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8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on RbN by Materials Project

RbN is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Rb1+ is bonded to six equivalent N1- atoms to form a mixture of corner and edge-sharing RbN6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Rb–N bond lengths are 3.06 Å. N1- is bonded to six equivalent Rb1+ atoms to form a mixture of corner and edge-sharing NRb6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbN by Materials Project

RbN is Halite, Rock Salt-like structured and crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Rb1+ is bonded to six equivalent N1- atoms to form a mixture of edge and corner-sharing RbN6 octahedra. The corner-sharing octahedra tilt angles range from 1–9°. There are a spread of Rb–N bond distances ranging from 3.00–3.14 Å. N1- is bonded to six equivalent Rb1+ atoms to form a mixture of edge and corner-sharing NRb6 octahedra. The corner-sharing octahedra tilt angles range from 1–9°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbN by Materials Project

RbN is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Rb1+ is bonded in a body-centered cubic geometry to eight equivalent N1- atoms. All Rb–N bond lengths are 3.14 Å. N1- is bonded in a body-centered cubic geometry to eight equivalent Rb1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbN by Materials Project

RbN is Halite, Rock Salt structured and crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Rb1+ is bonded to six equivalent N1- atoms to form a mixture of edge and corner-sharing RbN6 octahedra. The corner-sharing octahedra tilt angles range from 1–8°. There are a spread of Rb–N bond distances ranging from 3.03–3.12 Å. N1- is bonded to six equivalent Rb1+ atoms to form a mixture of edge and corner-sharing NRb6 octahedra. The corner-sharing octahedra tilt angles range from 1–8°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbN by Materials Project

RbN is Halite, Rock Salt structured and crystallizes in the orthorhombic Pmmn space group. The structure is three-dimensional. Rb1+ is bonded to six equivalent N1- atoms to form a mixture of corner and edge-sharing RbN6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are two shorter (3.02 Å) and four longer (3.09 Å) Rb–N bond lengths. N1- is bonded to six equivalent Rb1+ atoms to form a mixture of corner and edge-sharing NRb6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Design of Twisted Two-Dimensional Heterostructures and Performance Regulation Descriptor for Electrocatalytic Ammonia Production from Nitric Oxide

The electrocatalytic reduction of nitric oxide (NO) to ammonia (NH 3 ) represents an attractive alternative for valorizing waste NO streams (NORR). However, discovering efficient catalysts for NO-to-NH 3 conversion remains challenging. We have designed metal-intercalated twisted graphene-BN heterostructures, in which metal atoms act as electron-transfer bridges. The twisted configuration facilitates cross-interface charge transfer, redistributing electrons from the graphene–metal interface to the metal–BN interface and BN surface. This electronic modulation enables boron atom adjacent to the metal center in BN to serve as active sites, promoting strong chemisorption and enhanced activation of NO. After high-throughput screening of the stability and NO capture ability of various transition metal-intercalated twisted heterostructures, we have investigated systematically the NORR pathways across 30 candidates. The results show that the rBN-Ti-Gθ and rBN-V-Gθ heterostructures exhibit exceptional NO-to-NH 3 catalytic performance under optimized twisting conditions. Additionally, using sure independence screening and sparsifying operator (SISSO) for model training, we propose a descriptor and establish a relationship between the twist angle and catalytic activity. This study bridges the gap in applying twisted heterostructures to NORR electrocatalysis and provides new insights and strategies for designing high-performance NORR catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1980

3500-hour durability testing of ceramic materials for automotive gas turbine engines

A two-year durability program was performed by AiResearch Phoenix to evaluate four commercially available ceramic materials under simulated automotive gas turbine combustor discharge conditions. These conditions included extended cyclic thermal exposures up to 2500 F and 3500 hr. The four materials selected for evaluation were Norton NCX-34 hot pressed silicon nitride, AiResearch RBN 101 reaction bonded silicon nitride, Carborundum pressureless sintered alpha-SiC and Pure Carbon Co. (British Nuclear Fuels, Ltd.) Refel reaction sintered silicon carbide. These materials were initially exposed to 350 hr/1750 cycles at 1200 and 1370 C. Subsequent exposures to 1050, 2100 and 3500 hr were performed on those materials maintaining 50% of baseline strength after the initial exposure. Additional evaluations of exposed bars included dimensional and weight changes, dye penetrant, specific damping capacity changes, SEM fractography, and X-ray diffraction.

Carruthers, W. D.↗