Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Diamond”

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.

At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Study of the Structural and Morphological Properties of HPHT Diamond Substrates

The morphological and structural properties of a series of high-pressure high-temperature (HPHT) single-crystal diamond substrates are comprehensively studied by white-light optical interference microscopy, atomic-force microscopy, and X-ray diffraction analysis. Procedures that provide a means for characterizing the substrate parameters most critical for epitaxial application with the laboratory equipment are described. It is shown that the jewelry-type characterization of diamond substrates is insufficient to assess the possibility of their use for the epitaxial growth of chemical-vapor-deposited (CVD) diamond.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Evolution of Triplet Paramagnetic Centers in Diamonds Obtained by Sintering of Detonation Nanodiamonds at High Pressure and Temperature

The electron paramagnetic resonance (EPR) spectra of triplet centers in detonation nanodiamonds (DNDs) and diamond single crystals of submicrometer size, synthesized from those DNDs at high pressures and temperatures, are studied. In the EPR spectra of DNDs, signals from negatively charged nitrogen- vacancy centers (NV)/sup(-) with a g factor of g{sub 1} = 4.24 and multivacancies with g{sub 2} = 4.00 are observed. The signals from (NV)/sup(-) centers disappear in the spectra of diamond single crystals, and a quintet signal with g = 4.00 is detected at the position of the signal from multivacancies. Analysis of the shape and position of the quintet’ lines showed that this ESR signal is due to the pairs of nitrogen substitution centers in diamond, separated from each other by distances not exceeding 0.7 nm, between which a strong exchange interaction takes place. A comparison of the experimental data and the simulation results allows determining the spin-Hamiltonian parameters of the exchange-coupled pairs of paramagnetic impurity nitrogen atoms.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Ion Modification of the Field-Emission Properties of Diamond-Graphite Film Structures

The patterns of variation of structure-phase, morphological, and field-emission parameters of nanocomposite diamond-graphite film structures, which were synthesized in microwave plasma of ethanol vapors, with the dose of irradiation with nitrogen ions with an energy of 20 keV are studied. It is found that the morphological parameters of diamond-graphite structures subjected to small-dose irradiation differ only slightly from those of nonirradiated samples. In contrast, the field-emission properties of irradiated samples are altered significantly. The maximum density of field-emission currents increases when the field-emission excitation thresholds are raised. The optimum doses of nitrogen ion implantation resulting in a more than fivefold increase (relative to nonirradiated structures) in the maximum density of field-emission currents are determined. The physical and chemical mechanisms involved in the modification of surface and near-surface properties of diamond-graphite structures subjected to various doses of ion irradiation are examined.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Influence of Cobalt on the Adhesion Strength of Polycrystalline Diamond Coatings on WC–Co Hard Alloys

The influence of cobalt on the phase composition and adhesion strength of polycrystalline diamond coatings has been studied using scanning electron microscopy, Raman spectroscopy, and X-ray microanalysis. The coatings have been deposited on WC–Co hard alloy substrates in glow discharge plasma. It has been found that the catalytic amorphization of carbon only takes place during the direct synthesis of the diamond coating, when the cobalt vapor pressure over the substrate is high and the cobalt-related degradation of the synthesized diamond is absent.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

On a Possibility of the Overgrowth of Diamonds in the Hydrocarbon Atmosphere

The possibility to increase sizes of diamond crystals at least 25 μm by means of their annealing at a temperature of 1450 K in a hydrocarbon atmosphere has been studied. The initial diamond crystals are incorporated in the polyvinyl acetate layer on the surface of a silicon monocrystal and subjected to the annealing in methane atmosphere with low pressure in the presence of an external electric field with intensity up to 0.04 V/μm. Under these conditions the charged ions of methane dissociation products are accelerated and acquire the kinetic energy that is comparable with energy sufficient to form sp{sup 3}-hybride bonds, which can lead to an increase in the sizes of initial seed crystallites. The obtained substrates of a composite with a typical thickness not higher than 1.2 mm, which contain a joined diamond crystal in the carbon matrix, can be used as thermal conductive and electrical insulating spacers in devices for cooling items of electronic engineering.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Simulation of a Detector of Visible and Near-IR Electromagnetic Radiation Based on Artificial Diamond

A method for calculation of the I–V characteristic is proposed for a detector of visible and near-IR electromagnetic radiation based on artificial diamond with allowance for vertical flow of electric current. The method can be used when the free-path length of carriers in diamond is less than the scale of variations in the concentration of carriers. The method is used to determine the following detector characteristics: the dependence of current on voltage, distribution of carrier concentration, and electric potential for a particular variant of a photodetector based on polycrystalline diamond film consisting of nanosized single crystals doped with boron.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

A CVD Diamond-Based Photodetector for the Visible and Near-IR Spectral Range

A photodetector for the visible and near-IR spectral range has been created on the basis of a chemical- vapor-deposited diamond modulation-doped with boron. The detected electromagnetic radiation is absorbed in a thin Cr (7 nm)–Au (5.5 nm) bimetallic sublayer deposited on the surface of a modulationdoped diamond film comprising a highly doped (up to 5 × 10{sup 19} cm{sup –3}) 3-nm-thick delta-layer, low-doped (~10{sup 17} cm{sup –3}) 800-nm-thick sublayer, and highly doped (10{sup 20} cm{sup –3}) ~10-μm-thick sublayer with an ohmic Ti(50 nm)/Pt(15 nm)/Au(30 nm) contact. Holes generated in the bimetallic sublayer diffuse into diamond and are accelerated by an electric field in the low-doped sublayer to form a response photocurrent. The ampere/watt responsivity of the photodetector reaches 1 μA/W at a radiation wavelength of 445 nm and 0.18 μA/W at 1.06 μm.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

New Cluster Secondary Ions for Quantitative Analysis of the Concentration of Boron Atoms in Diamond by Time-of-Flight Secondary-Ion Mass Spectrometry

A new approach to quantitative analysis of the concentration of boron atoms in diamond using secondary- ion mass spectrometers with time-of-flight mass analyzers is proposed. Along with the known boron-containing lines (B, BC, BC{sub 2}), many lines related to cluster secondary ions BC{sub N} have been found in the mass spectrum; their intensity increases by one or two orders of magnitude when Bi{sub 3} probe ions are used. Lines BC{sub 4}, BC{sub 6}, BC{sub 2}, and BC{sub 8} have the highest intensity (in the descending order); when they are summed, the sensitivity increases by an order of magnitude in comparison with the known mode of detecting BC{sub 2}. The parameters of the boron δ-layer in single-crystal diamond films grown under optimal conditions have been measured to be unprecedented: the δ-layer width is about 2 nm, and the concentration is 6.4 × 10{sup 20} cm{sup –3} (the boron concentrations for doped and undoped diamonds differ by four orders of magnitude).

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Frictional Coefficients between Aluminum–Silicon Alloy and Cutting Inserts with MPCVD Diamond Coatings

The frictional coefficients at the front and rear surfaces of a VK6 hard-alloy cutter with experimental nano- and microcrystalline CVD diamond coatings applied in microwave plasma are determined by extrapolation to zero cut-layer thickness. It is found that, for diamond coatings with a single microcrystalline layer and those with both a microcrystalline layer and a nanocrystalline layer, the frictional coefficients are less than for an uncoated hard-alloy cutter and also for a cutter with a Sandvik diamond coating.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Undulatory Diamond Smoothing of Machine-Part Surfaces

The use of an industrial robot for undulatory diamond smoothing of machine-part surfaces is considered. The design of a robot for diamond smoothing of cylindrical and complex surfaces is described, and an example of an automatic machining line that includes a two-column industrial robot for undulatory smoothing is presented. In tests, the wear resistance of samples subjected to diamond smoothing on a lathe and to undulatory smoothing is compared.

42 ENGINEERING↗
DOE OSTI2025

Optimizing ensemble NV − spin properties of fluorescent diamond microparticles by systematic low pressure high temperature annealing

Low pressure high temperature annealing is a means for driving nitrogen and defect diffusion in diamond to reduce internal lattice damage without the need for technically complicated high-pressure cells. Herein, we perform a systematic time (5, 15, and 30 min) and temperature (1200 °C–1800 °C) study of effects of low-pressure high temperature annealing on photoluminescence, spin concentrations, and spin relaxation properties of NV centers in ca. 3 μm synthetic type 1b diamond particles. Annealing in the temperature range of ca. 1400 °C–1700 °C for even 5 min leads to a higher optically detected magnetic resonance contrast as compared to standard annealing at 900 °C for 2 h. Particles annealed at 1700 °C for 5 min exhibit a contrast close to about 13% as compared to about 9% for those annealed at 900 °C for 2 h. A reduction in the zero-field splitting strain parameter from E ≈ 4.5 MHz to ≈ 2.5 MHz and spectral linewidth from Δν ≈ 7 MHz to ≈ 4 MHz are observed even after 5 min annealing at 1700 °C. Improvements in these spectral parameters resulted in a roughly 2-fold reduction in the noise level of temperature monitoring experiment utilizing an ensemble of NV centers in the particles. Annealing in the temperature range of 1600 °C for 15 or 30 min or 1700 °C for 5 min resulted in NV T 1 relaxation times approaching ca. 5 ms typically observed for bulk diamond. Quantitative electron paramagnetic resonance (EPR) allowed for estimations of thermal activation energies of paramagnetic center annihilation. Monitoring the primary defect concentration (P1 and other defects with half integer spins) and utilizing second order kinetic modeling, an activation energy of 3.63 ± 0.28 eV was estimated. Alternatively, using the NV half field EPR signal and first order kinetic modeling, a similar activation energy 3.89 ± 0.29 eV was estimated.

NV centers↗
DOE OSTI2014

Rapid Growth of Nanostructured Diamond Film on Silicon and Ti–6Al–4V Alloy Substrates

Nanostructured diamond (NSD) films were grown on silicon and Ti–6Al–4V alloy substrates by microwave plasma chemical vapor deposition (MPCVD). NSD Growth rates of 5 µm/h on silicon, and 4 µm/h on Ti–6Al–4V were achieved. In a chemistry of H2/CH4/N2, varying ratios of CH4/H2 and N2/CH4 were employed in this research and their effect on the resulting diamond films were studied by X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. As a result of modifying the stock cooling stage of CVD system, we were able to utilize plasma with high power densities in our NSD growth experiments, enabling us to achieve high growth rates. Substrate temperature and N2/CH4 ratio have been found to be key factors in determining the diamond film quality. NSD films grown as part of this study were shown to contain 85% to 90% sp3 bonded carbon.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Data and Code for Atomic Scale Etching of Diamond: Insights from Molecular Dynamics Simulations

This work investigates the effects of argon ions, hydrogen atoms, and hydrogen ions on the diamond (100) surface using classical molecular dynamics simulations. The purpose of this investigation was to asses plasma processing techniques for applications in quantum device manufacturing. The simulations suggest that combining argon ion smoothing with selective, near threshold energy H removal of amorphous C could be an effective strategy for diamond surface engineering, leading to more reliable and sensitive diamond color center devices. Results were found to differ significantly with interatomic potential, and an analysis of these differences was also carried out. Included in this repository are LAMMPS source files, input scripts, and plotting scripts required to reproduce the data. Also included are the output data required to make all the plots included in the associated publication.

Brenner↗
DOE OSTI2016

Surface characteristics and damage distributions of diamond wire sawn wafers for silicon solar cells

This paper describes surface characteristics, in terms of its morphology, roughness and near-surface damage of Si wafers cut by diamond wire sawing (DWS) of Si ingots under different cutting conditions. Diamond wire sawn Si wafers exhibit nearly-periodic surface features of different spatial wavelengths, which correspond to kinematics of various movements during wafering, such as ingot feed, wire reciprocation, and wire snap. The surface damage occurs in the form of frozen-in dislocations, phase changes, and microcracks. The in-depth damage was determined by conventional methods such as TEM, SEM and angle-polishing/defect-etching. However, because these methods only provide local information, we have also applied a new technique that determines average damage depth over a large area. This technique uses sequential measurement of the minority carrier lifetime after etching thin layers from the surfaces. The lateral spatial damage variations, which seem to be mainly related to wire reciprocation process, were observed by photoluminescence and minority carrier lifetime mapping. Our results show a strong correlation of damage depth on the diamond grit size and wire usage.

14 SOLAR ENERGY↗
DOE OSTI2015

Proton recoil telescope based on diamond detectors for measurement of fusion neutrons

Diamonds are very promising candidates for the neutron diagnostics in harsh environments such as fusion reactor. In the first place this is because of their radiation hardness, exceeding that of Silicon by an order of magnitude. Also, in comparison to the standard on-line neutron diagnostics (fission chambers, silicon based detectors, scintillators), diamonds are less sensitive to γ rays, which represent a huge background in fusion devices. Finally, their low leakage current at high temperature suppresses the detector intrinsic noise. In this talk a CVD diamond based detector has been proposed for the measurement of the 14 MeV neutrons from D-T fusion reaction. The detector was arranged in a proton recoil telescope configuration, featuring a plastic converter in front of the sensitive volume in order to induce the (n,p) reaction. The segmentation of the sensitive volume, achieved by using two crystals, allowed to perform measurements in coincidence, which suppressed the neutron elastic scattering background. A preliminary prototype was assembled and tested at FNG (Frascati Neutron Generator, ENEA), showing promising results regarding efficiency and energy resolution. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Deployment of Diamond-Based Radiation Detector for Very High Dose Rate Measurements - 17042

The diamond-based radiation detector system has been developed at the University of Bristol to measure radiation within nuclear facilities known to exhibit high dose rates. The challenge at Sellafield site in the UK, described herein also applies to many other nuclear operators worldwide, making the transfer of diamond detector technology to other applications feasible. Development of an operator-friendly system, extensive detector testing and controlled calibrations have led to several successful deployments of the device at Sellafield site, providing them with valuable data about the radiological contamination within their highly active plants. Designed for measurements of intense radiation fields, this new tool for characterisation of radiologically hazardous environments is a game-changer, improving the availability and quality of dose rate data used in safety case justifications. Compared with conventional technology diamond detectors are radiation tolerant, miniature, and can measure an extraordinary range of dose rates. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Extreme Two‐Phase Cooling from Laser‐Etched Diamond and Conformal, Template‐Fabricated Microporous Copper

Abstract This paper reports the first integration of laser‐etched polycrystalline diamond microchannels with template‐fabricated microporous copper for extreme convective boiling in a composite heat sink for power electronics and energy conversion. Diamond offers the highest thermal conductivity near room temperature, and enables aggressive heat spreading along triangular channel walls with 1:1 aspect ratio. Conformally coated porous copper with thickness 25 µm and 5 µm pore size optimizes fluid and heat transport for convective boiling within the diamond channels. Data reported here include 1280 W cm −2 of heat removal from 0.7 cm 2 surface area with temperature rise beyond fluid saturation less than 21 K, corresponding to 6.3 × 10 5 W m −2 K −1 . This heat sink has the potential to dissipate much larger localized heat loads with small temperature nonuniformity (5 kW cm −2 over 200 µm × 200 µm with <3 K temperature difference). A microfluidic manifold assures uniform distribution of liquid over the heat sink surface with negligible pumping power requirements (e.g., <1.4 × 10 −4 of the thermal power dissipated). This breakthrough integration of functional materials and the resulting experimental data set a very high bar for microfluidic heat removal.

Palko, James W.↗
DOE OSTI2018

Silicon Oxide‐Rich Diamond‐Like Carbon: A Conformal, Ultrasmooth Thin Film Material with High Thermo‐Oxidative Stability

Abstract Silicon oxide‐containing diamond‐like carbon (a‐C:H:Si:O) films are a promising class of protective coatings for environmentally‐demanding applications owing to their lower residual stresses and superior thermal stability and oxidation resistance relative to undoped diamond‐like carbon. However, existing versions of a‐C:H:Si:O deposited by traditional methods such as plasma‐enhanced chemical vapor deposition (PECVD) undergo substantial degradation and oxidation at temperatures above 250 °C. This, together with the difficulty of PECVD in depositing conformal coatings on complex geometries such as high‐aspect‐ratio features, has limited the applicability of a‐C:H:Si:O. Here, the unique capabilities of plasma immersion ion implantation and deposition (PIIID) to grow silicon oxide‐rich diamond‐like carbon materials that are ultrasmooth, continuous, and conformal on high‐aspect‐ratio topographies are explored. The high concentration of silicon and oxygen in PIIID‐grown films (23 ± 5 at.% and 11 ± 4 at.%, respectively) is unrivalled for this class of materials, and drastically increases the resistance to oxidation at high temperatures, compared with PECVD‐grown films. The results open the path for using a‐C:H:Si:O in applications involving exposure of materials to extreme environments.

Mangolini, Filippo↗