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Free radical generation plays a key role in many biological processes including cell communication, maturation, and aging. In addition, free radical generation is usually elevated in cells under stress as is the case for many different pathological conditions. In liver tissue, cells produce radicals when exposed to toxic substances but also, for instance, in cancer, alcoholic liver disease and liver cirrhosis. However, free radicals are small, short-lived, and occur in low abundance making them challenging to detect and especially to time resolve, leading to a lack of nanoscale information. Recently, our group has demonstrated that diamond-based quantum sensing offers a solution to measure free radical generation in single living cells. The method is based on defects in diamonds, the so-called nitrogen-vacancy centers, which change their optical properties based on their magnetic surrounding. As a result, this technique reveals magnetic resonance signals by optical means offering high sensitivity. However, compared to cells, there are several challenges that we resolved here: Tissues are more fragile, have a higher background fluorescence, have less particle uptake, and do not adhere to microscopy slides. Here, we overcame those challenges and adapted the method to perform measurements in living tissues. More specifically, we used precision-cut liver slices and were able to detect free radical generation during a stress response to ethanol, as well as the reduction in the radical load after adding an antioxidant., Competing Interests: Competing interests statement:R.S. is founder of the spin off company QTsense. A patent has been filed about diamond-based quantum sensing in tissues. The other authors have no conflict of interest to declare.

Diamond magnetometry makes use of fluorescent defects in diamonds to convert magnetic resonance signals into fluorescence. Because optical photons can be detected much more sensitively, this technique currently holds several sensitivity world records for room temperature magnetic measurements. It is orders of magnitude more sensitive than conventional magnetic resonance imaging (MRI) for detecting magnetic resonances. Here, the use of diamond magnetometry to detect free radical production in single living cells with nanometer resolution is experimentally demonstrated. This measuring system is first optimized and calibrated with chemicals at known concentrations. These measurements serve as benchmarks for future experiments. While conventional MRI typically has millimeter resolution, measurements are performed on individual cells to detect nitric oxide signaling at the nanoscale, within 10-20 nm from the internalized particles localized with a diffraction limited optical resolution. This level of detail is inaccessible to the state-of-the-art techniques. Nitric oxide is detected and the dynamics of its production and inhibition in the intra- and extracellular environment are followed., (© 2022 The Authors. Small published by Wiley-VCH GmbH.)

Much of the current understanding of thermal effects in biological systems is based on macroscopic measurements. There is little knowledge about the local thermostability or heat tolerance of subcellular components at the nanoscale. Herein, we show that gold nanorod-fluorescent nanodiamond (GNR-FND) hybrids are useful as a combined nanoheater/nanothermometer in living cells. With the use of a 594 nm laser for both heating and probing, we measure the temperature changes by recording the spectral shifts of the zero-phonon lines of negatively charged nitrogen-vacancy centers in FNDs. The technique allows us to determine the rupture temperatures of individual membrane nanotubes in human embryonic kidney cells, as well as to generate high temperature gradients on the cell membrane for photoporation and optically controlled hyperthermia. Our results demonstrate a new paradigm for hyperthermia research and application., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We studied the feasibility of using a short-term culture of monocytes, isolated from peripheral donor blood, to assess the biological activity of different types of bionanomaterials (BNM): biodegradable polimeric particles, fiber and film substrates of micro- and nano-dimensions, fullerenes (F) and nanodiamonds (ND), which are either currently in use and/or potentially applicable in medicine. Additionally, the effect of creating a protein corona on ND and F particles was investigated. The cellular reduction of (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) is a well-established tool for assessing the viability/metabolic activity of cells. The scanning electron microscopy assay can detect fine changes in cell morphology. In the present study BNM have been shown to affect; in a size, chemical composition and morphological characteristics-dependent manner, the ability of monocytes to reduce MTT as well as their morphology. Moreover, the specific effects of ND and F on MTT reduction and cell morphology were exhibited in a dose-dependent manner and sensitive to the formation of surface protein corona. Our results suggest that short-term culture of monocytes is a sensitive model system for assessing the biological effects of BMPs in vitro., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Due to the unique and useful properties of nanodiamonds (ND), their production and use is rapidly increasing. Thus, more of these particles will be released into the environment and organisms will inevitably be exposed to them. The current knowledge about the toxicity of ND, especially in vivo toxicity, is fragmentary. In this study, the toxicity of nanodiamonds was assessed in Acheta domesticus following chronic exposure to different nominal concentrations of ND (20 and 200µgg(-1) food) administrated in food for the entire lifespan. The activity of oxidative stress enzymes (catalase, glutathione peroxidase), total antioxidant capacity, as well as the level of heat shock protein were determined. A significant increase in all of the measured parameters was observed after seven weeks of exposure in individuals exposed to higher concentrations of ND (200µgg(-1) food). In animals exposed to lower concentrations of ND (20µgg(-1) food), there were few significant changes to these parameters. Analysis of DNA damage performed after fourteen weeks using the comet assay revealed DNA instabilities in the insects, especially the ones that had been exposed to the higher doses of ND. These findings may suggest that the toxicity of ND is concentration dependent. While high doses interact in a toxic manner, trace amounts, which are more likely in the environment, might be safe for organisms. Extreme caution should be taken when handling nanodiamonds., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The chromatographic properties of high pressure high temperature synthesised diamond (HPHT) are investigated in normal phase mode of high performance liquid chromatography. Purified nonporous irregular shape particles of average particles size 1.2 μm and specific surface area 5.1 m(2) g(-1) were used for packing 100×4.6 mm ID or 50×4.6 mm ID stainless steel columns. The retention behaviour of several classes of compounds including alkyl benzenes, polyaromatic hydrocarbons (PAH), alkylphenylketones, phenols, aromatic acids and bases were studied using n-hexane-2-propanol mixtures as mobile phase. The results are compared with those observed for microdispersed sintered detonation nanodiamond (MSDN) and porous graphitic carbon (PGC). HPHT diamond revealed distinctive separation selectivity, which is orthogonal to that observed for porous graphitic carbon; while selectivities of HPHT diamond and microdispersed sintered detonation nanodiamonds are similar. Owing to non-porous particle nature, columns packed with high pressure high temperature diamond exhibited excellent mass transfer and produce separations with maximum column efficiency of 128,200 theoretical plates per meter., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Recently, the scientific community became aware of the potential ability of nanoparticles to cause toxicity in living organisms. Therefore, many of the implications for aquatic ecosystems and its effects on living organisms are still to be evaluated and fully understood. In this study, the toxicity of nanodiamonds (NDs) was assessed in the freshwater bivalve (Corbicula fluminea) following exposure to different nominal concentrations of NDs (0.01, 0.1, 1, and 10 mg l(-1)) throughout 14 days. The NDs were characterized (gravimetry, pH, zeta potential, electron microscopy, and atomic force microscopy) confirming manufacturer information and showing NDs with a size of 4-6 nm. Oxidative stress enzymes activities (glutathione-S-transferase, catalase) and lipid peroxidation were determined. The results show a trend to increase in GST activities after seven days of exposure in bivalves exposed to NDs concentrations (>0.1 mg l(-1)), while for catalase a significant increase was found in bivalves exposed from 0.01 to 1.0 mg l(-1) following an exposure of 14 days. The histological analysis revealed alterations in digestive gland cells, such as vacuolization and thickening. The lipid peroxidation showed a trend to increase for the different tested NDs concentrations which is compatible with the observed cellular damage., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Boron nitride has attracted scientific interest in recent years due to its potential use in electronics, both as hexagonal (hBN) and cubic (cBN) phases. While both are successfully realized through chemical vapor deposition, the heteroepitaxial growth of cBN on another iconic semiconductor, diamond is plagued with mixed‐phase formation. Employing first‐principles computations and a nanoreactor approach, the BN phase preferences are explored on diamond (001) controlled—as it is discovered—by the hydrogen gas concentration. In a limited‐hydrogen environment, the initial BN‐island expands along the diamond surface, forming a 3D metastable cubic phase that grows in the direction normal to the basal plane through kinetically‐limited nucleation, thus overcoming the thermodynamic preference toward the hBN phase. Comparatively, the amorphous phase is favored in the absence of hydrogen, while the hexagonal phase dominates at its high levels, elucidating numerous experimental observations. A obtained kinetic phase diagram connects the phase with hydrogen chemical potential to facilitate targeted phase selection. The results suggest that gas‐mediated nucleation kinetics provide feasible control for the precise synthesis. It also offers valuable guidance for the controllable synthesis of desired BN phases and advances research toward potential BN electronics. [ABSTRACT FROM AUTHOR]

Diamond containing nitrogen‐vacancy centers (NV−) is one of the most investigated materials for quantum technologies, because of this system's exceptional spin properties. Although the NV− optical transition is very bright, it suffers from spectral diffusion and weak zero‐phonon line, and is in the visible range. This limits integration into quantum photonic structures and interfacing with optical fiber networks. In contrast, rare earth (RE) ions exhibit extremely narrow and stable optical transitions, including erbium's 1.5 µm telecom wavelength. Combining RE with NV− properties through short‐range interactions is however challenging as RE do not readily enter the diamond lattice. In this work, a thin‐film‐based architecture in which RE and NV− centers can interact while preserving their unique properties is introduced. Thin films of Er3+:Y2O3 are grown by chemical vapor deposition on diamond substrates with well‐crystallized and highly textured structures. An extensive spectroscopic study of Er3+ transitions at room and low temperatures further reveals that photoluminescence spectra and decays are close to bulk materials. It is also shown that Y2O3 thin film deposition has no detrimental effects on NV− optical and spin properties. RE thin films deposited on diamond can thus be suitable for building hybrid materials for new functionalities in quantum sensing, communication, and processing. [ABSTRACT FROM AUTHOR]

Diamond as a templating substrate is largely unexplored, and the unique properties of diamond, including its large bandgap, thermal conductance, and lack of cytotoxicity, makes it versatile in emergent technologies in medicine and quantum sensing. Surface termination of an inert diamond substrate and its chemical reactivity are key in generating new bonds for nucleation and growth of an overlayer material. Oxidized high-pressure high temperature (HPHT) nanodiamonds (NDs) are largely terminated by alcohols that act as nucleophiles to initiate covalent bond formation when an electrophilic reactant is available. In this work, we demonstrate a templated synthesis of ultrathin boron on ND surfaces using trigonal boron compounds. Boron trichloride (BCl3), boron tribromide (BBr3), and borane (BH3) were found to react with ND substrates at room temperature in inert conditions. BBr3 and BCl3 were highly reactive with the diamond surface, and sheet-like structures were produced and verified with electron microscopy. Surface-sensitive spectroscopies were used to probe the molecular and atomic structure of the ND constructs' surface, and quantification showed the boron shell was less than 1 nm thick after 1–24 h reactions. Observation of the reaction supports a self-terminating mechanism, similar to atomic layer deposition growth, and is likely due to the quenching of alcohols on the diamond surface. X-ray absorption spectroscopy revealed that boron-termination generated midgap electronic states that were originally predicted by density functional theory (DFT) several years ago. DFT also predicted a negative electron surface, which has yet to be confirmed experimentally here. The boron-diamond nanostructures were found to aggregate in dichloromethane and were dispersed in various solvents and characterized with dynamic light scattering for future cell imaging or cancer therapy applications using boron neutron capture therapy (BNCT). The unique templating mechanism based on nucleophilic alcohols and electrophilic trigonal precursors allows for covalent bond formation and will be of interest to researchers using diamond for quantum sensing, additive manufacturing, BNCT, and potentially as an electron emitter. [ABSTRACT FROM AUTHOR]

Diamond nanoparticles represent an elegant class of nanoscale materials with promising applications in nanotechnology. Solid-state NMR is a powerful technique for investigating the atomic-level structure and dynamics of nanomaterials in their natural state. The present study illustrates the application of high-resolution 13C NMR to nanomaterials characterization, and the fundamental 13C spin–lattice relaxation times highlight the spatial arrangement of surface-associated paramagnetic centers around the core sp3 carbon assembly of diamond nanoparticles, delineating the unique size-dependent physicochemical characteristics of diamond nanoparticles. [ABSTRACT FROM AUTHOR]

Modern integrated circuits (ICs) take advantage of three-dimensional (3D) nanostructures in devices and interconnects to achieve high-speed and ultra-low-power performance. The choice of electrical insulation materials with excellent dielectric strength, electrical resistivity, strong mechanical strength, and high thermal conductivity becomes critical. Diamond possesses these properties and is recently recognized as a promising dielectric material for the fabrication of advanced ICs, which are sensitive to detrimental high-temperature processes. Therefore, a high-rate low-temperature deposition technique for large-grain, high-quality diamond films of the thickness of a few tens to a few hundred nanometers is desirable. The diamond growth rate by microwave plasma chemical vapor deposition (MPCVD) decreases rapidly with lowering substrate temperature. In addition, the thermal conductivity of non-diamond carbon is much lower than that of diamond. Furthermore, a small-grain diamond film suffers from poor thermal conductivity due to frequent phonon scattering at grain boundaries. This paper reports a novel MPCVD process aiming at high growth rate, large grain size, and high sp3/sp2 ratio for diamond films deposited on silicon. Graphite paste containing nanoscale graphite and oxy-hydrocarbon binder and solvent vaporizes and mixes with gas feeds of hydrogen, methane, and carbon dioxide to form plasma. Rapid diamond growth of diamond seeds at 450 °C by the plasma results in large-grained diamond films on silicon at a high deposition rate of 200 nm/h. [ABSTRACT FROM AUTHOR]

For single crystal diamond (SCD) to gain practical use in technical applications including solid state electronics, thin (< $1 ~\mu \text{m}$), doped epitaxial SCD layers with very low (<1 nm) surface roughness are required. Conventional SCD chemical mechanical polishing (CMP) processes are insufficient to meet the requirements of such applications because the material removal rate (MRR) is often characterized inappropriately, and the material removal uniformity is seldom considered. In this study, chemical vapor deposition (CVD) growth of two lightly boron doped (p-) epilayers was performed on 3° misoriented (100) high pressure high temperature substrates of 4.5 x $4.5 mm^{2}$ area. A subsequent 8-hour oxidative CMP process utilizing potassium permanganate and a novel self-leveling holder design decreased the average surface roughness from 3.83 nm and 1.57 nm to 0.20 nm and 0.16 nm for the two samples, respectively. MRRs were determined by evaluating five circular wear monitor structures in each sample by atomic force microscopy before and after the CMP process. The average MRRs were found to be 38.6 nm/hr and 37.3 nm/hr for the two samples. The purpose of this study is to demonstrate a CMP process suitable for polishing thin SCD epilayers to meet the needs of solid-state electronics applications. [ABSTRACT FROM AUTHOR]

Wafer‐scale heteroepitaxial diamond thin films demonstrate multiple advantages for a further development of integrated optical and quantum devices based on impurity–vacancy color centers. The main obstacle here is a high structural defect density characteristic for heteroepitaxial epilayers. In this work, technological methods of stress control, NV formation, and defect density reduction in diamond epilayers, which are based on principles of epitaxial lateral overgrowth (ELO) are reported on. Herein, material and quantum properties of NV‐doped diamond thin films obtained by patterned nucleation growth and by ELO of microstructured epilayers, are compared. It is demonstrated that a combination of both methods might have a significant potential for the wafer‐scale production of heteroepitaxial diamond for quantum devices. [ABSTRACT FROM AUTHOR]

Diamond is a fascinating material with exceptional optical and electronic properties, making it a highly desirable material for various applications. Herein, the effect of various types of defects and their concentration the optical and electronic properties of diamond is investigated and discussed. Using Boron and Nitrogen as dopants, we demonstrate how the electronic band structure can be tailored to achieve specific optical and electronic properties without compromising the crystal structure. Furthermore, Hydrogen interstitial defects enable the manipulation of the band structure and provide a better understanding of the correlation between band structure, density of states, and optical properties. Moreover, the validity of selected structures with high desirable electronic and optical properties as Hydrogen and oxygen evolution catalysts was explored and discussed. • N, B, and H dopants improved the efficacy of diamond catalytic properties. • Both type and concentration of dopant are significantly important. • 2B-2N-doped diamond showed a band gap energy of 2.35 eV. • The 3B-N-H structure is a good oxygen evolution reaction (OER) catalyst. • 3B&2H structure is a good hydrogen evolution reaction (HER) catalyst. [ABSTRACT FROM AUTHOR]

Achieving high-performance materials with superior mechanical properties and electrical conductivity, especially in large-sized bulk forms, has always been the goal. However, it remains a grand challenge due to the inherent trade-off between these properties. Herein, by employing nanodiamonds as precursors, centimeter-sized diamond/graphene composites were synthesized under moderate pressure and temperature conditions (12 GPa and 1,300 to 1,500 °C), and the composites consisted of ultrafine diamond grains and few-layer graphene domains interconnected through covalently bonded interfaces. The composites exhibit a remarkable electrical conductivity of 2.0 x 104 S m-1 at room temperature, a Vickers hardness of up to ~55.8 GPa, and a toughness of 10.8 to 19.8 MPa m1/2. Theoretical calculations indicate that the transformation energy barrier for the graphitization of diamond surface is lower than that for diamond growth directly from conventional sp² carbon materials, allowing the synthesis of such diamond composites under mild conditions. The above results pave the way for realizing large-sized diamond-based materials with ultrahigh electrical conductivity and superior mechanical properties simultaneously under moderate synthesis conditions, which will facilitate their large-scale applications in a variety of fields. [ABSTRACT FROM AUTHOR]

Fabrication techniques for nitrogen-vacancy centres in diamond require the creation of Frenkel defects (vacancy-interstitial pairs) the components of which can interact with formed NV centres affecting their photophysical properties. Here we use Density Functional Theory simulations of inter-defect electronic and strain interactions to explore how the NV centre and carbon self-interstitial interact in different configurations. We find that hybridization occurs between the NV centre e-orbitals and the carbon self-interstitial when an interstitial is present on the vacancy side of the NV centre. We propose that this phenomenon may explain the fluorescence blinking of NV centres observed during annealing. This article is part of the Theo Murphy meeting issue 'Diamond for quantum applications'. [ABSTRACT FROM AUTHOR]

The neutrally charged silicon-vacancy defect (SiV0) is a colour centre in diamond with spin S = 1, a zero-phonon line (ZPL) at 946 nm and long spin coherence, which makes it a promising candidate for quantum network applications. For the proper performance of such colour centres, all of them must have identical optical characteristics. However, in practice, there are factors that influence each individual centre. One of these factors is non-uniform isotope composition for both carbon atoms in diamond lattice and silicon atoms of dopant. In this work, we studied the isotopic shifts of SiV0 centres for CVD-grown epitaxial layers of isotopically enriched 12C and 13C diamonds, as well as for diamond with natural isotope composition but doped only with one isotope of Si (28Si, 29Si and 30Si). The detected shift was 1.60 meV for 12C/13C couple and 0.33 meV for 28Si/29Si and 29Si/30Si couples, which are close to the previously obtained values of the isotopic shift for the negatively charged silicon vacancy (SiV−), which indicates a similar model of interaction with the environment for these two charge states of the SiV colour centres. This article is part of the Theo Murphy meeting issue 'Diamond for quantum applications'. [ABSTRACT FROM AUTHOR]

Extensive research has been conducted on electronic properties of metal‐doped diamond for electrochemical applications. The codoped diamond has emerged as an important strategy to enhance their performance and impart novel characteristics. In the present investigation, density functional theory calculations are used to envisage the structural, electronic, and elastic properties of nitrogen‐vacancy (N‐V) and silicon‐vacancy (Si‐V) defects at the Σ3 (111) grain boundary (GB) in diamond. Further, the Li and Na atoms are introduced as a dopant into these defective structures, referred as Σ3Li(N‐V), Σ3Na(N‐V), Σ3Li(Si‐V), and Σ3Na(Si‐V). The results reveal that the doped structures considered in the investigation are energetically and dynamically stable. The presence of defects (i.e., dangling bonds due to the presence of vacancies and dopants) at the Σ3 (111) GB significantly alters the overall electronic property of the diamond. The adsorption energies calculated for the doped systems range from −1.2 and 8.38 eV. The Σ3Li(N‐V) shows negative adsorption energy, indicating the tendency of lithium atom to adsorb exothermic onto the GB of Σ3N‐V, whereas, other adsorptions are endothermic in nature. The choice of dopant plays a substantial role in altering the properties of diamond, while the mechanical properties of the investigated Σ3 (111) diamond structures vary marginally. [ABSTRACT FROM AUTHOR]

We report the development of multifunctional core/shell chemical vapor deposition diamond nanoparticles for the local photoinduced hyperthermia, thermometry, and fluorescent imaging. The diamond core heavily doped with boron is heated due to absorbed laser radiation and in turn heats the shell of a thin transparent diamond layer with embedded negatively charged SiV color centers emitting intense and narrowband zero-phonon lines with a temperature-dependent wavelength near 738 nm. The heating of the core/shell diamond nanoparticle is indicated by the temperature-induced spectral shift in the intensive zero-phonon line of the SiV color centers embedded in the diamond shell. The temperature of the core/shell diamond particles can be precisely manipulated by the power of the incident light. At laser power safe for biological systems, the photoinduced temperature of the core/shell diamond nanoparticles is high enough to be used for hyperthermia therapy and local nanothermometry, while the high zero-phonon line intensity of the SiV color centers allows for the fluorescent imaging of treated areas. [ABSTRACT FROM AUTHOR]

Graphene has a series of excellent physical and chemical properties. In recent years, the in situ growth of graphene on diamond substrate has been the research focus. In this paper, graphene (or graphite nanoplate) is grown on a diamond substrate by vacuum high‐temperature rapid annealing method with the catalysis of Ni. Annealing temperature and time are varied and graphene with different layer numbers, lattice defect densities, and topographies are produced on a diamond. Different kinds of characterization such as Raman spectroscopy, optical density meter, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM) are used to characterize and analyze these properties, further determine the critical temperature and critical time of diamond‐graphene transformation, and study the influence of temperature and time on the layer number and quality of graphene. After annealing at 850 °C for 30 min, the sample can grow ≈56 layers of high‐quality graphene, which has quite low roughness and few defects. [ABSTRACT FROM AUTHOR]

In recent years, the rapid progress in the field of GaN-based power devices has led to a smaller chip size and increased power usage. However, this has given rise to increasing heat aggregation, which affects the reliability and stability of these devices. To address this issue, diamond substrates with nanostructures were designed and investigated in this paper. The simulation results confirmed the enhanced performance of the device with diamond nanostructures, and the fabrication of a diamond substrate with nanostructures is demonstrated herein. The diamond substrate with square nanopillars 2000 nm in height exhibited optimal heat dissipation performance. Nanostructures can effectively decrease heat accumulation, resulting in a reduction in temperature from 121 °C to 114 °C. Overall, the simulation and experimental results in this work may provide guidelines and help in the development of the advanced thermal management of GaN devices using diamond micro/nanostructured substrates. [ABSTRACT FROM AUTHOR]

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5G communication, energy internet, new energy automobiles, quantum technology and other advanced and sophisticated fields have put forward new and higher requirements for the performance of semiconductors. The fourth generation of semiconductor diamond is known as the “ultimate semiconductor” because of its excellent physical and chemical properties. It is considered to be the most ideal material for developing the next generation of high power, high frequency, high temperature and low power loss electronic devices. However, the technical bottleneck of shallow n-type doping has hindered the development of diamond semiconductor applications to a certain extent. The research of surface terminals has provided new strategies for the development of diamond functionalization. Diamond has realized important applications such as field effect transistors, Schottky diodes, solar-blind ultraviolet detectors, electronic emission devices and near-surface color center tuning through surface terminals. The mechanism of surface terminals exerting effects is inseparable from the characteristics of their energy band structure. In this paper, the research methods of energy band structure of several common terminals are summarized, the characteristics of their energy band structures are analyzed, the mechanism of exerting effects in combination with the characteristics are introduced, finally prospected. [ABSTRACT FROM AUTHOR]

The application of deep ultraviolet detection (DUV) in military and civil fields has increasingly attracted the attention of researchers' attention. Compared with the disadvantages of organic materials, such as complex molecular structure and poor stability, inorganic materials are widely used in the field of DUV detection because of their good stability, controllable growth, and other characteristics. Rapid advances in preparing high-quality ultrawide-bandgap (UWBG) semiconductors have enabled the realization of various high-performance DUV photodetectors with different geometries, which provide an avenue for circumventing numerous disadvantages in traditional detectors. Herein, the development history and types of DUV detectors are briefly introduced. Typical UWBG detection materials and their preparation methods, as well as their research and application status in the field of DUV detection, are emphatically summarized and reviewed, including III-nitride semiconductors, gallium oxide, diamond, etc. Finally, problems pertaining to DUV detection materials, such as the growth of materials, the performance of devices, and their future development, are also discussed. [ABSTRACT FROM AUTHOR]

Filtration has emerged as a critical technology to reduce waterborne diseases caused by poor water quality. Filtration technology presents key challenges, such as membrane selectivity, permeability and biofouling. Nanomaterials can offer solutions to these challenges by varying the membranes’ mechanical and bactericidal properties. This research uses nanodiamond particles with facile surface functionality and biocompatibility properties that are added to membranes used for filtration treatments. Scanning and transmission electron microscopy (SEM and TEM) and Fourier transform infrared spectroscopy (FTIR) were performed to study the membrane surface. FTIR spectra confirms an increase in oxygen functional groups onto the ultradispersed diamond’s (UDD) surface following acid treatment. SEM images show particle deagglomeration of functionalized UDD at the membrane surface. Tensile strength tests were done to measure the UDD mechanical properties and Coliscan membrane filtration characterization was performed to determine the filter effectiveness. Polyether sulfone (PES) and polyvinylidene (PVDF) membranes expressed a change in their yield point when UDD was incorporated into the porous matrix. A significant microorganism reduction was obtained and confirmed using t-test analysis at a 95% level of confidence. UDD-embedded membranes exhibit a significant bactericidal reduction compared to commercial membranes suggesting these membranes have the potential to enhance current membrane filtration systems. [ABSTRACT FROM AUTHOR]

Tungsten carbide (WC) bulks from the sintering of WC powders possess excellent physical and chemical properties, widely used in high-precision optical molds, seals, nozzles and many other scenarios. To produce dense WC bulks, however, needs a very high sintering temperature (>1900 °C) and super fine WC powders due to the poor sinterability. The high sintering temperature required puts a huge strain on processing equipment, and the preparation of super fine WC powders involves many complex steps. In this work, dense WC bulks are prepared by spark plasmas sintering via self-densification reaction of nanodiamond with tungsten at 1700 °C. The use of nanodiamond enables dense WC bulks of a density of 98.1% and Vickers hardness of 21.8 GPa for a volume expansion associated with the change of diamond to graphite greatly reduces the porosity of as-prepared WC bulks, demonstrating a novel mechanism of self-densification reaction sintering. Besides, reaction between tungsten and diamond produces far less volume shrinkage than other allotropes of carbon, partly contributing to the densification of the as-prepared WC bulks. Our creative strategy has significant advantages over prevailing methods in preparing high-density WC bulks, facilitating the application of WC bulk materials in industrial production and providing a new insight into the preparation of dense bulks of other metal carbides. [ABSTRACT FROM AUTHOR]

In this article, Ni–B composite electrodeposition was prepared by nanodiamond and Y2O3 nanoparticles. Due to the synergistic strengthening effect of the two reinforcing phase particles on the Ni–B composite coating, the wear and corrosion resistance of the Ni–B/diamond-Y2O3 composite coating is significantly better than that of the single reinforcing material composite coating. In addition, the effect of electrodeposition pulse frequency on Ni–B/diamond-Y2O3 composite coating was studied in detail, and its characterization and performance tests were carried out. The results show that the Ni–B/diamond-Y2O3 nanocomposite coatings prepared with a pulse frequency of 100 Hz have finer grains and no agglomeration. The Ni–B/diamond-Y2O3 nanocomposite coating has the highest impedance under the pulse frequency of 100 Hz, the corrosion inhibition rate is 98.70%, and it has good corrosion resistance. At the same time, in the mechanical property test, the average microhardness is as high as 661.90 HV, the average friction coefficient is only 0.206, and the wear resistance is excellent. In conclusion, the Ni–B/diamond-Y2O3 nanocomposite coatings prepared under 100 Hz pulse have excellent wear and corrosion resistance. [ABSTRACT FROM AUTHOR]

Recent studies have revealed unprecedented fracture toughness in synthesized nanotwinned diamond (nt-diamond) due to the obstruction of dislocations by twin boundary. However, the atomic-scale interactions between dislocations and twin boundary in diamond remain elusive and unclear. In this work, we take advantage of the recently published interatomic potential for diamond's dislocation activity to study the interactions between (001) dislocation and (111) twin boundary in molecular dynamics (MD) simulations. The twin boundaries show obvious hindrance for (001) dislocation. In the penetrations, the shuffle-set dislocation will climb to the upper gliding plane and leave a vacancy tube behind. With the gradual increase of applied shear stress, the vacancy left on the twin boundary could launch another shuffle-set dislocation in the opposite direction in matrix. The mechanism revealed in this work show obvious difference between the interaction between twinning and dislocation in metals. This study will provide a fundamental understanding of the dislocation behaviors and their strengthening and toughing mechanisms in nt-diamond materials and the related materials. Atomic configuration of nanotwinned diamond with edge dislocations on {001} plane was established in this work to explore the interaction mechanisms between dislocations and twin boundarys. All molecular dynamics simulations are driven under high hydrostatic pressure witch can effectively suppress microcrack propagation in diamond and activate dislocation slip. The contact of dislocation gliding on (001) plane with TB1 could be divided into two stages, distortion and contraction. In the followed penetration process, the emitted partial dislocation continues to glide in the twin region and eventually makes contact with the TB2, leaving a long stacking fault behind witch is transient and has interesting healing mechanisms. During the interaction, the edge dislocation will climb to the adjacent shuffle plane on (001) plane, leaving a vacancy behind witch can lead to the nucleation of additional dislocations. [Display omitted] • The novel interaction mechanisms between (001) dislocation and (111) twin boundary in diamond. • The climbing mechanism for (001) dislocation and related dislocation emissionfrom vacancies on twin boundary in diamond. • The novel strengthening mechanism of (111) coherent twin boundary in diamond. [ABSTRACT FROM AUTHOR]

[Display omitted] • Etching atomically flat diamond (1 1 1) surfaces by Ni–C solid-solution reaction with Ni nano particles. • digging one-dimensional (1D) nanopits with a linear trench shape on diamond (1 1 1) • Discussing the mechanism for the formation of on dimensional nanopits on atomically flat diamond (1 1 1) surfaces. Diamond nanoprocessing technologies are essential for the development of diamond-based devices. However, the existing etching processes damage the diamond crystal, adversely affecting the characteristics of the corresponding device. Herein, we focused on the Ni–C solid-solution reaction as a nondamaging fabrication method. Ni films (10, 3, and 1 nm) were deposited on atomically flat surfaces (AFSs) of diamond (1 1 1) and annealed under H 2 gas flow. The Ni film aggregated into particles, and as the particle size decreased, Ni particles moved around, etching the diamond surface. Interestingly, when the diameter of the Ni nanoparticles was less than a few tens of nanometers, they dug one-dimensional (1D) nanopits with a linear trench shape on diamond AFS. We discuss the mechanism for the formation of these 1D nanopits in detail from the perspective of the etching-morphology dependence on the annealing time, Ni thickness, and gas atmosphere. The results of this study will improve our understanding of the Ni–C solid-solution reaction at the nanoscale and promote the development of damage-free nanofabrication techniques for diamond-based device applications. [ABSTRACT FROM AUTHOR]

Diamond thin films are promising wide band gap semiconductor materials for applications in electronic and microwave devices. Revealing the mechanism of how twin boundaries impact the band gap of diamond is of critical importance since they are the most common defects in polycrystalline diamond films. Here, nanocrystalline diamond films are synthesized by microwave plasma-enhanced chemical vapor deposition. The atomic and electronic structures of diamond lamellar and fivefold twins, and their evolution behaviors with the increase of axial tensile strain, are investigated by combining aberration-corrected transmission electron microscopy with first-principles calculations. There is no intrinsic stress concentration at the lamellar twin boundary, and its band gap equals to that of the bulk diamond (i.e. , 5.3 eV). An intrinsic in-plane compressive stress field is formed and the band gap is increased evidently (i.e. , 0.6 eV) in the center of fivefold twins. When applying an axial tensile strain up to 15%, the band gaps of the bulk diamond, lamellar and fivefold twins reduce significantly to 2.2 eV, 2.1 eV and 2.4 eV, respectively, which are mainly due to the decrease of p z orbital energy caused by the increase of axial bond length during the tensile process. Under the same axial tensile strain, the band gap of the fivefold twin is always larger than those of the lamellar twin and the bulk diamond due to the formation of in-plane five-membered carbon rings in the center. The findings of the tunable band gap by strain engineering will benefit for the innovation and design of advanced diamond functional devices. [Display omitted] • Atomic and electronic structures of diamond lamellar and fivefold twins under tensile strains have been investigated. • The band gap of fivefold twins is evidently larger than that of the bulk diamond. • Under axial tensile strains, the band gap of bulk diamond, lamellar and fivefold twins reduces significantly. • The reduction of band gap is due to the decrease of p z orbital energy caused by the increase of axial bond length. [ABSTRACT FROM AUTHOR]

Recent results on synthesis, structural, and physicochemical studies of complexes based on detonation nanodiamonds modified with metal-organic molecules with functional magnetic and fluorescent properties have been presented. Neutron scattering experiments have discovered subtle features of the assembly of electro-negative molecules of Eu diphthalocyanines and nanodiamonds with positive surface potential in aqueous media. Nanoscale ordering of diamonds reinforced by their linking via diphthalocyanines was confirmed by TEM. The stable complexes possess X-ray luminescent and magnetic properties. Such nanostructures with low toxicity are prospective as contrasting and photoactive agents for magnetic resonance imaging and photodynamic therapy. [ABSTRACT FROM AUTHOR]

For the preparation of diamond heat sinks with ultra-high thermal conductivity by Chemical Vapor Deposition (CVD) technology, the influence of diamond growth direction and electric field on thermal conductivity is worth exploring. In this work, the phonon and thermal transport properties of diamond in three crystal orientation groups (<100>, <110>, and <111>) were investigated using first-principles calculations by electric field. The results show that the response of the diamond in the three-crystal orientation groups presented an obvious anisotropy under positive and negative electric fields. The electric field can break the symmetry of the diamond lattice, causing the electron density around the C atoms to be segregated with the direction of the electric field. Then the phonon spectrum and the thermodynamic properties of diamond were changed. At the same time, due to the coupling relationship between electrons and phonons, the electric field can affect the phonon group velocity, phonon mean free path, phonon–phonon interaction strength and phonon lifetime of the diamond. In the crystal orientation [111], when the electric field strength is ±0.004 a.u., the thermal conductivity is 2654 and 1283 W · m − 1 K − 1 , respectively. The main reason for the change in the thermal conductivity of the diamond lattice caused by the electric field is that the electric field has an acceleration effect on the extranuclear electrons of the C atoms in the diamond. Due to the coupling relationship between the electrons and the phonons, the thermodynamic and phonon properties of the diamond change. [ABSTRACT FROM AUTHOR]

In this study, a gas-jet diamond synthesis method using a high-speed jet for the transportation of gases activated in microwave plasma of gases to a substrate was developed. Diamond was synthesized in a hydrogen–methane–argon mixture. The diamond synthesis rate (130 µm/h) exceeded the rate attained in earlier gas-jet experiments with activation in microwave plasma without argon additions. [ABSTRACT FROM AUTHOR]

Controlling inorganic structure and dimensionality through structure-directing agents is a versatile approach for new materials synthesis that has been used extensively for metal-organic frameworks and coordination polymers. However, the lack of 'solid' inorganic cores requires charge transport through single-atom chains and/or organic groups, limiting their electronic properties. Here, we report that strongly interacting diamondoid structure-directing agents guide the growth of hybrid metal-organic chalcogenide nanowires with solid inorganic cores having three-atom cross-sections, representing the smallest possible nanowires. The strong van der Waals attraction between diamondoids overcomes steric repulsion leading to a cis configuration at the active growth front, enabling face-on addition of precursors for nanowire elongation. These nanowires have band-like electronic properties, low effective carrier masses and three orders-of-magnitude conductivity modulation by hole doping. This discovery highlights a previously unexplored regime of structure-directing agents compared with traditional surfactant, block copolymer or metal-organic framework linkers.

A recent report on obtaining the n -type conductivity in diamonds doped with boron–oxygen complexes in a metal solvent (X. Liu et al., PNAS 2019) stimulates interest in the synthesis of diamonds in heterohydrocarbon systems with oxygen and boron. The simultaneous effect of boron and oxygen heteroatoms on phase transitions in a hydrocarbon system is examined in phenylboronic acid C 6 H 5 B(OH) 2 at pressures of 7–8.5 GPa and temperatures up to 1600 °C. At pressures of about 7 GPa and temperatures up to 1100 °C, the transformation of the precursor occurs through the stage of polymerization into a graphane-like phase with the subsequent formation of nanographite. Micro- and nanodiamonds are synthesized at 8.5 GPa and 1600 °C from the initial precursor and nanographite, which is a product of preliminary carbonization, respectively. Despite the presence of oxygen and boron in the growth system, the n -type conductivity in diamonds and nanographite is not detected. It is found that the degree of boron doping of diamond in hydrocarbon systems decreases in the presence of oxygen with a high chemical affinity to boron and that nanodiamonds in the carbonized product can be obtained when volatile components leave the system. [Display omitted] • Synthesis of diamonds from phenylboronic acid C 6 H 5 B(OH) 2 was studied at 7.5–8.5 GPa. • The n -type conductivity in diamonds due to co-doping with B and O is not detected. • Removing volatile components from carbonized precursor facilitates formation of nanodiamonds. • Introduction of oxygen to hydrocarbon system reduces concentration of boron in diamond. [ABSTRACT FROM AUTHOR]

A continuous-wave (CW) high-harmonic gyrotron driven by a low-power electron beam is a compact radiation source demanded by terahertz applications. Its physical feasibility, however, is hampered by ohmic losses and mode competition in the gyrotron cavity. An ultralow-loss diamond loading of the cavity can give a clue to this problem. This article is concerned with theoretical aspects of mode selection and design for a gyrotron cavity loaded with coaxial rod made of chemical vapor deposition (CVD) diamond. As an example, the design of a high-Q diamond-loaded cavity for a third-harmonic 658-GHz gyrotron powered by a 0.1-A, 15-kV electron beam is presented. It is shown that the designed cavity enables the gyrotron to produce up to 116-W output power in a single oscillating mode. [ABSTRACT FROM AUTHOR]

High-quality bi-concave 2D focusing diamond X-ray lenses of apex-radius R = 100 mm produced via laser-ablation and improved via mechanical polishing are presented here. Both for polished and unpolished individual lenses and for stacks of ten lenses, the remaining figure errors determined using X-ray speckle tracking are shown and these results are compared with those of commercial R = 50 mm beryllium lenses that have similar focusing strength and physical aperture. For two stacks of ten diamond lenses (polished and unpolished) and a stack of eleven beryllium lenses, this paper presents measured 2D beam profiles out of focus and wire scans to obtain the beam size in the focal plane. These results are complemented with small-angle X-ray scattering (SAXS) measurements of a polished and an unpolished diamond lens. Again, this is compared with the SAXS of a beryllium lens. The polished X-ray lenses show similar figure errors to commercially available beryllium lenses. While the beam size in the focal plane is comparable to that of the beryllium lenses, the SAXS signal of the polished diamond lenses is considerably lower. [ABSTRACT FROM AUTHOR]

In this work, we consider the inelastic scattering of incident electrons as a key process for analyzing the significant differences in secondary electron (SE) emission between diamond and graphite. Dielectric functions and energy- and momentum-dependent energy loss functions were obtained by first-principle calculations. These were then used to calculate the inelastic mean free path (IMFP) and stopping power in different directions. The results show that the properties of diamond are very close in different directions, and its IMFP is lower than that of graphite when the electron energy is higher than 30 eV. In graphite, the incident electrons may exhibit directional preferences in their motion. These results indicate that, in graphite, SEs are excited in deeper positions than in diamond, and more SEs move in a horizontal direction than in a vertical direction, which leads to the difference in secondary electron yield (SEY). [ABSTRACT FROM AUTHOR]

Nanodiamond combines the properties of both nanomaterials and diamond materials, resulting in different characteristics from that of micron and bulk diamond. In this work, the structure, optical properties and thermal stability of diamond samples with different sizes were studied by scanning electron microscopy, X-ray diffraction, spectroscopy techniques and thermogravimetric analysis. The results show that the sizes of three samples are 300 μm, 30 μm and 100 nm, respectively. Diamond samples with larger size present better crystal quality, and are confirmed to be Ⅰb type diamond because single nitrogen impurities are observed. In contrast, the crystallinity of nanodiamond samples is poor, and residual graphite is detected in nanodiamond samples from both XRD and Raman results. In addition, H2O, N—H and C—H bonds are observed in nanodiamond, suggesting there may be many organic reactive groups on surface. Two emission peaks are observed in both samples of 300 μm and 30 μm, originated from two types of nitrogen vacancy defects with neutral and negative charge respectively. In contrast, no emission is observed for nanodiamond because of fluorescence quenching from nonradiative center originated from organic groups and surface defects in the nanodiamond. Diamond samples with large size have the intensive absorption in the range from 300 nm to 525 nm, while the nanodiamond sample show strong absorption in the entire UV-visible-NIR region resulting in much lower transmittance. With the decrease of particle size, both the initial oxidizing temperature and oxidizing rate gradually decline. As a result, larger size samples have better thermal stability. [ABSTRACT FROM AUTHOR]

The formation and shock history of ureilite meteorites, a relatively abundant type of primitive achondrites, has been debated for decades. For this purpose, the characterization of carbon phases can provide further information on diamond and graphite formation in ureilites, shedding light on the origin and history of this meteorite group. In this work, we present X‑ray diffraction and micro-Raman spectroscopy analyses performed on diamond and graphite occurring in the ureilite Yamato 74123 (Y-74123). The results show that nano- and microdiamonds coexist with nanographite aggregates. This, together with the shock-deformation features observed in olivine, such as mosaicism and planar fractures, suggest that diamond grains formed by a shock event (≥15 GPa) on the ureilitic parent body (UPB). Our results on Y-74123 are consistent with those obtained on the NWA 7983 ureilite and further support the hypothesis that the simultaneous formation of nano- and microdiamonds with the assistance of a Fe-Ni melt catalysis may be related to the heterogeneous propagation and local scattering of the shock wave. Graphite geothermometry revealed an average recorded temperature (Tmax) of 1314 °C (±120 °C) in agreement with previously estimated crystallization temperatures reported for graphite in Almahata Sitta ureilite. [ABSTRACT FROM AUTHOR]

Herein, a radiation detector made of polycrystalline diamond with a boron (B)‐doped neutron converter layer is presented. The detector is fabricated by the hot filament chemical vapor deposition technique, and consists of an undoped free‐standing polycrystalline diamond layer and a B‐doped polycrystalline diamond top layer that serves as an electrical contact and a converter for neutron‐alpha conversion. Characterization of the diamond films and detector operation is presented. The results indicate that the B‐doped layer acts as an effective neutron‐alpha converter, whereby neutron detection is demonstrated in particle‐counting mode using a multichannel analyzer. [ABSTRACT FROM AUTHOR]

The effect of a magnetic field on the luminescence from an ensemble of NV-centers in diamond was studied experimentally and theoretically. It was found that the intensity of infrared luminescence associated with transitions between singlet levels of NV-centers showed a pronounced increase in a near-zero magnetic field. The influence of the power and polarization of the laser radiation on the amplitude and shape of the revealed local maximum in the IR-luminescence of NV-centers was investigated. An eight-level photophysical model of an NV-center in the presence of an arbitrarily directed magnetic field was constructed and used as a basis to calculate the intensity of the luminescence emitted by an ensemble of NV-centers in both the visible and infrared spectral regions. It was shown that a phenomenological allowance for cross relaxation of NV-centers between each other and with other diamond paramagnetic centers within the framework of this model allows the experimentally observed fluorescence features of an ensemble of NV-centers in the presence of weak magnetic fields to be described. [ABSTRACT FROM AUTHOR]

Development of carbon-based structures composed of nanoparticles with different type of orbital hybridization of carbon (sp2, sp3) made it possible to create new substances with advanced biomedical properties, luminescent, and magnetic when the carbon components are modified by lanthanides for the applications in Photodynamic Therapy or Magneto-Resonance Imaging. The presented results are devoted to the synthesis, physical-chemical and synchrotron studies of water-soluble complexes of detonation nanodiamonds (particle size 4–5 nm) and fullerenols Gd@C82(OH)X (X ∼ 30). The association of positively charged diamonds and electro-negative fullerenols created the complexes being stable under heating (25–70 °C) while the assembly of fullerenols with the diamonds carrying negative surface charges was less probable. Small angle scattering of synchrotron radiation revealed the association of diamonds into chain-like structures more stable due to additional linking of diamonds via fullerenols. Due to complexing, fullerenols got magnetic resonance properties of negative contrasting substances for MRI diagnostics. The tests on biological cells showed a low toxicity of complexes which can be used as prospective biomedical materials. [ABSTRACT FROM AUTHOR]

We here propose and demonstrate a novel “2-in-1” fiber consisting of two freely separated fiber ends and one fiber tip mounted with nanodiamonds (NDs) containing nitrogen vacancy (NV) centers. The fiber tip with ball lens is fabricated by fusing two parallel multimode fiber with arcing discharge. The excitation and collection of the integrated NV centers through the two fiber ends, can be optimized by manipulating the fabricated lens. We also demonstrate the feasibility of all-optical thermometry using this device. This endoscopy-like probe paves the way for developing fiber-based quantum device for flexible thermometry and magnetometry. [ABSTRACT FROM AUTHOR]

Dislocation behavior has been considered as the crucial reason for micro-scale plasticity and micro-damage of the diamond. In this research, based on the theory of discrete dislocation dynamics (DDD), the nanoscratch model was established to investigate the dislocation evolution and stress distributions of the chemical vapored deposition (CVD) diamond film, and further supported by experimental study. Well-designed nanoscratch experiments were performed to validate the simulation results. It can be found that dislocation multiplication occurred along the scratch path. Besides, the dislocation pile-up and local stress concentration are easier to be found inside the smaller grain stress concentration. And it causes the occurrence of crack initiation near the grain boundary. [ABSTRACT FROM AUTHOR]

The occurrence of shock-induced diamonds in ureilite meteorites is common and is used to constrain the history of the ureilite parent bodies. We have investigated a fragment of the Kenna ureilite by micro-X-ray diffraction, micro-Raman spectroscopy and scanning electron microscopy to characterize its carbon phases. In addition to olivine and pigeonite, within the carbon-bearing areas, we identified microdiamonds (up to about 10 μm in size), nanographite and magnetite. The shock features observed in the silicate minerals and the presence of microdiamonds and nanographite indicate that Kenna underwent a shock event with a peak pressure of at least 15 GPa. Temperatures estimated using a graphite geothermometer are close to 1180 °C. Thus, Kenna is a medium-shocked ureilite, yet it contains microdiamonds, which are typically found in highly shocked carbon-bearing meteorites, instead of the more common nanodiamonds. This can be explained by a relatively long shock event duration (in the order of 4–5 s) and/or by the catalytic effect of Fe-Ni alloys known to favour the crystallization of diamonds. For the first time in a ureilite, carletonmooreite with formula Ni 3 Si and grain size near 4–7 nm, was found. The presence of nanocrystalline carletonmooreite provides further evidence to support the hypothesis of the catalytic involvement of Fe-Ni bearing phases into the growth process of diamond from graphite during shock events in the ureilite parent body, enabling the formation of micrometer-sized diamond crystals. [ABSTRACT FROM AUTHOR]