Type IIa Diamond Research Articles

Photoluminescence Spectra of Helium Ion-Implanted Diamond.

Ion implantation in diamond crystals is widely used both for producing conducting microstructures in the bulk of the material and for creating isolated photon emitters in quantum optics, photonics, cryptography, and biosensorics. The photoluminescence (PL) spectra of helium ion-implanted diamonds are dominated by two sharp emission lines, HR1 and HR2 (from Helium-Related), at ~536 and 560 nm. Here, we report on PL studies of helium-related optical centers in diamonds. Experiments have been carried out on a (110) plate of natural single-crystal type IIa diamonds. The uniform distribution of radiation defects in a 700 nm-thick layer was obtained by ten cycles of multiple-energy (from 24 to 350 kV) helium ion implantation with a total dose of 5 × 1016 cm-2. The diamonds were annealed in steps in a vacuum oven at temperatures from 200 to 1040 °C. It is demonstrated that helium ion implantation in diamonds followed by annealing gives rise to more than a dozen various centers that are observed in the PL spectra in the range of 530-630 nm. The transformations of the PL spectra due to annealing are investigated in detail. The spectral shapes of phonon sidebands are determined for the HR1, HR2, and HR3 bands with ZPLs at ~536, 560, and 577 nm, respectively, and it is shown that these bands are attributed to interstitial-related centers in diamonds. The reported results are important for understanding the structure and properties of helium-related defects in diamonds.

Cutting efficiency of different dental diamond rotary instruments for sectioning monolithic zirconia and lithium disilicate crowns

BackgroundThe aim of this study was to determine the cutting efficiency of different diamond rotary instrument types for sectioning monolithic zirconia and lithium disilicate anatomical crowns.Materials and methodsThe study used 30 diamond rotary instruments divided into three groups: Zirconia cutting diamond bur (White Z), super coarse grit diamond bur (KBlack), and medium coarse grit diamond bur (KBlue); Two subgroups were assigned based on the crown materials including monolithic zirconia (5YSZ) and lithium disilicate (e.max) ceramics. The cutting efficiency was assessed by measuring the time required to fully section the crowns, followed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) of the dental burs before use and after every sectioned crown. A three-way ANOVA examined the effects of bur type, material type, and sectioning stage. If interaction exists, one-way ANOVA was used to compare the different subgroups, followed by the Tukey post hoc test. The significance level was assigned at α ≤ 0.05.ResultsThe results exhibited various cutting efficiencies among diamond rotary instruments and ceramic crown materials. White Z demonstrated superior cutting efficiency of zirconia crown compared with KBlack and KBlue for the first cutting cycles (p ≤ 0.05); the results tend to be more comparable at the third cutting cycle. However, the super coarse diamond bur exhibited higher efficiency in cutting lithium disilicate crowns than white Z and KBlue burs through all three cutting cycles(p ≤ 0.05). The diamond bur-cutting efficiency diminished after each use, irrespective of the bur type or the crown material (p ≤ 0.05); this was represented by the reduction of carbon and increased nickel matrix ratio after each bur usage.ConclusionWhite Z diamond bur showed higher cutting efficiency of zirconia in the first two cutting cycles; super coarse diamond bur is more efficient for cutting lithium disilicate crown in all of the cutting cycles. The amount of diamond on the burs reduced after each use, with no great impact on the material type when sectioning lithium disilicate and 5YSZ crowns.Clinical significanceThis study provides valuable insights for dental practitioners in selecting the appropriate diamond rotary instrument for crown sectioning. Practitioners can minimize the risk of damage and reduce the time required for crown removal, improving patient outcomes.

Insight into the nitrogen-vacancy center formation in type-Ib diamond by irradiation and annealing approach

Abstract Comprehending the microscopic formation of nitrogen vacancy (NV) centers in nitrogen-doped diamonds is crucial for enhancing the controllable preparation of NV centers and quantum applications. Irradiation followed by annealing simulations for a type-Ib diamond with a 900 ppm concentration of isolated nitrogen is conducted along different orientations and at different annealing temperatures. In these simulations, molecular dynamics (MD) with smoothly connected potential functions are implemented. MD simulations revealed the dynamic formation process of the NV center, which was subsequently verified by first-principles calculations and experiments. The results indicate that vacancies undergo one or multiple migrations by exchanging sites with neighboring atoms. There are three mechanisms for the formation of NV centers: direct irradiation-induced NV formation, irradiation with further annealing to form NV and vacancy migration (VM) during the annealing process. Furthermore, the results show that both VM and NV center formations are affected by orientations. This study clarifies the formation of NV centers across multiple scales and provides a solid foundation for the targeted preparation of NV centers.

Investigating the broom-like inclusions in type Ib diamond single crystal synthesized by high pressure high temperature

The exceptional properties of diamonds enable diverse applications. However, the applications are significantly hindered by its inclusions. In this study, a specific type of inclusion, broom-like inclusions, has been investigated. The broom-like inclusions in diamonds were synthesized through various high-pressure high-temperature (HPHT) experiments. The synthesis methods were optimized by adjusting the metal catalyst composition, synthesis temperature, Mg(OH)2 content, and nitrogen getter (Ti). The broom-like inclusion morphology and composition were physically characterized and analyzed using various methods. Optical microscopy and SEM were utilized to characterize the morphology and shape of the inclusions, while Raman spectroscopy and Fourier Transform Infrared Spectroscopy were employed to analyze the influence of the defects on the properties of diamonds and investigate the composition of the broom-like inclusions. Gaseous inclusions emerged as crucial for broom-like inclusion formation. They probably originated from residual gases like H2 and CH4. The investigation of broom-like inclusions within diamond crystals has led to the development of various synthetic methods for producing inclusion-free crystals. The findings of this study offer valuable insights into the nature and origin of these inclusions in diamonds, as well as provide strategies to mitigate their formation during production.

Extra-mantle Genetic Types of Diamond and Prospects for the Kamchatka Diamond-bearing Province of Russia

The results of studies of two new genetic types of diamonds discovered in Kamchatka and formed in extra-mantle conditions are presented, as evidenced by the absence of signs of post-crystallization annealing with the formation of aggregated nitrogen defects in them. The first of these types is defined by us as volcanic-atmoelectrogenic, formed directly in a volcanic ash-gas cloud due to deep-seated methane due to atmospheric electrical discharges. The second genetic type of diamonds, formed at a depth in the medium of a magmatic-pneumatolithic-hydrothermal ore deposit, can be defined as explosive-tuffizite. The industrial prospects of manifestations of these types give grounds to state the discovery in Russia of a new diamond-bearing province – Kamchatka.

Porous Silicon-Supported Catalytic Materials for Energy Conversion and Storage.

Porous silicon (Si) has a tetrahedral structure similar to that of sp3- hybridized carbon atoms in a typical diamond structure, which affords it unique chemical and physical properties including an adjustable intrinsic bandgap, a high-speed carrier transfer efficiency. It has shown great potential in photocatalysis, rechargeable batteries, solar cells, detectors, and electrocatalysis. This review introduces various porous Si-supported electrocatalysts and analyzes the reasons why porous Si is used as a new carrier/active sites from the perspectives of its molecular structure, electronic properties, synthesis methods, etc. The electrochemical applications of porous Si-based electrocatalysts in energy conversion reactions such as hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, and total water decomposition together with lithium-ion batteries (LIBs) and supercapacitors in energy storage are summarized. The challenges and future research directions for porous Si are also discussed. This review aims to deepen the understanding of porous Si and promote the development and applications of this new type of Si material.

Fabrication of lateral diamond MOSFET with buried pn-junctions by diamond surface planarization based on carbon solid solution into nickel

New fabrication processes for buried p+-type diamond using etching techniques based on the solid-solution reaction of carbon with nickel were proposed and demonstrated. Specifically, an inversion-channel diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with source and drain regions buried in the body were fabricated, and their operation were confirmed. An etching process using etching techniques based on the solid-solution reaction of carbon with nickel was applied to realize trench formation and planarization after the growth of a p+-type diamond. The fabricated MOSFET exhibited drain current density equivalent to that of conventional MOSFET with source and drain p+-type regions deposited as islands on an n-type body, and ideal field-effect transistor characteristics with linear and saturation regions, and the drain current density was controlled by the gate voltage. However, the surface protrusion structure owing to the incomplete planarization process limited the device characteristics. The proposed fabrication processes for buried layers are expected to function as an important selective doping technique for diamond electronic devices such as ion implantation.

Quantitative characterization of occupational sites of implanted P atoms in diamond

The authors implanted P atoms at 50 and 140-keV energies with respective fluences of 1×1014 and 2×1014/cm2 into diamond thin films synthesized by chemical vapor deposition on the type-Ib diamond substrate formed by high-pressure and high-temperature conditions. The occupational sites of implanted P atoms were determined in each processing stage of P implantation, ion-beam-induced epitaxial crystallization (IBIEC) annealing by 3-MeV-Ne2+ ion irradiation at 750°C, and thermal annealing at 850°C in vacuum, by quantitatively comparing the random and channeling yields in Rutherford backscattering (RBS) measurements. In the analysis of RBS spectra, simulated distributions were fitted to the experimentally obtained spectra and we quantitatively identified the occupational sites and ratio of implanted P atoms. In addition, we investigated the diffusion phenomenon of implanted P atoms during annealing processes from the depth profile of scattered He ions. Consequently, the averaged occupational ratio in the substitutional lattice site was stably recorded around 50%. From the depth profile in the RBS spectra, thermal diffusion of implanted P atoms was clearly observed during the last thermal annealing after MeV-IBIEC annealing. We finally discuss the potentials of the MeV-IBIEC irradiation at relatively low temperatures applying to useful and credible annealing methods for electrical activation as well as recovery of damaged crystallinity.

The characterization of diamond single crystal growing along (100) after annealing treatment under high pressure and high temperature

Diamond has many desirable properties. In this study, temperature gradient method was used to prepare a series of type Ib diamond single crystals, which were processed again to obtain and characterize Type IaA diamonds with even more desirable properties. Before annealing, Fourier-transformed infra-red(FTIR) spectra of diamond showed peaks at 1130 cm−1 and 1344 cm−1; After annealing, the peak at 1282 cm−1 was appeared in FTIR spectra of diamonds This data indicated that the isolated nitrogen in diamond aggregated after high-pressure and high-temperature (HPHT) method annealing experiment. Moreover, photoluminescence (PL) spectra suggested that no nitrogen-related color centers existed in the diamond before annealing. In contrast, after annealing, a peak at 637 nm appeared in the PL spectra, indicating the appearance of NV−colors centers type Ib diamond post-annealing. The experimental results show that type Ib diamond crystals can be decolorized after 60 min of annealing under 7 GPa and 1850 °C, which makes part of the area transparent. Under 7 GPa and 2100 °C, type Ib diamond crystals can produce NV color center when annealed for 3 min. With increasing annealing temperature and prolonged annealing duration, the density and size of etch pits on the crystal surface escalated. Therefore, this study provides a guideline for the decolorization of diamonds by HPHT annealing. Moreover, this study also reports a method to change the crystal type and obtain NV color centers under ultra-high-temperature annealing conditions of 7 GPa pressure and 2100 °C temperature, which can be applied to develop quantum materials.

Direct Multiphoton Femtosecond Infrared Laser Excitation of a Diamond Lattice in the Two-Phonon Region and Modification of Color Centers

The nonlinear absorption of ultrashort laser pulses with intensities of 0.17–1.7 TW/cm2 at an intrinsic two-photon absorption wavelength of 4673 nm in type IIb diamond has been studied experimentally. It has been shown that the main absorption mechanism in the studied sample is two-photon absorption with a coefficient of β2 = (72 ± 7) cm/TW. Transmission microspectroscopy, visible photoluminescence, and infrared Fourier-transform microspectroscopy have demonstrated the possibility of laser-induced transformation of nitrogen impurity centers in synthetic type Ib diamond at higher radiation intensities.

Synthesis and nitrogen content regulation of diamond in a high-pressure hydrogen-rich environment

The regulating nitrogen content of diamond in a hydrogen-rich high-temperature and high-pressure (HPHT) growth environment was systematically investigated in this work by developing three growth systems, namely, “FeNi+Ti”, “FeNi+C3N6H6”, and “FeNi+Ti+C3N6H6”. Optical microscopy, infrared spectroscopy, and photoluminescence (PL) spectroscopy measurements were conducted to analyze the spectroscopic characteristics of diamonds grown in these three systems. From our analysis, it was demonstrated that the presence of hydrogen in the sp3 hybrid C–H does not directly affect the color of the diamond and facilitates the increase of the nitrogen-vacancy (NV) center concentration in a high-nitrogen-content diamond. In addition, titanium plays an important role in nitrogen removal, while its impact on hydrogen doping within the diamond lattice is insignificant. Most importantly, by regulating the ratio of nitrogen impurities that coexist in the nitrogen and hydrogen HPHT environment, the production of hydrogenous IIa-type diamond, hydrogenous Ib-type diamond, and hydrogenous high-nitrogen-type diamonds was achieved with a nitrogen content of less than 1 ppm to 1600 ppm.

Hydrogen-related defects in diamond: A comparison between observed and calculated FTIR spectra

A comprehensive and up-to-date compilation of observed and calculated hydrogen (H)-related peaks that occur in the near- and middle-infrared spectra of diamond is presented. The experimental database contains >300 observed peaks attributed to H-related impurities in natural diamond. The database of calculated peaks includes data from first-principles simulations of the FTIR spectra of different VxNyHz defects in diamond and contains >300 peaks that correspond to different C-H, N-H, and B-H vibrational modes for each VxNyHz defect. Less than ~10 % of observed H-related peaks have been assigned to specific defects. Consequently, the computational database was constructed to better understand the properties of different VxNyHz defects that may correspond to different observed peaks. In general, hydrogen-rich diamonds with a dominant Type Ib character and thus poorly aggregated N, show a larger number of low-intensity, H-related peaks compared to diamonds with a dominant Type Ia character. For example, ~51 % of observed H-related peaks are only observed in Type Ib diamonds, ~9 % of peaks are only observed in diamonds with a dominant Type Ia character and ~40 % of peaks are observed in both Type Ia and Type Ib diamonds. There is a major increase in the number of distinct H-related peaks in Type IaA + Ib diamonds compared to Type Ib diamonds suggesting N-aggregation processes responsible for the formation of A-centers may also produce many distinct VxNyHz defects capable of trapping H. There is a major decrease in the number of H-related peaks in Type IaA > Ib diamonds compared to Type IaA + Ib diamonds suggesting that many of the VxNyHz defects associated with the initial production of A-centers become unstable with increasing mantle residence time and the progressive loss of C-centers. These defects likely combine (or disaggregate and then re-combine) to form fewer, relatively more intense, H-related peaks observed in Type IaA > Ib diamonds. Many of these peaks persist through continued annealing in the mantle and are observed in Type IaA, IaAB, and IaB diamonds. Our data suggests that N and H incorporation are not correlated during diamond growth and that in the early stages of diamond residence, H is incorporated into many distinct VxNyHz defects that involve C- and A-centers. With continued residence and annealing, and the progressive formation A-centers and loss of C-centers, these defects aggregate to form relatively fewer, presumably more stable, VxNyHz defects such as VN3H.

Sublithospheric Diamonds: Plate Tectonics from Earth's Deepest Mantle Samples

Sublithospheric diamonds and the inclusions they may carry crystallize in the asthenosphere, transition zone, or uppermost lower mantle (from 300 to ∼800 km), and are the deepest minerals so far recognized to form by plate tectonics. These diamonds are distinctive in their deformation features, low nitrogen content, and inclusions of these major mantle minerals: majoritic garnet, clinopyroxene, ringwoodite, CaSi perovskite, ferropericlase, and bridgmanite or their retrograde equivalents. The stable isotopic compositions of elements within these diamonds (δ11B, δ13C, δ15N) and their inclusions (δ18O, δ56Fe) are typically well outside normal mantle ranges, showing that these elements were either organic (C) or modified by seawater alteration (B, O, Fe) at relatively low temperatures. Metamorphic minerals in cold slabs are effective hosts that transport C as CO3 and H as H2O, OH, or CH4 below the island arc and mantle wedge. Warming of the slab generates carbonatitic melts, supercritical aqueous fluids, or metallic liquids, forming three types of sublithospheric diamonds. Diamond crystallization occurs by movement and reduction of mobile fluids as they pass through host mantle via fractures—a process that creates chemical heterogeneity and may promote deep focus earthquakes. Geobarometry of majoritic garnet inclusions and diamond ages suggest upward transport, perhaps to the base of mantle lithosphere. From there, diamonds are carried to Earth's surface by eruptions of kimberlite magma. Mineral assemblages in sublithospheric diamonds directly trace Earth's deep volatile cycle, demonstrating how the hydrosphere of a rocky planet can connect to its solid interior. ▪Sublithospheric diamonds from the deep upper mantle, transition zone, and lower mantle host Earth's deepest obtainable mineral samples.▪Low-temperature seawater alteration of the ocean floor captures organic and inorganic carbon at the surface eventually to become some of the most precious gem diamonds.▪Subduction transports fluids in metamorphic minerals to great depth. Fluids released by slab heating migrate, react with host mantle to induce diamond crystallization, and may trigger earthquakes.▪Sublithospheric diamonds are powerful tracers of subduction—a plate tectonic process that deeply recycles part of Earth's planetary volatile budget.

Linear and nonlinear analytical equations for fast design of three types of triangular-amplified compliant mechanisms

Compliant amplification mechanisms based on the triangular principle have attracted considerable applications in precision and other engineering fields due to their compactness and efficient amplification capacity. However, a fast engineering design for geometric nonlinearity of large strokes is still much challenging. We report herein a series of analytical equations of nonlinear amplification ratio, input and output stiffness for three commonly-used triangular-amplified compliant mechanisms, namely the rhombus, diamond and bridge types. The pronounced geometric nonlinearities of axially-loaded stiffening and kinematics-arching effects are explicitly formulated. The proposed nonlinear formulas can be directly degenerated as the linear models by vanishing the nonlinear terms, which enables a comprehensive analysis of linear and nonlinear kinetostatics, and hence offers a straightforward way for the fast performance evaluation and size synthesis/optimization. This relieves an engineer's experience and knowledge for an ab initio modeling process. The prediction error is discussed and some insights into the linear and nonlinear characteristics of the three commonly-used triangular-amplified compliant mechanisms are outlined that confirms the advantage of analytical equations bringing to a fast engineering analysis and design.

Study on super impact resistant polycrystalline diamond compacts with homogeneous PCD/WC-Co interlayer

With ultra-deep wells exceeding 10,000 m, the downhole drilling environment has become increasingly harsh and challenging and poses higher and more urgent requirements for the improvement of mechanical properties of polycrystalline diamond compact (PDC) cutters. In this work, four different types of polycrystalline diamond (PCD) structures were utilized with the purpose of exploiting both the advantages of homogeneous PCD/WC-Co composites in the impact toughness and the advantages of pure PCD composites in the wear resistance. Each PCD layer was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy. The indentation hardness, wear resistance and impact resistance of PDC cutters were evaluated using nanoindentation instrument, vertical turret lathe and progressive drop tester, respectively. The field trials of the developed PDC cutters in the ultra-well above 8000 m were also carried out. The experimental results demonstrated that PDC cutters with homogeneous PCD/WC-Co interlayer have excellent impact resistance while the pure PCD top layer ensures the cutter's hardness and wear resistance. Through observing the cracks in the diamond layer after mechanical performance testing, it was discovered that the homogeneous PCD/WC-Co interlayer has the capability of promoting the deflection of cracks on a macroscopic level. In addition, the inclusion of WC-Co alters the fracture mode of the PCD layer from transgranular fracture to mixed-mode fracture, which well explains the toughening mechanism of PCD/WC-Co cutter. This work provides valuable insights for the development of high-quality PDC cutters, and has important significance for the further design of efficient rock-cutting materials and comprehensive improvement of the drilling performance of PDC bits.

Effect of abrasive on tribological behavior and polishing effect of β-Ga2O3(100) substrate

Given the problems of easy cleavage and unfavorable surface integrity in the processing of β-Ga2O3(100), the effects of abrasive type (diamond, silicon carbide, alumina, cerium oxide) and abrasive particle size (W3, W2, W1, W0.5) on substrate processing were investigated via friction and polishing experiments. The results demonstrated that a strong correlation exists between the surface integrity of the β-Ga2O3(100) substrate and abrasive type, and it was determined that the diamond abrasive with sharp cutting edges was optimal. The abrasive particle size significantly affected the friction wear and polishing effect of β-Ga2O3(100). The use of fine abrasive particles can effectively inhibit the formation of cleavage pits and scratches. After polishing with the W0.5 diamond, the surface roughness (Ra) of the substrate decreased to 3.8 nm, and the scratch depth decreased to 18 nm. The abrasive particle size significantly affected the friction wear and polishing effect of β-Ga2O3(100). The shape and size of the abrasive are crucial factors affecting the processing of the β-Ga2O3(100) substrate. The diamond abrasive particle size distribution was uniform, and the axial ratio of the abrasive was predominantly between 0.6 and 0.9. The surface material of the substrate was removed via the “three-body rolling” method, so the polishing effect was optimal.

Mechanical, electrochemical and permeability behaviour of Ti6Al–4V scaffolds fabricated by electron beam powder bed fusion for orthopedic implant applications: The role of cell type and cell size

Ti–6Al–4V scaffolds have attracted much attention for biomedical applications owing to their bone-mimicking mechanical properties and better bone tissue in-growth and additive manufacturing can be employed to fabricate complex geometry scaffolds. The present study aimed to investigate the effects of scaffold architecture on the mechanical, electrochemical, and permeability behaviour of Ti–6Al–4V scaffolds fabricated by electron beam powder bed fusion (EB-PBF). For this, scaffolds with diamond and rhombic dodecahedron cell types, having various cell sizes, were designed and successfully fabricated. Chemical etching minimized the surface defects and improved the geometric fidelity of the scaffolds compared to the original designs. The larger the cell size, the coarser the dual α/β phase microstructure due to the higher heat accumulation in thicker struts. The scaffold architecture proved significant effects on the mechanical properties, where all scaffolds were mechanically comparable with human bone. Short/long-term electrochemical corrosion tests indicated that the corrosion performance significantly improved with an increase in cell size, irrespective of the cell type; this was attributed to the lower exposure of surface area to the electrolyte, coarse microstructure and a higher fraction of β phase. This study recommended that the EB-PBF Ti–6Al–4V scaffolds are promising candidates for orthopaedic implant applications from mechanical and electrochemical points of view.

Effect of thermobaric treatment on magnetic and superconductive properties of HPHT-grown nitrogen-doped diamond crystals

The effect of thermobaric treatment (TBT) at Р = 5.5 GPa T = 1900 °C for 4 h on the concentration of single substitutional atoms (P1 centers) in nitrogen-doped synthetic single crystal Ib type diamonds grown by the temperature gradient high-pressure high-temperature (TG-HPHT) method and on their magnetic properties in the temperature range of 2–300 K was investigated. The initial concentration of P1 centers in 2 crystals was 3.0 × 1019 cm−3 and 5.6 × 1019 cm−3, respectively, which decreased by ~96–98 % after TBT. At T < 10 K, an anomalous hysteresis of the magnetic moment is observed in the range of magnetic fields up to Hc = 70 kOe, the amplitude of which is half the value of the paramagnetic saturation moment, corresponding to the number of spins of the P1 centers. The shape of the hysteresis loops after subtracting an intrinsic diamond diamagnetic component and the calculated paramagnetic component indicates a granular (local) superconducting state. The fact that the amplitude of the magnetic moment generated by superconducting currents is equal to half the total number of Bohr magnetons of P1 centers may indicate that elementary currents occur in pairs of adjacent P1 centers. As a result of a decrease in the number of P1 centers in diamonds after TBT, the saturation values of the paramagnetic moment and the amplitude of the diamagnetic moment of the induced superconducting currents decrease proportionally.

P1 Center Electron Spin Clusters Are Prevalent in Type Ib Diamonds.

Understanding the spatial distribution of the P1 centers is crucial for diamond-based sensors and quantum devices. P1 centers serve as polarization sources for dynamic nuclear polarization (DNP) quantum sensing and play a significant role in the relaxation of nitrogen vacancy (NV) centers. Additionally, the distribution of NV centers correlates with the distribution of P1 centers, as NV centers are formed through the conversion of P1 centers. We utilized DNP and pulsed electron paramagnetic resonance (EPR) techniques that revealed strong clustering of a significant population of P1 centers that exhibit exchange coupling and produce asymmetric line shapes. The 13C DNP frequency profile at a high magnetic field revealed a pattern that requires an asymmetric EPR line shape of the P1 clusters with electron-electron (e-e) coupling strengths exceeding the 13C nuclear Larmor frequency. EPR and DNP characterization at high magnetic fields was necessary to resolve energy contributions from different e-e couplings. We employed a two-frequency pump-probe pulsed electron double resonance technique to show cross-talk between the isolated and clustered P1 centers. This finding implies that the clustered P1 centers affect all of the P1 populations. Direct observation of clustered P1 centers and their asymmetric line shape offers a novel and crucial insight into understanding magnetic noise sources for quantum information applications of diamonds and for designing diamond-based polarizing agents with optimized DNP efficiency for 13C and other nuclear spins of analytes. We propose that room temperature 13C DNP at a high field, achievable through straightforward modifications to existing solution-state NMR systems, is a potent tool for evaluating and controlling diamond defects.

Synthesis and Characterization of Fe–C–Si System Ib-Type Gem-Grade Diamond Single Crystals under High Temperature and Pressure

Synthesis and Characterization of Fe–C–Si System Ib-Type Gem-Grade Diamond Single Crystals under High Temperature and Pressure