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At least 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

High-Field Quantum Diamond Magnetometers for Fusion Diagnostics (Final Technical Report)

Summary of research performed to enable all-optical quantum diamond magnetometers for fusion diagnostics, including: the physical mechanisms enabling all-optical photoluminescence contrast as a function of magnetic field magnitude and direction for dense ensembles of nitrogen vacancy (NV) centers in diamond; the characterization and optimization of NV-diamond material; and related investigations and student training.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Latest Results on Radiation Tolerance of Diamond Detectors

At present most experiments at the CERN Large Hadron Collider (LHC) are planning upgrades in the next 5-10 years for their innermost tracking layers as well as luminosity monitors to be able to take data as the luminosity increases and CERN moves toward the High Luminosity-LHC (HL-LHC). These upgrades will most likely require more radiation tolerant technologies than exist today. As a result this is one area of intense research, and Chemical Vapour Deposition (CVD) diamond is one such technology. CVD diamond has been used extensively in beam condition monitors as the innermost detectors in the highest radiation areas of all LHC experiments. This talk describes the preliminary radiation tolerance measurements of the highest quality polycrystalline CVD material for a range of proton energies and neutrons obtained with this material with the goal of elucidating the issues that should be addressed for future diamond based detectors. The talk presents the evolution of various semiconductor parameters as a function of dose.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Size-Dependent Electrical Transport Properties in Conducting Diamond Nanostripes

With the advances in nanofabrication technology, horizontally aligned and well-defined nitrogen-doped ultrananocrystalline diamond nanostripes can be fabricated with widths in the order of tens of nanometers. The study of the size-dependent electron transport properties of these nanostructures is crucial to novel electronic and electrochemical applications. In this paper, 100 nm thick n-type ultrananocrystalline diamond thin films were synthesized by microwave plasma-enhanced chemical vapor deposition method with 5% N2 gas in the plasma during the growth process. Then the nanostripes were fabricated using standard electron beam lithography and reactive ion etching techniques. The electrical transport properties of the free-standing single nanostripes of different widths from 75 to 150 nm and lengths from 1 to 128 μm were investigated. The study showed that the electrical resistivity of the n-type ultrananocrystalline diamond nanostripes increased dramatically with the decrease in the nanostripe width. The nanostripe resistivity was nearly doubted when the width was reduced from 150 nm to 75 nm. The size-dependent variability in conductivity could originate from the imposed diffusive scattering of the nanostripe surfaces which had a further compounding effect to reinforce the grain boundary scattering.

Zhou, Andrew F. (ORCID:0000000243050409)↗
DOE OSTI2019

The Stability of a Nanoparticle Diamond Lattice Linked by DNA

The functionalization of nanoparticles (NPs) with DNA has proven to be an effective strategy for self-assembly of NPs into superlattices with a broad range of lattice symmetries. By combining this strategy with the DNA origami approach, the possible lattice structures have been expanded to include the cubic diamond lattice. This symmetry is of particular interest, both due to the inherent synthesis challenges, as well as the potential valuable optical properties, including a complete band-gap. Using these lattices in functional devices requires a robust and stable lattice. Here, we use molecular simulations to investigate how NP size and DNA stiffness affect the structure, stability, and crystallite shape of NP superlattices with diamond symmetry. We use the Wulff construction method to predict the equilibrium crystallite shape of the cubic diamond lattice. We find that, due to reorientation of surface particles, it is possible to create bonds at the surface with dangling DNA links on the interior, thereby reducing surface energy. Consequently, the crystallite shape depends on the degree to which such surface reorientation is possible, which is sensitive to DNA stiffness. Further, we determine dependence of the lattice stability on NP size and DNA stiffness by evaluating relative Gibbs free energy. We find that the free energy is dominated by the entropic component. Increasing NP size or DNA stiffness increases free energy, and thus decreases the relative stability of lattices. On the other hand, increasing DNA stiffness results in a more precisely defined lattice structure. Thus, there is a trade off between structure and stability of the lattice. Our findings should assist experimental design for controlling lattice stability and crystallite shape.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1979

Experiments with diamond-turned metal X-ray mirrors

It is noted that the primary advantages of diamond turning technology for the fabrication of X-ray telescope mirrors is in the smoothness of the finished surface and the control of the position of the cutter afforded by the precision slides and computer-assisted positioners which form the surface. The paper summarizes the Caltech work in attempting to make Wolter Type I telescope mirrors using the diamond turning facilities at the Oak Ridge Y-12 laboratory. Attention is given to such factors as the use of aluminum with copper plating and electroless nickel coating. It is found that although the diamond turning capability of the Y-12 lab is capable of making good X-ray mirror contours, there are problems in the process which have limited the accuracy achieved by this technique.

Garmire, G. P.↗
NASA NTRS1982

The uses of Man-Made diamond in wafering applications

The continuing, rapid growth of the semiconductor industry requires the involvement of several specialized industries in the development of special products geared toward the unique requirements of this new industry. A specialized manufactured diamond to meet various material removal needs was discussed. The area of silicon wafer slicing has presented yet anothr challenge and it is met most effectively. The history, operation, and performance of Man-Made diamond and particularly as applied to silicon wafer slicing is discussed. Product development is underway to come up with a diamond specifically for sawing silicon wafers on an electroplated blade.

Fallon, D. B.↗
NASA NTRS1981

The failure strengths of perfect diamond crystals

Finite elasticity analysis is extended to the 110 direction, where off axis strain symmetry is not present, and the third order elastic data are obtained for diamond. The compressive yield strengths of perfect diamond crystals loaded in the 100, 110, and 111 directions are predicted to be 2.2, 5.6, and 2.8 Mbars, respectively, while the corresponding tensile fracture strengths are 1.0, 0.5, and 0.5 Mbars. From these results and from Hertz theory it is predicted that ring fracture of spherically tipped diamonds pressed against a flat will occur at pressures of 1.8-1.9 Mbars, substantially below the yield pressure (above 3 Mbars). Modification of the tip shape leads to a predicted increase in the pressure at which fracture occurs.

Whitlock, J.↗
NASA NTRS1984

Diamond shines in high-power devices

The 20-W S-band power amplifiers aboard the GOES E and F spacecraft exemplify the problems that type-IIa diamond heat sinks have been developed to solve, including the requirement for junction temperatures to be kept below 125 C. Diamond heat sinks allow high power S-band semiconductors to operate at a flange temperature of 70 C without exceeding the stipulated maximum junction temperature. Type-IIA diamond, which is an excellent electrical insulator, possesses a thermal conductivity four times better than pure copper at 100 C, and outperforms BeO by an even greater margin. Higher costs are offset by high reliability. Attention is presently given to the results of tests conducted by the NASA Goddard Space Flight Center.

Line, L.↗
NASA NTRS1986

A new method for fabrication of diamond-dust blocking filters

Thermal embedding of diamond dust onto a polyethylene-coated Al plate has been used to make a blocking filter for FIR applications. The Al plate is sandwiched between two Mylar 'blankets' and the air between the layers is removed by means of a small vacuum pump. After the polyethylene is heated and softened, the diamond dust is applied to the polyethylene coating using a brush. The optimum diamond dust grain sizes corresponding to polyethylene layer thicknesses of 9-12 microns are given in a table, and the application of the blocking filter to spectrometric measurements in the FIR is described. An exploded view diagram of the layered structure of the blocking filter is provided.

Collard, H. R.↗
NASA NTRS1986

High-pressure ruby and diamond fluorescence - Observations at 0.21 to 0.55 terapascal

A diamond-anvil, high-pressure apparatus was used to extend the upper pressure limit of static laboratory experiments. Shifts of the R1 strong fluorescent line of ruby were observed that correspond to static pressures of 0.21 to 0.55 terapascal (2.1 to 5.5 megabars) at 25 C. Sensitive spectroscopic techniques in the pressure range 0.15 to 0.28 terapascal were used to observe ruby and diamond fluorescence separately; these two fluorescent emissions overlap strongly at high pressures. At pressures greater than approximately 0.28 terapascal, the diamond fluorescence diminished and the ruby fluorescence reappeared strongly. Pressure was determined by extrapolation of the calibrated shift of the ruby R1 line.

Xu, J. A.↗
NASA NTRS1987

Are small diamonds thermodynamically stable in the interstellar medium?

Very small diamond particles (50 A diameter) are shown to be thermodynamically stable with respect to similar sized graphite particles for reasonable values of the surface free energies of diamond and graphite. Small diamonds are likely to be stable against both thermal evaporation and chemical attack in the general interstellar medium. A few of the consequences of these conclusions are examined.

Nuth, Joseph A., III↗
NASA NTRS1988

The nature and origin of interstellar diamond

The C-delta component of the Allende meteorite is a microscopic diamond some of whose properties seem in conflict with those expected of diamond. High spatial resolution analytical data are presented here which may help explain such results. Surface and interfacial carbon atoms in the component, which may comprise as much as 25 percent of the total, impart an 'amorphous' character to some spectral data. These data support the proposed high-pressure conversion of amorphous carbon and graphite into diamonds due to grain-grain collisions in the ISM, although a low-pressure mechanism of formation cannot be ruled out.

Blake, David F.↗
NASA NTRS1988

Growth of diamond by RF plasma-assisted chemical vapor deposition

A system has been designed and constructed to produce diamond particles by inductively coupled radio-frequency, plasma-assisted chemical vapor deposition. This is a low-pressure, low-temperature process used in an attempt to deposit diamond on substrates of glass, quartz, silicon, nickel, and boron nitride. Several deposition parameters have been varied including substrate temperature, gas concentration, gas pressure, total gas flow rate, RF input power, and deposition time. Analytical methods employed to determine composition and structure of the deposits include scanning electron microscopy, absorption spectroscopy, scanning Auger microprobe spectroscopy, and Raman spectroscopy. Analysis indicates that particles having a thin graphite surface, as well as diamond particles with no surface coatings, have been deposited. Deposits on quartz have exhibited optical bandgaps as high as 4.5 eV. Scanning electron microscopy analysis shows that particles are deposited on a pedestal which Auger spectroscopy indicates to be graphite. This is a phenomenon that has not been previously reported in the literature.

Meyer, Duane E.↗
NASA NTRS1988

Elimination of pressure-induced fluorescence in diamond anvils

At pressures above one megabar (100 GPa) in high-pressure diamond anvil cell experiments, the ruby fluorescence signal needed for pressure calibration is increasingly difficult to measure. A primary cause of this difficulty is the presence of an intense pressure-induced diamond fluorescence. A tentative identification of this pressure-induced fluorescence is given, a technique for the elimination of this fluorescence is reported. It is demonstrated that weak ruby signals, completely hidden by diamond fluorescence, are now easily measured with this technique.

Eggert, Jon H.↗
NASA NTRS1989

Diamond films for laser hardening

Laser-damage experiments were performed on free-standing polycrystalline diamond films prepared by plasma-enhanced CVD. The high laser-induced stress resistance found for this material makes it useful for thin-film coatings for laser optics. Results for diamond-coated silicon substrates demonstrate the enhanced damage threshold imparted by diamond thin-film coatings to materials susceptible to laser damage.

Albin, S.↗
NASA NTRS1990

Ubiquitous interstellar diamond and SiC in primitive chondrites - Abundances reflect metamorphism

It is shown here that interstellar diamond and SiC were incorporated into all groups of chondrite meteorites. Abundances rapidly go to zero with increasing metamorphic grade, suggesting that metamorphic destruction is responsible for the apparent absence of these grains in most chondrites. In unmetamorphosed chondrites, abundances normalized to matrix content are similar for different classes. Diamond samples from chondrites of different classes have remarkably similar noble-gas constants and isotropic compositions, although constituent diamonds may have come from many sources. SiC seems to be more diverse, partly because grains are large enough to measure individually, but average characteristics seem to be similar from meteorite to meteorite. These observations suggest that various classes of chondritic meteorites sample the same solar system-wide reservoir of interstellar grains.

Huss, Gary R.↗
NASA NTRS1991

Optical transitions in diamond at ultrahigh pressures

Optical studies on diamond at ultrahigh pressures are described which show that the unique properties of diamonds are affected by such stresses. Spectroscopic measurements show that the optical absorption edge shifts from UV to red with increasing pressures, and Raman scattering measurements how evidence for new structural transitions associated with large macroscopic deformation, beginning at a pressure of about 150 GPa. The changes are reversible and are associated with intense luminescence peaks at 2.0-2.2 eV under 458-514 nm radiation. These results may be related to the onset of bandgap closure in the approach to a new high-pressure phase. These spectral features must also be taken into account when diamond is used as optical windows for ultrahigh-pressure investigations.

Mao, H. K.↗