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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Enhanced quantum efficiency of high-purity silicon imaging detectors by ultralow temperature surface modification using Sb doping

A low temperature process for Sb doping of silicon has been developed as a backsurface treatment for high-purity n-type imaging detectors. Molecular beam epitaxy (MBE) is used to achieve very high dopant incorporation in a thin, surface-confined layer. The growth temperature is kept below 450 °C for compatibility with Al-metallized devices. Imaging with MBE-modified 1kx1k charge coupled devices ((CCDs) operated in full depletion has been demonstrated. Dark current is comparable to the state-of-the-art process, which requires a high temperature step. Quantum efficiency is improved, especially in the UV, for thin doped layers placed closer to the backsurface. Near 100% internal quantum efficiency has been demonstrated in the ultraviolet for a CCD with a 1.5 nm silicon cap layer.

Nikzad, Shouleh↗
DOE OSTI2020

Materials Data on Sb(MoO4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sb(WBr3)5 by Materials Project

W5Br12SbBr3 crystallizes in the triclinic P-1 space group. The structure is one-dimensional and consists of four antimony tribromide molecules and two W5Br12 ribbons oriented in the (0, 1, 0) direction. In each W5Br12 ribbon, there are ten inequivalent W+3.60+ sites. In the first W+3.60+ site, W+3.60+ is bonded to five Br1- atoms to form edge-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.60–2.65 Å. In the second W+3.60+ site, W+3.60+ is bonded to five Br1- atoms to form edge-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.54–2.66 Å. In the third W+3.60+ site, W+3.60+ is bonded to five Br1- atoms to form a mixture of edge and corner-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.57–2.71 Å. In the fourth W+3.60+ site, W+3.60+ is bonded to five Br1- atoms to form edge-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.55–2.66 Å. In the fifth W+3.60+ site, W+3.60+ is bonded to five Br1- atoms to form a mixture of edge and corner-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.57–2.73 Å. In the sixth W+3.60+ site, W+3.60+ is bonded to five Br1- atoms to form edge-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.59–2.66 Å. In the seventh W+3.60+ site, W+3.60+ is bonded to five Br1- atoms to form edge-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.54–2.67 Å. In the eighth W+3.60+ site, W+3.60+ is bonded to five Br1- atoms to form edge-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.54–2.66 Å. In the ninth W+3.60+ site, W+3.60+ is bonded to five Br1- atoms to form a mixture of edge and corner-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.57–2.70 Å. In the tenth W+3.60+ site, W+3.60+ is bonded to five Br1- atoms to form a mixture of edge and corner-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.56–2.72 Å. There are twenty-four inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 12-coordinate geometry to three W+3.60+ atoms. In the second Br1- site, Br1- is bonded in a 5-coordinate geometry to three W+3.60+ atoms. In the third Br1- site, Br1- is bonded in a 10-coordinate geometry to three W+3.60+ atoms. In the fourth Br1- site, Br1- is bonded in a 5-coordinate geometry to three W+3.60+ atoms. In the fifth Br1- site, Br1- is bonded in a 2-coordinate geometry to two W+3.60+ atoms. In the sixth Br1- site, Br1- is bonded in a 2-coordinate geometry to two W+3.60+ atoms. In the seventh Br1- site, Br1- is bonded in a 2-coordinate geometry to two W+3.60+ atoms. In the eighth Br1- site, Br1- is bonded in a 2-coordinate geometry to two W+3.60+ atoms. In the ninth Br1- site, Br1- is bonded in a single-bond geometry to one W+3.60+ atom. In the tenth Br1- site, Br1- is bonded in a single-bond geometry to one W+3.60+ atom. In the eleventh Br1- site, Br1- is bonded in a bent 120 degrees geometry to two W+3.60+ atoms. In the twelfth Br1- site, Br1- is bonded in a single-bond geometry to one W+3.60+ atom. In the thirteenth Br1- site, Br1- is bonded in a distorted bent 120 degrees geometry to two W+3.60+ atoms. In the fourteenth Br1- site, Br1- is bonded in a 8-coordinate geometry to three W+3.60+ atoms. In the fifteenth Br1- site, Br1- is bonded in a 4-coordinate geometry to three W+3.60+ atoms. In the sixteenth Br1- site, Br1- is bonded in a 4-coordinate geometry to three W+3.60+ atoms. In the seventeenth Br1- site, Br1- is bonded in a 5-coordinate geometry to three W+3.60+ atoms. In the eighteenth Br1- site, Br1- is bonded in a 2-coordinate geometry to two W+3.60+ atoms. In the nineteenth Br1- site, Br1- is bonded in a 2-coordinate geometry to two W+3.60+ atoms. In the twentieth Br1- site, Br1- is bonded in a 2-coordinate geometry to two W+3.60+ atoms. In the twenty-first Br1- site, Br1- is bonded in a 2-coordinate geometry to two W+3.60+ atoms. In the twenty-second Br1- site, Br1- is bonded in a single-bond geometry to one W+3.60+ atom. In the twenty-third Br1- site, Br1- is bonded in a single-bond geometry to one W+3.60+ atom. In the twenty-fourth Br1- site, Br1- is bonded in a single-bond geometry to one W+3.60+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sb(MoS2)6 by Materials Project

(MoS2)6Sb crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one antimony molecule and four MoS2 clusters. In two of the MoS2 clusters, Mo+4.50+ is bonded in a 2-coordinate geometry to two S2- atoms. There are one shorter (2.32 Å) and one longer (2.33 Å) Mo–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted single-bond geometry to one Mo+4.50+ and one S2- atom. The S–S bond length is 2.08 Å. In the second S2- site, S2- is bonded in a 2-coordinate geometry to one Mo+4.50+ and one S2- atom. In two of the MoS2 clusters, there are two inequivalent Mo+4.50+ sites. In the first Mo+4.50+ site, Mo+4.50+ is bonded in a 1-coordinate geometry to two S2- atoms. There are one shorter (2.32 Å) and one longer (2.33 Å) Mo–S bond lengths. In the second Mo+4.50+ site, Mo+4.50+ is bonded in a 1-coordinate geometry to two S2- atoms. There are one shorter (2.32 Å) and one longer (2.33 Å) Mo–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 2-coordinate geometry to one Mo+4.50+ and one S2- atom. The S–S bond length is 2.09 Å. In the second S2- site, S2- is bonded in a 1-coordinate geometry to one Mo+4.50+ and one S2- atom. The S–S bond length is 2.09 Å. In the third S2- site, S2- is bonded in a distorted single-bond geometry to one Mo+4.50+ and two S2- atoms. The S–S bond length is 3.75 Å. In the fourth S2- site, S2- is bonded in a 1-coordinate geometry to one Mo+4.50+ and two S2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Lifting Triplet Degeneracy Through Organic‐Cation Driven Structural Perturbation to Modulate Luminescence of Sb 3+ ‐Doped Double Perovskite

The spin-orbit coupling (SOC) and the Jahn-Teller effect (JTE) alter the orbital degeneracy in materials, leading to unique optical, electronic, and magnetic properties essential in spintronics, quantum computing, and light-emitting diodes (LEDs). Here, the study employs luminescent p-xylylenediammonium (PXA) instead of Cs+ in Cs2NaInCl6 to yield 2D Sb3+-doped (PXA)2NaInCl8 double perovskite and demonstrates a non-degenerate triplet state resulting from enhanced JTE in the strong SOC regime, featuring distinct emission centers. Consequently, a broadband emission from both PXA and [SbCl6]3− spans the entire spectrum (350–750 nm), representing a rare single-source multi-emissive 2D perovskite. With in-depth comparative structural, temperature-dependent photo-physical, and theoretical studies, it is elucidated that the synergistic effect of SOC and JTE on the Eg and T2g lattice modes modulate the electronic structure of [SbCl6]3− by splitting the doubly degenerate E levels of 3 T$^{*}_{1u}$ into non-degenerate states. The physical model, supported by theoretical studies, explains the energy level splitting required to realize two kinds of radiative minima in the relaxed excited state.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Electronic Topological Transition as a Route to Improve Thermoelectric Performance in Bi 0.5 Sb 1.5 Te 3

The electronic structure near the Fermi surface determines the electrical properties of the materials, which can be effectively tuned by external pressure. Bi0.5Sb1.5Te3 is a p-type thermoelectric material which holds the record high figure of merit at room temperature. Here it is examined whether the figure of merit of this model system can be further enhanced through some external parameter. With the application of pressure, it is surprisingly found that the power factor of this material exhibits λ behavior with a high value of 4.8 mW m –1 K –2 at pressure of 1.8 GPa. Such an enhancement is found to be driven by pressure-induced electronic topological transition, which is revealed by multiple techniques. Together with a low thermal conductivity of about 0.89 W m –1 K –1 at the same pressure, a figure of merit of 1.6 is achieved at room temperature. The results and findings highlight the electronic topological transition as a new route for improving the thermoelectric properties.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Microstructural Coarsening Kinetics and Mechanical Property Changes in Long-Term Aged Sn–Pb–Sb Solder Joints

Tin-lead-antimony (50Sn–47Pb–3Sb wt.%) soldered assemblies were mechanically tested approximately 30 years after initial production and found to have solder joints of reduced strength. The microstructure of this solder alloy exhibits a ternary eutectic structure with Sn-rich, Pb-rich, and SnSb phases. Accelerated aging was performed to evaluate solder microstructural coarsening and associated strength of laboratory solder joints to correlate these properties to the “naturally aged” solder joints. Isothermal aging was conducted at room temperature, 55, 70, 100, and 135 °C and aging times that ranged from 0.1 to 365 days. The coarsening kinetics of the Pb-rich phase were determined through optical microscopy and image analysis methods established in previous studies on binary Sn–Pb solder. A kinetic equation was developed with time exponent n of 0.43 and activation energy of 24000 J/mol, suggesting grain boundary diffusion or other fast diffusion pathways controlling the microstructural evolution. Compression testing and Vickers microhardness showed significant strength loss within the first 20–30 days after soldering; then, the microstructure and mechanical properties changed more slowly over long periods of time. Further, by combining accelerated aging data and the microstructure-based kinetics, strength predictions were made that match well with the properties of the actual soldered assemblies naturally aged for 30 years. However, aging at the highest temperature of 135 °C produced anomalous behavior suggesting that extraneous aging mechanisms are active. Therefore, data obtained at this temperature or higher should not be used. Overall, the combined microstructural and mechanical property methods used in this study confirmed that the observed reduction in strength of ~ 30-year-old solder joints can be accounted for by the microstructural coarsening that takes place during long-term solid-state aging.

36 MATERIALS SCIENCE↗