Diamond Materials Research Articles

The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team.

We have designed and constructed a new system for micro-machining parts and sample assemblies used for diamond anvil cells and general user operations at the High Pressure Collaborative Access Team, sector 16 of the Advanced Photon Source. The new micro-machining system uses a pulsed laser of 400 ps pulse duration, ablating various materials without thermal melting, thus leaving a clean edge. With optics designed for a tight focus, the system can machine holes any size larger than 3 μm in diameter. Unlike a standard electrical discharge machining drill, the new laser system allows micro-machining of non-conductive materials such as: amorphous boron and silicon carbide gaskets, diamond, oxides, and other materials including organic materials such as polyimide films (i.e., Kapton). An important feature of the new system is the use of gas-tight or gas-flow environmental chambers which allow the laser micro-machining to be done in a controlled (e.g., inert gas) atmosphere to prevent oxidation and other chemical reactions in air sensitive materials. The gas-tight workpiece enclosure is also useful for machining materials with known health risks (e.g., beryllium). Specialized control software with a graphical interface enables micro-machining of custom 2D and 3D shapes. The laser-machining system was designed in a Class 1 laser enclosure, i.e., it includes laser safety interlocks and computer controls and allows for routine operation. Though initially designed mainly for machining of the diamond anvil cell gaskets, the laser-machining system has since found many other micro-machining applications, several of which are presented here.

First use of single-crystal diamonds as fission-fragment detector

Single-crystal chemical vapor-deposited diamond (sCVD) was investigated for its ability to act as fission-fragment detector. In particular we investigated timing and energy resolution for application in a simultaneous time-of-flight and energy measurement to determine the mass of the detected fission fragment. Previous tests have shown that poly-crystalline chemical vapor deposited (pCVD) diamonds provide sufficient timing resolution, but their poor energy resolution did not allow complete separation between very low-energy fission fragments, α-particles and noise. Our present investigations prove artificial sCVD diamonds to show similar timing resolution as pCVD diamonds close to 100ps. Improved pulse-height resolution allows the unequivocal separation of fission fragments, and the detection efficiency reaches 100%, but remains with about a few percent behind requirements for fragment-mass identification. With high-speed digital electronics a timing resolution well below 100ps is possible. However, the strongly varying quality of the presently available diamond material does not allow application on a sufficiently large scale within reasonable investments.

Porous diamond with high electrochemical performance

Synthetic diamond materials are currently attracting attention for applications such as thin films supercapacitors or medical implantable electrodes where chemically stable materials featuring high double layer capacitance as well as low electrochemical impedance are sought. Those properties may be reached with high aspect ratio diamond provided that current collection is done efficiently through the diamond layer. In this paper, we introduce a very novel material, namely SPDia™, based on boron-doped diamond grown on a highly porous polypyrrole scaffold prepared by chemical vapour deposition. This composite was first characterised by SEM and Raman spectroscopy to cheque the diamond crystallinity and the structural evolution of the polypyrrole during the CVD process. Then cyclic voltammetry and electrochemical impedance spectroscopy were performed to assess its electrochemical reactivity. It was found to exhibit remarkable properties, that include a large double layer capacitance with values reaching up to 3mFcm−2 in aqueous LiClO4 and a low electrochemical impedance, thus highly competitive with respect to other nanostructured diamond materials as recently reported.

Microwave-assisted efficient conjugation of nanodiamond and paclitaxel.

Nanodiamond has recently received considerable attention due to the various possible applications in medical field such as drug delivery and bio-labeling. For this purpose suitable and effective surface functionalization of the diamond material are required. A versatile and reproducible surface modification method of nanoscale diamond is essential for functionalization. We introduce the input of microwave energy to assist the functionalization of nanodiamond surface. The feasibility of such a process is illustrated by comparing the biological assay of ND-paclitaxel synthesized by conventional and microwave irradiating. Using a microwave we manage to have approximately doubled grafted molecules per nanoparticle of nanodiamond.

Fabrication and characterization of polycrystalline diamond detectors for fast neutron monitoring

Diamond detectors have been fabricated using commercially available detector grade polycrystalline CVD substrates for fast neutron measurement in the Indian TBM Experiment at the upcoming ITER facility. Subsequent to fabrication, the detectors were characterized for leakage current and for response to alpha particles from 238+239Pu source. The detectors were observed to have low leakage currents at a field of 1Vµm−1. The stability of the alpha response and improvement in the count rate were achieved by β-irradiation using 90Sr β source. The fast neutron response of the detectors was studied using a D–T fast neutron source in India. The detectors showed linear response in the measured neutron flux of 2.86×105–8.76×106ncm−2s−1. The neutron response of detectors of 100µm and 300µm thicknesses was compared experimentally to study the neutron response dependence on detector thickness. Experimental results show that the detector of 100µm thickness has better performance compared to the detector of thickness of 300µm. The results presented in this paper confirm the suitability of commercially available films from Diamond Materials, GmbH, Germany for detector fabrication for fast neutron monitoring. The details of detector fabrication and results of characterization are presented in this paper.

Thermally stable, electrically conductive diamond material prepared by high-pressure, high-temperature processing of a graphite + boron carbide mixture

An electrically conductive boron-doped diamond material with high thermal stability and good mechanical properties has been synthesized at high pressures from powder mixtures of graphite and boron carbide. Specific microstructure and high elastic moduli of samples obtained indicate the formation of polycrystalline diamond matrix in the material. The unique combination of physicochemical properties offered by heavily boron-doped diamond can extend its application area as an electrostructural material capable of operating in aggressive media.

Gold nanoparticle-ultrananocrystalline diamond hybrid structured materials for high-performance optoelectronic device applications.

Hybridization of gold nanoparticles in the ultrananocrystalline diamond materials improves the electrical conductivity of the materials to a high level of 230 (Ω cm)(-1) with a sheet carrier concentration of 8.9 × 10(20) cm(-2). These hybrid materials show enhanced electron field emission (EFE) properties, viz. a low turn-on field of 2.1 V μm(-1) with a high EFE current density of 5.3 mA cm(-2) (at an applied field of 4.9 V μm(-1)) and the life-time stability up to a period of 372 min. The fabrication of these hybrid materials with high conductivity and superior EFE behaviors is a direct and simple process which opens new prospects in flat panel displays and high brightness electron sources.

Silicon and germanium nanocrystals: properties and characterization.

Group-IV nanocrystals have emerged as a promising group of materials that extends the realm of application of bulk diamond, silicon, germanium and related materials beyond their traditional boundaries. Over the last two decades of research, their potential for application in areas such as optoelectronic applications and memory devices has been progressively unraveled. Nevertheless, new challenges with no parallel in the respective bulk material counterparts have arisen. In this review, we consider what has been achieved and what are the current limitations with regard to growth, characterization and modeling of silicon and germanium nanocrystals and related materials.

The influence of surface functionalisation on the electrical properties and thermal stability of nanodiamonds

Detonation nanodiamond (ND) has recently emerged as a useful new class of diamond material. However, to date there has been little investigation of the electrical properties of this material. Due to the nanoscale dimensions, the surface functionalisation of the individual ND is of particular importance to the characteristics of ND films. Here, hydrogen and oxygen termination of ND, verified using Fourier transform infrared spectroscopy, are shown to strongly influence the electronic properties of NDs. Hydrogen terminated ND exhibiting a far greater resilience to thermal decomposition when compared to the oxygen terminated NDs. Moreover, H-NDs also displayed so-called “surface conductivity,” a property displayed by hydrogen-terminated bulk diamond films, whilst O-NDs display properties high resistivity. These results indicate that under the correct conditions ND layers can display similar electrical properties to “bulk” diamond thin films.

Recent Advances on Diamond Surfaces and Devices

Diamond represents a well-known gemstone and traditional industrial material in applications such as cutting and polishing. However, since about 20 years ago, diamond is rising as a new semiconductor material with many unique properties, unrivalled by other materials. Research and development during these years was initially focused on getting high quality, electronic grade diamond materials, possibly without defects and impurities. Nowadays, synthetic high quality diamonds for electronic application are reality and available commercially. Based on this tremendous progress in diamond technology many new fundamental phenomena have been and are being discovered and diamond is studied in diverse fields from nuclear physics and spintronics to biology and medicine. In this respect it is intriguing that originally unwanted defects and impurities have now become one of the key functional elements in diamond research and applications. This makes evident that diamond can bring surprises and shine bright even as a semiconductor. In this special issue of physica status solidi (a) we aim at bringing you refl ection of the most recent activity and advances in diamond science and technology, although without being able to be comprehensive in this already large and quickly developing field. To accomplish this aim, the issue is based on inviting several topical contributions from recognized scientists as well as on selection of papers that were actively contributed by authors worldwide. The articles come from Europe, Asia, and Australia and demonstrate truly intercontinental collaborations. The special issue is organized into fundamental and applied subjects such as growth, impurity and defect control, surface structuring of diamond, surface chemistry, electron emission and excitons in diamond and, of course, diamond devices. Note that while they represent their own research fields these subjects are also obviously interrelated. We would like to attract your attention in particular to the two Feature Articles in this issue. Kane M. O'Donnell and co-workers discuss a new way of generating the highly useful negative electron affinity and facilitate electron emission by merging diamond with lithium 1. Electron emission is indeed a crucial and intensively studied phenomenon in diamond, as shown by the article of I-Nan Lin and coworkers 2. It finds interest from chemistry and biology to power devices, in particular because of its use in applications benefiting our daily lives and contributing to our sustainable future. These and other collected articles show that the research and understanding of diamond and its surfaces is still far from finished and new discoveries may be just behind the corner. Therefore, we strived for an expedite peer-review and editorial process and we hope that you will find the presented works interesting, timely and inspirational. Prague & Hasselt, September 2014 Bohuslav Rezek Miloš Nesládek Ken Haenen

Fuzzy Comprehensive Model Analysis of New Diamond Material Based on VC Programming

This paper has designed a new diamond computer evaluation method by the use of the diamond evaluation model, and the combination of VC programming technology, and the method has been introduced into the evaluation of regional tourism comprehensive competitiveness. In order to achieve the comprehensive evaluation function of new diamond model, we have designed new diamond comprehensive fuzzy evaluation model by using fuzzy evaluation function to, and have the developed computer evaluation system of regional tourism competitiveness by combining VC programming technology. The system uses the market, enterprises and infrastructure the three aspects of evaluation factors to score the tourism competitiveness, which has realized the evaluation of computer automation function. Competitiveness of regional tourism industry in Shandong, Yunnan and Gansu and other areas is respectively scored through the function, and the results indicate that the comprehensive evaluation score of Yunnan is the highest, and that of Gansu is the lowest.

Friction pair evaluation of cartilage–diamond for partial joint repair

Alternative approaches to replace total joint replacement are desirable to reduce the massive loss of healthy tissues. The tribological performance of the cartilage–diamond contact in deionized water and calf bovine serum environments was investigated in this study. To optimize lubrication, hydrogen and ammonia treatments were applied on diamond surfaces. Adhesion and wettability on the same were evaluated to determine the impact of functionalization on surface properties. It was found that the friction between the cartilage and diamond decreased with an increase in the load. This is related to the interaction between two contacting surfaces. Under dry conditions, the hydrogen treatment enabled a reduction in friction while the ammonia treatment increased it. The lubricated friction, however, is determined by two effects: the surface area covered by the lubricant and their interactions. Our results show that the microcrystalline diamond without functionalization provided the lowest friction (coefficient of 0.02–0.03) while sliding against cartilage in serum. The reason is that microcrystalline diamond attracts more molecules that dominate the lubricating performance. This research demonstrated that diamond materials could be suitable as implants as well as to locally repair them.

Diffusion Wear Mechanism of Single Crystal Diamond Tool in Machining Die Steels

Ultra-precision diamond cutting of ferrous metals has not been successful in application due to significant tool wear. In this work, numerical simulations and experimental investigations are presented in order to study the interface diffusion between diamond tool and workpiece materials. A diffusion model with respect to carbon atoms from diamond tool penetrating into chips and machined surface was established. The numerical simulation results of the diffusion process reveal that the distribution laws of carbon atoms concentration have a close relationship with diffusion distance, diffusion time and the original carbon concentration of the work material. In addition, diamond face cutting tests of die steels with different carbon content are conducted at different depth of cuts and feed rates to verify the previous simulation results. The wear morphology of rake face and flank face of diamond tool were detected by scanning electron microscopy. Energy dispersive X-ray analysis was proposed to investigate the change in chemical composition of the chips and machined surface. The results of this work benefit for a better understanding on the diffusion wear mechanism in single crystal diamond cutting of ferrous metals.

Evidence for multiple diamondite-forming events in the mantle

A collection of 35 diamondite samples (polycrystalline diamond aggregates, sometimes referred to as framesites), assumed to be from southern Africa, have been studied to investigate their infrared (IR) spectroscopic characteristics. Due to the abundance of sub-micrometer, interlocking diamonds (polycrystalline) with mineral and fluid inclusions within the diamond material affecting their transparency, only fragments from 10 of the samples provided high-quality data. The IR spectra showed a wide range of generally high-nitrogen concentrations (386-2677 ppm), with a full range of nitrogen aggregation states, from pure IaA to pure IaB. Platelet characteristics were interpreted as being regular (i.e., not having been affected by deformation and/or heating events), meaning the nitrogen aggregation data could be interpreted with confidence. Surprisingly, the platelet data showed a positive correlation between their intensity (integrated area) and peak position. The primary hydrogen band (at 3107 cm-1) and secondary band (at 1405 cm) are both often present in the samples’ spectra, but show no correlation with any other characteristic. There is also no correlation between the samples’ paragenesis (as defined by their garnet chemistry) and any of the IR characteristics. While we have no independent determination of the samples mantle residence age, nor the temperature they resided at, we infer that diamondite formation has occurred episodically over a large time frame in single and distinct growth events (as opposed to over a short time frame but over a large depth/temperature range). This idea is more in keeping with the theory that C-O-H diamond- (and diamondite-) forming fluids are the result of localized small volume processes. Interestingly, one sample contained fluid inclusions that exhibited a water:carbonate molar ratio (~0.8), similar to the saline and silicic end-members of the monocrystalline diamond-forming fluid chemical spectrum.

Determination of the KQclinfclin,Qmsr fmsr correction factors for detectors used with an 800 MU/min CyberKnife(®) system equipped with fixed collimators and a study of detector response to small photon beams using a Monte Carlo method.

In a previous work, output ratio (ORdet) measurements were performed for the 800 MU/min CyberKnife(®) at the Oscar Lambret Center (COL, France) using several commercially available detectors as well as using two passive dosimeters (EBT2 radiochromic film and micro-LiF TLD-700). The primary aim of the present work was to determine by Monte Carlo calculations the output factor in water (OFMC,w) and the [Formula: see text] correction factors. The secondary aim was to study the detector response in small beams using Monte Carlo simulation. The LINAC head of the CyberKnife(®) was modeled using the PENELOPE Monte Carlo code system. The primary electron beam was modeled using a monoenergetic source with a radial gaussian distribution. The model was adjusted by comparisons between calculated and measured lateral profiles and tissue-phantom ratios obtained with the largest field. In addition, the PTW 60016 and 60017 diodes, PTW 60003 diamond, and micro-LiF were modeled. Output ratios with modeled detectors (ORMC,det) and OFMC,w were calculated and compared to measurements, in order to validate the model for smallest fields and to calculate [Formula: see text] correction factors, respectively. For the study of the influence of detector characteristics on their response in small beams; first, the impact of the atomic composition and the mass density of silicon, LiF, and diamond materials were investigated; second, the material, the volume averaging, and the coating effects of detecting material on the detector responses were estimated. Finally, the influence of the size of silicon chip on diode response was investigated. Looking at measurement ratios (uncorrected output factors) compared to the OFMC,w, the PTW 60016, 60017 and Sun Nuclear EDGE diodes systematically over-responded (about +6% for the 5 mm field), whereas the PTW 31014 Pinpoint chamber systematically under-responded (about -12% for the 5 mm field). ORdet measured with the SFD diode and PTW 60003 diamond detectors were in good agreement with OFMC,w except for the 5 mm field size (about -7.5% for the diamond and +3% for the SFD). A good agreement with OFMC,w was obtained with the EBT2 film and micro-LiF dosimeters (deviation less than 1.4% for all fields investigated). [Formula: see text] correction factors for several detectors used in this work have been calculated. The impact of atomic composition on the dosimetric response of detectors was found to be insignificant, unlike the mass density and size of the detecting material. The results obtained with the passive dosimeters showed that they can be used for small beam OF measurements without correction factors. The study of detector response showed that ORdet is depending on the mass density, the volume averaging, and the coating effects of the detecting material. Each effect was quantified for the PTW 60016 and 60017 diodes, the micro-LiF, and the PTW 60003 diamond detectors. None of the active detectors used in this work can be recommended as a reference for small field dosimetry, but an improved diode detector with a smaller silicon chip coated with tissue-equivalent material is anticipated (by simulation) to be a reliable small field dosimetric detector in a nonequilibrium field.

The Development of Diamond Strength Testing System based on Microprocessor

In order to improve the quality of diamond and other super-hard materials, fast and accurate detection of its strength is significant. The System use air pressure, broken automatic detection, automatic samples, testing is completed automatically returned. By resistance strain gauges to the pressure value is converted to voltage signal, after a highprecision A / D converter chip into a numerical quantity, given to high-performance MCU processing. Sample test system can be set according to sample size, data communications, data statistics and report printing, with a large-screen LCD display, dynamic display of strength parameters of the distribution curve. System is reliable test data stability, good repeatability and high reliability.

Corrosion behaviour of silicon carbide–diamond composite materials in aqueous solutions

The corrosion behaviour of the relatively new silicon carbide bonded diamond materials (ScD) was investigated in NaOH, H2SO4 and hydrothermal conditions and compared with that of conventional SSiC and SiSiC-materials. The corrosion resistance increases with decreasing diamond grain size. In H2SO4 all investigated materials show a very high corrosion resistance, whereas in NaOH and under hydrothermal conditions above 100 °C some leaching of residual silicon takes place. Nevertheless the fine grained ScD material exhibits a residual strength of 400 MPa after 200 h corrosion in NaOH at 90 °C. Under the same conditions the strength of the SiSiC-material reduces to 50 MPa. The silicon carbide-diamond composites demonstrate corrosion resistance superior to SiSiC and wear properties analogous to that of conventional superhard materials. This material would therefore be suitable for use in demanding corrosive wear applications.

ChemInform Abstract: Recent Developments and Applications of Nanodiamonds as Versatile Bioimaging Agents

AbstractReview: 75 refs.

Small and Bright: Nanodiamonds for tissue repair, drug delivery, and biodetection

Transforming diamond sizes from the micron regime into a few billionths of a meter probably doesn't increase their value in jewelry, but it certainly adds an extraordinary value in numerous physical science, engineering, and medical applications. Nanodiamonds are generally defined as synthetic diamond materials that have crystalline or feature sizes (e.g., grain or particle sizes) between 1 and 100 nm (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> -10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> m) and include two forms: particulate (zero-dimensional) and thin film (two-dimensional). Figure 1 shows particulate nanodiamond (PND) and nanodiamond thin films under a scanning electron microscope (SEM) and atomic force microscope (AFM). Because the nanodiamond thin film is actually composed of nanosized columnar crystals or grains, the material is usually called nanocrystalline diamond (NCD) or ultra-NCD (UNCD, grains sizes <;10 nm).

Nanoscale nuclear magnetic resonance with a 1.9-nm-deep nitrogen-vacancy sensor

We present nanoscale NMR measurements performed with nitrogen-vacancy (NV) centers located down to about 2 nm from the diamond surface. NV centers were created by shallow ion implantation followed by a slow, nanometer-by-nanometer removal of diamond material using oxidative etching in air. The close proximity of NV centers to the surface yielded large 1H NMR signals of up to 3.4 uT-rms, corresponding to ~330 statistically polarized or ~10 fully polarized proton spins in a ~(1.8 nm)^3 detection volume.