycle of the star. The outer planet in this system may be a potential candidate for future direct-imaging missions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1995

Microrefrigeration by a pair of normal metal/insulator/superconductor junctions

We suggest and demonstrate experimentally that two normal metal/insulator/superconductor (NIS) tunnel junctions combined in series to form a symmetric SINIS structure can operate as an efficient Peltier refrigerator. Specifically, it is shown that the SINIS structure with normal-state junction resistences of 1.0 and 1.1 kOmega is capable of reaching a temperature of about 100 mK starting from 300 mK. We estimate the corresponding cooling power to be 1.5 pW per total junction area of 0.8 micrometers(exp 2) at T = 300 mK. This cooling power density implies that scaling of junction area up to about 1 mm(exp 2) should bring the cooling power into the microW range.

Leivo, M. M.↗
DOE OSTI2021

Changes in Hydrogen Concentration and Defect State Density at the Poly-Si/SiOx/c-Si Interface Due to Firing

We determined the density of defect states of poly-Si/SiOx/c-Si junctions featuring a wet chemical interfacial oxide from lifetime measurements using the MarcoPOLO model to calculate recombination and contact resistance in poly-Si/SiOx/c-Si-junctions. In samples that did not receive any hydrogen treatment, the Dit,cSi is about 2 × 1012 cm-2 eV1 before firing and rises to 3–7 × 1012 cm2 eV1 during firing at measured peak temperatures between 620 °C and 863 °C. To address the question of why AlOx/SiNy stacks in contrast to pure SiNy layers for hydrogenation during firing provides better passivation quality, we have measured the hydrogen concentrations at the poly-Si/SiOx/c-Si interface as a function of AlOx layer thickness and compared these to J0 and calculated Dit,c-Si values. We observe an increase of the hydrogen concentration at the SiOx/c-Si interface upon firing as a function of the firing temperature that exceeds the defect concentrations at the interface several times. However, the AlOx layer thickness appears to cause an increase in hydrogen concentration at the SiOx/c-Si interface in these samples rather than exhibiting a hydrogen blocking property.

41 EE - Solar Energy Technologies Office (EE-4S)↗