Lonsdaleite,also known as hexagonal diamond,is an allotrope of carbon with a hexagonal crystal structure,which was discovered in the nanostructure of the Canyon Diablo meteorite.Theoretical calculations have shown tha...Lonsdaleite,also known as hexagonal diamond,is an allotrope of carbon with a hexagonal crystal structure,which was discovered in the nanostructure of the Canyon Diablo meteorite.Theoretical calculations have shown that this structure gives it exceptional physical properties that exceed those of cubic diamond,making it highly promising for groundbreaking applications in superhard cutting tools,wide-bandgap semiconductor devices,and materials for extreme environments.As a result,the controllable synthesis of hexagonal diamond has emerged as a cutting-edge research focus in materials science.This review briefly outlines the progress in this area,with a focus on the mechanisms governing its key synthesis conditions,its intrinsic physical properties,and its potential applications in various fields.展开更多
Negatively charged boron vacancy(V_(B)^(-))spin defects are stable in nanoscale hexagonal boron nitride(hBN)flakes,which can be easily integrated into two-dimensional materials and devices to serve as both sensors and...Negatively charged boron vacancy(V_(B)^(-))spin defects are stable in nanoscale hexagonal boron nitride(hBN)flakes,which can be easily integrated into two-dimensional materials and devices to serve as both sensors and protective materials.Ion irradiation is frequently employed to create V_(B)^(-)spin defects in hBN.However,the optimal ion irradiation parameters remain unclear,even though they play a crucial role in determining the depth and density of the defects,which in turn affect sensing sensitivity.In this work,we optimize the carbon ion irradiation parameters for creating V_(B)^(-)spin defects by varying the irradiation dose and the incident angle.For 30 keV carbon ion irradiation,the optimal irradiation dose to create a V_(B)^(-)ensemble is determined to be 4×10^(13)ions/cm^(2),and both continuous and pulsed optically detected magnetic resonance measurements are used to estimate the magnetic sensitivity and spin coherence properties.Moreover,the incident angle of energetic ions is found to influence both the depth and density distributions of the V_(B)^(-)ensemble,a factor that is often overlooked.These results pave the way for improving the performance of quantum sensors based on hBN spin defects by optimizing the irradiation parameters.展开更多
It is significant to process textures with special functions similar to animal surfaces based on bionics and improve the friction stability and contact comfort of contact surfaces for the surface texture design of tac...It is significant to process textures with special functions similar to animal surfaces based on bionics and improve the friction stability and contact comfort of contact surfaces for the surface texture design of tactile products.In this paper,a bionic hexagonal micro-convex texture was prepared on an acrylic surface by laser processing.The friction mechanism of a finger touching the bionic hexagonal micro-convex texture under different touch speeds and pressures,and the effect of the height of the texture on tactile perception were investigated by finite element,subjective evaluation,friction,and EEG tests.The results showed that the deformation friction was the main friction component when the finger touched the bionic hexagonal texture,and the slipperiness and friction factor showed a significant negative correlation.As the touch speed decreased or the touch force increased,the hysteresis friction of the fingers as well as the interlocking friction increased,and the slipperiness perception decreased.The bionic hexagonal texture with higher convexity caused a higher friction factor,lower slipperiness perception,and lower P300 peak.Hexagonal textures with lower convexity,lower friction factor,and higher slipperiness perception required greater brain attentional resources and intensity of tactile information processing during tactile perception.展开更多
In this study,we employed molecular dynamics simulations to investigate the interfacial thermal conductance(ITC)and phonon transport of heterostructures composed of graphene(GE)and quasi-hexagonal phase fullerene(qHPC...In this study,we employed molecular dynamics simulations to investigate the interfacial thermal conductance(ITC)and phonon transport of heterostructures composed of graphene(GE)and quasi-hexagonal phase fullerene(qHPC60).We examined the effects of size,interface interaction coefficients,and thermal equilibrium time on the ITC of the GE/qHPC60 heterostructure.展开更多
Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin ...Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin manipulation.This study investigates defect formation in h-BN using focused helium ion beam(He^(+)FIB)irradiation and post-annealing treatments.We demonstrate that helium ion irradiation at doses up to 2×10^(9) ions/μm^(2) does not induce phase transitions or amorphization.Spectroscopic analyses,including differential reflectance spectroscopy(DRS),photoluminescence(PL),and Raman spectroscopy,reveal substantial defect formation and structural modifications.Notably,the irradiation induces a softening of in-plane and interlayer phonon modes,characterized by frequency redshifts of 10.5 cm^(-1) and 3.2 cm^(-1),respectively.While high-temperature thermal annealing mitigates lattice defects and facilitates single-photon emission,the E_(2g) peak width remains 38%broader and the shear mode peak width is 60%broader compared to pre-annealing conditions in the Raman spectra,indicating residual structural degradation.These findings provide insights into defect engineering mechanisms in h-BN,offering guidance for optimizing processing conditions and advancing quantum and optoelectronic device technologies.展开更多
Track reconstruction algorithms are critical for polarization measurements.Convolutional neural networks(CNNs)are a promising alternative to traditional moment-based track reconstruction approaches.However,the hexagon...Track reconstruction algorithms are critical for polarization measurements.Convolutional neural networks(CNNs)are a promising alternative to traditional moment-based track reconstruction approaches.However,the hexagonal grid track images obtained using gas pixel detectors(GPDs)for better anisotropy do not match the classical rectangle-based CNN,and converting the track images from hexagonal to square results in a loss of information.We developed a new hexagonal CNN algorithm for track reconstruction and polarization estimation in X-ray polarimeters,which was used to extract the emission angles and absorption points from photoelectron track images and predict the uncer-tainty of the predicted emission angles.The simulated data from the PolarLight test were used to train and test the hexagonal CNN models.For individual energies,the hexagonal CNN algorithm produced 15%-30%improvements in the modulation factor compared to the moment analysis method for 100%polarized data,and its performance was comparable to that of the rectangle-based CNN algorithm that was recently developed by the Imaging X-ray Polarimetry Explorer team,but at a lower computational and storage cost for preprocessing.展开更多
Topological physics has evolved from its initial focus on fermionic systems to the exploration of bosonic systems,particularly phononic excitations in crystalline materials.Two-dimensional(2D)topological phonons emerg...Topological physics has evolved from its initial focus on fermionic systems to the exploration of bosonic systems,particularly phononic excitations in crystalline materials.Two-dimensional(2D)topological phonons emerge as promising candidates for future technological applications.Currently,experimental verification of 2D topological phonons has remained exclusively limited to graphene,a constraint that hinders their applications in phononic devices.Here,we report experimental evidence of topological phonons in monolayer hexagonal boron nitride using advanced high-resolution electron energy loss spectroscopy.Our high-precision measurements explicitly demonstrate two topological nodal rings in monolayer hexagonal boron nitride,protected by mirror symmetry,expanding the paradigm of 2D topological phonons beyond graphene.This research not only deepens fundamental understanding of 2D topological phonons,but also establishes a phononic device platform based on wide-bandgap insulators,crucial for advancements in electronics and photonics applications.展开更多
In this paper,we propose a numerical calculation model of the multigroup neutron diffusion equation in 3D hexagonal geometry using the nodal Green's function method and verified it.We obtained one-dimensional tran...In this paper,we propose a numerical calculation model of the multigroup neutron diffusion equation in 3D hexagonal geometry using the nodal Green's function method and verified it.We obtained one-dimensional transverse integrated equations using the transverse integration procedure over 3D hexagonal geometry and denoted the solutions as a nodal Green's functions under the Neumann boundary condition.By applying a quadratic polynomial expansion of the transverse-averaged quantities,we derived the net neutron current coupling equation,equation for the expansion coefficients of the transverse-averaged neutron flux,and formulas for the coefficient matrix of these equations.We formulated the closed system of equations in correspondence with the boundary conditions.The proposed model was tested by comparing it with the benchmark for the VVER-440 reactor,and the numerical results were in good agreement with the reference solutions.展开更多
In this paper,the mechanical response of a one-dimensional(1D)hexagonal piezoelectric quasicrystal(PQC)thin film is analyzed under electric and temperature loads.Based on the Euler-Bernoulli beam theory,a theoretical ...In this paper,the mechanical response of a one-dimensional(1D)hexagonal piezoelectric quasicrystal(PQC)thin film is analyzed under electric and temperature loads.Based on the Euler-Bernoulli beam theory,a theoretical model is proposed,resulting in coupled governing integral equations that account for interfacial normal and shear stresses.To numerically solve these integral equations,an expansion method using orthogonal Chebyshev polynomials is employed.The results provide insights into the interfacial stresses,axial force,as well as axial and vertical deformations of the PQC film.Additionally,fracture criteria,including stress intensity factors,mode angles,and the J-integral,are evaluated.The solution is compared with the membrane theory,neglecting the normal stress and bending deformation.Finally,the effects of stiffness and aspect ratio on the PQC film are thoroughly discussed.This study serves as a valuable guide for controlling the mechanical response and conducting safety assessments of PQC film systems.展开更多
Despite advances in photocatalytic half-reduction reactions,challenges remain in effectively utilizing electron-hole pairs in concurrent redox processes.The present study involved the construction of a p-n junction Co...Despite advances in photocatalytic half-reduction reactions,challenges remain in effectively utilizing electron-hole pairs in concurrent redox processes.The present study involved the construction of a p-n junction Co_(3)O_(4)/Zn_(3)In_(2)S_(6)(CoZ)hybrid with a complementary band edge potential.The photocatalyst formed by the 2D assembled-nanostructure portrayed an optimal yield of 13.8(H_(2))and 13.1(benzaldehyde)mmol g^(-1)h^(-1)when exposed to light(λ>420 nm),surpassing 1%Pt-added ZIS(12.4(H_(2))and 10.71(benzaldehyde)mmol g^(-1)h^(-1)).Around 95%of the electron-hole utilization rate was achieved.The solar-to-hydrogen(STH)and apparent quantum yield(AQY)values of 0.466%and 4.96%(420nm)achieved by this system in the absence of sacrificial agents exceeded those of previous works.The exceptional performance was mostly ascribed to the synergistic development of adjoining p-n heterojunctions and the built-in electric field for effective charge separation.Moreover,scavenger studies elucidated the intricate mechanistic enigma of the dual-redox process,in which benzaldehyde was produced via O-H activation and subsequent C-H cleavage of benzyl alcohol over CoZ hybrids.Furthermore,the widespread use of the optimal 1-CoZ composites was confirmed in multiple photoredox systems.This work presents an innovative perspective on the construction of dual-functioning p-n heterojunctions for practical photoredox applications.展开更多
Silicon carbide(SiC)junction barrier Schottky(JBS)diode has been widely used in power electronic systems due to its excellent physical characteristics and electrical performance,and the structural design of its source...Silicon carbide(SiC)junction barrier Schottky(JBS)diode has been widely used in power electronic systems due to its excellent physical characteristics and electrical performance,and the structural design of its source area has a particularly significant impact on the performance.This study provides a comparative analysis of the SiC JBS diode performance of different hexagonal structures,aiming to provide theoretical support and practical guidance for the optimization of JBS diode performance.Through theoretical derivation,experimental verification and data processing,the paper deeply analyzes the influence of hexagonal structure on JBS diode current distribution and breakdown voltage,and proposes a targeted optimization strategy.展开更多
The concept of the time-modulated array has been emerging as an alternative to the complex phase shifters,which lowers the cost of the array feeding network due to the utilization of radio frequency(RF)switches.The va...The concept of the time-modulated array has been emerging as an alternative to the complex phase shifters,which lowers the cost of the array feeding network due to the utilization of radio frequency(RF)switches.The various forms of hexagonal antenna array geometries can be used for applications like surveillance tracking in phased array radar and wireless communication systems.This work proposes the generalized array factor(AF)for the hexagonal antenna array geometry based on time modulation.The time modulation in generalized hexagonal geometry can maintain the fixed static amplitude excitation,giving more flexibility over time.Furthermore,a novel trapezoidal switching function is also proposed and applied to the generalized array factor to enable future researchers to use this array factor in the field of advancement to observe how switching schemes like trapezoidal and rectangular affect the array pattern's side lobe level(SLL).The generalized equation can be utilized for the analysis and synthesis of radiation characteristics of the time-modulated hexagonal array(TMHA),time-modulated concentric hexagonal array(TMCHA),time-modulated hexagonal cylindrical array(TMHCA),and time-modulated hexagonal concentric cylindrical array(TMHCCA).The numerical result illustrates the generation of AF of time-modulated hexagonal structures and also shows that the trapezoidal switching sequence outperforms the rectangular switch using the cat swarm optimization(CSO)approach.展开更多
Silicone rubber(SR) composites are most widely used as thermal interface materials(TIMs) for electronics heat dissipation. Thermal impedance as the main bottleneck limiting the performance of TIMs is usually neglected...Silicone rubber(SR) composites are most widely used as thermal interface materials(TIMs) for electronics heat dissipation. Thermal impedance as the main bottleneck limiting the performance of TIMs is usually neglected. Herein, the thermal impedance of SR composites loaded with different levels of hexagonal boron nitride(h-BN) as TIMs was elaborated for the first time by the ASTM D 5470 standard test and finite element analysis. It was found that elastic modulus and surface roughness of SR composites increased with the increase of h-BN content, indicating that the conformity was reduced. When the assembly pressure was 0.69 MPa, there existed an optimal h-BN content at which the contact resistance was minimum(0.39 K·cm^(2)·W^(-1)). Although the decreased bond line thickness(BLT) by increasing the assembly pressure was beneficial to reduce the thermal impedance, the proper assembly pressure should be selected to prevent the warpage of the contact surfaces and the increase in contact resistance, according to the compression properties of the SR composites. This study provides valuable insights into fabrication of high-performance TIMs for modern electronic device applications.展开更多
In an era where the concept of green development is deeply rooted, magnesium(Mg) alloy as a light metal has a long-term development prospect in the process of energy saving, emission reduction and environmental improv...In an era where the concept of green development is deeply rooted, magnesium(Mg) alloy as a light metal has a long-term development prospect in the process of energy saving, emission reduction and environmental improvement. However, anti-corrosion performance of Mg alloy is poor due to the high chemical activity and low equilibrium potential, which limits the development of Mg alloy products.Herein, three-dimensional mesopore hollow polypyrrole spheres(MHPS) were prepared, and the MHPS was inserted into the middle of the stacked hexagon boron nitride(h-BN) lamellae, which allowed the hBN to be separated forming a further composite with abundant pore structure. Subsequently, the MHPS/hBN-OH composite was uniformly sprayed on the Mg alloy surface via simple spraying method to form the superhydrophobic surface(SHS). Finally, the slippery liquid infused porous surface(SLIPS) was successfully fabricated by applying drops of silicone lubricant on the superhydrophobic coating surface. After a series of characterization and testing, the results showed that the stacking of h-BN lamellae was significantly reduced after h-BN was successfully embedded by MHPS. In addition, the fabricated SLIPS have excellent self-cleaning, mechanical stability, anti-icing and anti-corrosion properties. Therefore, the method of embedding polymer microspheres not only offers a new strategy for h-BN exfoliation, but also the successful prepared SLIPS largely retards the corrosion of Mg alloy while providing new ideas for the development of SLIPS.展开更多
Aim To study dislocation elasticity theory in quasicrystals. Methods A dislocation was separated into pure edge part and pure screw part and their superposition was used to find the elastic field. Results and Conclu...Aim To study dislocation elasticity theory in quasicrystals. Methods A dislocation was separated into pure edge part and pure screw part and their superposition was used to find the elastic field. Results and Conclusion The elastic solution of a straight dislocation parallel to the quasiperiodic axis in 1D hexagonal quasicrystals was obtained and the generalized Peach Koehler force on a dislocation in quasicrystals was given.展开更多
Large-scale synthesis of ZnO hexagonal pyramids was achieved by a simple thermal decomposition route of precursor at 240 oC in the presence of PEG400. The precursor was obtained by room-temperature solid-state grindin...Large-scale synthesis of ZnO hexagonal pyramids was achieved by a simple thermal decomposition route of precursor at 240 oC in the presence of PEG400. The precursor was obtained by room-temperature solid-state grinding reaction between Zn（CH3COO）2-2H2O and Na2CO3. Crystal structure and morphology of the products were analyzed and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and high-resolution transmission electron microscopy （HRTEM）. The results of further experiments show that PEG400 has an important role in the formation of ZnO hexagonal pyramids. Difference between the single and double hexagonal pyramid structure may come from the special thermal decomposition reaction. The photoluminescence （PL） spectra of ZnO hexagonal pyramids exhibit strong near-band-edge emission at about 386 nm and weak green emission at about 550 nm. The Raman-active vibration at about 435 cm-1 suggests that the ZnO hexagonal pyramids have high crystallinity.展开更多
Super performance InGaP/GaAs heterojunction bipolar transistors (HBTs) with hexagonal emitter are described.The fabricated HBT shows excellent DC characteristics with low V CE offset voltage (<0 15V) and ...Super performance InGaP/GaAs heterojunction bipolar transistors (HBTs) with hexagonal emitter are described.The fabricated HBT shows excellent DC characteristics with low V CE offset voltage (<0 15V) and low knee voltage (<0 5V).Over 14V of the collector base breakdown voltage BV CBO and over 9V of the collector emitter breakdown voltage BV CEO are obtained.For a self aligned InGaP/GaAs HBT with 2μm×10μm emitter area,the f T is extrapolated to 92GHz and f max is extrapolated to 105GHz.These great values are obtained due to the hexagonal emitter and laterally etched undercut (LEU) of collector,indicating the great potential of InGaP/GaAs HBTs for high speed digital circuit and microwave power applications.展开更多
Three kinds of composite alumina refractories were prepared with tabular alumina （3-1 and 1-0 mm） as aggregates,tabular alumina powder,α-Al2 O3 micropowder,and Si powder as matrix,adding 3 mass％ hexagonal boron ni...Three kinds of composite alumina refractories were prepared with tabular alumina （3-1 and 1-0 mm） as aggregates,tabular alumina powder,α-Al2 O3 micropowder,and Si powder as matrix,adding 3 mass％ hexagonal boron nitride （h-BN）,3 mass％ flake graphite and 10 mass％ flake graphite,respectively.Cold physical properties,hot modulus of rupture,oxidation resistance,thermal shock resistance and slag corrosion resistance of the specimens were compared.The results show that：（1） physical properties and hot modulus of rupture of Al2 O3-h-BN refractories are slightly different from those of low carbon Al2 O3-C refractories,but better than those of traditional Al2 O3-C refractories with 10 mass％ graphite ; （2） Al2 O3-h-BN refractories have better thermal shock resistance and oxidation resistance than the carbon containing refractories,while similar slag resistance with low carbon Al2 O3-C refractories ; （3） h-BN can replace flake graphite as a starting material for the preparation of composite alumina refractories,considering the overall properties of the material.展开更多
Using the complex variable function method and the technique of conformal mapping, the anti-plane shear problem of an elliptic hole with asymmetric colfinear cracks in a one-dimensional hexagonal quasi-crystal is solv...Using the complex variable function method and the technique of conformal mapping, the anti-plane shear problem of an elliptic hole with asymmetric colfinear cracks in a one-dimensional hexagonal quasi-crystal is solved, and the exact analytic solutions of the stress intensity factors （SIFs） for mode Ⅲ problem are obtained. Under the limiting conditions, the present results reduce to the Griffith crack and many new results obtained as well, such as the circular hole with asymmetric collinear cracks, the elliptic hole with a straight crack, the mode T crack, the cross crack and so on. As far as the phonon field is concerned, these results, which play an important role in many practical and theoretical applications, are shown to be in good agreement with the classical results.展开更多
Hexagonal boron nitride(h-BN),with unique structural and properties,has shown enormous potentitoward variety of possible applications.By virtue of partially-ionic character of BN chemical bonds anusually large specifi...Hexagonal boron nitride(h-BN),with unique structural and properties,has shown enormous potentitoward variety of possible applications.By virtue of partially-ionic character of BN chemical bonds anusually large specific surface area,h-BN-related nanostructures exhibit appealing adsorption propertiewhich can be widely applied for separation and purification towards energy and environment treatmenIn this review,recent progress in designing h-BN micro,nano-structure,controlled synthesis,performancoptimizing as well as energy and environment-related adsorption applications are summarized.Strategieto tailor the h-BN can be classified as morphology control,element doping,defect control and surfacmodification,focusing on how to optimize the adsorption performance.In order to insight the intrinsimechanism of tuning strategies for property optimization,the significant adsorption applications of h-Btowards hydrogen storage,CO2 capture,pollutants removal from water and adsorption desulfurization arpresented.展开更多
基金the National Natural Science Foundation of China(12274170 and 52225203)。
文摘Lonsdaleite,also known as hexagonal diamond,is an allotrope of carbon with a hexagonal crystal structure,which was discovered in the nanostructure of the Canyon Diablo meteorite.Theoretical calculations have shown that this structure gives it exceptional physical properties that exceed those of cubic diamond,making it highly promising for groundbreaking applications in superhard cutting tools,wide-bandgap semiconductor devices,and materials for extreme environments.As a result,the controllable synthesis of hexagonal diamond has emerged as a cutting-edge research focus in materials science.This review briefly outlines the progress in this area,with a focus on the mechanisms governing its key synthesis conditions,its intrinsic physical properties,and its potential applications in various fields.
基金supported by the National Key Research and Development Program Project(2024YFF0726104)Key Laboratory of Modern Optical Technologies of the Education Ministry of China,Soochow University(Grant No.KJS2135)+1 种基金a China Postdoctoral Science Foundation Funded Project(Grant No.2024M751236)the Jiangxi Provincial Natural Science Foundation(Grant No.20232BAB211030).
文摘Negatively charged boron vacancy(V_(B)^(-))spin defects are stable in nanoscale hexagonal boron nitride(hBN)flakes,which can be easily integrated into two-dimensional materials and devices to serve as both sensors and protective materials.Ion irradiation is frequently employed to create V_(B)^(-)spin defects in hBN.However,the optimal ion irradiation parameters remain unclear,even though they play a crucial role in determining the depth and density of the defects,which in turn affect sensing sensitivity.In this work,we optimize the carbon ion irradiation parameters for creating V_(B)^(-)spin defects by varying the irradiation dose and the incident angle.For 30 keV carbon ion irradiation,the optimal irradiation dose to create a V_(B)^(-)ensemble is determined to be 4×10^(13)ions/cm^(2),and both continuous and pulsed optically detected magnetic resonance measurements are used to estimate the magnetic sensitivity and spin coherence properties.Moreover,the incident angle of energetic ions is found to influence both the depth and density distributions of the V_(B)^(-)ensemble,a factor that is often overlooked.These results pave the way for improving the performance of quantum sensors based on hBN spin defects by optimizing the irradiation parameters.
基金the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.48)。
文摘It is significant to process textures with special functions similar to animal surfaces based on bionics and improve the friction stability and contact comfort of contact surfaces for the surface texture design of tactile products.In this paper,a bionic hexagonal micro-convex texture was prepared on an acrylic surface by laser processing.The friction mechanism of a finger touching the bionic hexagonal micro-convex texture under different touch speeds and pressures,and the effect of the height of the texture on tactile perception were investigated by finite element,subjective evaluation,friction,and EEG tests.The results showed that the deformation friction was the main friction component when the finger touched the bionic hexagonal texture,and the slipperiness and friction factor showed a significant negative correlation.As the touch speed decreased or the touch force increased,the hysteresis friction of the fingers as well as the interlocking friction increased,and the slipperiness perception decreased.The bionic hexagonal texture with higher convexity caused a higher friction factor,lower slipperiness perception,and lower P300 peak.Hexagonal textures with lower convexity,lower friction factor,and higher slipperiness perception required greater brain attentional resources and intensity of tactile information processing during tactile perception.
基金supported by the National Natural Science Foundation of China(Grant No.12204130)the Fundamental Research Funds for the Central University of China(Grant No.2019ZDPY16)+2 种基金the Basic Research Project of Xuzhou City(Grant No.KC22043)the support funded by the Graduate Innovation Program of China University of Mining and Technology(Grant Nos.2024WLJCRCZL266 and 2024WLJCRCZL294)the Postgraduate Research Practice Innovation Program of Jiangsu Province(Grant No.KYCX24_2692)。
文摘In this study,we employed molecular dynamics simulations to investigate the interfacial thermal conductance(ITC)and phonon transport of heterostructures composed of graphene(GE)and quasi-hexagonal phase fullerene(qHPC60).We examined the effects of size,interface interaction coefficients,and thermal equilibrium time on the ITC of the GE/qHPC60 heterostructure.
基金supported by the National Natural Science Foundation of China(Grant Nos.11727902,12074372,12174385,12334014,and 12304112).
文摘Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin manipulation.This study investigates defect formation in h-BN using focused helium ion beam(He^(+)FIB)irradiation and post-annealing treatments.We demonstrate that helium ion irradiation at doses up to 2×10^(9) ions/μm^(2) does not induce phase transitions or amorphization.Spectroscopic analyses,including differential reflectance spectroscopy(DRS),photoluminescence(PL),and Raman spectroscopy,reveal substantial defect formation and structural modifications.Notably,the irradiation induces a softening of in-plane and interlayer phonon modes,characterized by frequency redshifts of 10.5 cm^(-1) and 3.2 cm^(-1),respectively.While high-temperature thermal annealing mitigates lattice defects and facilitates single-photon emission,the E_(2g) peak width remains 38%broader and the shear mode peak width is 60%broader compared to pre-annealing conditions in the Raman spectra,indicating residual structural degradation.These findings provide insights into defect engineering mechanisms in h-BN,offering guidance for optimizing processing conditions and advancing quantum and optoelectronic device technologies.
基金supported by the National Natural Science Foundation of China(No.12025301)the Tsinghua University Initiative Scientific Research Program.
文摘Track reconstruction algorithms are critical for polarization measurements.Convolutional neural networks(CNNs)are a promising alternative to traditional moment-based track reconstruction approaches.However,the hexagonal grid track images obtained using gas pixel detectors(GPDs)for better anisotropy do not match the classical rectangle-based CNN,and converting the track images from hexagonal to square results in a loss of information.We developed a new hexagonal CNN algorithm for track reconstruction and polarization estimation in X-ray polarimeters,which was used to extract the emission angles and absorption points from photoelectron track images and predict the uncer-tainty of the predicted emission angles.The simulated data from the PolarLight test were used to train and test the hexagonal CNN models.For individual energies,the hexagonal CNN algorithm produced 15%-30%improvements in the modulation factor compared to the moment analysis method for 100%polarized data,and its performance was comparable to that of the rectangle-based CNN algorithm that was recently developed by the Imaging X-ray Polarimetry Explorer team,but at a lower computational and storage cost for preprocessing.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1403000,X.Z.No.2021YFA1400200,X.Z.+6 种基金No.2022YFA1204900,H.P.and No.2020YFA0308800,J.S.)the National Natural Science Foundation of China(Grant No.12274446,X.Z.No.12374172,J.S.No.11974045,J.S.No.61888102,J.S.)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000,J.G.&X.Z.)。
文摘Topological physics has evolved from its initial focus on fermionic systems to the exploration of bosonic systems,particularly phononic excitations in crystalline materials.Two-dimensional(2D)topological phonons emerge as promising candidates for future technological applications.Currently,experimental verification of 2D topological phonons has remained exclusively limited to graphene,a constraint that hinders their applications in phononic devices.Here,we report experimental evidence of topological phonons in monolayer hexagonal boron nitride using advanced high-resolution electron energy loss spectroscopy.Our high-precision measurements explicitly demonstrate two topological nodal rings in monolayer hexagonal boron nitride,protected by mirror symmetry,expanding the paradigm of 2D topological phonons beyond graphene.This research not only deepens fundamental understanding of 2D topological phonons,but also establishes a phononic device platform based on wide-bandgap insulators,crucial for advancements in electronics and photonics applications.
文摘In this paper,we propose a numerical calculation model of the multigroup neutron diffusion equation in 3D hexagonal geometry using the nodal Green's function method and verified it.We obtained one-dimensional transverse integrated equations using the transverse integration procedure over 3D hexagonal geometry and denoted the solutions as a nodal Green's functions under the Neumann boundary condition.By applying a quadratic polynomial expansion of the transverse-averaged quantities,we derived the net neutron current coupling equation,equation for the expansion coefficients of the transverse-averaged neutron flux,and formulas for the coefficient matrix of these equations.We formulated the closed system of equations in correspondence with the boundary conditions.The proposed model was tested by comparing it with the benchmark for the VVER-440 reactor,and the numerical results were in good agreement with the reference solutions.
基金Supported by the National Natural Science Foundation of China (Nos. 11902293 and 12272353)。
文摘In this paper,the mechanical response of a one-dimensional(1D)hexagonal piezoelectric quasicrystal(PQC)thin film is analyzed under electric and temperature loads.Based on the Euler-Bernoulli beam theory,a theoretical model is proposed,resulting in coupled governing integral equations that account for interfacial normal and shear stresses.To numerically solve these integral equations,an expansion method using orthogonal Chebyshev polynomials is employed.The results provide insights into the interfacial stresses,axial force,as well as axial and vertical deformations of the PQC film.Additionally,fracture criteria,including stress intensity factors,mode angles,and the J-integral,are evaluated.The solution is compared with the membrane theory,neglecting the normal stress and bending deformation.Finally,the effects of stiffness and aspect ratio on the PQC film are thoroughly discussed.This study serves as a valuable guide for controlling the mechanical response and conducting safety assessments of PQC film systems.
基金support provided by the Ministry of Higher Education Malaysia under the Fundamental Research Grant Scheme(FRGS)(No.FRGS/1/2024/TK08/XMU/02/1)supported by the PETRONAS-Academia Collaboration Dialogue(PACD 2023)grant,provided by PETRONAS Research Sdn.Bhd.(PRSB)+6 种基金the Ministry of Science,Technology and Innovation(MOSTI)Malaysia under the Strategic Research Fund(SRF)(S.22015)supported by the National Natural Science Foundation of China(No.22202168)Guangdong Basic and Applied Basic Research Foundation(No.2021A1515111019)support from the State Key Laboratory of Physical Chemistry of Solid Surfaces,Xiamen University(No.2023X11)supported by the Embassy of the People's Republic of China in Malaysia(EENG/0045)funded by Xiamen University Malaysia Investigatorship Grant(No.IENG/0038)Xiamen University Malaysia Research Fund(ICOE/0001,XMUMRF/2021-C8/IENG/0041 and XMUMRF/2025-C15/IENG/0080).
文摘Despite advances in photocatalytic half-reduction reactions,challenges remain in effectively utilizing electron-hole pairs in concurrent redox processes.The present study involved the construction of a p-n junction Co_(3)O_(4)/Zn_(3)In_(2)S_(6)(CoZ)hybrid with a complementary band edge potential.The photocatalyst formed by the 2D assembled-nanostructure portrayed an optimal yield of 13.8(H_(2))and 13.1(benzaldehyde)mmol g^(-1)h^(-1)when exposed to light(λ>420 nm),surpassing 1%Pt-added ZIS(12.4(H_(2))and 10.71(benzaldehyde)mmol g^(-1)h^(-1)).Around 95%of the electron-hole utilization rate was achieved.The solar-to-hydrogen(STH)and apparent quantum yield(AQY)values of 0.466%and 4.96%(420nm)achieved by this system in the absence of sacrificial agents exceeded those of previous works.The exceptional performance was mostly ascribed to the synergistic development of adjoining p-n heterojunctions and the built-in electric field for effective charge separation.Moreover,scavenger studies elucidated the intricate mechanistic enigma of the dual-redox process,in which benzaldehyde was produced via O-H activation and subsequent C-H cleavage of benzyl alcohol over CoZ hybrids.Furthermore,the widespread use of the optimal 1-CoZ composites was confirmed in multiple photoredox systems.This work presents an innovative perspective on the construction of dual-functioning p-n heterojunctions for practical photoredox applications.
文摘Silicon carbide(SiC)junction barrier Schottky(JBS)diode has been widely used in power electronic systems due to its excellent physical characteristics and electrical performance,and the structural design of its source area has a particularly significant impact on the performance.This study provides a comparative analysis of the SiC JBS diode performance of different hexagonal structures,aiming to provide theoretical support and practical guidance for the optimization of JBS diode performance.Through theoretical derivation,experimental verification and data processing,the paper deeply analyzes the influence of hexagonal structure on JBS diode current distribution and breakdown voltage,and proposes a targeted optimization strategy.
文摘The concept of the time-modulated array has been emerging as an alternative to the complex phase shifters,which lowers the cost of the array feeding network due to the utilization of radio frequency(RF)switches.The various forms of hexagonal antenna array geometries can be used for applications like surveillance tracking in phased array radar and wireless communication systems.This work proposes the generalized array factor(AF)for the hexagonal antenna array geometry based on time modulation.The time modulation in generalized hexagonal geometry can maintain the fixed static amplitude excitation,giving more flexibility over time.Furthermore,a novel trapezoidal switching function is also proposed and applied to the generalized array factor to enable future researchers to use this array factor in the field of advancement to observe how switching schemes like trapezoidal and rectangular affect the array pattern's side lobe level(SLL).The generalized equation can be utilized for the analysis and synthesis of radiation characteristics of the time-modulated hexagonal array(TMHA),time-modulated concentric hexagonal array(TMCHA),time-modulated hexagonal cylindrical array(TMHCA),and time-modulated hexagonal concentric cylindrical array(TMHCCA).The numerical result illustrates the generation of AF of time-modulated hexagonal structures and also shows that the trapezoidal switching sequence outperforms the rectangular switch using the cat swarm optimization(CSO)approach.
基金financially supported by Sichuan Science and Technology Program (No.2022YFH0090)the Fundamental Research Funds for the Central Universities。
文摘Silicone rubber(SR) composites are most widely used as thermal interface materials(TIMs) for electronics heat dissipation. Thermal impedance as the main bottleneck limiting the performance of TIMs is usually neglected. Herein, the thermal impedance of SR composites loaded with different levels of hexagonal boron nitride(h-BN) as TIMs was elaborated for the first time by the ASTM D 5470 standard test and finite element analysis. It was found that elastic modulus and surface roughness of SR composites increased with the increase of h-BN content, indicating that the conformity was reduced. When the assembly pressure was 0.69 MPa, there existed an optimal h-BN content at which the contact resistance was minimum(0.39 K·cm^(2)·W^(-1)). Although the decreased bond line thickness(BLT) by increasing the assembly pressure was beneficial to reduce the thermal impedance, the proper assembly pressure should be selected to prevent the warpage of the contact surfaces and the increase in contact resistance, according to the compression properties of the SR composites. This study provides valuable insights into fabrication of high-performance TIMs for modern electronic device applications.
基金financially supported by National Natural Science Foundation of China (Nos.51872245, 52103269)the Natural Science Key Foundation of Gansu Province+4 种基金China (No.23JRRA680)the Excellent Doctoral Student Project of Natural Science Foundation of Gansu Province (No.23JRRA695)the Gansu Province University Industrial Support Plan Project (No.2023CYZC-16)the Science and Technology Development Plan Project of Lanzhou City(No.2022-2-78)the Gansu International Scientific and Technological Cooperation Base of Water-Retention Chemical Functional Materials and Longyuan Young Talent for financial support。
文摘In an era where the concept of green development is deeply rooted, magnesium(Mg) alloy as a light metal has a long-term development prospect in the process of energy saving, emission reduction and environmental improvement. However, anti-corrosion performance of Mg alloy is poor due to the high chemical activity and low equilibrium potential, which limits the development of Mg alloy products.Herein, three-dimensional mesopore hollow polypyrrole spheres(MHPS) were prepared, and the MHPS was inserted into the middle of the stacked hexagon boron nitride(h-BN) lamellae, which allowed the hBN to be separated forming a further composite with abundant pore structure. Subsequently, the MHPS/hBN-OH composite was uniformly sprayed on the Mg alloy surface via simple spraying method to form the superhydrophobic surface(SHS). Finally, the slippery liquid infused porous surface(SLIPS) was successfully fabricated by applying drops of silicone lubricant on the superhydrophobic coating surface. After a series of characterization and testing, the results showed that the stacking of h-BN lamellae was significantly reduced after h-BN was successfully embedded by MHPS. In addition, the fabricated SLIPS have excellent self-cleaning, mechanical stability, anti-icing and anti-corrosion properties. Therefore, the method of embedding polymer microspheres not only offers a new strategy for h-BN exfoliation, but also the successful prepared SLIPS largely retards the corrosion of Mg alloy while providing new ideas for the development of SLIPS.
文摘Aim To study dislocation elasticity theory in quasicrystals. Methods A dislocation was separated into pure edge part and pure screw part and their superposition was used to find the elastic field. Results and Conclusion The elastic solution of a straight dislocation parallel to the quasiperiodic axis in 1D hexagonal quasicrystals was obtained and the generalized Peach Koehler force on a dislocation in quasicrystals was given.
基金Project (BK2009379) supported by the Natural Science Foundation of Jiangsu Province, ChinaProject (1006-56XNA12069) supported by the Nanjing University of Aeronautics and Astronautics Research Funding, China+3 种基金Projects (51172108, 91023020) supported by the National Natural Science Foundation of ChinaProject (IRT0968) supported by the Program for Changjiang Scholars and Innovative Research Team in University, ChinaProject (NCET-10-0070) supported by the Program for New Century Excellent Talents in University, ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions, China
文摘Large-scale synthesis of ZnO hexagonal pyramids was achieved by a simple thermal decomposition route of precursor at 240 oC in the presence of PEG400. The precursor was obtained by room-temperature solid-state grinding reaction between Zn（CH3COO）2-2H2O and Na2CO3. Crystal structure and morphology of the products were analyzed and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and high-resolution transmission electron microscopy （HRTEM）. The results of further experiments show that PEG400 has an important role in the formation of ZnO hexagonal pyramids. Difference between the single and double hexagonal pyramid structure may come from the special thermal decomposition reaction. The photoluminescence （PL） spectra of ZnO hexagonal pyramids exhibit strong near-band-edge emission at about 386 nm and weak green emission at about 550 nm. The Raman-active vibration at about 435 cm-1 suggests that the ZnO hexagonal pyramids have high crystallinity.
文摘Super performance InGaP/GaAs heterojunction bipolar transistors (HBTs) with hexagonal emitter are described.The fabricated HBT shows excellent DC characteristics with low V CE offset voltage (<0 15V) and low knee voltage (<0 5V).Over 14V of the collector base breakdown voltage BV CBO and over 9V of the collector emitter breakdown voltage BV CEO are obtained.For a self aligned InGaP/GaAs HBT with 2μm×10μm emitter area,the f T is extrapolated to 92GHz and f max is extrapolated to 105GHz.These great values are obtained due to the hexagonal emitter and laterally etched undercut (LEU) of collector,indicating the great potential of InGaP/GaAs HBTs for high speed digital circuit and microwave power applications.
文摘Three kinds of composite alumina refractories were prepared with tabular alumina （3-1 and 1-0 mm） as aggregates,tabular alumina powder,α-Al2 O3 micropowder,and Si powder as matrix,adding 3 mass％ hexagonal boron nitride （h-BN）,3 mass％ flake graphite and 10 mass％ flake graphite,respectively.Cold physical properties,hot modulus of rupture,oxidation resistance,thermal shock resistance and slag corrosion resistance of the specimens were compared.The results show that：（1） physical properties and hot modulus of rupture of Al2 O3-h-BN refractories are slightly different from those of low carbon Al2 O3-C refractories,but better than those of traditional Al2 O3-C refractories with 10 mass％ graphite ; （2） Al2 O3-h-BN refractories have better thermal shock resistance and oxidation resistance than the carbon containing refractories,while similar slag resistance with low carbon Al2 O3-C refractories ; （3） h-BN can replace flake graphite as a starting material for the preparation of composite alumina refractories,considering the overall properties of the material.
基金supported by the National Natural Science Foundation of China (Grant No 10761005)the Inner Mongolia Natural Science Foundation of China (Grant No 200607010104)
文摘Using the complex variable function method and the technique of conformal mapping, the anti-plane shear problem of an elliptic hole with asymmetric colfinear cracks in a one-dimensional hexagonal quasi-crystal is solved, and the exact analytic solutions of the stress intensity factors （SIFs） for mode Ⅲ problem are obtained. Under the limiting conditions, the present results reduce to the Griffith crack and many new results obtained as well, such as the circular hole with asymmetric collinear cracks, the elliptic hole with a straight crack, the mode T crack, the cross crack and so on. As far as the phonon field is concerned, these results, which play an important role in many practical and theoretical applications, are shown to be in good agreement with the classical results.
基金financially supported by the National Natural Science Foundation of China (Nos. 21606113, 21676128, and 21722604)the International Postdoctoral Exchange Fellowship by China Postdoctoral Science Foundation (No. 20170055)
文摘Hexagonal boron nitride(h-BN),with unique structural and properties,has shown enormous potentitoward variety of possible applications.By virtue of partially-ionic character of BN chemical bonds anusually large specific surface area,h-BN-related nanostructures exhibit appealing adsorption propertiewhich can be widely applied for separation and purification towards energy and environment treatmenIn this review,recent progress in designing h-BN micro,nano-structure,controlled synthesis,performancoptimizing as well as energy and environment-related adsorption applications are summarized.Strategieto tailor the h-BN can be classified as morphology control,element doping,defect control and surfacmodification,focusing on how to optimize the adsorption performance.In order to insight the intrinsimechanism of tuning strategies for property optimization,the significant adsorption applications of h-Btowards hydrogen storage,CO2 capture,pollutants removal from water and adsorption desulfurization arpresented.
