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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Enhancement of structure images of interstellar diamond microcrystals by image processing

Image processed high resolution TEM images of diamond crystals found in oxidized acid residues of carbonaceous chondrites are presented. Two models of the origin of the diamonds are discussed. The model proposed by Lewis et al. (1987) supposes that the diamonds formed under low pressure conditions, whereas that of Blake et al (1988) suggests that the diamonds formed due to particle-particle collisions behind supernova shock waves. The TEM images of the diamond presented support the high pressure model.

O'Keefe, Michael A.↗
NASA NTRS2000

Diagnostic Techniques Used to Study Chemical-Vapor-Deposited Diamond Films

The advantages and utility of chemical-vapor-deposited (CVD) diamond as an industrial ceramic can only be realized if the price and quality are right. Until recently, this technology was of interest only to the academic and basic research community. However, interest has grown because of advances made by leading CVD diamond suppliers: 1) Reduction of the cost of CVD polycrystalline diamond deposition below $5/carat ($8/sq cm); 2) Installation of production capacity; 3) Epitaxial growth of CVD single-crystal diamond. Thus, CVD diamond applications and business are an industrial reality. At present, CVD diamond is produced in the form of coatings or wafers. CVD diamond film technology offers a broader technological potential than do natural and high-pressure synthetic diamonds because size, geometry, and eventually cost will not be as limiting. Now that they are cost effective, diamond coatings - with their extreme properties - can be used in a variety of applications. Diamond coatings can improve many of the surface properties of engineering substrate materials, including erosion, corrosion, and wear resistance. Examples of actual and potential applications, from microelectromechanical systems to the wear parts of diamond coatings and related superhard coatings are described. For example, diamond coatings can be used as a chemical and mechanical barrier for the space shuttles check valves, particularly on the guide pins and seat assemblies.

Miyoshi, Kazuhisa↗
NASA NTRS1986

Diamond like carbon coatings: Categorization by atomic number density

Dense diamond-like hydrocarbon films grown at the NASA Lewis Research Center by radio frequency self bias discharge and by direct ion beam deposition were studied. A new method for categorizing hydrocarbons based on their atomic number density and elemental composition was developed and applied to the diamond-like hydrocarbon films. It was shown that the diamond-like hydrocarbon films are an entirely new class of hydrocarbons with atomic number densities lying between those of single crystal diamond and adamantanes. In addition, a major review article on these new materials was completed in cooperation with NASA Lewis Research Center personnel.

Angus, John C.↗
NASA NTRS1991

Simulation studies for surfaces and materials strength

Investigations were carried out in the following three areas. First, a simulation study was conducted to investigate the early stages of a nucleation and growth mechanism taking place on diamond surfaces. The energetically most favorable binding sites were calculated along with the binding energies for up to three carbon atoms deposited on the planes of a diamond crystal. Secondly, calculations were carried out to analyze energies and structural properties for restructured patterns of the surface of a diamond. Two different model functions, developed recently for carbon, were employed in the calculations. Lastly, a crack propagation process for the graphitic basal plane, was investigated using a molecular dynamics technique. Interactions among carbon atoms in the system were calculated using the Tersoff potential energy function.

Halicioglu, Timur↗
DOE OSTI2024

Exploring mounting solutions for cryogenically cooled thin crystal optics in high power density x-ray free electron lasers

This study investigates three mounting methods—clamping, soldering, and a hybrid clamping–soldering approach—for cryogenically cooled thin diamond crystals crucial to stable operation of X-ray Free Electron Laser (XFEL) systems. While clamping methods exhibit temperature resilience and flexibility, meticulous design is required to prevent stress-induced warping and reduce thermal contact area. Soldering methods offer reliable mechanical and thermal bonding but encounter challenges due to the coefficient of thermal expansion mismatch at cryogenic temperatures. The hybrid method, integrating clamping and soldering with strain relief cuts, effectively mitigates overall distortion caused by mounting and XFEL thermal loads. These findings offer a novel mounting solution for high-performance x-ray optics in XFEL research and applications, ensuring stability and optimal functionality in cryogenic conditions.

Instruments & Instrumentation↗
DOE OSTI2026

Ultrafast vertical photoconductive intrinsic diamond switch with high current (17.1 A at 1 kV)

Here, this Letter reports on a vertical, bulk-conducting photoconductive semiconductor switch (PCSS) fabricated on an intrinsic Type IIa single-crystal diamond substrate. Under near-bandgap excitation at 225 nm with a 20 μ J pulse, a strong photocurrent response of 17.1 A at 1 kV DC bias magnitude is obtained by (i) tuning the optical trigger wavelength to the “matched-absorption” window (224–235 nm) near the band edge, where the optical penetration depth becomes comparable to the 500 μ m substrate thickness, and (ii) choosing the bias polarity ensuring electron-dominant conduction, given that electrons have a higher mobility than holes in diamond. The PCSS has an area-normalized responsivity of 54.2 mA W −1 cm −2 and an effective on-resistance of 8.48 Ω, with a fast 90%–10% transient fall time of 25 ns, attributed to carrier sweep-out. These results support vertical, bulk-conducting intrinsic diamond PCSS as a promising platform for high-power optical switching and provide new insight into intrinsic photoconductivity in diamond.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2023

Diamond rotors

The resolution of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra remains bounded by the spinning frequency, which is limited by the material strength of MAS rotors. Since diamond is capable of withstanding 1.5–2.5x greater MAS frequencies, compared to state-of-the art zirconia, we fabricated rotors from single crystal diamond. When combined with bearings optimized for spinning with helium gas, diamond rotors could achieve the highest MAS frequencies to date. Furthermore, the excellent microwave transmission properties and thermal conductivity of diamond could improve sensitivity enhancements in dynamic nuclear polarization (DNP) experiments. The fabrication protocol we report involves novel laser micromachining and produced rotors that presently spin at ω r = 111.000 ± 0.004 kHz, with stable spinning up to 124 kHz, using N 2 gas as the driving fluid. Here, we present the first proton-detected 13 C/ 15 N MAS spectra recorded using diamond rotors, a critical step towards studying currently inaccessible ex-vivo protein samples with MAS NMR. Previously, the high aspect ratio of MAS rotors (~10:1) precluded fabrication of MAS rotors from diamond.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2020

Impact Shock Origin of Diamonds in Ureilite Meteorites

The origin of diamonds in ureilite meteorites is a timely topic in planetary geology as recent studies have proposed their formation at static pressures >20 GPain a large planetary body, like diamonds formed deep within the Earth ́s mantle. We investigated fragments of three diamond-bearing ureilites (two from the Almahata Sitta polymict ureilite and one from the NWA 7983 main group ureilite). In NWA7983 we found an intimate association of large monocrystalline diamonds (up to atleast 100 μm), nanodiamonds, nanographite, and nanometric grains of metallic iron,cohenite, troilite and likely schreibersite. The diamonds show a striking texture pseudo morphing inferred original graphite laths.The silicates in NWA 7983 recorda high degree of shock metamorphism. The presence of both large mono crystalline diamonds and nano diamonds in a highly shocked ureilite can be explained by catalyzed transformation from graphite during an impact shock event characterized by peak pressures possibly as low as 15 GPa for relatively long duration (on the scale of few seconds). The formation of “large” (as opposed to nano-) diamond crystals could have been enhanced by the catalytic effect of metallic Fe-Ni-C liquid coexisting with graphite. We found no evidence that formation of micrometer(s)sized diamonds or associated Fe-S-P phases in ureilites require high static pressures and long formation times. It is unlikely that any of the diamonds in ureilites formed in bodies as large as Mars or Mercury.

Fabrizio Nestola↗
DOE OSTI2025

Heterogenous Integration of Boron-Doped p -Diamond with Monolayer n -MoS 2 for PN Junctions Operating at Room Temperature

Diamond has tremendous potential for power electronics, due to its superior thermal conductivity, large electric field strength, and high carrier mobilities. However, the absence of a reliable room temperature n-type transport has impeded any advancements in diamond-based electronics. Here, we circumvent this bottleneck by integrating n-type two-dimensional (2D) monolayers of molybdenum disulfide (MoS 2 ) with boron doped p-type single crystal diamond and demonstrate 2D/3D heterostructure-based PN junction diodes that operate at room temperature with excellent rectification characteristics. Our diodes achieve a maximum forward current density (J D ) of ∼4000 A/cm 2 , an ideality factor (η) value of ∼3.7, and a rectification ratio (RR) of 10 6 . We find that the origin of current rectification stems from the interlayer recombination of majority carriers driven by direct tunnelling (DT) and Fowler Nordheim (FN) tunnelling mechanisms. In conclusion, our demonstration can open new avenues for diamond-based power electronics through its integration with 2D materials.

2D/3D integration↗
DOE OSTI2023

Transonic dislocation propagation in diamond

Here, the motion of line defects (dislocations) has been studied for more than 60 years, but the maximum speed at which they can move is unresolved. Recent models and atomistic simulations predict the existence of a limiting velocity of dislocation motion between the transonic and subsonic ranges at which the self-energy of dislocation diverges, though they do not deny the possibility of the transonic dislocations. We used femtosecond x-ray radiography to track ultrafast dislocation motion in shock-compressed single-crystal diamond. By visualizing stacking faults extending faster than the slowest sound wave speed of diamond, we show the evidence of partial dislocations at their leading edge moving transonically. Understanding the upper limit of dislocation mobility in crystals is essential to accurately model, predict, and control the mechanical properties of materials under extreme conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Structural, optical, and thermal properties of BN thin films grown on diamond via pulsed laser deposition

Heterostructures based on ultrawide-bandgap (UWBG) semiconductors (bandgap > 4.0 eV), such as BN and diamond, hold significant importance for the development of high-power electronics in the next generation. However, achieving in situ heteroepitaxy of BN/diamond or vice versa remains exceptionally challenging due to the complex growth kinetics involved. In this work, we grew BN thin film on (100) single-crystal diamonds using pulsed laser deposition and investigated its structural, magnetic, optical, and thermal properties. Throughout this study, the structural analyses confirmed the growth of BN films, which exhibited diamagnetic behavior at room temperature. Notably, the film demonstrated anisotropic refractive index characteristics within the visible-to-near-infrared wavelength range. The room-temperature cross-plane thermal conductivity of BN is 1.53 ± 0.77 W/mK, while the thermal conductance of the BN/diamond interface is 20 ± 2 MW/m 2 ⁢K. These findings have significant implications for a range of device applications based on UWBG BN/diamond heterostructures.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Charge collection efficiency of diamond and silicon sensors irradiated with alpha particles

To evaluate the viability of using semiconductors as sensor materials in a detector for the Associated Particle Imaging technique, the radiation hardness of silicon and diamond diodes to alpha particles has been assessed. Here, the detector lifetimes for both silicon and diamond sensors were measured under the prolonged exposure to alpha particles emitted by an 241 Am source. The silicon detector was exposed to alpha radiation for approximately two months, reaching an accumulated fluence of ~ 1.5 x 10 12 α cm –2 . Additionally, by using a high purity single-crystal diamond with coplanar electrodes operating with full charge collection, the diamond detector response was measured over approximately ten months reaching an accumulated fluence of over 6 x 10 12 α cm –2 cm.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Dislocation generation in diamond under extreme loading

Diamond is, by virtue of its high bonding forces and Peierls-Nabarro barrier stresses, among the hardest materials on earth due to the difficulty of generating and moving dislocations. We demonstrate, using molecular dynamics and analytical calculations, that the generation of defects is dependent on loading orientation. Shock-loading single-crystal diamond along [001] and [011] to a stress of 137 GPa did not reveal dislocations, whereas loading along [111] generated profuse dislocations. The introduction of a void at the latter orientation generated dislocations at 72.6 GPa. Two slip systems were identified: <011>{100} and <112>{111}. The threshold for plastic deformation in diamond is orientation dependent and significantly lower than reported in previous studies: 0.14 G (shear modulus). The void collapse generated localized amorphization for [001]. In conclusion, these results on the anisotropy of plasticity and void effects have relevance for the improvement of symmetry in the collapse of diamond capsules in inertial fusion experiments.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Boron isotopes in blue diamond record seawater-derived fluids in the lower mantle

Boron is a quintessential crustal element but its conspicuous presence in diamond – a mantle mineral – raises questions about potential subduction pathways for boron and other volatiles. It has been a long-standing goal to characterize the isotopic composition of boron in blue, boron-bearing (Type IIb) diamonds to reveal its origin. Mineral inclusions indicate that Type IIb diamonds crystallize at transition zone to lower mantle depths, meaning that if the boron is subducted it would trace a pathway of volatile elements into the deep mantle. Here, using off-line laser ablation sampling, we present the first boron isotope compositions, along with trace element contents and carbon isotope compositions, of a suite of blue diamonds mainly sourced from the Cullinan diamond mine in South Africa. The ten analyzed blue diamonds have a wide range in δ 11 B, between -9.2 ± 2‰ and -0.5 ± 2‰, compared to the more restricted range for mid-ocean ridge basalts (-7.1 ± 0.9‰). Carbon isotope values for the blue diamonds range between -20.6 and -1.8‰, with a mode at -17‰, significantly more negative than the main mantle mode at -5‰. Combined, the boron and carbon isotope compositions require fluid input from subducted oceanic lithosphere down into deep mantle source regions of blue diamonds. This finding highlights a deep subduction pathway for volatiles to stoke the source regions of deeply-derived magmas.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1986

Depositing Diamondlike Carbon Films

New process demonstrated to make thin films (usually thousands of angstroms to few microns thick) that have properties of diamonds. Various plasma and ion-beam techniques employed to generate films. Films made by radio-frequency plasma decomposition of hydrocarbon gas or other alkanes, by low-energy carbon-ion-beam deposition, or by ion plating and dual ion technique using carbon target. Advantages of new process over others are films produced, though amorphous, are clear, extremely hard, chemically inert, of high resistivity, and have index of refraction of 3.2 properties similar to those of single-crystal diamonds. Films have possible uses in microelectronic applications, high-energy-laser and plastic windows, corrosion protection for metals, and other applications where desired properties of film shaped during the film-formation process.

Mirtich, M. J.↗
DOE OSTI2024

Confirming X-ray Parametric Down Conversion by Time-Energy Correlation

We present measurements of X-ray Parametric Down Conversion at the Advanced Photon Source synchrotron facility. Using an incoming pump beam at 22 keV, we observe the simultaneous, elastic emission of down-converted photon pairs generated in a diamond crystal. The pairs are detected using high count rate silicon drift detectors with low noise. Production by down-conversion is confirmed by measuring time-energy correlations in the detector signal, where photon pairs within an energy window ranging from 10 to 12 keV are only observed at short time differences. By systematically varying the crystal misalignment and detector positions, we obtain results that are consistent with the constant total of the down-converted signal. Our maximum rate of observed pairs was 130 /hour, corresponding to a conversion efficiency for the down-conversion process of 5.3±0.5×10 -13 .

47 OTHER INSTRUMENTATION↗