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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Imaging the Local Charge Environment of Nitrogen-Vacancy Centers in Diamond

Characterizing the local internal environment surrounding solid-state spin defects is crucial to harnessing them as nanoscale sensors of external fields. This is especially germane to the case of defect ensembles which can exhibit a complex interplay between interactions, internal fields, and lattice strain. Working with the nitrogen-vacancy (NV) center in diamond, we show that local electric fields dominate the magnetic resonance behavior of NV ensembles at a low magnetic field. We propose a simple microscopic model that quantitatively captures the observed spectra for samples with NV concentrations spanning more than two orders of magnitude. Motivated by this understanding, we propose and implement a new method for the nanoscale localization of individual charges within the diamond lattice; our approach relies upon the fact that the charge induces a NV dark state which depends on the electric field orientation.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS1996

Properties of Diamond and Diamond-Like Clusters in Nanometric Dimensions

Variations in materials properties of small clusters of nanometric dimensions were investigated. Investigations were carried out for diamond and diamond-like particles in spherical shapes. Calculations were performed for clusters containing over 1000 carbon atoms. Results indicate that as the cluster size diminishes, (i) the average cohesive energy becomes weaker, (ii) the excess surface energy increases, and (iii) the value for stiffness decreases.

Halicioglu, Timur↗
DOE OSTI2023

Development of Large-Volume-Diamond Anvil Cell for Neutron Diffraction: The Neutron Diamond Anvil Cell Project at ORNL

10 years ago, Dave Mao, director of EFree (energy frontier research in extreme environments), a DOE energy frontier recognized the importance of neutron science for energy research. The subsequent establishment of a neutron group within EFree lead to the establishment of an “Instrument Development Team” for SNAP, the High-Pressure beamline at the Spallation Neutron Source at Oak Ridge National Laboratory in Tennessee. The idea was to develop novel high pressure techniques to expand the pressure range for neutron diffraction. A goal was set to reach half megabar levels (50 GPa), which at the time was considered as extremely challenging. Here we will give a brief overview of the developments during the last decade in this novel area of research. Fortunately, during this period multi carat diamond anvils have become available mainly by the chemical vapor deposition process (CVD), making research in this pressure range and beyond rather routine. This paper shows the latest developments in large anvil designs, compact multiple ton diamond cells and some examples of high-quality neutron diffraction patterns of sample sizes far below conventional levels.

Boehler, Reinhard↗
DOE OSTI2023

Diamonds in the Rough: Direct Surface Enhanced Infrared Spectroscopic Evidence of Nitrogen Reduction on Boron-Doped Diamond Supported Metal Catalysts

In situ investigations of electrocatalytic processes of increasing societal interest such as the nitrogen reduction reaction (NRR) re-quire aggressive experimental conditions that are not readily compatible with surface sensitive techniques such as attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). A method for performing ATR-SEIRAS studies at very negative potentials where conventional IR-active films delaminate, and fail is reported. The method relies on a thin film of very robust boron-doped diamond deposited on a micromachined Si wafer, which provides extended mid-IR transparency at long wavelengths. SEIRAS activity is achieved by electrodepositing gold nanoparticles onto the conductive BDD layer. The Au@BDD layers are shown to sustain prolonged periods of electrolysis at negative potentials with no degradation of the modifying layer. The efficacy of these substrates for electrocatalysis is demonstrated by studying the reduction of N 2 at -1.5 V vs Ag/AgCl in an aqueous-based electrolyte. So under these conditions, direct spectroscopic evidence of both NH 3 and hydrazine formed from the nitrogen reduction reaction (NRR) is provided.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Cinema:Snap: Real-time tools for analysis of dynamic diamond anvil cell experiment data

We report we developed tools and a workflow for real-time analysis of data from dynamic diamond anvil cell experiments performed at user light sources. These tools allow users to determine the phases of matter observed during the compression of materials in order to make decisions during an experiment to improve the quality of experimental results and maximize the use of scarce experimental facility time. The tools fill a gap in dynamic compression data analysis tools that are real-time, are flexible to the needs of high-pressure scientists, connect to automated processing of results, can be easily incorporated into workflows with existing tools and data formats, and support remote experimental data analysis workflows. Specific analytics developed include novel automated two-peak analysis for overlapping peaks and multiple phases, coordinated views of pressure and temperature values, full-compression contour plots, and configurable views of integrated x-ray diffraction. We present an experimental use case to show how the tools produce real-time analytics that help the scientists revise parameters for the next compression

47 OTHER INSTRUMENTATION↗