Surface Diagrams Research Articles

Analysis and optimization of thermo-hydraulic characteristics of phase change slurry in wavy MCHS with porous fins based on RSM and desirability methods

In this study, the hydromechanical and diathermanous characteristics of microencapsulated phase change material (MPCM) slurry in wavy microchannel heat sink (MCHS) with porous fins are investigated by using two–phase mixture and Dacry–Brinkman–Forchheimer models. Based on the finite volume method (FVM) and response surface methodology (RSM), 54 cases considering 6 structural parameters are carried out. The correlations of Nusselt number (Nu) and friction factor (f) in straight and wavy microchannels with phase change slurry and porous fin designs are creatively proposed and unified. The maximum deviations between the actual and predicted values of Nu and f are 13.24% and 14.21%, respectively. In addition, the effects of radiator's parameters on Nu and f are emphatically discussed and analyzed by using three-dimensional surface diagram. It reveals that within the range of parameters tested, wavy amplitude (A) has the most obvious effect on responses, while channel aspect ratio (α) has the least impact on them. Moreover, the interactive effects between the five structural parameters are significant and complex, as one factor influences the impact of another on responses. Finally, the optimal parameters are obtained by desirability method with the goal of maximum Nu and minimum f. The results indicate that the overall performance of optimized configuration improved by 48.6% over the initial design. Our results may provide helpful guidance for the optimization design of MCHS, as significant improvement in heat transfer coefficient is expected to save substantial operating costs.

Numerical Solution of Inviscid and Viscous Flow Across NACA0010 Airfoil with different Angles of Attack

The role of the airfoil in all engineering fields is very important. Airfoil designs are utilized in various applications such as aircraft wings, helicopter rotor blades, sails, fans, and turbine compressors. In the case of aircraft, airfoils are accountable for generating lift force and determining if it is adequate for balancing the aircraft's weight, as well as determining the amount of drag force that should be applied to the body. They also play a vital role in optimizing blade performance, as well as the heat and operational efficiency of turbines. Airfoils are moving in the flow passing by them, and they show different responses based on many parameters such as whether the flow is smooth or turbulent, viscous or inviscid, flow velocity, angle of attack, multidimensionality of velocity components, etc. For aeronautics vehicles and wind turbines, a large number of studies have been conducted to analyze aerodynamic forces on two dimensional airfoils as well as flow phenomena associated with different Reynolds numbers. Main object of this research is to figure out the flow characteristics around the airfoil body and analyze aerodynamic performance of airfoil. In order to investigate the computational efficiency of flow models, numerical examination has been done for flow across NACA0010 airfoil by using 2D Computational Fluid Dynamics (CFD) solver, ANSYS FLUENT 18.0, at various angle of attack (0o to 13o) for inviscid flow and (-30o to 30o) for viscous flow. Lift and drag coefficients and C p for lower and upper airfoil surface and velocity diagram based on different angle of attack has been solved for the sample under two different flow regimes. The contours of velocity were simulated, and stall point was noticed from 13° angle of attack in inviscid flow and 24o in viscous flow. In the non-viscous state, lift coefficient and drag coefficient was higher, in comparison with viscous flow.

Phase diagram to demarcate supercritical, transcritical, and continuous phase regimes for binary fluid equilibrium mixing relevant to combustion applications

A robust methodology to develop phase diagrams of binary fluid mixtures at fixed thermodynamic conditions (pressure, temperature, and mole fraction) as well as of two initially separated fluids undergoing mixing near critical conditions are presented for fluids and conditions relevant to rockets, gas turbines, and diesel engine applications. Phase equilibria of mixtures are first examined to provide insight into the continuous-phase mixing behavior (including but not limited to supercritical behavior), and to develop a broadly applicable phase-diagram for binary fluid mixtures at fixed conditions. Next, adiabatic mixing theory and reduced Helmholtz equations of state are used to predict the thermodynamic conditions required to attain continuous-phase binary fluid mixing near critical conditions. Then, a 3D surface diagram (P, Tfuel, Tamb) separating single and two-phase regions is constructed by varying the ambient pressure and the initial temperatures of the two fluids. Polynomial fits of the 3D surfaces for 10 different binary mixtures are tabulated for nitrogen–alkane and methane–oxygen blends relevant to air-breathing and propellant based engines, respectively.

Association of nocturnal sleep duration and midday napping with subjective poor hearing among middle-aged and older adults in China.

Hearing loss has occurred as a critical concern for aging and health. However, it remains unknown whether nocturnal sleep and midday napping duration are associated with hearing loss in middle-aged and older adults. The study comprised 9,573 adults from China Health and Retirement Longitudinal Study, who have completed the survey for sleep characteristics and subjective functional hearing. We collected self-reported nocturnal sleep duration (<5, 5 to <6, 6 to <7, 7 to <9, ≥9 h/night) and midday napping duration (≤5, 5 to ≤30, and >30 min). The sleep information was classified into different sleep patterns. The primary outcome was self-reported hearing loss events. Multivariate Cox regression models and restricted cubic splines were used to investigate the longitudinal association of sleep characteristics with hearing loss. We applied Cox generalized additive models and bivariate exposure-response surface diagrams to visualize the effects of different sleep patterns on hearing loss. We confirmed 1,073 cases of hearing loss (55.1% female) during the follow-up. After adjusting for demographic characteristics, lifestyle factors and health condition, nocturnal sleep with < 5 h was positively associated with hearing loss [hazard ratio (HR): 1.45, 95% confidence interval [CI]: 1.20, 1.75]. Individuals with napping for 5 to ≤30 min had a 20% (HR: 0.80, 95%CI: 0.63, 1.00) lower risk of hearing loss compared with those with napping ≤ 5 min. Restrictive cubic splines showed the reverse J-shaped association between nocturnal sleep and hearing loss. Moreover, we found significant joint effects of sleeping < 7 h/night and midday napping ≤ 5 min (HR: 1.27, 95% CI: 1.06, 1.52) on hearing loss. Bivariate exposure-response surface diagrams also reflected the finding that short sleep without napping existed the highest risk of hearing loss. Compared with persistently sleeping moderately (7-9 h/night), those who persistently slept < 7 h/night or shifted from < 7 h/night to moderate or > 9 h/night had higher risks of hearing loss. Inadequate nocturnal sleep was associated with an elevated risk of poor subjective hearing in middle-aged and older adults, while moderate napping decreased the risk of hearing loss. Keeping sleep stable within recommendation duration may be a useful strategy for preventing poor hearing loss.

The molecular level study of the fate of the CH3CH2C(O)OCH(O)CH3 radical derived from ethyl propionate

ABSTRACT A quantum chemical study has been presented on the decomposition of CH3CH2C(O)OCH(O • )CH3 which is derived from ethyl propionate (CH3CH2C(O)OCH2CH3) using the M06-2X/6-31 + G(d,p) level of theory. The thermal decomposition of CH3CH2C(O)OCH(O • )CH3 is essential to understand the chemistry of combustion of ethyl propionate. Here, the decomposition and oxidative pathways, bond fission and alpha ester rearrangement of CH3CH2C(O)OCH(O • )CH3 have been explored. We have obtained transition states for the different pathways and further verified each transition state by performing intrinsic reaction coordinate (IRC) calculations. The density of state spectra (DOS) was calculated using GaussSum software. The single-point energy calculations are performed at the same function but using larger basis sets such as 6-311++G(d,p) and 6-311++G(3df,2p). We have shown all stationary points and transition states involved in reaction pathways on the potential energy surface (PES) diagram and also discussed the thermochemistry of each reaction pathway. The thermal rate constants of various channels in the decomposition of CH3CH2C(O)OCH(O • )CH3 are determined using the Conventional Transition State Theory (CTST) in the temperature range of 250–450 K and 1atm. From PES, thermochemistry and kinetics analysis, we found that α-ester rearrangement produces propionic acid, which is dominant over the oxidative pathway for the decomposition of CH3CH2C(O)OCH(O • )CH3.

A quality learning environment: an assessment of spaciousness of architectural design studios of Iraqi Kurdistan region universities using fuzzy logic

PurposeSpaciousness is defined as “the feeling of openness or room to wander” that has been affected by various physical factors. The purpose of this paper is to assess the spaciousness of space to determine how spacious the space is. Furthermore, the study intends to propose a fuzzy-based model to assess the degree of spaciousness in terms of physical parameters such as area, proportion, the ratio of window area to floor area and color value.Design/methodology/approachFuzzy logic is the most appropriate mathematical model to assess uncertainty using nonhomogeneous variables. In contrast to conventional methods, fuzzy logic depends on partial truth theory. MATLAB Fuzzy Logic Toolbox was used as a computational model including a fuzzy inference system (FIS) using linguistic variables called membership functions to define parameters. As a result, fuzzy logic was used in this study to assess the spaciousness degree of design studios in universities in the Iraqi Kurdistan region.FindingsThe findings of the presented fuzzy model show the degree to which the input variables affect a space perceived as larger and more spacious. The relationship between parameters has been represented in three-dimensional surface diagrams. The positive relationship of spaciousness with the area, window-to-floor area ratio and color value has been determined. In contrast, the negative relationship between spaciousness and space proportion is described. Moreover, the three-dimensional surface diagram illustrates how the changes in the input values affect the spaciousness degree. Besides, the improvement in the spaciousness degree of the design studio increases the quality learning environment.Originality/valueThis study attempted to assess the degree of spaciousness in design studios. There has been no attempt carried out to combine educational space learning environments and computational methods. This study focused on the assessment of spaciousness using the MATLAB Fuzzy Logic toolbox that has not been integrated so far.

Study on Stable Phase Equilibria of Quinary System LiBr–NaBr–KBr–MgBr2–H2O at 298.15 K

According to the composition characteristics of mineral elements in underground brine in the Sichuan basin of China, the complete phase equilibria and phase diagram of the quinary system LiBr–NaBr–KBr–MgBr2–H2O were studied at 298.15 K. Using the experimentally determined solubilities and equilibrium solids, the spatial stereo phase diagram of the quinary system, the dry base projection phase diagrams of the saturated surfaces of the four salts MgBr2·6H2O, KBr, LiBr·2H2O, and NaBr·2H2O, and the corresponding water content diagrams were plotted, respectively. The experimental results show that at 298.15 K, in addition to the four original components, the anhydrous salt NaBr and the double salt KBr·MgBr2·6H2O are formed. The phase diagram of the quinary system at 298.15 K contains 10 univariate curves, three invariant points, and six equilibrium solid-phase crystallization regions (KBr crystallization region, NaBr crystallization region, NaBr·2H2O crystallization region, MgBr2·6H2O crystallization region, LiBr·2H2O crystallization region, KBr·MgBr2·6H2O crystallization region). When MgBr2·6H2O or KBr is saturated, LiBr has a strong salting-out effect on KBr, NaBr, or MgBr2 and NaBr, while when LiBr·2H2O is saturated, MgBr2 has a salting-out effect on KBr and NaBr. All four saturated projection surfaces have MgBr2·6H2O, and NaBr is generated. These phase equilibrium data can provide a theoretical basis to guide underground brine mining and extract useful components.

Understanding ZnO surface defects from first-principles simulation

The single native defects on ZnO surfaces have been experimentally found to play an essential role in different applications of ZnO nanostructures. In this work, by means of first-principles density functional theory combined with atomistic thermodynamics and the nudged-elastic band method, we investigated the electronic properties, stability under the temperatures and pressures, and migration mechanism of the six different point defects on the non-polar (101̄0) and (112̄0) ZnO surfaces. Our results elucidate the defective energy states formed within the band gap of the ZnO surfaces, their orbital properties, and the defect-induced local surface magnetic moments. The former quantity is shown to be in good agreement with the available experimental photoluminescence measurements, reflecting this work’s highly accurate theoretical method. The thermodynamic phase diagrams of the pristine surfaces against the formation of the defects demonstrate that under the thermodynamic equilibrium condition with the oxygen reservoir, the most stable surface structures are the free-defect structures, consistent with the scanning tunneling microscopy measurement, while the oxygen-vacancy defect surfaces are only stable at the lower oxygen chemical potentials. Furthermore, we simulate the energy barriers of the different defect migration mechanisms, which describe how the defects are suppressed to form pristine surfaces.

Design optimization and statistical modeling of recycled waste-based additive for a variety of construction scenarios on heaving ground.

To minimize the environmental burdens and to promote natural resource conservation and sustainability, a composite additive (CA) is proposed using paper and wood industry waste, i.e., lignosulphonate (LS) and lime (LM) as a replacement for conventional stabilizers. However, the implication of this proposed stabilizer for real construction scenarios requires a multi-objective optimization for a thorough guideline for practitioners. In this regard, the response surface methodology is used for the mix design optimization of the proposed CA for various construction scenarios (i.e., buildings, roadways, and slopes). An extensive testing program is designed and conducted to obtain different geotechnical parameters related to the mechanical, volumetric change, and hydraulic behavior of the soil with special attention to the stabilization mechanism. The interplay between variables (LS and LM) and responses is examined using the effective 3D surface diagrams, and mathematical models are derived for which the difference between R2, Adj R2, and Pred R2 is found to be less than 0.2. In addition, LM is found to be more sensitive in terms of mechanical and hydraulic parameters than LS whereas LS moderately contributes to altering the parameters related to the volumetric change and hydraulic behavior. The optimized mix design of CA (i.e., LS:LM) is determined against the expansive soil stabilization for foundation, subgrade, and slope stability cases which are found to be 1.03:3.57, 0.84:2.90, and 0.9:2.75 as best suitable for these cases, respectively. Predicted responses for the optimal solution for slope stability cases are found to have an error of 0-9.6%. The stabilization mechanism shows that LS and LM work well in conjunction and lead to a more stable soil structure with better interlocking and cementation between soil particles along with the formation of new cementing materials, i.e., calcium aluminate hydrate (CAH) and calcium silicate gel (CSH). The LS in CA is observed to reduce the LM concentration in soil stabilization by up to 45% with improved geotechnical performance. Thus, the proposed CA is vital for natural resource conservation and paper and wood industry-related waste management.

Three-Way Fuzzy Sets and Their Applications (III)

Three-way fuzzy inference is the theoretical basis of three-way fuzzy control. The proposed TCRI method is based on a Mamdani three-way fuzzy implication operator and uses one inference and simple composition operation. In order to effectively improve the TCRI method, this paper proposes a full implication triple I algorithm for three-way fuzzy inference and gives the triple I solution to the TFMP problem. The emphasis of our research is R0 and Go¨del triple I solution, which is related to three-way residual implication, as well as Zadeh’s and Mamdani’s triple I solution, which is based on three-way fuzzy implication operator. Then the three-way fuzzy controller is constructed by the proposed Zadeh’s and R0 triple I algorithm. Finally, the proposed triple I algorithm is applied to the three-way fuzzy control system, and its advantage is illustrated by the three-dimensional surface diagram of the control variable.

Progress of Heterogeneous Iridium-Based Water Oxidation Catalysts.

The water oxidation reaction (or oxygen evolution reaction, OER) plays a critical role in green hydrogen production via water splitting, electrochemical CO2 reduction, and nitrogen fixation. The four-electron and four-proton transfer OER process involves multiple reaction intermediates and elementary steps that lead to sluggish kinetics; therefore, a high overpotential is necessary to drive the reaction. Among the different water-splitting electrolyzers, the proton exchange membrane type electrolyzer has greater advantages, but its anode catalysts are limited to iridium-based materials. The iridium catalyst has been extensively studied in recent years due to its balanced activity and stability for acidic OER, and many exciting signs of progress have been made. In this review, the surface and bulk Pourbaix diagrams of iridium species in an aqueous solution are introduced. The iridium-based catalysts, including metallic or oxides, amorphous or crystalline, single crystals, atomically dispersed or nanostructured, and iridium compounds for OER, are then elaborated. The latest progress of active sites, reaction intermediates, reaction kinetics, and elementary steps is summarized. Finally, future research directions regarding iridium catalysts for acidic OER are discussed.

DFT study on aerial degradation of product radicals derived from the reaction of 1H–Heptafluorocyclopentene (cyc‐CF2CF2CF2CF = CH − ) with OH radical

In this manuscript, aerial oxidation of primary product radicals has been studied which are obtained from the reaction of cyc‐CF2CF2CF2CF = CH − with •OH. Geometry optimization and frequency calculations of all species were performed using M11 functional along with 6–311++G(d,p) basis set. We have explored all reaction species including transition states on the potential energy surface (PES) diagram. In addition to this, we have also determined the thermochemistry (i.e. ΔrH0 and ΔrG0) of all the successive reaction steps involved in the reaction. From PES and thermochemistry results, it has been found that COF2, CHO-CFO and CHO-CF2CF2CF2CFO are the end degradation product.

Material removal mechanisms, processing characteristics and surface analysis of Cf-ZrB2-SiC in micro-EDM

Cf-ZrB2-SiC is a new composite material with excellent properties for making the next-generation aerospace component. This material is extremely difficult to removal by mechanical machining, and there is a lack of research on feasible secondary processing methods of this composite at present. Micro-EDM is not limited by material hardness, so it is very suitable for machining this material. In this paper, the Material removal mechanisms and processing characteristics of Cf-ZrB2-SiC by micro-EDM is analyzed. The removal mechanism of composite materials is explored though the discharge crater morphology, and the single-discharge experiments of each phase materials with different medium and different energies are also carried out as a reference. Electrical discharge milling experiments of Cf-ZrB2-SiC are performed to explore the medium on processing index, and found that the best surface quality and maximum processing efficiency can be realized in kerosene. An experiment with four factors (pulse width, voltage, peak current, capacitance) and three indexes (surface roughness, MRR, TWR) is designed to analyze the Cf-ZrB2-SiC process characteristics of micro-EDM and the response surface diagram and second-order regression equation are obtained. Milling the Cf-ZrB2-SiC by electrical discharge according to the optimal combination of surface roughness parameters deduced above, the as-machined surface is analyzed including the surface morphology by SEM, element content by EDS and the surface phase by XRD. The feasibility and advantages of micro-EDM on machining Cf-ZrB2-SiC are prove.

RETRACTED: Optimization of combustion, performance, and emission characteristics of a dual-fuel diesel engine powered with microalgae-based biodiesel/diesel blends and oxyhydrogen

• Diesel engine was powered with ternary blends of biodiesel-diesel-oxyhydrogen. • Third-generation biodiesel was synthesized from biomass of Azolla Pinnata . • A low-cost device-31 plates generator generated oxyhydrogen gas. • Oxyhydrogen addition improved engine performance and lowered emissions. • Box-Behnken design coupled with desirability approach used for optimization. The current study explores and improves the effects of engine load, injection time, and oxyhydrogen fuel flow rate on the combustion and emissions characteristics of a diesel engine. Experiment with the combustion and exhaust characteristics of a medium-sized diesel engine working in tri-fuel mode using microalgae oil methyl ester-diesel blends as injected fuel and an oxyhydrogen gas combination as inducted fuel. The Box-Behnken design (BBD) was used to reduce the number of testing. The parameters and proposed attributes were calculated utilizing response surface techniques and BBD-generated quadratic models. The response surface analysis displayed the patterns of input interactions on the output using surface diagrams. The desirability-based optimization revealed the optimal engine operating parameters as 22.92° crank angles advance, 76% engine load, and 0.92 L per minute oxyhydrogen flow rate. At these optimized operating ranges, the performance and combustion output of the study was 30.8 % brake thermal efficiency (BTE), 0.3 kg/kWh brake specific fuel consumption (BSFC), and 65.6 bar peak cylinder pressure (PCP). On the emission front, the CO emission was 0.0107%, UHC was 26 ppm, and NO x was 853 ppm. The optimized values were validated through experimental testing, and all the results were within 7% of the model-predicted output. The addition of oxyhydrogen significantly improved the combustion of an algal biodiesel-diesel-oxyhydrogen-powered diesel engine in terms of fuel efficiency and fuel consumption and lower carbon-based emission levels except for nitrogen oxide emissions.

Effect of Ta on the microstructure and mechanical properties of W Ta alloys prepared by arc melting

Herein, W–xTa alloys (x = 0, 10, 20, 30, 40, and 50 wt%) were fabricated using the arc-melting method to improve the strain capacity of tungsten. The effects of Ta on the microstructure and mechanical properties of the fabricated alloys were investigated. The WTa alloys with different Ta contents formed a single-phase WTa solid solution after arc melting, and their average grain size changed from 1056 to 243 μm with increasing Ta content, indicating a grain refinement effect. The hardness, compressive strength, and compressive strain of W improved after the addition of Ta, with the compressive strength and compressive strain of W40Ta reaching 1.63 GPa and 9.54%, respectively, thus achieving the best comprehensive mechanical properties. The fracture surface diagram suggested that a mixed fracture mode of intergranular fracture and transgranular dissociation fracture gradually formed with the increasing of Ta content. Transmission electron microscopic analysis showed that the dislocation density of the compressed W40Ta alloy increased considerably compared with that of pure W, edge dislocation slip was also found to be an important slip mechanism in addition to screw dislocation slip. This study provides insights into the performance optimization, reinforcement design, and strengthening mechanisms of W–xTa alloys.

Single-crystal XRD, Hirshfeld surfaces, 3D energy framework calculations, and DFT studies of 4,5-diphenyl-1,3,4-thiadiazole-2-thiolate: A mesoionic compound

The single crystal of mesoionic 4,5-diphenyl-1,3,4-thiadiazolium-2-thiolate 2 was obtained by the solvent evaporation method. The compound was characterized by spectroscopic and analytical techniques. The structure-property relationship of the mesoionic compound 2 was elucidated by single-crystal X-ray diffraction (XRD) data and density functional theory (DFT) methods. The XRD studies showed that compound 2 crystallized in monoclinic, P21/n space group. In the mesoionic ring, the exocyclic C14-S1 bond length was 1.676 (2) Å and the ring C1-S2 bond length was 1.705 (2) Å as a characteristic feature of the existence of dual charges. The crystal packing of the compound showed an interesting zig-zag type pattern of arrangement of molecules when viewed along [101]. The highest percentage of intercontact was found between sulfur and hydrogen in the Hirshfeld surface analysis. The computational studies were performed using the DFT method for the determination of the molecular and electronic properties. The frontier molecular orbitals give an idea of the delocalization of electrons in the molecule, and the energy gap describes the electron transport potential and excitation for reactivity of the molecule. The charge distribution in the compound was visualized using the molecular electrostatic potential surface diagram. Mulliken atomic charges were calculated to study the chemical nature of the molecule. The computational investigations suggested that mesoionic 4,5-diphenyl-1,3,4-thiadiazolium-2-thiolate is electrophilic and dipolar.

Phantom traversable wormholes in modified teleparallel gravity

The current analysis is devoted to exploring the physical properties of wormhole geometry for the phantom regime in f(T,τ) gravity, where τ represents the trace of the stress–energy–momentum tensor and T represents the torsion. To complete this study, we take two diagonal and off-diagonal t et rads for f(T,τ) gravity with spherically symmetric static spacetime. In the first part of this study, the shape function is calculated in the framework of the linear equation of state with the diagonal case. All the necessary wormhole conditions and energy conditions are discussed in the phantom regime. The shape function with the phantom regime in f(T,τ) gravity is calculated here for the first time. Further, we use the specific shape function to discuss the valid region for the energy conditions with the diagonal and off-diagonal t et rads and give a comparison by considering the validity region of the energy conditions. We give the embedded surface diagram for a better understanding of the connection between the two different regions of the spacetime for the phantom case. The existence of the exotic matter is confirmed in all the cases discussed here, as the null energy condition is shown to be violated.

Optimization of Repair Process Parameters for Open-Arc Surfacing Welding of Grinding Rolls Based on the Response Surface Method

The dilution rate of surfacing layers and the quality of weld forming are important factors affecting the quality of surfacing layers in open-arc surfacing. They are determined by the interaction of various surfacing parameters. In this paper, the response surface method is used to optimize the process parameters of open-arc surfacing welding. Mathematical models of the surfacing current, surfacing voltage, surfacing speed, dilution rate and weld residual height were established, and the reliability of the models was verified by variance analysis. By performing an analysis of the perturbation diagram and response surface diagram, the influence law of each influencing factor on the response value was obtained. The parameters of surfacing welding were optimized by setting optimization targets, and the experimental results of optimized parameters were compared with the predicted results. The optimized surfacing parameters were tested by grinding roller surfacing repair. The experimental results show that the quality of the grinding roller can meet the repair requirements. This shows that the model can be used to guide the surface repair of rollers and is of great significance to ensure the surface-repair quality of rollers.

Origin of two-dimensional hole gas formation on Si-treated diamond surfaces: Surface energy band diagram perspective

The Si terminal is considered to be able to form two-dimensional hole gas as hydrogen terminal, however, further confirmation of theory and experiments is necessary. In this study, the energy band diagram for the type IIa diamond surface after Si surface treatment was investigated experimentally. The results revealed a Fermi level of 0.2 eV above the valance band maximum, work function of 4.89 eV, and electron affinity of χ=-0.38eV. The energy band diagram of the Si-treated surface was similar to that of a hydrogen-terminated surface, which possesses the suitable chemical potential window facilitating electrons transfer from valance band to the aqueous adsorbed layer. Maybe this is the origin of the currently reported C–Si diamond two-dimensional hole gas channel. In addition, the conductivity of Si-treated surface varying with vacuum degree was observed, and the Hall measurement results showed that hole mobility and concentration are 69 cm2/V∙S and 3.92E + 10 cm−2 respectively.

Coexistence of carbonyl and ether groups on oxygen-terminated (110)-oriented diamond surfaces

Diamond-based materials have unique properties that are exploited in many electrochemical, optical, thermal, and quantum applications. When grown via chemical vapor deposition (CVD), the growth rate of the (110) face is typically much faster than the other two dominant crystallographic orientations, (111) and (100). As such, achieving sufficiently large-area and high-quality (110)-oriented crystals is challenging and typically requires post-growth processing of the surface. Whilst CVD growth confers hydrogen terminations on the diamond surface, the majority of post-growth processing procedures render the surface oxygen-terminated, which in turn impacts the surface properties of the material. Here, we determine the oxygenation state of the (110) surface using a combination of density functional theory calculations and X-ray photoelectron spectroscopy experiments. We show that in the 0–1000 K temperature range, the phase diagram of the (110) surface is dominated by a highly stable phase of coexisting and adjacent carbonyl and ether groups, while the stability of peroxide groups increases at low temperatures and high pressures. We propose a mechanism for the formation of the hybrid carbonyl-ether phase and rationalize its high stability. We further corroborate our findings by comparing simulated core-level binding energies with experimental X-ray photoelectron spectroscopy data on the highest-quality (110)-oriented diamond crystal surface reported to date.