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The incorporation of boron into a diamond lattice holds the potential to advance X-ray optics, offering the capability to manipulate various parameters of the lattice. This includes enhancing near-infrared absorption relative to pure diamond, thereby enabling Q-switchable optics. The use of MeV boron implantation emerges as a promising method for precisely doping the diamond lattice. However, for these optics to function effectively as Bragg-reflecting mirrors, ion implantation must be executed with meticulous attention to maintaining a strain-free, perfect diamond lattice. This study aimed to investigate the feasibility of utilizing a 9 MeV ion beam for high energy boron implantation. Different areas of a high-pressure, high-temperature (HPHT) diamond sample were subjected to irradiation with 9 MeV Boron ions, ranging in fluences from 5×1015 to 2.5×1016ions/cm2. Following boron implantation, high-temperature vacuum annealing was performed to restore the diamond lattice. Our assessment utilized X-ray rocking curve imaging, surface profilometry, and micro-Raman spectroscopy, with additional observations on near-infrared transmission properties. Our measurement of high-quality Bragg reflection through X-ray rocking curve imaging, sensitive to implantation-induced strain and defects, served as an key diagnostic for the effectiveness of this ion-implanted sample as a Bragg-reflecting optic.

The creation of SiV−, GeV−, and SnV− are presented by the atmospheric annealing in the argon flow. Compared to high‐pressure annealing, in which gas cannot flow, atmospheric annealing with an inert gas flow not only causes less degradation of the sample surface but also has the advantage of reducing equipment cost and preparation time. Excessive annealing time has been shown to reduce the amount of centers created. The optimal annealing time that maximizes formations depends on the type of diamond sample and the implanted ions. Furthermore, inspired by the split‐vacancy structure of the group IV–V centers, atmospheric pre‐annealing at 600 °C to increase the amount of di‐vacancy is demonstrated, followed by annealing at 1800 °C for 1 min. A shorter duration of high‐temperature annealing is expected to qualitatively reduce stress and deterioration of the crystallinity of the diamond sample. [ABSTRACT FROM AUTHOR]

Diamond properties can be tuned by doping and ion-beam irradiation is one of the most powerful techniques to do it in a controlled way, but it also produces damage and other aftereffects. Of particular interest is boron doping which, in moderate concentrations, causes diamond to become a p-type semiconductor and, at higher boron concentrations, a superconductor. Nevertheless, the preparation of superconducting boron-doped diamond by ion implantation is hampered by amorphization and subsequent graphitization after annealing. The aim of this work was to explore the possibility of creating boron-doped diamond superconducting regions and to provide a new perspective on the damage induced in diamond by MeV ion irradiation. Thus, a comprehensive analysis of the damage and eventual recovery of diamond when irradiated with 9 MeV B ions with different fluences has been carried out, combining Raman, photoluminescence, electrical resistivity, X-ray diffraction and Rutherford Backscattering/Ion-channeling. It is found that, as the B fluence increases, carbon migrates to interstitial sites outside of the implantation path and an amorphous fraction increases within the path. For low fluences (∼1015 ions/cm2), annealing at 1000 °C is capable to fully recovering the diamond structure without graphitization. However, for higher fluences (≥5 × 1016 ions/cm2), those required for superconductivity, the recovery is important, but some disorder still remains. For high fluences, annealing at 1200 °C is detrimental for the diamond lattice and graphite traces appear. The incomplete healing of the diamond lattice and the interstitial location of B can explain that optimally doped samples do not exhibit superconductivity. [Display omitted] • For high B fluences, C migrates outward to interstitial sites and induces strain. • Even for high fluences, annealing at 1000 °C allows recovering of diamond lattice. • Annealing at 1200 °C is detrimental and graphite traces appear. • Higher conductivity occurs in boron-doped diamond after 1000 °C annealing. • Remnant disorder and interstitial location of B could hamper superconductivity. [ABSTRACT FROM AUTHOR]

This study analyzes dislocation densities, stress levels, and crystal quality in the epitaxial lateral overgrowth (ELO) areas of CVD epitaxial layer on substrate with laser-cut holes of varying shapes and side orientations. It revealed that the shape and side orientation of holes on the substrate significantly impacted the quality of the ELO layers. Rectangular holes with the 〈100〉 crystal orientation on the sides favor improving the quality of CVD diamond. Under optimized conditions, the tensile stress of the ELO areas decreased as well as the dislocation density reduced to 3 × 105 cm−2, approximately 20 times lower than the non-ELO areas. [Display omitted] [ABSTRACT FROM AUTHOR]

On the basis of modeling of stresses, we analyzed the technological conditions guaranteeing the required cutting properties of grinding wheels in the operations of rough and finishing grinding performed in the course of their dressing by turning with diamond tools. We performed the theoretical analysis of force interactions between diamond crystals and abrasive grains and established stresses formed in the "abrasive grain–diamond crystal" contact system. The models of equivalent stresses were created according to the theory of maximum normal stresses. We also considered the theoretical aspects of simulation of the stresses in the "abrasive grain–diamond crystal" impact system with regard for the contact strength of the material of grains. [ABSTRACT FROM AUTHOR]

The incorporation of boron into a diamond lattice holds the potential to advance X-ray optics, offering the capability to manipulate various parameters of the lattice. This includes enhancing near-infrared absorption relative to pure diamond, thereby enabling Q-switchable optics. The use of MeV boron implantation emerges as a promising method for precisely doping the diamond lattice. However, for these optics to function effectively as Bragg-reflecting mirrors, ion implantation must be executed with meticulous attention to maintaining a strain-free, perfect diamond lattice. This study aimed to investigate the feasibility of utilizing a 9 MeV ion beam for high energy boron implantation. Different areas of a high-pressure, high-temperature (HPHT) diamond sample were subjected to irradiation with 9 MeV Boron ions, ranging in fluences from 5 × 10 15 to 2.5 × 10 16 ions / cm 2. Following boron implantation, high-temperature vacuum annealing was performed to restore the diamond lattice. Our assessment utilized X-ray rocking curve imaging, surface profilometry, and micro-Raman spectroscopy, with additional observations on near-infrared transmission properties. Our measurement of high-quality Bragg reflection through X-ray rocking curve imaging, sensitive to implantation-induced strain and defects, served as an key diagnostic for the effectiveness of this ion-implanted sample as a Bragg-reflecting optic. [Display omitted] • X-ray cavity Q-switching benefits from diamonds with high near-infrared absorption. • Single crystal HPHT diamonds were implanted with boron to increase NIR absorption. • X-ray rocking curve imaging, surface profilometry and micro-Raman assess lattice quality. [ABSTRACT FROM AUTHOR]

Boron doped diamonds (BDD) with boron concentration above 1019 at./cm3, grown under conditions of high isostatic pressure by the temperature gradient method, were studied by Transmission Electron Microscopy methods, EELS analysis and X-ray diffraction analysis. It was shown that boron is distributed unevenly in the grown crystal. It was found that in places of maximum boron content, interplanar distances d 111 increase from 0.206 to approximately 0.2065 nm. Parallel bands were discovered, the boundaries of which are fragments of the intermediate carbon phase (ICP-phase). Numerous twins along the {111} plane, as well as fragments of rhombohedral 9R phase, were discovered. [Display omitted] [ABSTRACT FROM AUTHOR]

The measurements of electron Channeling Radiation (CR) have been performed at ELBE linear electron accelerator of the Forschungszentrum Dresden-Rossendorf. The aim of performing these experiments was to optimize radiation yield and spectral line width of CR in order to apply channeling radiation for preparing a monochromatic X-ray source. Diamond crystals can be used in relatively high electron currents due to their high Debye temperature and the large thermal conductivity. Measurements of (110) planar channeling radiation have been performed at electron energies of 14.6, 17, 30, and 34 MeV, using diamond crystals of 42.5, 102, 168, and 500 μm thick. These data resulted in installing an X-ray source in ELBE linear electron accelerator. The electron beam with an average current of up to 200 μA allows reaching photon rates between 1010 s-1 and 1011 s-1 per 10% bandwidth. Photon energy can be tuned by changing the electron beam energy. Monochromisation of CR and bremsstrahlung background reduction has been investigated applying X-ray diffraction at a graphite crystal

Theoretical and experimental investigations have provided a deep insight into the process of diamond dressing of vitrified grinding wheels under the mechanisms of micro- or macrofracture of abrasive grits. This permits determining the process parameters dressing in coarse and finish grinding operations. The authors propose equations for finding the depth of dressing for various types of have been proposed for different wheel working layer states. [ABSTRACT FROM AUTHOR]

Disordering of crystal lattice induced by irradiation with fast neutrons and other high-energy particles is used for the deep modification of electrical and optical properties of diamonds via significant nanoscale restructuring and defects engineering. Raman spectroscopy was employed to investigate the nature of radiation damage below the critical graphitization level created when chemical vapor deposition and natural diamonds are irradiated by fast neutrons with fluencies from 1 × 1018 to 3 × 1020 cm−2 and annealed at the 100–1700 °C range. The significant changes in the diamond Raman spectra versus the neutron-irradiated conditions are associated with the formation of intrinsic irradiation-induced defects that do not completely destroy the crystalline feature but decrease the phonon coherence length as the neutron dose increases. It was shown that the Raman spectrum of radiation-damaged diamonds is determined by the phonon confinement effect and that the boson peak is present in the Raman spectra up to annealing at 800–1000 °C. Three groups of defect-induced bands (first group = 260, 495, and 730 cm−1; second group = 230, 500, 530, 685, and 760 cm–1; and third group = 335, 1390, 1415, and 1740 cm−1) were observed in Raman spectra of fast-neutron-irradiated diamonds.

Abstract During the last decades many studies have been carried out to investigate how point defects and aggregates respond and evolve in natural Type Ia diamonds as a result of treatments, and a number of underlying mechanisms have been identified and interpreted. However, the analysis of radiation-induced creation/ionization of defects, as well as their migration and aggregation in secondary defect structures, often requires experimental approaches which can hardly constitute a simple-to-use diagnostic tool for the identification of artificially treated diamonds. Here we disclose a novel simple indicator of artificial exposure of Type Ia diamonds to ionizing radiations and subsequent annealing. This indicator consists in narrow photoluminescence lines in the red region, between 681 and 725 nm, we recently found to result from vacancies trapped by interstitial carbon aggregates and platelets. Our results demonstrate that interstitial structures become sites of vacancy trapping – by thermal migration of radiation-induced vacancies – only when diamond undergoes treatments. We give the rigorous validation of the new spectroscopic probe of artificial treatments analysing photoluminescence and infrared absorption spectra of well-known H1b and H1c centres in a hundred samples. Importantly, the method is based on emission lines which do not require neither high photon-energy excitation nor cryogenic temperatures. Graphical abstract Unlabelled Image Highlights • PL features have been studied in a set of 50 natural and 50 treated diamonds. • We monitored the Da line at 681 nm and the Db doublet at 705 nm and 725 nm. • The D lines were observed only in irradiated and annealed diamonds. • The presence of D lines is related to the H1b and H1c infrared absorption centers. • The D lines can be used as PL probe of artificial treatments in yellow diamonds. [ABSTRACT FROM AUTHOR]

Abstract To clarify the anisotropic evolution of damaged carbons on a mechanically polished diamond surface under low-temperature (473 K) annealing, molecular dynamics simulation is performed in this work to represent the mechanical polishing and low-temperature annealing coupled treatment on the {100} and {110} crystal planes. Coordination number, atomic density and atomic structure analyses are employed to reveal the variation laws, and a new algorithm is further developed to extract well-arranged sp2 carbon atoms from damaged carbon atoms. The results show that more sp2 hybridizations appear on the {110} plane after polishing, yielding a defect density of more than 1 × 1022 vac/cm3, which is the atomic origin for the graphitization in the followed low-temperature annealing. Raman spectroscopy and electron energy loss spectroscopy analyses confirm that the graphite is only detectable on the polished {110} plane. In annealing of the polished {110} plane, graphitization is a visible evolution for the damaged carbons in the topmost surface layer, and the ordered sp2 and sp3 hybridizations increase monotonously. Resultantly, the atomic density of damaged surface layer decreases from 3.21 g/cm3 to 2.47 g/cm3, which is close to the density of graphite, 2.25 g/cm3. On the polished {100} plane, the ordered sp2 and sp3 hybridizations and atomic density of damaged surface layer change hardly upon annealing. In contrast, the amorphous sp2 phases increase considerably. In the deeper surface layer, the amorphous sp3 carbons grow back to the tetrahedral structures at the interface between diamond cubic and ordered sp2 structures, which has no anisotropy in annealing. Graphical abstract Unlabelled Image Highlights • The behaviors of the polished {100} and {110} planes upon annealing is compared. • Graphite carbons are only observable on the mechanically polished {110} plane. • The evolution of damaged carbons in low-temperature annealing has anisotropy. [ABSTRACT FROM AUTHOR]

Dislocation nucleation plays a key role in plastic deformation of diamond crystal. In this paper, homogeneous and heterogeneous nucleation nature for diamond 1 6 112 glide set dislocation and 1 2 110 shuffle set dislocation is studied by combining molecular dynamics method and continuum mechanics models. Our results show that although heterogeneous dislocation nucleation can decrease its activation energy, the activation energy at 0 GPa for diamond heterogeneous nucleation is still in the range of 100 eV. For 1 6 112 glide set and 1 2 110 shuffle set homogeneous nucleation, their critical nucleation shear stress approaches to diamond's ideal shear strength which implies that those dislocations do not nucleate before diamond structural instability only by a purely shearing manner. While for 1 6 112 glide set and 1 2 110 shuffle set heterogeneous nucleation, their critical nucleation shear stresses are 28.9 GPa and 48.2 GPa, these values are less than diamond's ideal shear strength which implies that these dislocations may be nucleated heterogeneously under certain shear stress condition. In addition, our results also indicate there exists a deformation mode transformation for diamond deformation behavior at strain rate of 10 −3 /s. Our results provide a new insight into diamond dislocation nucleation and deformation. [ABSTRACT FROM AUTHOR]

The γ -radiation by electrons with the energy of ∼ 200  MeV in a 100 μ m-thick diamond crystal has been measured at the MAX-lab experimental facility, when the electrons are incident on the crystal along the 〈 100 〉 axis. In this case, the intensity of the -radiation with the energy ∼ 1–2 MeV is approximately 16 times higher than that in amorphous matter of the same thickness. Theoretical calculations based on the quasi-classical QED approximation are in good agreement with the experimental data. The analysis of the radiation mechanisms has shown that the main contribution to the radiation intensity resulted from electrons, moving in the above-barrier regime and at small angles to the crystal axis. [ABSTRACT FROM AUTHOR]

Single crystal diamonds grown by chemical vapor deposition (CVD) before and after different post-growth treatments were studied using optical spectroscopy. The most pronounced changes in color were observed after irradiation with subsequent annealing at 800 °C whereas a weakening of gray tint took place after the high-pressure high-temperature annealing. Low-pressure high-temperature annealing in microwave plasmas of different composition and by electric arc discharge did not produce a noticeable effect on the diamond properties. Signals from nitrogen-vacancy complexes were detected in the absorption and luminescence spectra of CVD diamonds, but the pink tint in the irradiated and annealed diamonds is due to Si V complexes, not N V. The peaks at 150 and 262 K associated with boron were observed in thermoluminescence (TL) curve of original CVD diamonds. Combined irradiation and annealing allowed us to create deep traps of charge carriers responsible for TL peaks in the 430 to 470 K range, which made CVD diamonds promising for TL dosimetry. [ABSTRACT FROM AUTHOR]

We discuss the early stages of AlN growth on the oxygenated diamond (111) surface based on first principles calculations in the framework of density functional theory. Some stable adsorption sites of Al and N atoms are found on the O/diamond (111) surface that in consequence allow formation of two AlN structures with distinct morphologies, which are characterized by different energetic structures. They reflect the way how strain present in the system is released in the relaxation process of deposited layers. Two essential charge carrier redistributions occur within the topmost carbon substrate layers, the first one is a result of oxygenation of the diamond (111) surface, and the second one is a consequence of deposition of 1st Al monolayer on O/diamond (111). Finally, it is demonstrated that passivation of the diamond (111) surface by a layer with mixed O and H atoms does not result in the formation of a stable AlN structure, due to considerably large buckling of the system's top layers. [ABSTRACT FROM AUTHOR]

In this paper, the two-stage process of the uniform distribution of n-layer graphenes in a mixture for sintering polycrystalline diamond at high pressures and temperatures is described. Due to the preliminary deposition of a nanopowder layer on the surface of diamond crystals, at the second stage of mixing the uniform application of a layer of the n-layer graphenes powder on the prepared surface and mixture uniform in the properties are achieved. This approach ultimately makes it possible to produce diamond polycrystals stable in properties. In particular, the current-conducting diamond polycrystals are obtained. [ABSTRACT FROM PUBLISHER]

The N H, N B and N B H co-doped diamond are synthesized at pressures of 5.0–6.0GPa and temperatures of 1300–1650 °C. The reaction pressure and temperatures for the transformation of graphite-to-diamond are significantly increased with the increasing of light elements content in the starting materials. The results of SEM reveal that the major surfaces defect of growth diamond in this study are steps and distort growth reliefs. The presence of re-entrant corner provided by the twinned structure play an important role in the formation of strip and slice diamond morphology.FTIR and XPS measurementsindicate that the special element composition of N H, N B and N B H co-dopeddiamond synthesized from this work will provide important information for the design of high performance diamond related materials. We also discussthe direct correlation between the formation mechanism of the natural diamond and thesynergistic doping effect of N, B, H element. [ABSTRACT FROM AUTHOR]

Angular distributions of parametric X-ray radiation (PXR) from 255 MeV electrons incident on a 50 μm thick diamond crystal are presented. Almost all experiments on the angular distributions of PXR have been performed using Si crystals. The purpose of the present work is to extend this research to diamond crystals. An imaging plate was adopted as a two-dimensional position-sensitive X-ray detector, and high-quality PXR angular distribution data were successfully obtained. The measured PXR angular distributions were compared with those predicted theoretically and good agreement was obtained. The cause of the slight difference observed around the center position (Bragg direction) is also discussed. [ABSTRACT FROM AUTHOR]

Diamond in polymeric composites provides superior mechanical and thermal properties due to its controllable surface chemistry and large accessible surface area. Homogeneous dispersion of diamond in matrix and improved interfacial bondings between diamond and matrix are two important issues to achieve high performance and prevent structural failures in composite manufacturing. In the present work, the surface of submicron scale mono-crystalline diamond was functionalized by hydrazine hydrate and then dispersed in polymethyl methacrylate (PMMA) matrix homogenously by electrospinning technique. This process circumvented aggregations of diamond particles and provided homogeneous dispersion in polymer matrix. Structural morphologies of diamond reinforced PMMA electrospun fibers were adjusted by tailoring polymer concentration, diamond content, flow rate and applied voltage to attain an ideal fiber structure having continuous network without beads. PMMA was used as a polymeric carrier to improve the bonding interactions with epoxy matrix. Flexural tests indicated that the addition of 1 wt% functionalized diamond based electrospun fiber in epoxy matrix improved flexural modulus by 36.4% and flexural strength by 28.1%. Therefore, controlling the surface chemistry of diamond provides better interfacial interactions in reinforcing agent and thus load transfer was realized efficiently in epoxy specimen. In addition, thermal stability of epoxy composites was improved by the addition of diamond particles in electrospun structure. [ABSTRACT FROM AUTHOR]

Single crystal diamond is a suitable material for the next generation particle detectors because of the superior electrical properties and the high radiation tolerance. In order to investigate charge transport properties of diamond particle detectors, transient currents generated in diamonds by single swift heavy ions (26 MeV O 5 + and 45 MeV Si 7 + ) are investigated. Two dimensional maps of transient currents by single ion hits are also measured. In the case of 50 μm-thick diamond, both the signal height and the collected charge are reduced by the subsequent ion hits and the charge collection time is extended. These results are thought to be attributable to the polarization effect in diamond and it appears only when the transient current is dominated by hole current. In the case of 6 μm-thick diamond membrane, an “island” structure is found in the 2D map of transient currents. Signals in the islands shows different applied bias dependence from signals in other regions, indicating different crystal and/or metal contact quality. Simulation study of transient currents based on the Shockley-Ramo theorem clarifies that accumulation of space charges changes distribution of electric field in diamond and causes the polarization effect. [ABSTRACT FROM AUTHOR]

We have studied the near-surface damage in a diamond crystal caused by irradiation with swift boron ions and its healing after high-temperature annealing. A diamond crystal was irradiated with 9-MeV 11 B 3 + ions with fluence values between 1 × 10 15 and 4.42 × 10 16 ions/cm 2 to generate various levels of lattice damage. The ions loose energy to the lattice and, according to simulations, stop at a depth of about 5 μm, where they form a thin buried implantation layer. For the near-surface layers damage is produced by the ions at high kinetic energy before they slow down. Only intrinsic defects can be produced, with no boron atoms. The lattice damage of the near-surface layers and its recovery after annealing for 1 h at 1000°C were studied by Raman and photoluminescence spectroscopies. Back-scattered light from a 514.5-nm laser beam was collected from the sample surface, probing a depth of a few micrometers. We observe some disordering of the lattice plus the formation of neutral vacancies, interstitial and other lattice defects. After annealing the Raman spectrum shows a significant recovery of the lattice order and the disappearance of isolated neutral vacancies. Residual damage is confirmed by the luminescence spectrum, that shows the appearance of new spectral features. [ABSTRACT FROM AUTHOR]

Type IIa large diamond crystals were synthesized in FeNiCo-C system with Ti (Cu) as nitrogen getter by temperature gradient method (TGM) under high pressure and high temperature (HPHT) conditions. Diamonds grew upon (111) facet under 5.4 GPa and 1620 K while black powder appeared around the growing diamond crystal. And the black powder covered the growing crystals in cap shape and restrained the diamond growth drastically with growth time prolonged. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized to characterize the black powder described above and the regrown graphite obtained from the growth process of traditional type Ib diamonds. The black powder was proved to be micro-crystal graphite powder and the powder was similar to the regrown graphite. However, there were obvious differences between the micro-crystal graphite powder and the regrown graphite. The present discussion about precipitation mechanisms of micro-crystal graphite powder implied that the added Ti (Cu) and related reaction-products in FeNiCo-C system could change solvent property of the catalyst, which affected solubility curve of graphite. Furthermore, the practice of diamond growth indicated that the relatively high temperature and relatively low pressure conditions were remarkably responsible for the precipitation of micro-crystal graphite powder. [ABSTRACT FROM AUTHOR]

The internal strain states of three typical types of industrial single-crystal diamonds, i.e., natural type Ia, synthetic type Ib and synthetic type IIa diamonds, were quantitatively evaluated by birefringent retardation (Δn), residual stress and microfracture strength. The variation width of retardation between crystals was Δn = 10 to 200 nm for natural Ia diamonds, Δn = 10 to 100 nm for synthetic Ib diamonds, and Δn = 1 to 10 nm for synthetic IIa diamonds. Natural Ia diamonds with a retardation of 80 nm or more had a mosaic-shaped strain, and diamonds with moderate or less strain exhibited growth striation-like strain. Synthetic Ib diamonds showed no such patterns, but radial patterns were observed. No distinct strain patterns were observed in the synthetic IIa diamonds. The residual stress (GPa) distributions within each crystal were estimated by the Raman peak shift (cm−1). The variation in the residual stress of the natural Ia diamonds was about ±0.1 GPa, while that in the synthetic Ib diamonds was as small as ±0.005 GPa, and almost no variation was observed in the synthetic IIa diamonds. The distribution of microfracture strength of each crystal was evaluated by measuring the crack initiation load (N) with a spherical nano-polycrystalline diamond (NPD) indenter of Φ50 μm. The variation in the crack initiation load within the crystal was also as large as 21 N (from 4 to 25 N) for natural Ia diamond, but as small as 6 N (12–18 N) for synthetic Ib diamond, and even smaller as 3 N (19–22 N) for synthetic IIa diamond. In addition, in synthetic Ib diamond, localized internal strains were observed where dislocation defects derived from the seed crystal existed, and it was confirmed that the residual stress at these locations changed largely and the strength decreased. [Display omitted] • Strain states of various diamond crystals are quantitatively evaluated by retardation. • Variations of retardation in natural crystals are much larger than synthetic crystals. • Large variation of retardation leads large variations in strain and fracture strength • In crystals containing dislocation defects, strong strain occurs around the defects. [ABSTRACT FROM AUTHOR]