Nanoscale Diamond Research Articles

Nanoscale diamond quantum sensors for many-body physics

Nanoscale diamond quantum sensors for many-body physics

Research on the fabrication of high-quality patterned diamond using femtosecond laser

Diamond, known for its exceptional thermal, electrical, and mechanical properties, is widely used in precision machining tools, MEMS, and electronic devices. However, because of its extreme hardness and chemical inertness, diamond machining is highly challenging. Femtosecond laser technology, with its high instantaneous energy and minimal heat-affected zone, has emerged as an effective method for the precision machining of diamond. This study explores the application of 1026 nm and 513 nm femtosecond lasers in diamond grooving. The experimental results indicate that with increasing laser energy density, both groove width and depth increase, accompanied by a rise in amorphous carbon and graphite contents, resulting in increased tensile stress and decreased crystallinity in the machined region. Notably, the 513 nm laser demonstrates higher precision, achieving narrower grooves suitable for fine machining of diamond. Molecular dynamics simulations and experimental data reveal that the formation of amorphous carbon and graphite phases is the primary mechanism for deep ablation, and no significant anisotropy is observed during the process, allowing for the uniform fabrication of micro-nanostructures. TEM analysis confirms the presence of amorphous carbon and nanocrystalline diamond at the groove bottom, indicating phase transformation and also the formation of nanoscale diamond particles in regions of concentrated femtosecond laser energy. This study provides experimental and theoretical support for the high-quality fabrication of micro-nanostructures on diamond, with significant implications for its advanced applications.

Roughness control in the processing of 2-inch polycrystalline diamond films on 4H-SiC wafers

Diamond is an essential material for the manufacture of semiconductors devices, infrared optical windows, heat dissipation and other fields. The applications have put forward a practical demand that the diamond substrates have an ultra-smooth surface and are free of structural damage. However, precision polishing of diamond is challenging due to the extreme hardness and chemical inertness. The focus of this study is to prepare nanoscale smooth polycrystalline diamond films with roughness Ra down to 0.1 nm using chemical and mechanical synergies. After processing, the surface roughness and quality of CVD diamond film were characterized, and a material removal mechanism was proposed. The graphitization process is accelerated when diamond contacts the transition metal Fe in the mechanical polishing process. In chemical mechanical polishing process, the polished surface of diamond C is transformed into deformed diamond C* under friction. A relatively soft polishing pad is used to increase the contact area with the diamond, which is transformed into a softer, easy-to-remove structure under the action of potassium permanganate oxidant, and then the reaction layer is removed again by mechanical friction.

Spin–wave dynamics in perpendicularly magnetized antidot multilayers

Using all-optical time-resolved magneto-optical Kerr effect measurements we demonstrate an efficient modulation of the spin–wave (SW) dynamics via the bias magnetic field orientation around nanoscale diamond shaped antidots that are arranged on a square lattice within a [Co(0.75 nm)/Pd(0.9 nm)]8 multilayer with perpendicular magnetic anisotropy (PMA). Micromagnetic modeling of the experimental results reveals that the SW modes in the lower frequency regime are related to narrow shell regions around the antidots, where in-plane (IP) domain structures are formed due to the reduced PMA, caused by Ga+ ion irradiation during the focused ion beam milling process of antidot fabrication. The IP direction of the shell magnetization undergoes a striking change with magnetic field orientation, leading to the sharp variation of the edge localized (shell) SW modes. Nevertheless, the coupling between such edge localized and bulk SWs for different orientations of bias field in PMA systems gives rise to interesting Physics and attests to new prospects for developing energy efficient and hybrid-system-based next-generation nanoscale magnonic devices.

Chemical-Biological Activity of Nanodiamond Colloids

The study of the Nanoscale Diamonds (NDs) and their water suspensions has opened huge opportunities for their technological and biomedical applications. Therefore, the interaction of ND with water is actively studied. However, insufficient attention has been paid to the biochemical behavior of suspensions with low carbon content, despite their great scientific prospects. This work aims to fill this gap in scientific literature.

Blue-white electroluminescence of diamond/WS2 quantum dot composite films

Two kinds of diamond films with completely different morphologies were prepared on N-type heavily doped silicon wafers by microwave plasma chemical vapor deposition (MPCVD) method, namely, micron-scale large grain polycrystalline diamond film dominated by (220) crystal plane (220DF) and nano-scale small grain polycrystalline diamond film dominated by (111) crystal plane (111DF). And WS2 quantum dot powder was obtained by aqueous liquid phase ultrasonic method. Then, the 111DF/WS2 quantum dot composite structure film (111DWSF) and 220DF/WS2 quantum dot composite structure film (220DWSF) were prepared by applying WS2 quantum dot powder uniformly on diamond film substrate. The results of electroluminescence (EL) detection show that the 220DWSF device emits visible blue light, and the main peak of EL spectrum is located at 443 nm in the blue region. The 111DWSF device emits white light, and the corresponding EL spectra show strong emission peaks in the blue region (454 nm), green region (536 nm) and red region (632 nm) respectively, meanwhile, the luminous intensity of 111DWSF device is much higher than that of 220DWSF device. In addition, it is also found that the 220DWSF EL device does not show obvious rectification characteristics, while the 111DWSF EL device has obvious rectification characteristics. After FN fitting of the IV characteristic curve of 111DWSF EL device, the tunneling characteristics of electrons are found in the region of high electric field intensity.

Nanodiamond-Enhanced Magnetic Resonance Imaging.

Nanodiamonds (ND) hold great potential for diverse applications due to their biocompatibility, non-toxicity, and versatile functionalization. Direct visualization of ND by means of non-invasive imaging techniques will open new venues for labeling and tracking, offering unprecedented and unambiguous detection of labeled cells or nanodiamond-based drug carrier systems. The structural defects in diamonds, such as vacancies, can have paramagnetic properties and potentially act as contrast agents in magnetic resonance imaging (MRI). The smallest nanoscale diamond particles, detonation ND, are reported to effectively reduce longitudinal relaxation time T1 and provide signal enhancement in MRI. Using in vivo, chicken embryos, direct visualization of ND is demonstrated as a bright signal with high contrast to noise ratio. At 24 h following intravascular application marked signal enhancement is noticed in the liver and the kidneys, suggesting uptake by the phagocytic cells of the reticuloendothelial system (RES), and in vivo labeling of these cells. This is confirmed by visualization of nanodiamond-labeled macrophages as positive (bright) signal, in vitro. Macrophage cell labeling is not associated with significant increase in pro-inflammatory cytokines or marked cytotoxicity. These results indicate nanodiamond as a novel gadolinium-free contrast-enhancing agent with potential for cell labeling and tracking and over periods of time.

Self-healing of fractured diamond.

Materials that possess the ability to self-heal cracks at room temperature, akin to living organisms, are highly sought after. However, achieving crack self-healing in inorganic materials, particularly with covalent bonds, presents a great challenge and often necessitates high temperatures and considerable atomic diffusion. Here we conducted a quantitative evaluation of the room-temperature self-healing behaviour of a fractured nanotwinned diamond composite, revealing that the self-healing properties of the composite stem from both the formation of nanoscale diamond osteoblasts comprising sp2- and sp3-hybridized carbon atoms at the fractured surfaces, and the atomic interaction transition from repulsion to attraction when the two fractured surfaces come into close proximity. The self-healing process resulted in a remarkable recovery of approximately 34% in tensile strength for the nanotwinned diamond composite. This discovery sheds light on the self-healing capability of nanostructured diamond, offering valuable insights for future research endeavours aimed at enhancing the toughness and durability of brittle ceramic materials.

Quantum Diamonds at the Beach: Chemical Insights into Silica Growth on Nanoscale Diamond using Multimodal Characterization and Simulation.

Surface chemistry of materials that host quantum bits such as diamond is an important avenue of exploration as quantum computation and quantum sensing platforms mature. Interfacing diamond in general and nanoscale diamond (ND) in particular with silica is a potential route to integrate room temperature quantum bits into photonic devices, fiber optics, cells, or tissues with flexible functionalization chemistry. While silica growth on ND cores has been used successfully for quantum sensing and biolabeling, the surface mechanism to initiate growth was unknown. This report describes the surface chemistry responsible for silica bond formation on diamond and uses X-ray absorption spectroscopy (XAS) to probe the diamond surface chemistry and its electronic structure with increasing silica thickness. A modified Stöber (Cigler) method was used to synthesize 2-35 nm thick shells of SiO2 onto carboxylic acid-rich ND cores. The diamond morphology, surface, and electronic structure were characterized by overlapping techniques including electron microscopy. Importantly, we discovered that SiO2 growth on carboxylated NDs eliminates the presence of carboxylic acids and that basic ethanolic solutions convert the ND surface to an alcohol-rich surface prior to silica growth. The data supports a mechanism that alcohols on the ND surface generate silyl-ether (ND-O-Si-(OH)3) bonds due to rehydroxylation by ammonium hydroxide in ethanol. The suppression of the diamond electronic structure as a function of SiO2 thickness was observed for the first time, and a maximum probing depth of ∼14 nm was calculated. XAS spectra based on the Auger electron escape depth was modeled using the NIST database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to support our experimental results. Additionally, resonant inelastic X-ray scattering (RIXS) maps produced by the transition edge sensor reinforces the chemical analysis provided by XAS. Researchers using diamond or high-pressure high temperature (HPHT) NDs and other exotic materials (e.g., silicon carbide or cubic-boron nitride) for quantum sensing applications may exploit these results to design new layered or core-shell quantum sensors by forming covalent bonds via surface alcohol groups.

Peroxydisulfate Peroxidation of Cyanobacterial Cells Catalyzed by Non-Graphitic N-Doped Nanodiamonds

Non-graphitic nitrogen-doped nano-scale diamonds were tested in the laboratory for their ability to activate peroxydisulfate for treating Microcystis-laden water. Flocculation was observed and up to 99.8% of the cyanobacterial cells were removed. The flocs’ composition showed that nano-scale diamonds with activated persulfate promoted the release of protein-like and humic-like substances during the treatment, which could have promoted agglomeration. Comprehensive analyses suggest that both radical and radical-free mechanisms were involved. Extracellular substances associated with the Microcystis cells were modified to function as active bioflocculants, leading to self-flocculation and sedimentation.

Templated Synthesis of Diamond Nanopillar Arrays Using Porous Anodic Aluminium Oxide (AAO) Membranes

Diamond nanostructures are mostly produced from bulk diamond (single- or polycrystalline) by using time-consuming and/or costly subtractive manufacturing methods. In this study, we report the bottom-up synthesis of ordered diamond nanopillar arrays by using porous anodic aluminium oxide (AAO). Commercial ultrathin AAO membranes were adopted as the growth template in a straightforward, three-step fabrication process involving chemical vapor deposition (CVD) and the transfer and removal of the alumina foils. Two types of AAO membranes with distinct nominal pore size were employed and transferred onto the nucleation side of CVD diamond sheets. Subsequently, diamond nanopillars were grown directly on these sheets. After removal of the AAO template by chemical etching, ordered arrays of submicron and nanoscale diamond pillars with ~325 nm and ~85 nm diameters were successfully released.

Stimulated emission cross sections and temperature‐dependent spectral shifts of neutral nitrogen‐vacancy centers in diamonds

AbstractThe neutral nitrogen‐vacancy (NV0) defects in diamond are photostable color centers, suitable for a wide range of applications in science and engineering. However, the photophysical properties of the centers have not yet been fully characterized. This work measured the stimulated emission cross sections of NV0 in a single‐crystal diamond by two‐photon excitation of its matrix at 344 nm. From the measured photoluminescence spectrum and the fluorescence lifetime of 20 ± 1 ns, we determined a peak stimulated emission cross section of 1.43 ± 0.07 × 10−17 cm2 at 650 nm for the NV0 centers. In addition, we have also examined the thermal shifts of the zero‐phonon line of NV0 centers in nanoscale diamonds (~100 nm in diameter) over the temperature range of 30–120°C. A temperature measurement sensitivity of 0.2 K·Hz−1/2 was achieved, which is about two‐fold better than that of NV−, despite that the fluorescence intensity of NV0 is about six‐fold lower than that of NV− in the same nanoparticles. The result is attributed to the smaller electron–phonon coupling strength of the neutral center, compared with its negatively charged counterpart.

Prospects for the Use of Fluorinated Nanodiamonds in the Synthesis of Superhard Composites

The paper considers the possibilities of the practical use of nanoscale diamonds with a fluorine-functionalized surface for the synthesis of diamond composites under high pressures and temperatures. Optimal compositions of the initial mixtures and parameters of thermobaric treatment are established. It is shown that composites obtained by sintering homogeneous mixtures of fluorinated microdiamonds and nanodiamonds with the addition of aluminum and cobalt have an increased level of heat resistance and wear resistance which significantly exceeds the level of commercial samples.

Endohedral σ-Diradical Nitrogen-Vacancy Diamond Nanoclusters with a Confined Magnetic Space and Strong Electronic Spin Couplings.

The electronic properties and their modulations for the nitrogen-vacancy (NV) centers in various nanoscale diamonds are of profound current interest because of their potential applications. However, although the NV centers as chromophores in diamond are the most widely studied, surprisingly, little is known about their magnetic spin coupling properties up to now. Here, we for the first time show, using the spin-polarized DFT calculations, that the NV centers can act as unique endohedral σ-diradical magnets in diamond nanoclusters and exhibit quite strong ferromagnetic (FM) or antiferromagnetic (AFM) spin coupling characteristics due to their unique endotetrahedral structures with favorable radical-radical contacts. Although the neutral NV center (NV0) in its doublet ground state exhibits quite strong AFM spin coupling among three radical C-sites (i.e., an AFM triradical center), interestingly, excess electron injection can convert it to a FM diradical magnet (i.e., the triplet ground state NV-) with almost unchanged J-coupling magnitude, and the J-coupling of the nanocluster can be noticeably enhanced by F-termination of the surface due to triradical spin delocalization mediated by excess electron. However, interior modification (one C in the endotetrahedron core is substituted by N or B or is hydrogenated) can assign the nanocluster perfect AFM diradical character. The spin coupling strength presents a quasilinear correlation with the distance between the two C radicals in the NV core for the same size of the clusters and a high linear correlation with the energy difference between two singly occupied molecular orbitals. Clearly, the FM and AFM couplings as well as their switching behavior in such NV defect diamond nanoclusters featuring the endohedral σ-diradicals are a novel type of promising magnetic material motifs. These findings open up promising spintronic application prospects of the NV diamonds and provide helpful information for the design of inorganic magnetic materials and logic devices.

Effect of nanodiamonds on fluorescence enhancement of tryptophan phototransformation reaction products in the presence of halocarbons

The role of nanodiamonds in the reaction of photochemical transformation of tryptophan in the presence of halogen hydrocarbons has been studied. The photochemical transformation of free tryptophan in a suspension with diamond nanoparticles and in a hybrid complex with them when exposed to UV radiation in the presence of chloroform is investigated. Data from stationary and time-resolved spectroscopic studies show the presence of non-radiative transfer of electron excitation energy between tryptophan molecules and its photodestruction products for the case of a covalent complex with a nanodiamond. It is shown that in the presence of energy transfer, an increase in the intensity of integral fluorescence occurs in the range of ~ 450 nm. Thus, a covalent tryptophan complex with a nanodiamond can serve as a fluorescent marker for the presence of chloroform in solution. Keywords: nanoscale diamonds, hybrid complexes, tryptophan phototransformation, spectral-luminescent properties, fluorescence decay kinetics, chloroform.

A Study on Focused Ion Beam (FIB) Milling Machining and Fabrication Technology of Nano-Scale Diamond Tool for Machining Fine-Patterns in a Free-Form Surfaces.

Recently, the technology of the industry has been increasing for diffractive optical elements, holograms, optical components, and next-generation display components. The advanced high value-added industry is designing fine patterns on ultra-precision optical components and applying them to various industries. In the case of the ultra-fine pattern, a contact-type machining technique is required because it requires a precise pattern in nano-scale units. In this paper, the fabrication technology of ultra-precision diamond which is essential in the ultra-precision processing technology was suggested. The material used in the experiment was a single-crystal diamond tool (SCD), and the equipment for machining the SCD used a focused ion beam (FEI COMPANY, system Nova 600) equipment. The back fire method was applied without metal coating in order to carry out the process study and the focused beam of 30 keV Ga+ ions were carried out processing for various fabrication of diamond cutting tools. As a result of applying the backfire method through the process experiment, the cutting edge width of the ultra-precision diamond tool was verified 275 nm.

EFFECT OF NANODIAMONDS ON OPERATIONAL CHARACTERISTICS OF FILLED COMPOSITE MATERIALS

The paper presents the results of a study evaluating the effect of the addition of nanosized detonation diamond of the NA-SP brand on the characteristics of a filled polymer composition based on SKU PFL-100 prepolymer manufactured by Kazan Synthetic Rubber Plant JSC cured by 4,4'-methylene-bis-orthochloraniline. The scale of heterogeneity of the carbon powder was estimated. It is shown that the studied additive allows you to create a fairly dense and developed structure in a dispersion medium. The discussion of interfacial interaction at the nanodiamond – polyurethane interface is carried out, as well as the influence of the carbon nature of the filler particles. A possible chemical interaction between the functional groups of the prepolymer, hardener and particles of the studied additives is shown. The results of the experimental evaluation show that the combination of chemistry features (the presence of functional groups) and the mechanics of nanodiamond powder affects both the physical and mechanical properties of the filled polyurethane composition and its thermal stability. It was found that the introduction of up to 1% detonation diamond allows to increase the strength and stiffness of the polymer by approximately 2 times. As a result of the approximation of the experimental data, quadratic dependences of the physical and mechanical characteristics of the filled polyurethane system on the content of nanoscale diamonds in the range 0 - 1% (mass.) were obtained. The results of thermogravimetric analysis show that the introduction of 1% (mass.) detonation diamond powder can increase the temperature of destructive processes by about 20 °С. Anomalies in the dynamics of the process of dissociation of filled polyurethane are noted. It has been suggested that the introduction of detonation diamond leads to the initiation of secondary synthesis reactions with the formation of allophate and biuret groups with low temperature stability.

Label‐Free Phase Change Detection of Lipid Bilayers Using Nanoscale Diamond Magnetometry

AbstractThe nitrogen‐vacancy (NV) center in diamond is a quantum sensor with exceptional quality for highly sensitive nanoscale analysis of nuclear magnetic resonance (NMR) spectra and thermometry. In this study, nanoscale phase change detection of lipid bilayers is investigated utilizing ensemble‐averaged nuclear spin detection from small volume ≈(6 nm)3, which is determined by the depth of the NV center. Analysis of nanoscale NMR signal confirms thickness of lipid bilayer to be 6.2 nm ± 3.4 nm with proton density of 65 protons per nm3 on top of diamond sample. The result of the correlation spectroscopy from nanoscale volume is compared with the 2D molecular diffusion model constructed by Monte Carlo simulation combined with results from molecular dynamics (MD) simulation. There is a change in diffusion constant from 1.5 ± 0.25 nm2 µs−1 to 3.0 ± 0.5 nm2 µs−1 when the temperature changes from 26.5 to 36.0 °C. The results demonstrate that the multi‐parameter detection of changes in translational diffusion and temperature is possible in label‐free measurements using nanoscale diamond magnetometry. The method paves the way for label‐free imaging of cell membranes for understanding their phase composition and dynamics.

Metallization of diamond

Experimental discovery of ultralarge elastic deformation in nanoscale diamond and machine learning of its electronic and phonon structures have created opportunities to address new scientific questions. Can diamond, with an ultrawide bandgap of 5.6 eV, be completely metallized, solely under mechanical strain without phonon instability, so that its electronic bandgap fully vanishes? Through first-principles calculations, finite-element simulations validated by experiments, and neural network learning, we show here that metallization/demetallization as well as indirect-to-direct bandgap transitions can be achieved reversibly in diamond below threshold strain levels for phonon instability. We identify the pathway to metallization within six-dimensional strain space for different sample geometries. We also explore phonon-instability conditions that promote phase transition to graphite. These findings offer opportunities for tailoring properties of diamond via strain engineering for electronic, photonic, and quantum applications.

Profile of Subra Suresh

During his long and distinguished career, Subra Suresh has made crucial contributions to the field of engineering. While finishing up high school in India in the 1970s, however, Suresh was not even sure of going to college, let alone becoming an engineer. Nonetheless, Suresh decided to take a shot at the entrance examination for the prestigious Indian Institutes of Technology. “A month before my exam, I bought a book to prepare and worked through some practice questions and just thought, go try it,” Suresh says. “To my surprise, I got in.” His degree in mechanical engineering from Indian Institutes of Technology Madras would turn out to be the starting point of a wide-ranging research career. Subra Suresh. Image credit: Nanyang Technological University, Singapore. Suresh’s research interests would eventually span engineering, basic science, and medicine. His multidisciplinary work led to elected memberships in all three US National Academies: The National Academy of Engineering in 2002, the National Academy of Sciences in 2012, and the National Academy of Medicine in 2013. Suresh has held several prestigious positions, from being dean of Massachusetts Institute of Technology’s School of Engineering and president of Carnegie Mellon University to leading the National Science Foundation (NSF) of the United States. Now President of Nanyang Technological University, Singapore, Suresh continues to push forward in research with his recent work on deforming nanoscale diamond. In his Inaugural Article (1), Suresh and his colleagues show computationally that it is possible to make nanoscale diamond behave like a metal with respect to select properties, which would open up a wide array of applications in microelectronics, optoelectronics, and solar energy. After obtaining his bachelor’s degree at Indian Institutes of Technology Madras, a scholarship offer led Suresh to attend Iowa State University for a Master’s degree in mechanical engineering. When he left for …