Search NASA⌕ Search

SEARCH · Search NASA

Results for “BeSiN2”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on BeSiN2 by Materials Project

BeSiN2 is Chalcopyrite structured and crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Be2+ is bonded to four equivalent N3- atoms to form BeN4 tetrahedra that share corners with four equivalent BeN4 tetrahedra and corners with eight equivalent SiN4 tetrahedra. All Be–N bond lengths are 1.78 Å. Si4+ is bonded to four equivalent N3- atoms to form SiN4 tetrahedra that share corners with four equivalent SiN4 tetrahedra and corners with eight equivalent BeN4 tetrahedra. All Si–N bond lengths are 1.75 Å. N3- is bonded to two equivalent Be2+ and two equivalent Si4+ atoms to form corner-sharing NBe2Si2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BeSiN2 by Materials Project

BeSiN2 is Chalcopyrite-like structured and crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. Be2+ is bonded to four N3- atoms to form BeN4 tetrahedra that share corners with four equivalent BeN4 tetrahedra and corners with eight equivalent SiN4 tetrahedra. There are a spread of Be–N bond distances ranging from 1.77–1.79 Å. Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with four equivalent SiN4 tetrahedra and corners with eight equivalent BeN4 tetrahedra. There is two shorter (1.75 Å) and two longer (1.76 Å) Si–N bond length. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded to two equivalent Be2+ and two equivalent Si4+ atoms to form corner-sharing NBe2Si2 tetrahedra. In the second N3- site, N3- is bonded to two equivalent Be2+ and two equivalent Si4+ atoms to form corner-sharing NBe2Si2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BeSiN2 by Materials Project

BeSiN2 is Enargite-like structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. Be2+ is bonded to four N3- atoms to form BeN4 tetrahedra that share corners with six equivalent BeN4 tetrahedra and corners with six equivalent SiN4 tetrahedra. There is three shorter (1.74 Å) and one longer (1.86 Å) Be–N bond length. Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with six equivalent BeN4 tetrahedra and corners with six equivalent SiN4 tetrahedra. There is one shorter (1.69 Å) and three longer (1.80 Å) Si–N bond length. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded to one Be2+ and three equivalent Si4+ atoms to form corner-sharing NBeSi3 tetrahedra. In the second N3- site, N3- is bonded to three equivalent Be2+ and one Si4+ atom to form corner-sharing NBe3Si tetrahedra.

36 MATERIALS SCIENCE↗
NASA NTRS1983

Hardness of dense beta-Si3N4

The effects of small changes in the concentration of an oxygen content densification aid on the room temperature microhardness of hot isostatically pressed and sintered beta-Si3N4 ceramics are studied. The compositions studied were Si3N4 containing 7 wt. pct BeSiN2, a fixed nonoxide densification aid, and 1.9-3.7 wt. pct oxygen as a second, variable densification aid. A proportional relationship between high density and high oxygen content, regardless of heat treatment type, is noted.

Greskovich, C.↗
DOE OSTI2023

Measurement of neutrino oscillations using neutrino and antineutrino beams in the NOvA experiment

NOvA is a long-baseline accelerator neutrino oscillation experiment using the NuMIneutrino beam from Fermilab. Its main physics goals are to probe the 3-flavour oscillationparameters: neutrino mass hierarchy, CP-violating phase dcp and octant of .23 mixingangle by observing electron neutrino appearance and muon neutrino disappearance. Twofunctionally identical detectors are placed off-axis from the centre of the NuMI beam.The near detector at Fermilab is 100 m underground, and the far detector is locatedon the surface at Ash River, 810 km away from the beam source. The initial neutrinobeam spectra are measured using the near detector data and the oscillation parametersare extracted by fitting the observed data to the predicted neutrino spectrum in the fardetector.This thesis is centered around how to improve the sensitivity of |.m232| and .23 measurementsin the muon neutrino disappearance analysis. NOvA will take data for about12 years. The operation of the NOvA experiment for each year costs tens of millions ofdollars, thus it is valuable to maximise the sensitivity of the analysis. Three samples ofmuon neutrino events are studied in this thesis to improve the analysis sensitivities. First,higher energy muon neutrinos are investigated by extending the energy range in NOvA’scurrent standard analysis. Second, for the sample of events used in NOvA’s existing analysis,a new energy estimator which has been developed to improve the neutrino energy resolution is considered. Furthermore, in addition to binning the events as function ofenergy and hadronic energy fraction, three particle identifiers are introduced to separateneutrino events by signal purity to reduce the effects from backgrounds. Third, an additionallower purity sample of muon neutrino charged current (CC) events that look similarto neutral current events and have not been included in NOvA’s existing analyses havebeen studied.This thesis reanalyses NOvA’s data used in the 2020 analysis, corresponding to anexposure of 13.60×1020 protons on target (POT) in the neutrino beam mode recordedfrom February 6, 2014 to March 20, 2020, and 12.50×1020 protons on target in theantineutrino beam mode recorded between June 29, 2016 to February 26, 2019. Thisthesis has implemented a fit to Asimov fake data, generated where sin2 .23 = 0.59 and.m232 = 2.5 × 10-3 eV2. These sensitivity studies show that the uncertainty range of|.m232| at 1 s in the new analysis is reduced by 5.5% and the significance of maximaldisappearance rejection improves by 7.7%, compared to the standard analysis. This isequivalent to adding 11-16% more data. The best fit values of the oscillation parametersfrom fitting to the far detector (FD) data with the new analysis are found to besin2 .23 = 0.568+0.025-0.043 (sin2 .23 = 0.454+0.046-0.026) and .m232 = 2.399+0.055-0.070 × 10-3 eV2 (.m232= -2.427+0.055-0.067 × 10-3 eV2) for the normal (inverted) hierarchy. The difference in thebest fit for sin2 .23 (.m232) between the new analysis and NOvA’s 2020 analysis is around2% (1.4%). The uncertainty range at 1 s for .m232 decrease by 8% (4%) for the normalhierarchy (inverted hierarchy) compared to the standard analysis. The uncertainty rangefor sin2 .23 is close to the standard analysis. This thesis also implements the fit from combiningelectron neutrino appearance and muon neutrino disappearance. The combinedanalysis shows that the best fit values are very close to the standard analysis. However,the uncertainty range of .m232 at 1 s is reduced by 3.7% using the new analysis. The maximaldisappearance significance is not improved in the new analysis, but the new analysisslightly improves the rejection of the disfavoured octant.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗