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For a graph G and a set Z of four distinct vertices of G, a diamond on Z is a subgraph of G such that, for some labeling Z = { v 1 , v 2 , v 3 , v 4 } , there are three internally disjoint paths P 1 , P 2 , P 3 with end vertices v 1 , v 2 with v 3 , v 4 on P 1 , P 2 , respectively. Therefore, this yields a K 4 − -subdivision with branch vertices on Z. We characterize graphs G that contain no diamond on a prescribed set Z of four vertices, under the assumption that for every v ∈ Z there are three paths of G from v to Z − { v } , mutually disjoint except for v. Moreover, we can find two “different” such subdivisions, if one exists. Our proof is based on Mader's S-paths theorem.

More translucent dental zirconias have been developed by incorporating the cubic phase and reducing the tetragonal phase content that undergoes transformation toughening, leading to reduced mechanical properties. Whether the clinically relevant mechanical property of the edge chipping toughness of the material is also reduced is unclear.The purpose of this in vitro study was to evaluate the edge chipping toughness and translucency of translucent zirconia, 3mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), and lithium disilicate.Two translucent zirconia products, Katana and Lava Esthetic; one 3Y-TZP, Lava Plus; and one lithium disilicate, IPS e.max Press were prepared and tested for phase composition via X-ray diffraction (XRD) (n=3), translucency via a spectrophotometer (n=20), and edge chipping via a universal testing machine with a custom-machined specimen holder and diamond indenter (n=20). The 3Y-TZP and lithium disilicate served as the optimal control materials for edge chipping and translucency, respectively. Translucency was compared with 1-way ANOVA and edge toughness with ANCOVA (α=.05).The XRD showed the 3Y-TZP to be almost completely tetragonal phase compared with the 2 translucent zirconia products that were predominantly cubic. Katana UTML and IPS e.max Press had a statistically similar (P.05) translucency that was significantly (P.05) greater than that of Lava Esthetic and Lava Plus. The edge toughness of Katana UTML was 304 N/mm, IPS e.max Press was 354 N/mm, Lava Esthetic was 394 N/mm, and Lava Plus was 717 N/mm, with significance rankings of Katana UTMIPS e.max Press=Lava EstheticLava Plus.Some translucent zirconias had translucency similar to that of lithium disilicate; however, as translucency increased with increased cubic content, edge toughness decreased.

The physical and chemical stability of tailing deposits sometimes have conflicting priorities, yet they are rarely examined congruently comprehensively. This paper presents an investigation of the combined geotechnical and geochemical behaviours of two samples of diamond ore tailings. Detailed basic and advanced geotechnical laboratory characterisation tests were conducted to evaluate the particle size distribution, hindered sedimentation, compressibility, hydraulic conductivity and undrained shear strength of both tailings. Furthermore, duplicate specimens to evaluate the drainage effluent’s geochemical compositions were conducted to evaluate the compliance with regulatory concentration criteria. The cation and anion concentrations of the expelled water were analysed at different consolidation stages, along with other basic geochemical index properties such as pH, redox potential and electrical conductivity. Both the geotechnical large strain consolidation testing and geochemical pore fluid collection were performed in a controlled-temperature environment to represent the cold climatic regime at the mine site. Tests were performed in a walk-in freezer with a nominal ambient temperature of 4–5°C. Moreover, the drainage effluent from the large-strain consolidation geochemical duplicates was collected using an innovative sampling system that ensured that the sample was not exposed to the atmosphere. The geotechnical and geochemical implications of both tailing treatments are discussed.

In this study, a diamond-based neutron scatter camera (DNSC) was developed for neutron spectroscopy in high flux environments. The DNSC was evaluated experimentally and through simulations. It was simulated using several Monte Carlo codes in a two-array layout. The two-array model included two diamond detectors. The simulation reconstructed the spectra of 252Cf and 239Pu–Be neutron sources with high accuracy (∼93%). The two-diamond array system was experimentally evaluated, demonstrating the neutron spectroscopy capabilities of the DNSC. The reconstructed spectrum of the 239Pu–Be source manifested the characteristic peaks of the source. The advantage of a DNSC over a NSC is its ability to define any neutron double-scattering events without the need to absorb incident neutrons in the second detector, and atomic recoil energy information is not needed to determine the incident neutron energy.

Three-dimensional (3D) porous boron-doped diamond (BDD) film is an attractive electrode material but tough to synthesize. Herein, the 3D porous BDD films were constructed in a facile and template-free way. The BDD/non-diamond carbon (NDC) composite films were firstly fabricated by hot filament chemical vapor deposition (HFCVD) technique, and then the porous BDD films with 3D interconnected porous microstructure, different pore size and NDC-free diamond were achieved by selective removal of NDC. It is manifested that higher electrochemical response, large double layer capacitance (17.54 mF/cm2) in diamond electrodes, wide electrochemical window of 2.6 V and superior long-term stability were achieved for 3D porous BDD film. This derives from the synergistic effect of microstructure and phase composition of the porous films. 3D interconnected structure possesses prominent improvement of effective surface area and accessible porous channel, significantly enhancing the species adsorption and mass transfer. The 3D porous BDD films, composed of NDC-free diamond, exhibit excellent structural stability and corrosion resistance, which favor the enhancement of long-term stability and water splitting overpotential. The facile fabricating approach and excellent structure/electrochemical character demonstrate the appealing application in many electrochemical fields for 3D porous BDD films, such as energy storage and conversion, wastewater treatment and purification.

This study investigated changes in the retentive force of telescopic crowns fabricated by combining a zirconia primary crown and a fiber-reinforced composite (FRC) secondary crown.Primary zirconia crowns were produced with a nominal convergence angle of 0°. Forty-eight secondary crowns were milled from FRC and divided into three study groups (n=16/group) based on milling parameters and post-milling adjustment. The offset parameter used for the final milling step of the inner crown surface was adjusted for a tight initial fit in Group 1 (milling offset: +10 µm, i.e., 2 × 10 µm = 20 µm lower inner diameter compared with the CAD file of the crown) and for improved initial fit (milling offset: -10 µm, i.e., an enlargement of the inner crown diameter by 2 × 20 µm = 40 µm in relation to Group 1) in Groups 2 and 3. The inner surfaces of the secondary crowns were polished with diamond paste in Groups 1 and 2, and silicon points were used for Group 3. The retentive force was measured using a universal testing device. The secondary crown was placed on the primary crown, with the final fitting force set to a load of 100 N. This test was conducted before and after aging (10,000 insertion/removal cycles) under dry and wet conditions. A generalized linear model was used to estimate the differences in the retentive force to elucidate the effects of the milling parameters and polishing methods.We realized an initial retentive force of approximately 10 N. In Groups 2 and 3, the difference was statistically significant between the dry and wet conditions before aging (P0.05). There was no significant difference between the dry and wet conditions after aging in any of the groups (P0.05).An adequate initial retentive force can be achieved with telescopic crowns combining zirconia and FRC.

In this paper, we give a generalization of the reverse H\"{o}lder's diamond-$\alpha$ inequality on time scales by introducing two parameters. We note that many inequalities related to the H\"{o}lder's inequality can be obtained via this inequality.

A four-layered W/Cu functionally graded material (FGM) (W90% + Cu10%/W80% + Cu20%/W70% + Cu30%/W60% + Cu40%, wt.% fraction) and a four-layered diamond/W–Cu FGM (W90% + Cu10%/W80% + Cu20%/W70% + Cu30%/W55% + Cu40% + diamond5%, wt.% fraction) were fabricated by microwave sintering. The thermal conductivity and thermal shock resistance of diamond/W–Cu FGM and W–Cu FGM were investigated. The morphologies of the diamond particles and different FGMs were analyzed using AFM, SEM, EDS, and TEM. The results show that a 200 nm rough tungsten coating was formed on the surface of the diamond. The density of the tungsten-coated diamond/W–Cu FGM, obtained by microwave sintering at 1200 °C for 30 min, was 94.66%. The thermal conductivity of the four-layered diamond/W–Cu FGM was 220 W·m-1·K-1, which is higher than that of the four-layered W/Cu FGM (209 W m−1 K−1). This indicates that adding an appropriate amount of tungsten-coated diamond to the high Cu layer W/Cu FGM improves the thermal conductivity of the composite. The diamond/W–Cu FGM sintered at 1200 °C for 10 min exhibited better thermal shock resistance than diamond/W–Cu FGM sintered at 1100 °C for 10 min.

Femtosecond laser processing is a non-thermal process with less heat effect on a target material and is applied to dielectric and difficult-to-machine materials, such as titanium alloy and diamond. Femtosecond laser processing has been used for 3-dimensional shape generation in recent years, and increasing accuracy and productivity are required for such generation by femtosecond lasers. However, a 2.5-dimensional computer-aided manufacturing (CAM) system, which is mainly used in femtosecond laser processing, does not satisfy the requirement for complicated 3-dimensional shape generation. Therefore, there is a need for the development of a 3-dimensional CAM system for high-precision and productive 3-dimensional processing. Furthermore, for the 3-dimensional CAM system, quantitative identification of a 3-dimensional removal shape through ablation is necessary. This study proposes the development of a simulation method to accurately predict the 3-dimensional removal shape through femtosecond laser processing, including the piecewise approximation of the ablation rate and absorptance correction. At the same time, a similar 3-dimensional shape as that found through the experimental results was obtained during the simulation by considering the mechanical errors of the laser processing machine in the simulation model. Furthermore, an on-machine measurement system was developed to efficiently identify the ablation parameters.

This paper reports the direct current and radio frequency characteristics of two-dimensional hole gas (2DHG) diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with microwave-plasma-chemical-vapor-deposition regrown P++-diamond (B ≈ 1 × 1022 cm−3) layers as their source and drain regions. To evaluate the ohmic contact resistance, two patterns of transmission line method were fabricated—one with P++-diamond/2DHG diamond interfaces and the other with only the P++-diamond layer. Three resistance components (metal/P++-diamond contact resistance (0.39 Ωmm), P++-diamond access resistance, and P++-diamond/2DHG contact resistance (∼0.65 Ω mm) were evaluated for the first time. The introduction of the P++-diamond ohmic contacts generated a drain current density of 1 A/mm and an output power density of 3.6 W/mm at a quiescent drain voltage (VDS, Q) of −50 V at 1 GHz; an output power of 1.7 W was achieved at a VDS, Q of −40 V at 1 GHz with a 1 mm gate width. These values were obtained in 2DHG diamond MOSFETs with a regrown P++-diamond layer with 1 μ m gate length. These results indicate that regrown P++-diamond has the potential to improve the drain current density and output power density of 2DHG diamond field-effect transistors.

Polymer/highly-conductive carbon composites are used as dielectrics. However, a high dielectric loss is induced by leakage current. In this study, ternary polymer composites with hydroxyfullerene and diamond were fabricated. Ternary composites exhibited more promising dielectric traits compared with polymer/hydroxyfullerene composites. A high dielectric constant was achieved using polar hydroxyfullerene. A significantly reduced dielectric loss was achieved owing to insulative diamond. Polymer/hydroxyfullerene interaction and branching of leakage current were studied. The best ternary composite showed a dielectric constant of ∼26 and dielectric loss of ∼0.21 at 20 Hz. This work may enable the large-scale fabrication of advanced dielectrics.

We studied the morphological nature of various thin films such as silicon carbide (SiC), diamond (C), germanium (Ge), and gallium nitride (GaN) on silicon substrate Si(100) using the pulsed laser deposition (PLD) method and Monte Carlo simulation. We, for the first time, systematically employed the visibility algorithm graph to meticulously study the morphological features of various PLD grown thin films. These thin-film morphologies are investigated using random distribution, Gaussian distribution, patterned heights, etc. The nature of the interfacial height of individual surfaces is examined by a horizontal visibility graph (HVG). It demonstrates that the continuous interfacial height of the silicon carbide, diamond, germanium, and gallium nitride films are attributed to random distribution and Gaussian distribution in thin films. However, discrete peaks are obtained in the brush and step-like morphology of germanium thin films. Further, we have experimentally verified the morphological nature of simulated silicon carbide, diamond, germanium, and gallium nitride thin films were grown on Si(100) substrate by pulsed laser deposition (PLD) at elevated temperature. Various characterization techniques have been used to study the morphological, and electrical properties which confirmed the different nature of the deposited films on the Silicon substrate. Decent hysteresis behavior has been confirmed by current-voltage (IV) measurement in all the four deposited films. The highest current has been measured for GaN at ∼60 nA and the lowest current in SiC at ∼30 nA level which is quite low comparing with the expected signal level (μA). The HVG technique is suitable to understand surface features of thin films which are substantially advantageous for the energy devices, detectors, optoelectronic devices operating at high temperatures.

Supersonic boundary-layer transitions triggered by a diamond-shaped roughness element were investigated by direct numerical simulation based on a finite volume formulation with a high-order minimum...

An attempt to increase the strengths of bonding between diamond and filler metal in producing high-precision machining tools was made in this paper by proposing new ultrasonic-assisted laser brazing (UALB) technique in which the UALB process was performed using a fiber laser and Ni–Cr filler alloy, followed by the paraxial feeding of diamond powder. In addition, to examine the impact of an ultrasonic vibration on the mechanical properties of diamond at its bonding interface, the brazing process was carried out with and without suppression in ultrasonic vibration, and the microstructure and mechanical properties of diamond at the bonding interface were observed, measured and compared. The results showed that the ultrasonic assistance had improved the strengths of the bonding of diamond with the filler alloy by reducing surface cracks, increasing the wettability of molten filler, and forming and crystalizing directional carbides of Cr3C2 and Cr7C3 with a higher density.

The effect of nano diamond (ND) content on the microstructure, mechanical properties, and thermal conductivity of ZK60+x (x = 0, 0.05, 0.1, 0.15, 0.2 wt%) ND composites were investigated. The microstructures of ND/ZK60 composites were observed, which indicated that the nanoscale MgZn2 and ND particles distributed evenly in the α-Mg matrix. The tensile yield strength (TYS) and compressive yield strength (CYS) of the composites first increased remarkably and then decreased with further increasing the ND content. Due to the surface area of the matrix-diamond interface increased and the grains sizes of composites decreased with the amount of ND increase, which cause the coefficient of thermal expansion (CTE) of the composites reduced significantly. Meanwhile, the thermal conductivity of the composite material decreases from 129 W·m − 1·K − 1 to 116 W·m − 1·K − 1 with the content of ND increasing from 0.05% to 2.0%. The thermal conductivity of the composites increases to the maximum and then decrease with the increase of temperature (in temperature range of 273 - 573 K). The ZK60+0.05 ND showed superior mechanical and thermal conductivity property, TYS of 343.97 MPa, CYS of 341.74 MPa, elongation of 15.71%, CTE of 7.3 × 10−6 K − 1, and thermal conductivity of 129 W·m − 1·K − 1 at room temperature. It is demonstrated that the ND content has an obvious influence on the microstructure, mechanical properties, and thermal conductivity of ND/ZK60 composites.

A diamond film was synthesized by chemical vapor deposition, where a hot graphite plate was used to thermally activate methane and hydrogen. The effect of parameters on the diamond films grown, such as pressure ranging from 40 to 100 torr, methane concentration in hydrogen varying from 0.5 to 2 vol %, and substrate temperatures from 1020 to 1140 °C, were studied. Diamond films with nanocrystalline to polycrystalline crystal sizes were obtained. A maximum growth rate of 0.8 μm/h was obtained, and the quality is comparable to diamond films synthesized by the hot metal filament chemical vapor deposition method. In contrast to the hot filament method, this method does not use a metallic filament as thermal activator. Therefore, the diamond films contain no metal contaminants and thus can be used for electronic and biomedical applications. The absence of metal contaminants was confirmed using different methods.

Taking advantage of the superflat surface of ultrananocrystalline diamond (UNCD), highly precise UNCD nanowire (NW) arrays were fabricated to develop high-performance UV photodetectors. The large surface-to-volume ratio of a nanowire significantly increases the number of surface trap states, and the reduced dimensionality effectively confines the active area of the charge carrier and shortens the transit time, which results in an enhanced photoconductivity and response speed. In this paper, the zero-biased UV photodetectors based on nitrogen-incorporated ultrananocrystalline diamond nanowire arrays have been demonstrated and characterized. The estimated responsivity was 2.0 A/W for 350 nm incident light when the device operated at room temperature. The UVA and UVB photocurrent signals from this visible blind photodetector were well defined with a rise and decay time of less than 1 s.

Beyond the sparkle, other properties of diamond havegained increasing attention in the past few decades amongchemists and physicists. Color centers-impurities formed byone or a few foreign atoms or vacancies in the diamondlattice-are one reason for this. While pure diamond istransparent, the presence of color centers causes changes incoloration. Color centers introduce additional electronic statesin the wide band gap of diamond, giving rise to transitions thatabsorb and emit light in the visible spectrum.

Conventional electrodeposition is used to develop Ni-Al2O3 nano-composite over the Al-2618 surface through nickel-plated immersion. Scratch investigation was carried out with respect to various process parameters such as immersion temperature, packing of particles and current density. The scratch resistance of electrodeposition composition was determined with the Ducom TR102-Scratch testing device and it was fortified with Rockwell C diamond stylus (0.2 mm rad.). Microscopic analysis was made of the morphology and scratch stages of the electrodeposited layer. The results indicates coating layer narrowly imitates the surface contour, as well as the toughness of a substance is influenced by its strength. Also the better adhesive strength could be achieve by higher temperatures, moderate particle loading and current density.

In this study, nanoscratch experiments using side-forward multiple scans by friction force microscope with triangular pyramidal monocrystalline diamond tip were conducted on a ( 0001 ) plane sapphire wafer substrate to clarify the ductile-regime machining mechanism including its anisotropy. Various characteristics, such as scratch force, depth and specific energy for each scratch direction on C-plane of sapphire, were manifested by a friction force microscope, and the specific scratch energy showed a trend of three-fold symmetry. Subsequently, cutting chips which adhere to the diamond tip exhibited plastic deformations features were testified by a scanning election microscope. Based on slip/twinning systems of sapphire, Schmid factor was calculated for each scratch direction using the resultant force, and the calculated Schmid factors on the rhombohedral planes became the highest. Following the results, the resolved shear stresses along the twinning directions on the rhombohedral planes were calculated using a simple chip formation model, and they were several times larger than the critical resolved shear stress for rhombohedral twinning. As a result, it was found that when the scratch direction is set so that one of the three faces of the diamond tip is close to parallel to one of the rhombohedral planes, the rhombohedral plane acts as the chip shear plane and the specific scratch/cutting energy can be minimized. The cross-sectional transmission electron microscope images of scratched sub-surface also distinctly displayed the existence of subsurface damages consisting of twins and stacking faults relating rhombohedral planes.

This work presents an experimental thermal evaluation of new and innovative porous morphologies suitable for volumetric solar receivers. Five new morphologies, four of them based on the repetition of single unit cells: diamond, rotated cube, tetrakaidecahedron, cube shifted, and a random morphology following the Voronoi tessellation technique were tested. In addition, for emerging geometries, two different cell size configurations were evaluated: one with constant cell size dimension and one with cell's size changing with flux direction. All the lattices were analysed experimentally in a lab-scale solar simulator. The results were compared with the ones of the already established and more conventional silicon carbide honeycomb and random foams proving that a gain in performance is achievable with the Voronoi morphology, both with constant cell size and increasing cell size pattern.

Present paper delineates a novel route adopted for successfully manufacturing single layer brazed patterned diamond wheels with enhanced attributes. A pneumatic pick-drop methodology is used for placing the grits in a uniform and patterned manner. Instead of commonly used Ni-Cr alloys, a novel formulation of μ-TiC inoculated composite Ag-Cu-Ti filler has been preferred, which helped in arresting crack formation at the root of grit brazement and simultaneously ensured high bond wear characteristics. Addition of μ-TiC particles substantially improved wear characteristics of basic Ag-Cu-Ti alloy but tend to impair its wetting ability on diamond surface with increase in its wt% in the composition. Therefore, its presence in the filler was restricted to only 2 wt% to keep such compromise within acceptable level. Wheels developed using active Ag-Cu fillers were further subjected to performance evaluation by grinding of WC-Co cermets. The operating parameters were changed in such a way that wheels experienced increasing order of grinding-aggressiveness. The degree of aggressiveness in the grit-work interaction has been defined by a unifying scalar quantity, termed as “aggressiveness number”. No trace of wheel loading was observed even in the most aggressive condition due to uniformly spaced grits. The failure counts of diamond grits are also related to this scalar. A detailed analysis is presented to address the suitability of μ-TiC reinforcement in the formulation of active Ag-Cu filler in the light of the grinding force and grit retention ability of the wheels.

Precision grinding with ultrathin arc-shaped diamond (UAD) grinding wheels provides a satisfactory solution for the fabrication of high-quality microstructures on tungsten carbide (WC) molds. However, ultrathin grinding wheels are difficult to be trued, due to the limited small grinding wheel profile. In this paper, an on-machine truing method for ultrathin arc-shaped diamond grinding wheels is proposed. First, a model of the three-axis linkage controlling truing for the diamond grinding wheel was introduced. Then, the effects of the setting and measurement errors of the grinding wheel on the profile radius were theoretically analyzed. A mathematical model of the error was developed. Furthermore, an aspherical microstructure array of tungsten carbide was ground by the trued diamond grinding wheel. The experimental results demonstrated that the expected arc radius of the grinding wheel could be achieved and the binderless tungsten carbide mold could be ground efficiently and precisely. The profile error of the grinding wheel (diameter of 23 mm, thickness of 0.38 mm) reached 8.5 μm . An aspherical microstructure array surface of tungsten carbide with a form accuracy of 15 μm was obtained by grinding with the trued diamond grinding wheel without additional compensation.

Energy-dispersive X-ray diffraction (EDXRD) is extremely insensitive to sample morphology when implemented in a back-reflection geometry. The capabilities of this non-invasive technique for cultural heritage applications have been explored at high resolution at the Diamond Light Source synchrotron. The results of the XRD analysis of the pigments in 40 paints, commonly used by 20th century artists, are reported here. It was found that synthetic organic pigments yielded weak diffraction patterns at best, and it was not possible to unambiguously identify any of these pigments. In contrast, the majority of the paints containing inorganic pigments yielded good diffraction patterns amenable to crystallographic analysis. The high resolution of the technique enables the extraction of a range of detailed information: phase identification (including solid solutions), highly accurate unit cell parameters, phase quantification, crystallite size and strain parameters and preferred orientation parameters. The implications of these results for application to real paintings are discussed, along with the possibility to transfer the technique away from the synchrotron and into the laboratory and museum through the use of state-of-the-art microcalorimeter detectors. The results presented demonstrate the exciting potential of the technique for art history and authentication studies, based on the non-invasive acquisition of very high quality crystallographic data., Comment: Main article: 25 pages, 5 figures; Supplementary information: 35 pages, 37 figures. Accepted for publication in the Journal of Cultural Heritage with revisions

We have discovered that Q-carbon is extremely resistant to radiation damage under ion irradiations involving extreme atomic displacements and electronic excitations. Using 5 MeV Au+ ions, the Q-carbon films on sapphire substrates were irradiated in the dose range 3.3 to 10 dpa (displacements-per-atom). After the ion irradiations, detailed studies on the atomic structure and bonding characteristics showed that atomic structure and bonding characteristics of amorphous Q-carbon remained essentially unchanged to 10 dpa of radiation damage, which is equivalent to over twenty years of neutron damage in a conventional reactor. There was an ion-beam mixed layer below the Q-carbon layer, whose thickness increased from 5 nm to 10 nm, as the dose increased from 3.3 to 10 dpa. This layer was found to be mostly amorphous with a mixture Al2O3 and Al4C3. This layer, formed as a result of enhanced forward scattering and ballistic ion beam mixing, exhibited composition consistent with detailed TRIM calculations. We also found that nanodiamonds (3 nm average size) embedded in Q-carbon grew to about 60 nm after 6.6 dpa and shrank to about 40 nm after 10 dpa. We discuss the mechanism for the growth and shrinkage of metastable phase of diamond under nonequilibrium ion irradiations.

This letter reports the successful demonstration of large-current and high-voltage (001) vertical-type two-dimensional hole gas (2DHG) diamond trench metal-oxide-semiconductor field-effect transistors (MOSFETs) with a p--drift layer. The fabricated transistor demonstrated a maximum drain current density of 210 mA/mm, a field-effect-mobility of 61 cm2V-1s-1, and a specific on-resistance of 23 mΩ cm2. Moreover, a high breakdown voltage of 580 V with a gate-drain length of 10 μm was obtained, which is the highest value reported for a vertical-type diamond MOSFET to date. These characteristics indicate that a vertical-type diamond MOSFET using a p--drift layer may be used to realize a pchannel power device with a high breakdown voltage and low on-resistance.

The miniaturization of boron-doped diamond (BDD) electrodes is an important requirement for application to the study of electrochemical processes in living beings. In this work, we describe the fab...

Composite TiN film was prepared on AZ31 at four sets of different deposition temperatures. X-ray diffraction and X-ray fluorescent were employed to determine the structure, residual stress, thickness and chemical elements. A scratch tester with Rockwell C diamond styli and electrochemical workstation were used to evaluate the adhesion and corrosion behavior of the obtained film. The effects of deposition temperature on structure, residual stress, adhesion, thickness and corrosion behavior were investigated as well. The results show that the films are composed of TiN with (111), (200) and (222) planes, Ti with (002) plane, and Cr (110) plane. The maximum residual compressive stress is about 413.4 MPa, and the elements distribution is not uniform when the film deposited at 150 °C. With the increase of deposition temperature, the grain size and crystallinity increase, the thickness decreases, the residual stress decreases first and then increases, the film becomes more compact and has better corrosion resistance. However, when the deposition temperature is greater than 250 °C, the surface roughness and the thermal stress begin to increase, the bonding performance and the corrosion resistance also decrease.

Nanodiamonds (NDs) were prepared under ambient pressure by sublimation decomposition of silicon carbide in an intermediate frequency furnace for only 8 min. The synthesis proceeded in the temperature range of 2600-2800°C without any catalyst or highly active gas components (such as H2, alkane, and halogen). The conversion began at 2600°C and produced NDs with particle sizes in the range of 1-5 nm with a uniform particle shape and excellent dispersion. The linear reaction kinetics allowed for rapid transformation to any depth with reasonable control of the temperature. The linear rate constant (Kl) for the reaction at 2800°C was 37.5 mm/h, which is 31.2 times that of the reaction at 2600°C. The SiC sublimation decomposition produced carbon atoms that filled the SiC lattice vacancies or were combined with the suspended carbon chain bonds to form sp3 carbon, while the diffusion of amorphous carbon atoms promoted nucleation and growth of diamond. High-resolution transmission electron microscopy analysis indicated that the NDs were separated from the SiC matrix by break-off due to propagation of the reaction front. This SiC sublimation decomposition method is considered simple, fast, environmentally friendly and promising for industrial-scale production.

Schottky contacts have been used to fabricate normally-off lateral reverse-blocking MESFETs on p-type (boron-doped) O-terminated monocrystalline diamond. The devices utilized an ohmic source contact but both gate and drain contacts were Schottky in nature. Boron-doped p-channel diamond MESFETs reported to date display the less attractive normally-on characteristics. Here, the normally-off transistor delivered a current level of ~1.5 μAmm⁻¹ at a negative $V_{GS}$ of 0.8 V and a transconductance (gₘ) of 16 μSmm⁻¹, measured at room temperature (RT); at a temperature of 425 K, these values rose to ~70 μAmm⁻¹ for $I_{DS}$ and a gₘ value of 260 μSmm⁻¹. In both cases, a negligible gate leakage current was measured with no breakdown apparent at the maximum field investigated here (3.7 x 10⁵ V/m⁻¹). The Schottky gate demonstrates a well-behaved control of the channel even at higher temperatures. The high-temperature operation, normally-off behavior, and diamond's inherent radiation hardness make this transistor promising for harsh environment applications.

Trevor Evans was responsible for revealing the main physical processes which take place in natural diamond both in the upper mantle of the earth, where it is stabilized by high pressure and temperature, and as it is ejected by volcanic action to the surface. By measuring the activation energies required for graphitization, he clarified the reason for its very long life as a metastable crystal, valuable both as a gemstone and as an industrial abrasive. He learned how to make diamond specimens for examination in the transmission electron microscope, which enabled his discovery of dislocation loops and platelet precipitates in nitrogen-containing (type 1) stones. In a series of exacting laboratory experiments under geologically relevant conditions he pioneered the study of the emergence of nitrogen from solution to precipitation during the ejection process. In synthetic diamonds, using high-energy electron irradiation, he was able to reproduce the sequence of all the various types of nitrogen aggregation found in natural diamond. His work played a major role underpinning the characterization of gemstones, explaining many features of their colour. For many years he led diamond research in the UK, supported by De Beers. His work stimulated and has been confirmed by research in many other laboratories around the world.

We propose that the use of tightly stacked three-dimensional (3D) diamond-shaped Ge nanowire (NW) gate-all-around field-effect transistor (Ge-NW GAAFET) is a feasible approach to continuous scaling. The proposed devices with the Al2O3 dielectric exhibit high ISAT of 1200 μA/μm (pFET) and 1100 μA/μm (nFET), high ION/IOFF ratio of approximately 1×105, and steep subthreshold swing (SS) close to 70mV/dec. Superior gate control of the Ge-NW GAAFET was confirmed by the 3D TCAD simulation for the sub-3nm node applications. The formation of the tightly stacked Ge NWs is fully compatible with the complementary metal oxide semiconductor (CMOS) technology platform using only alternating isotropic and anisotropic dry etching, thus showing promising potential for extending CMOS scaling in the vertical direction.

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.

Metal-bonded diamond tools are widely used for machining hard and brittle materials such as ceramic and stone. The metal bonds are normally based on alloys composed of Fe, Co, Ni, Cu, Sn, Zn, or Cr. However, high heavy metal concentrations are hazardous to the environment and tool operators. Furthermore, the high density of these metal bonds results in excessively heavy tools, requiring high energy and intensive labor during operation. Therefore, we propose two environmentally friendly and lightweight metal bonds based on NiAl and FeAl intermetallics for diamond tools by reactive hot-press sintering. The effect of sintering temperature on the microstructure and mechanical properties of NiAl and FeAl was examined and the tribological behavior of NiAl and FeAl on Si3N4 ceramic balls was investigated. Grinding performance of the sintered diamond tools on Si3N4 ceramic was also compared. Our results reveal that B2-ordered NiAl and FeAl are obtained at sintering temperatures in the range of 700–1100 °C. The relative density of sintered NiAl is higher than that of FeAl, while the Vickers hardness and flexural strength of NiAl are lower than that of FeAl. Compared with FeAl, NiAl demonstrates higher wear resistance in a friction test against Si3N4 ceramic, while FeAl-bonded diamond tools demonstrate a higher grinding ratio than NiAl-bonded diamond tools due to enhanced self-sharpening ability. Nevertheless, diamond tools based on both NiAl and FeAl can be used to grind Si3N4 ceramics.

Ultrasonic vibration-assisted inner-diameter (ID) sawing (UVAIDS) has been proved as an effective slicing process for mono-crystalline silicon in improving the surface quality of wafers. The sawing force is regarded as one of the most critical refers to evaluate the sawing performance. Modeling sawing force is significantly helpful to understand the influence of sawing variables on the sawing process. Currently, there is no publication on the sawing force model for the UVAIDS of hard and brittle materials. This investigation presents a mechanistic model for the normal force in the one-dimensional ultrasonic vibration-assisted ID sawing hard and brittle materials. Based on brittle fracture mode in material removal mechanism, the sawing force model is developed beginning from the analysis of a single diamond abrasive grain. A series of experiments on sawing mono-crystalline silicon are performed to verify this model. The experimental results show that the measured sawing forces agree with the theoretical sawing forces calculated by this model. Besides, the influence of sawing variables including ultrasonic vibration amplitude, feed rate, spindle speed, cutting-edge thickness, abrasive size, dimensions of the saw blade, and workpiece on the sawing force are also analyzed and discussed. This mechanistic model can be used to predict the normal force in the UVAIDS of hard and brittle materials.

The article presents the results of experimental research on the grinding of corundum ceramics in the pre-sintered state, with spherical diamond heads. The aim of the experiment was to determine the effect of grain size and feed rate on selected aspects of the grinding process of corundum ceramics with the use of spherical diamond heads. In the experiment, grinding wheels with a ball diameter of 3 mm and different grain sizes were used; the grain numbers were D64, D91, D126 and D181. The tests were carried out on the Ultrasonic 20 Linear machining center at a constant rotational rate of the grinding wheel n = 38,000 rpm and a grinding depth of 30 µm. The feed rate was set on 3 values: 200, 400 and 600 mm / min. During the research, the process temperature was recorded with a thermal imaging camera. The topography of grinding wheels before and after the grinding process and the topography of the ground surface were also measured. The parameters Sa and Ŝz (Ŝz= Spk+Sk+Svk) were used to characterize the grinding heads. The conducted analyses showed the dependence of the parameters Sa and Ŝz of new grinding heads on the grain size described by the quadratic function (R^(2 )≥0.94). Statistically significant changes in the parameters Sa and Ŝz on the cutting surface of the grinding wheel, which occurred as a result of its wear, were observed. There was no significant relationship between the feed rate and the wear of grinding heads, probably due to the relatively small volume of the material removed. A positive correlation between the Sa and Ŝz parameters of the ground object and the grain size was observed. The research also showed an increase in the process temperature with an increase in the feed rate and an increase in the grain size.

Diamond turning, fly-cutting, and milling are the primary manufacturing technologies for generating free-form surfaces; however, they are not sufficiently effective in machining free-form optics on hard and brittle materials. Ultra-precision grinding has been demonstrated to have an outstanding capability in machining difficult-to-cut materials. Therefore, we proposed a novel surface generation technique for free-form optics based on a slow tool servo with diamond grinding wheels (STS-DGW). First, the generation strategies of the wheel path for grinding biconical optics were explored. Subsequently, the generation process of surface topography was theoretically analysed, and the interference between the diamond wheel and biconical optics in the process of surface generation was checked. Eventually, typical biconical free-form optics were fabricated on single-crystal silicon. Submicron profile accuracy and nanometer surface roughness were achieved, and the influence of the processing parameters on the surface topography and material removal mechanism was investigated.

In this study, substrate temperature (t), total pressure (p), methane flow (M), and carbon dioxide flow (C) were examined for depositing diamond coatings on cemented tungsten carbide substrates (WC-Co; 6 wt.%) under an atmosphere of CH4–H2–CO2. The Taguchi method and analytical hierarchy process method were used to plan the parameters and the sequencing of the parameters, respectively. The results show that three schemes with improved parameters could be identified using the Taguchi method, and the best sequence for these parameters (t = 750 °C; p = 6 kPa; M = 7 mL/min; C = 4 mL/min) was obtained using the analytical hierarchy process method; these results were verified experimentally.

The demand for high-performance grinding wheels is gradually increasing due to rapid industrial development. Vitrified bond diamond composite is a versatile material for grinding wheels used in the backside grinding step of Si wafer production. However, the properties of the vitrified bond diamond composite are controlled by the characteristics of the diamond particles, the vitrified bond, and pores and are very complicated. The main objective of this study was to investigate the effects of SiO2–Na2O–B2O3–Al2O3–Li2O–K2O–CaO–MgO–ZrO2–TiO2–Bi2O3 glass powder on the sintering, microstructure, and mechanical properties of the vitrified bond diamond composite. The elemental distributions of the composite were analyzed using electron probe micro-analysis (EPMA) to clarify the diffusion behaviors of various elements during sintering. The results showed that the relative density and transverse rupture strength of the composite sintered at 620 °C were 91.7% and 126 MPa, respectively. After sintering at 680 °C, the glass powder used in this study exhibited a superior forming ability without an additional pore foaming agent. The relative density and transverse rupture strength of the composite decreased to 48.2% and 49 MPa, respectively. Moreover, the low sintering temperature of this glass powder protected the diamond particles from graphitization during sintering, as determined by X-ray diffraction and Raman spectrum. Furthermore, the EPMA results indicate that Na diffused and segregated at the interface between the diamond particles and vitrified bond, contributing to the improved bonding. The diamond particles can remain effectively bonded by the vitrified bond even after fracture.

To improve the grinding precision and efficiency of diamond abrasives in slurries, a new type of porous diamonds was prepared by the thermochemical corrosion method. Fe, Fe2O3 and Fe/Fe2O3 were separately used as corrosive agent to explore formation mechanism of porous diamond. The results showed that Fe began to graphitize diamond at 800 °C, whereas Fe2O3 began to oxidize diamond at 700 °C. Neither was able to individually corrode the diamonds into a porous structure. Impressively, it was when a mixture of Fe and Fe2O3 powders was used as the corrosive agent that the diamonds were able to take on a porous structure. Compared to ordinary diamonds, the porous diamonds produced in our study had outstanding advantages of high specific surface area and larger pore volume, which resulted in the porous diamonds having remarkable self-sharpening properties. Grinding contrast experiments were conducted on sapphire substrates using ordinary diamonds slurry and porous diamonds slurry. Notably, when porous diamonds were used as a grinding agent in the slurry, the sapphire substrate removal rate remarkably increased by 26%, and the surface roughness (Ra) of the sapphire substrate significantly decreased by 31%. In this paper, a simple and robust method was proposed to fabricate diamonds with a novel structure, which may help to reduce the surface grinding damage inflicted on hard and brittle materials and improve the quality of processed surfaces and grinding efficiency.

Here we report tuning of structural parameters of La2Sn2O7 by Nd substitution at La-site in a quest to effectively control the dielectric response as a small variation in lattice parameters can result in large dielectric fluctuations. For this purpose, a series of Nd-substituted La2Sn2O7 was synthesized using sol gel auto-combustion route. The formation of stable cubic pyrochlore phase with consistent variation in the lattice parameters was observed in structural analysis. The morphological investigations revealed a spherical shape of La2Sn2O7 particles which transformed to diamond like shape with a systematic variation in grain size by increasing the Nd contents. The variation in grain size dominantly affected the dielectric dispersion in the vast frequency range. Less energy loss and improved dielectric properties make La1.2Nd0.8Sn2O7 a potential candidate for utilization in energy storage devices. The complex modulus analysis provided an insightful view which helped to distinguish the mobility range of charge carriers in different frequency ranges.

Experiments are conducted to quantify leakage through holes in a geomembrane (GMB) overlain by tailings with 30% fines and underlain by a well-graded gravel. Analytical and empirical equations for predicting leakage through a circular hole are used to analyze the data. Test results show that changing the hole shape from circular to noncircular increases the leakage. Leakage through 2000 mm2 triangular, diamond, and square holes are all 15% higher than the 2000 mm2 circular hole. An increase by up to 33% is observed for a rectangular hole. The analytical equations for predicting leakage and head loss through a hole given by the modified Rowe-Booker equation are experimentally verified. The spatial distribution of fines content within about five diameters of the hole is shown to have a notable impact on leakage. Up to a 100% increase in leakage is detected due to 3% reduction in the fines content around the hole. For homogeneous tailings, the ratio of head loss within the hole and above the hole to total head loss are independent of consolidation stress and water head and primarily depend on the hole geometry (i.e., shape and size). Finally, the combined effect of tailings thickness and water head on leakage is discussed.