A facile sol–gel method and heating treatment process have been reported to synthesize the wurtzite phase ZnO nanofilms with the preferential growth orientation along the[001]direction on the FTO substrates.The as-pr...A facile sol–gel method and heating treatment process have been reported to synthesize the wurtzite phase ZnO nanofilms with the preferential growth orientation along the[001]direction on the FTO substrates.The as-prepared wurtzite phase ZnO nanofilms-based memristor with the W/ZnO/FTO sandwich has demonstrated a reliable nonvolatile bipolar resistive switching behaviors with an ultralow set voltage of about +3 V and reset voltage of approximately-3.6 V,high resistive switching ratio of more than two orders of magnitude,good resistance retention ability(up to 10^(4)s),and excellent durability.Furthermore,the resistive switching behavior in the low-resistance state is attributed to the Ohmic conduction mechanism,while the resistive switching behavior in the high-resistance state is controlled by the trap-modulated space charge limited current(SCLC)mechanism.In addition,the conductive filament model regulated by the oxygen vacancies has been proposed,where the nonvolatile bipolar resistive switching behaviors could be attributed to the formation and rupture of conductive filaments in the W/ZnO/FTO memristor.This work demonstrates that the as-prepared wurtzite phase ZnO nanofilms-based W/ZnO/FTO memristor has promising prospects in future nonvolatile memory applications.展开更多
Although room-temperature superconductivity is still difficult to achieve,researching materials with electrical conductivity significantly higher than that of copper will be of great importance in improving energy eff...Although room-temperature superconductivity is still difficult to achieve,researching materials with electrical conductivity significantly higher than that of copper will be of great importance in improving energy efficiency,reducing costs,lightening equipment weight,and enhancing overall performance.Herein,this study presents a novel copper-carbon nanofilm composite with enhanced conductivity which has great applications in the electronic devices and electrical equipment.Multilayer copper-carbon nanofilms and interfaces with superior electronic structures are formed based on copper materials using plasma immersion nanocarbon layer deposition technology,effectively enhancing conductivity.Experimental results show that for a five-layer copper-carbon nanofilm composite,the conductivity improves significantly when the thickness of the carbon nanofilm increases.When the carbon nanofilm accounts for 16%of the total thickness,the overall conductivity increases up to 30.20%compared to pure copper.The mechanism of the enhanced conductivity is analyzed including roles of copper atom adsorption sites and electron migration pathways by applying effective medium theory,first-principles calculations and density of states analysis.Under an applied electric field,the high-density electrons in the copper film can migrate into the nanocarbon film,forming highly efficient electron transport channels,which significantly enhance the material’s conductivity.Finally,large-area electrode coating equipment is developed based on this study,providing the novel and robust strategy to enhance the conductivity of copper materials,which enables industrial application of copper-carbon nanocomposite films in the field of high conductivity materials.展开更多
Two-dimensional(2D)noble transition-metal dichalcogenide materials(NTMDs)have garnered remarkable attention due to their intriguing properties exhibiting potential applications in nanoelectronics,optoelectronics,and p...Two-dimensional(2D)noble transition-metal dichalcogenide materials(NTMDs)have garnered remarkable attention due to their intriguing properties exhibiting potential applications in nanoelectronics,optoelectronics,and photonics.The electronic structure and physical properties of 2D NTMDs can be effectively modulated using alloy engineering strategy.Nevertheless,the precise growth of wafer-scale 2D NTMDs alloys remains a significant challenge.In this work,we have achieved the controllable preparation of wafer-scale(2-inch)2D PdS_(2x)Se_(2(1-x)) nanofilms(NFs)with fully tunable compositions on various substrates using pre-deposited Pd NFs assisted chemical vapor deposition technique.High-performance photodetectors based on the PdS_(2x)Se_(2(1-x))NFs were fabricated,which exhibit broadband photodetection performance from visible to near-infrared(NIR)wavelength range at room temperature.Significantly,the PdS0.9Se1.1-based photodetectors display a responsivity up to 0.192 A W^(-1) and a large specific detectivity of 5.5×1011 Jones for 850 nm light,enabling an excellent high-resolution NIR single-pixel imaging(SPI)without an additional filtering circuit.Our work paves a new route for the controlled synthesis of wafer-scale and high-quality 2D NTMDs alloy NFs,which is essential for designing advanced optoelectronic devices.展开更多
A multifunctional polymeric nanofilm of triazinedithiolsilane monosodium salt, which can resist corrosion and activatecopper surface concurrently, was prepared by galvanostatic technique and the following hydrolysis-c...A multifunctional polymeric nanofilm of triazinedithiolsilane monosodium salt, which can resist corrosion and activatecopper surface concurrently, was prepared by galvanostatic technique and the following hydrolysis-condensation approach.Electrochemical tests were carried out to evaluate the resistant ability of nanofilm. The changes of functional groups atop thenanofilms were monitored with Fourier transform infrared spectroscopy （FT-IR） and contact angles （CA） simultaneously. Thechemical composition and the morphology of the polymeric nanofilm were investigated by X-ray photoelectron spectroscopy （XPS）and scanning electron microscope （SEM）, respectively. The results reveal that the preferentially developed disulfide units protect thecopper during the whole preparation process, and the subsequently hydrolyzed nanofilms without/with heating shape into newinterface phases bearing the multifunctionality. This multifunctional interface （the polymeric nanofilm on copper surface） opens upthe possibilities for other OH-containing reagents to be anchored onto copper surface in demanding researches or industrialapplications.展开更多
The in-plane electrical and thermal conductivities of several polycrystalline platinum and gold nanofilms with different thicknesses are measured in a temperature range between the boiling point of liquid nitrogen （...The in-plane electrical and thermal conductivities of several polycrystalline platinum and gold nanofilms with different thicknesses are measured in a temperature range between the boiling point of liquid nitrogen （77K） and room temperature by using the direct current heating method. The result shows that both the electrical and thermal conductivities of the nanofilms reduce greatly compared with their corresponding bulk values. However, the electrical conductivity drop is considerably greater than the thermal conductivity drop, which indicates that the influence of the internal grain boundary on heat transport is different from that of charge transport, hence leading to the violation of the Wiedemann-Franz law. We build an electron relaxation model based on Matthiessen＇s rule to analyse the thermal conductivity and employ the Mayadas ＆ Shatzkes theory to analyse the electrical conductivity. Moreover, a modified Wiedemann-Franz law is provided in this paper, the obtained results from which are in good agreement with the experimental data.展开更多
The effect of piezoelectricity on phonon properties and thermal conductivity of gallium nitride （GaN） nanofilms is theoretically investigated. The elasticity model is utilized to derive the phonon properties in spat...The effect of piezoelectricity on phonon properties and thermal conductivity of gallium nitride （GaN） nanofilms is theoretically investigated. The elasticity model is utilized to derive the phonon properties in spatially confined GaN nanofilms. The piezoelectric constitutive relation in GaN nanofilms is taken into account in calculating the phonon dispersion relation. The modified phonon group velocity and phonon density of state as well as the phonon thermal conductivity are also obtained due to the contribution of piezoelectricity. Theoretical results show that the piezoelectricity in GaN nanofilms can change significantly the phonon properties such as the phonon group velocity and density of states, resulting in the variation of the phonon thermal conductivity of GaN nanofilms remarkably. Moreover, the piezoelectricity of GaN can modify the dependence of thermal conductivity on the geometrical size and temperature. These results can be useful in modeling the thermal performance in the active region of GaN-based electronic devices.展开更多
Surface charges can modify the elastic modulus of nanostructure,leading to the change of the phonon and thermal properties in semiconductor nanostructure.In this work,the influence of surface charges on the phonon pro...Surface charges can modify the elastic modulus of nanostructure,leading to the change of the phonon and thermal properties in semiconductor nanostructure.In this work,the influence of surface charges on the phonon properties and phonon thermal conductivity of GaN nanofilm are quantitatively investigated.In the framework of continuum mechanics,the modified elastic modulus can be derived for the nanofilm with surface charges.The elastic model is presented to analyze the phonon properties such as the phonon dispersion relation,phonon group velocity,density of states of phonons in nanofilm with the surface charges.The phonon thermal conductivity of nanofilm can be obtained by considering surface charges.The simulation results demonstrate that surface charges can significantly change the phonon properties and thermal conductivity in a GaN nanofilm.Positive surface charges reduce the phonon energy and phonon group velocity but increase the density of states of phonons.The surface charges can change the size and temperature dependence of phonon thermal conductivity of GaN nanofilm.Based on these theoretical results,one can adjust the phonon properties and temperature/size dependent thermal conductivity in GaN nanofilm by changing the surface charges.展开更多
Single-phase multiferroic BiFeO3 and rare-earth metal of holmium （Ho） doped BiFeO3 nanofilms were prepared on Pt （100）/Ti/SiO2/Si wafer via solution-gelation technique. It was suggested that the lattice distortion...Single-phase multiferroic BiFeO3 and rare-earth metal of holmium （Ho） doped BiFeO3 nanofilms were prepared on Pt （100）/Ti/SiO2/Si wafer via solution-gelation technique. It was suggested that the lattice distortion happened with the lattice parameter of d decreasing after doping rare-earth metal of Ho. Meanwhile, the structure of nanofilms transformed from hexahedron phase to tetragonal phase after doping Ho. The analysis on X-ray photoelectron spectroscopy （XPS） indicated that the ratio of Fe3~ cations to Fe2＋ cations increased with the increase of binding energy between Fe and O and decrease of that between Bi and O after doping Ho. The present work provided an available way on enhancing multiferroic of BiFeO3 nanofilms.展开更多
The self-assembled silicon substrate. The resultant contact angle meter and atomic method was introduced to successfully obtain film was characterized by means of X-ray rare earth（RE） nanofilm on a single-crystal ph...The self-assembled silicon substrate. The resultant contact angle meter and atomic method was introduced to successfully obtain film was characterized by means of X-ray rare earth（RE） nanofilm on a single-crystal photoelectron spectroscopy （XPS）, ellipsometer, force microscopy （AFM）. The scratch experiment was performed for interfacial adhesion measurement of the RE film. The friction and wear behavior of RE nanofilm was examined on a DF-PM reciprocating friction and wear tester. The results indicate the RE nanofilm is of low coefficient of friction （COF） and high wear resistance. These desirable characteristics of RE nanofilm together with its nanometer thickness, strong bonding to the substrate and low surface energy make it a promising choice as a solid lubricant film in micro electromechanical system （MEMS） devices.展开更多
The structure and dynamics of water in a thick film on an ionic surface are studied by molecular dynamic simulations. We find that there is a dense monolayer of water molecules in the vicinity of the surface. Water mo...The structure and dynamics of water in a thick film on an ionic surface are studied by molecular dynamic simulations. We find that there is a dense monolayer of water molecules in the vicinity of the surface. Water molecules within this layer not only show an upright hydrogen-down orientation, but also an upright hydrogen-up orientation. Thus, water molecules in this layer can form hydrogen bonds with water molecules in the next layer. Therefore, the two-dimensional hydrogen bond network of the first layer is disrupted, mainly due to the 0 atoms in this layer, which are affected by the next layer and are unstable. Moreover, these water molecules exhibit delayed dynamic behavior with relatively long residence time compared with those bulk-like molecules in the other layers. Our study should be halpful to further understand the influence of water film thickness on the interfacial water at the solid-liquid interface.展开更多
Research on the propagation of elastic waves in piezoelectric nanostructures is very limited.The frequency dispersion of Love waves in layered piezoelectric nanostructures has not yet been reported when surface effect...Research on the propagation of elastic waves in piezoelectric nanostructures is very limited.The frequency dispersion of Love waves in layered piezoelectric nanostructures has not yet been reported when surface effects are taken into account.Based on the surface elasticity theory,the propagation of Love waves with surface effects in a structure consisting of a nanosized piezoelectric film and a semi-infinite elastic substrate is investigated focusing on the frequency dispersion curves of different modes.The results show that under the electrically-open conditions,surface effects give rise to the dependence of Love wave dispersion on the film thickness when the thickness of the piezoelectric film reduces to nanometers.For a given wave frequency,phase velocity of Love waves in all dispersion modes exhibit obvious toward shift as the film thickness decreases or the surface parameters increase.Moreover,there may exist a cut-off frequency in the first mode dispersion below which Love waves will be evanescent in the structure due to surface effects.The cut-off frequency depends on the film thickness,the surface parameters and the bulk material properties.展开更多
Cardiovascular disease(CVD)is a global health problem and is thought to be responsible for almost half of all deaths in the world.Nevertheless,currently available diagnostic methods for CVD are strongly depended on cl...Cardiovascular disease(CVD)is a global health problem and is thought to be responsible for almost half of all deaths in the world.Nevertheless,currently available diagnostic methods for CVD are strongly depended on clinical observation and monitoring,which commonly result in false diagnosis.Herein,an attractive strategy of a metal-organic framework(MOF)nanofilm-based laser desorption/ionization mass spectrometry(LDI-MS)was developed for enhancing serum metabolic profiling,which could provide precise diagnosis and molecular subtyping of CVD.The porous MOF nanofilm fabricated on indium-tin oxide(ITO)glass possessed enhanced ionization efficiency and size-exclusion effect,which endowed it as substrate with high sensitivity and selectivity for serum metabolites.Furthermore,the MOF nanofilm with uniform surface and high orientation provided high-quality and high-reproducibility serum metabolic profiles(SMPs)without any tedious pretreatment.Further analysis of extracted serum metabolic fingerprints could successfully distinguish patients with CVD from healthy controls and also differentiate two major subtypes of CVD.This work not only extends the application of MOF nanofilm as an attractive MS probe,but also provide an alternative way for precise diagnosis of CVD in molecular level.展开更多
The thermal properties of a nanostructured semiconductor are affected by multi-physical fields,such as stress and electromagnetic fields,causing changes in temperature and strain distributions.In this work,the influen...The thermal properties of a nanostructured semiconductor are affected by multi-physical fields,such as stress and electromagnetic fields,causing changes in temperature and strain distributions.In this work,the influence of stress-dependent thermal conductivity on the heat transfer behavior of a GaN-based nanofilm is investigated.The finite element method is adopted to simulate the temperature distribution in a prestressed nanofilm under heat pulses.Numerical results demonstrate the effect of stress field on the thermal conductivity of GaN-based nanofilm,namely,the prestress and the thermal stress lead to a change in the heat transfer behavior in the nanofilm.Under the same heat source,the peak temperature of the film with stress-dependent thermal conductivity is significantly lower than that of the film with a constant thermal conductivity and the maximum temperature difference can reach 8.2 K.These results could be useful for designing GaN-based semiconductor devices with higher reliability under multi-physical fields.展开更多
We investigate the formations of wurtzite （WZ） SiC nano polytypes in zinc blende （ZB） SiC nanofilms hetero-grown on Si-（100） substrates via low pressure chemical vapor deposition （LPCVD） by adjusting the Si/C ...We investigate the formations of wurtzite （WZ） SiC nano polytypes in zinc blende （ZB） SiC nanofilms hetero-grown on Si-（100） substrates via low pressure chemical vapor deposition （LPCVD） by adjusting the Si/C ratio of the introduced precursors. Through SEM, TEM, and Raman characterizations, we find that the nanofilms consist of discrete WZ SiC nano polytypes and ZB SiC polytypes composed of WZ polytypes （WZ ＋ ZB） and disordered ZB SiC polytypes, respectively, according to Si/C ratios of 0.5, 1.5, and 3. We attribute the WZ polytype formation to being due to a kinetic mechanism based on the Si/C surface saturation control.展开更多
Gallium nitride（GaN）, the notable representative of third generation semiconductors, has been widely applied to optoelectronic and microelectronic devices due to its excellent physical and chemical properties. In th...Gallium nitride（GaN）, the notable representative of third generation semiconductors, has been widely applied to optoelectronic and microelectronic devices due to its excellent physical and chemical properties. In this paper, we investigate the surface scattering effect on the thermal properties of GaN nanofilms. The contribution of surface scattering to phonon transport is involved in solving a Boltzmann transport equation（BTE）. The confined phonon properties of GaN nanofilms are calculated based on the elastic model. The theoretical results show that the surface scattering effect can modify the cross-plane phonon thermal conductivity of GaN nanostructures completely, resulting in the significant change of size effect on the conductivity in GaN nanofilm. Compared with the quantum confinement effect, the surface scattering leads to the order-of-magnitude reduction of the cross-plane thermal conductivity in GaN nanofilm. This work could be helpful for controlling the thermal properties of Ga N nanostructures in nanoelectronic devices through surface engineering.展开更多
Peptide frictions in water nanofilms of various thicknesses on a mica surface are studied via molecular dynamics simulations. We find that the forced lateral motion of the peptide exhibits stick-slip behaviour at low ...Peptide frictions in water nanofilms of various thicknesses on a mica surface are studied via molecular dynamics simulations. We find that the forced lateral motion of the peptide exhibits stick-slip behaviour at low water coverage; in contrast, the smooth gliding motion is observed at higher water coverage. The adsorbed peptide can form direct peptide-surface hydrogen bonds as well as indirect peptide-water-surface hydrogen bonds with the substrate. We propose that the stick-slip phenomenon is attributed to the overall effects of direct and indirect hydrogen bonds formed between the surface and the peptide.展开更多
In this work, the prerequisite and mode of electromagnetic response of Al nanof ilms to electromagnetic wave field was suggested. Reflectance, transmittance in infrared region and carrier density of the films was meas...In this work, the prerequisite and mode of electromagnetic response of Al nanof ilms to electromagnetic wave field was suggested. Reflectance, transmittance in infrared region and carrier density of the films was measured. With the carrier density of the films, the dependence of their plasma frequencies on the film thickness was obtained. On the other hand, the dependence of absorptance on the frequency of electromagnetic wave field was set up by using the measured reflectance and transmittance, which provided plasma frequency-film thickness relation as well. Similarity of both plasma frequency-film thickness relations proved plasma resonance as a mode of electromagnetic response in Al nanofilms.展开更多
The assessment of nanomechanical properties of a single amyloid fibril in a confined space provides important information for understanding the role of fibrils in a cell microenvironment. In this study, the structure ...The assessment of nanomechanical properties of a single amyloid fibril in a confined space provides important information for understanding the role of fibrils in a cell microenvironment. In this study, the structure and nanomechanical properties of different fibrils formed in water nanofilms on mica surface are carefully investigated by using the new atomic force microscopy imaging mode-peak force quantitative nanomechanics （PF-QNM）. We find that two types of fibrils with different morphologies are formed in water nanofilm on mica. The compression elasticities of these two types of fibrils are 3.9±0.9 and 2.5±0.6 GPa, respectively. The remarkable difference is possibly due to the structural discrepancy in two types of fibrils.展开更多
A transparent phase-pure anatase TiO_(2)nanofilm was prepared through magnetron sputtering method,and a subsequent annealing treatment awarded it the superhydrophilic characteristic.To make clear the mechanism of the ...A transparent phase-pure anatase TiO_(2)nanofilm was prepared through magnetron sputtering method,and a subsequent annealing treatment awarded it the superhydrophilic characteristic.To make clear the mechanism of the heat-induced superhydrophilicity,the chemical composition and surface morphology of the film were investigated in detail and compared before and after the annealing treatment mainly by field emission scanning electron microscopy(FESEM),X-ray diffraction method(XRD),Raman spectroscopy,and X-ray photoelectron spectroscope(XPS).The results suggest that the probable mechanism is in accordance with the UV-induced mechanism,where the heat-induced surface oxygen vacancies and hydroxyl radicals play important roles for achieving the superhydrophilicity.展开更多
A continuum theoretical scheme for self-rolling nanotubes from bilayers by mismatch is obtained by considering surface elasticity,surface stress,and symmetry lowering effects.For an ultrathin nanofilm with only severa...A continuum theoretical scheme for self-rolling nanotubes from bilayers by mismatch is obtained by considering surface elasticity,surface stress,and symmetry lowering effects.For an ultrathin nanofilm with only several nanometers in thickness,isotropic mismatch,and isotropic surface stress usually induce anisotropic rolling behavior.The isotropic Timoshenko formula should be modified anisotropically to explain the mechanical behavior of anisotropic rolling structure of nanotubes accurately.The nanofilm rolls up in tangential direction while remaining straight in cylindrical direction theoretically.Therefore,in this paper the anisotropic shape of nanotubes is taken into consideration.Along the cylindrical direction,although it maintains straight and its residual strain is uniform,the stress varies in the radial direction due to the Poisson's effect of tangential strain.The results of the current theory applied to Si-Si nanotube,InAs-GaAs nanotube,and InGaAs-Cr nanotube systems show good agreement with the experimental data.Beside the surface elasticity effect and surface stress effect,the symmetry breaking and the anisotropic rolling structure are of great importance in theoretically describing the mechanical behavior of rolling-up of nanotubes.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62341305,61805053,and 22269002)the Science and Technology Project of Guangxi Zhuang Autonomous Region,China(Grant Nos.AD19110038 and AD21238033)。
文摘A facile sol–gel method and heating treatment process have been reported to synthesize the wurtzite phase ZnO nanofilms with the preferential growth orientation along the[001]direction on the FTO substrates.The as-prepared wurtzite phase ZnO nanofilms-based memristor with the W/ZnO/FTO sandwich has demonstrated a reliable nonvolatile bipolar resistive switching behaviors with an ultralow set voltage of about +3 V and reset voltage of approximately-3.6 V,high resistive switching ratio of more than two orders of magnitude,good resistance retention ability(up to 10^(4)s),and excellent durability.Furthermore,the resistive switching behavior in the low-resistance state is attributed to the Ohmic conduction mechanism,while the resistive switching behavior in the high-resistance state is controlled by the trap-modulated space charge limited current(SCLC)mechanism.In addition,the conductive filament model regulated by the oxygen vacancies has been proposed,where the nonvolatile bipolar resistive switching behaviors could be attributed to the formation and rupture of conductive filaments in the W/ZnO/FTO memristor.This work demonstrates that the as-prepared wurtzite phase ZnO nanofilms-based W/ZnO/FTO memristor has promising prospects in future nonvolatile memory applications.
基金support from the National Natural Science Foundation of China(61574091)National Natural Science Foundation of China Key Program(50730008).
文摘Although room-temperature superconductivity is still difficult to achieve,researching materials with electrical conductivity significantly higher than that of copper will be of great importance in improving energy efficiency,reducing costs,lightening equipment weight,and enhancing overall performance.Herein,this study presents a novel copper-carbon nanofilm composite with enhanced conductivity which has great applications in the electronic devices and electrical equipment.Multilayer copper-carbon nanofilms and interfaces with superior electronic structures are formed based on copper materials using plasma immersion nanocarbon layer deposition technology,effectively enhancing conductivity.Experimental results show that for a five-layer copper-carbon nanofilm composite,the conductivity improves significantly when the thickness of the carbon nanofilm increases.When the carbon nanofilm accounts for 16%of the total thickness,the overall conductivity increases up to 30.20%compared to pure copper.The mechanism of the enhanced conductivity is analyzed including roles of copper atom adsorption sites and electron migration pathways by applying effective medium theory,first-principles calculations and density of states analysis.Under an applied electric field,the high-density electrons in the copper film can migrate into the nanocarbon film,forming highly efficient electron transport channels,which significantly enhance the material’s conductivity.Finally,large-area electrode coating equipment is developed based on this study,providing the novel and robust strategy to enhance the conductivity of copper materials,which enables industrial application of copper-carbon nanocomposite films in the field of high conductivity materials.
基金supported by Open Research Fund of Songshan Lake Materials Laboratory(No.2023SLABFK08)Key Research and Development Program of Hunan Province(No.2022GK2007)+2 种基金Key Project from Department Education of Hunan Province(No.22A0123)National Natural Science Foundation of China(No.11974301)Graduate Student Research Innovation of Xi-angtan University(No.XDCX2024Y198).
文摘Two-dimensional(2D)noble transition-metal dichalcogenide materials(NTMDs)have garnered remarkable attention due to their intriguing properties exhibiting potential applications in nanoelectronics,optoelectronics,and photonics.The electronic structure and physical properties of 2D NTMDs can be effectively modulated using alloy engineering strategy.Nevertheless,the precise growth of wafer-scale 2D NTMDs alloys remains a significant challenge.In this work,we have achieved the controllable preparation of wafer-scale(2-inch)2D PdS_(2x)Se_(2(1-x)) nanofilms(NFs)with fully tunable compositions on various substrates using pre-deposited Pd NFs assisted chemical vapor deposition technique.High-performance photodetectors based on the PdS_(2x)Se_(2(1-x))NFs were fabricated,which exhibit broadband photodetection performance from visible to near-infrared(NIR)wavelength range at room temperature.Significantly,the PdS0.9Se1.1-based photodetectors display a responsivity up to 0.192 A W^(-1) and a large specific detectivity of 5.5×1011 Jones for 850 nm light,enabling an excellent high-resolution NIR single-pixel imaging(SPI)without an additional filtering circuit.Our work paves a new route for the controlled synthesis of wafer-scale and high-quality 2D NTMDs alloy NFs,which is essential for designing advanced optoelectronic devices.
基金Project(2013DFR40700)supported by International S&T Cooperation Program of ChinaProjects(21174034,51003019,51302280)supported by the National Natural Science Foundation of China
文摘A multifunctional polymeric nanofilm of triazinedithiolsilane monosodium salt, which can resist corrosion and activatecopper surface concurrently, was prepared by galvanostatic technique and the following hydrolysis-condensation approach.Electrochemical tests were carried out to evaluate the resistant ability of nanofilm. The changes of functional groups atop thenanofilms were monitored with Fourier transform infrared spectroscopy （FT-IR） and contact angles （CA） simultaneously. Thechemical composition and the morphology of the polymeric nanofilm were investigated by X-ray photoelectron spectroscopy （XPS）and scanning electron microscope （SEM）, respectively. The results reveal that the preferentially developed disulfide units protect thecopper during the whole preparation process, and the subsequently hydrolyzed nanofilms without/with heating shape into newinterface phases bearing the multifunctionality. This multifunctional interface （the polymeric nanofilm on copper surface） opens upthe possibilities for other OH-containing reagents to be anchored onto copper surface in demanding researches or industrialapplications.
基金supported by the National Natural Science Foundation of China(Grant Nos 50676046 and 50730006)
文摘The in-plane electrical and thermal conductivities of several polycrystalline platinum and gold nanofilms with different thicknesses are measured in a temperature range between the boiling point of liquid nitrogen （77K） and room temperature by using the direct current heating method. The result shows that both the electrical and thermal conductivities of the nanofilms reduce greatly compared with their corresponding bulk values. However, the electrical conductivity drop is considerably greater than the thermal conductivity drop, which indicates that the influence of the internal grain boundary on heat transport is different from that of charge transport, hence leading to the violation of the Wiedemann-Franz law. We build an electron relaxation model based on Matthiessen＇s rule to analyse the thermal conductivity and employ the Mayadas ＆ Shatzkes theory to analyse the electrical conductivity. Moreover, a modified Wiedemann-Franz law is provided in this paper, the obtained results from which are in good agreement with the experimental data.
基金support received from the National Natural Science Foundation of China (11472243, 11302189, 11321202)the Doctoral Fund of Ministry of Education of China (20130101120175)
文摘The effect of piezoelectricity on phonon properties and thermal conductivity of gallium nitride （GaN） nanofilms is theoretically investigated. The elasticity model is utilized to derive the phonon properties in spatially confined GaN nanofilms. The piezoelectric constitutive relation in GaN nanofilms is taken into account in calculating the phonon dispersion relation. The modified phonon group velocity and phonon density of state as well as the phonon thermal conductivity are also obtained due to the contribution of piezoelectricity. Theoretical results show that the piezoelectricity in GaN nanofilms can change significantly the phonon properties such as the phonon group velocity and density of states, resulting in the variation of the phonon thermal conductivity of GaN nanofilms remarkably. Moreover, the piezoelectricity of GaN can modify the dependence of thermal conductivity on the geometrical size and temperature. These results can be useful in modeling the thermal performance in the active region of GaN-based electronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11772294,11621062,and 11302189)the Fundamental Research Funds for the Central Universities,China(Grant No.2017QNA4031)
文摘Surface charges can modify the elastic modulus of nanostructure,leading to the change of the phonon and thermal properties in semiconductor nanostructure.In this work,the influence of surface charges on the phonon properties and phonon thermal conductivity of GaN nanofilm are quantitatively investigated.In the framework of continuum mechanics,the modified elastic modulus can be derived for the nanofilm with surface charges.The elastic model is presented to analyze the phonon properties such as the phonon dispersion relation,phonon group velocity,density of states of phonons in nanofilm with the surface charges.The phonon thermal conductivity of nanofilm can be obtained by considering surface charges.The simulation results demonstrate that surface charges can significantly change the phonon properties and thermal conductivity in a GaN nanofilm.Positive surface charges reduce the phonon energy and phonon group velocity but increase the density of states of phonons.The surface charges can change the size and temperature dependence of phonon thermal conductivity of GaN nanofilm.Based on these theoretical results,one can adjust the phonon properties and temperature/size dependent thermal conductivity in GaN nanofilm by changing the surface charges.
基金Project supported by National Key Projects for Basic Research of China(2012CB626815)the National Natural Science Foundation of China(11264026,10904065)+1 种基金Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(NJYT-12-B05)Inner Mongolia Science Foundation for Distinguished Young Scholars(2014JQ01)
文摘Single-phase multiferroic BiFeO3 and rare-earth metal of holmium （Ho） doped BiFeO3 nanofilms were prepared on Pt （100）/Ti/SiO2/Si wafer via solution-gelation technique. It was suggested that the lattice distortion happened with the lattice parameter of d decreasing after doping rare-earth metal of Ho. Meanwhile, the structure of nanofilms transformed from hexahedron phase to tetragonal phase after doping Ho. The analysis on X-ray photoelectron spectroscopy （XPS） indicated that the ratio of Fe3~ cations to Fe2＋ cations increased with the increase of binding energy between Fe and O and decrease of that between Bi and O after doping Ho. The present work provided an available way on enhancing multiferroic of BiFeO3 nanofilms.
文摘The self-assembled silicon substrate. The resultant contact angle meter and atomic method was introduced to successfully obtain film was characterized by means of X-ray rare earth（RE） nanofilm on a single-crystal photoelectron spectroscopy （XPS）, ellipsometer, force microscopy （AFM）. The scratch experiment was performed for interfacial adhesion measurement of the RE film. The friction and wear behavior of RE nanofilm was examined on a DF-PM reciprocating friction and wear tester. The results indicate the RE nanofilm is of low coefficient of friction （COF） and high wear resistance. These desirable characteristics of RE nanofilm together with its nanometer thickness, strong bonding to the substrate and low surface energy make it a promising choice as a solid lubricant film in micro electromechanical system （MEMS） devices.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10975175, 90923002, and 21073222)the Postdoctoral Science Foundation of China (Grant No. 20100480645)+1 种基金the Postdoctoral Scientific Program of Shanghai, China (Grant No. 11R21418100)Chinese Academy of Sciences(Grant No. KJCX2-EW-N03)
文摘The structure and dynamics of water in a thick film on an ionic surface are studied by molecular dynamic simulations. We find that there is a dense monolayer of water molecules in the vicinity of the surface. Water molecules within this layer not only show an upright hydrogen-down orientation, but also an upright hydrogen-up orientation. Thus, water molecules in this layer can form hydrogen bonds with water molecules in the next layer. Therefore, the two-dimensional hydrogen bond network of the first layer is disrupted, mainly due to the 0 atoms in this layer, which are affected by the next layer and are unstable. Moreover, these water molecules exhibit delayed dynamic behavior with relatively long residence time compared with those bulk-like molecules in the other layers. Our study should be halpful to further understand the influence of water film thickness on the interfacial water at the solid-liquid interface.
基金Supported by National Natural Science Foundation of China(Grant No.11372261)Excellent Young Scientists Supporting Project of Science and Technology Department of Sichuan Province,China(Grant No.2013JQ0030)+4 种基金Supporting Project of Department of Education of Sichuan Province,China(Grant No.2014zd3132)Opening Project of Key Laboratory of Testing Technology for Manufacturing ProcessSouthwest University of Science and Technology-Ministry of Education,China(Grant No.12zxzk02)Fund of Doctoral Research of Southwest University of Science and Technology,China(Grant No.12zx7106)Postgraduate Innovation Fund of Southwest University of Science and Technology,China(Grant No.15ycx128)
文摘Research on the propagation of elastic waves in piezoelectric nanostructures is very limited.The frequency dispersion of Love waves in layered piezoelectric nanostructures has not yet been reported when surface effects are taken into account.Based on the surface elasticity theory,the propagation of Love waves with surface effects in a structure consisting of a nanosized piezoelectric film and a semi-infinite elastic substrate is investigated focusing on the frequency dispersion curves of different modes.The results show that under the electrically-open conditions,surface effects give rise to the dependence of Love wave dispersion on the film thickness when the thickness of the piezoelectric film reduces to nanometers.For a given wave frequency,phase velocity of Love waves in all dispersion modes exhibit obvious toward shift as the film thickness decreases or the surface parameters increase.Moreover,there may exist a cut-off frequency in the first mode dispersion below which Love waves will be evanescent in the structure due to surface effects.The cut-off frequency depends on the film thickness,the surface parameters and the bulk material properties.
基金supported by the National Natural Science Foundation of China(Nos.21974021 and 22036001)the Major Project of Science and Technology of Fujian Province(No.2020HZ06006)。
文摘Cardiovascular disease(CVD)is a global health problem and is thought to be responsible for almost half of all deaths in the world.Nevertheless,currently available diagnostic methods for CVD are strongly depended on clinical observation and monitoring,which commonly result in false diagnosis.Herein,an attractive strategy of a metal-organic framework(MOF)nanofilm-based laser desorption/ionization mass spectrometry(LDI-MS)was developed for enhancing serum metabolic profiling,which could provide precise diagnosis and molecular subtyping of CVD.The porous MOF nanofilm fabricated on indium-tin oxide(ITO)glass possessed enhanced ionization efficiency and size-exclusion effect,which endowed it as substrate with high sensitivity and selectivity for serum metabolites.Furthermore,the MOF nanofilm with uniform surface and high orientation provided high-quality and high-reproducibility serum metabolic profiles(SMPs)without any tedious pretreatment.Further analysis of extracted serum metabolic fingerprints could successfully distinguish patients with CVD from healthy controls and also differentiate two major subtypes of CVD.This work not only extends the application of MOF nanofilm as an attractive MS probe,but also provide an alternative way for precise diagnosis of CVD in molecular level.
基金This research is supported by the National Natural Science Foundation of China(Grant Nos.11772294,11621062)the Fundamental Research Funds for the Central Universities(Grant No.2017QNA4031).
文摘The thermal properties of a nanostructured semiconductor are affected by multi-physical fields,such as stress and electromagnetic fields,causing changes in temperature and strain distributions.In this work,the influence of stress-dependent thermal conductivity on the heat transfer behavior of a GaN-based nanofilm is investigated.The finite element method is adopted to simulate the temperature distribution in a prestressed nanofilm under heat pulses.Numerical results demonstrate the effect of stress field on the thermal conductivity of GaN-based nanofilm,namely,the prestress and the thermal stress lead to a change in the heat transfer behavior in the nanofilm.Under the same heat source,the peak temperature of the film with stress-dependent thermal conductivity is significantly lower than that of the film with a constant thermal conductivity and the maximum temperature difference can reach 8.2 K.These results could be useful for designing GaN-based semiconductor devices with higher reliability under multi-physical fields.
基金supported by the National Natural Science Foundation of China(Grant No.61274007)the Beijing Natural Science Foundation,China(GrantNo.4132074)
文摘We investigate the formations of wurtzite （WZ） SiC nano polytypes in zinc blende （ZB） SiC nanofilms hetero-grown on Si-（100） substrates via low pressure chemical vapor deposition （LPCVD） by adjusting the Si/C ratio of the introduced precursors. Through SEM, TEM, and Raman characterizations, we find that the nanofilms consist of discrete WZ SiC nano polytypes and ZB SiC polytypes composed of WZ polytypes （WZ ＋ ZB） and disordered ZB SiC polytypes, respectively, according to Si/C ratios of 0.5, 1.5, and 3. We attribute the WZ polytype formation to being due to a kinetic mechanism based on the Si/C surface saturation control.
基金supported by the National Natural Science Foundation of China(Grant Nos.11302189 and 11321202)the Doctoral Fund of Ministry of Education of China(Grant No.20130101120175)
文摘Gallium nitride（GaN）, the notable representative of third generation semiconductors, has been widely applied to optoelectronic and microelectronic devices due to its excellent physical and chemical properties. In this paper, we investigate the surface scattering effect on the thermal properties of GaN nanofilms. The contribution of surface scattering to phonon transport is involved in solving a Boltzmann transport equation（BTE）. The confined phonon properties of GaN nanofilms are calculated based on the elastic model. The theoretical results show that the surface scattering effect can modify the cross-plane phonon thermal conductivity of GaN nanostructures completely, resulting in the significant change of size effect on the conductivity in GaN nanofilm. Compared with the quantum confinement effect, the surface scattering leads to the order-of-magnitude reduction of the cross-plane thermal conductivity in GaN nanofilm. This work could be helpful for controlling the thermal properties of Ga N nanostructures in nanoelectronic devices through surface engineering.
基金supported by the National Natural Science Foundation of China (Grant No.10825520)the National Basic Research Program of China (Grant No.2007CB936000)the National Science Foundation for Post-Doctoral Scientists of China (Grant No.20100480645)
文摘Peptide frictions in water nanofilms of various thicknesses on a mica surface are studied via molecular dynamics simulations. We find that the forced lateral motion of the peptide exhibits stick-slip behaviour at low water coverage; in contrast, the smooth gliding motion is observed at higher water coverage. The adsorbed peptide can form direct peptide-surface hydrogen bonds as well as indirect peptide-water-surface hydrogen bonds with the substrate. We propose that the stick-slip phenomenon is attributed to the overall effects of direct and indirect hydrogen bonds formed between the surface and the peptide.
文摘In this work, the prerequisite and mode of electromagnetic response of Al nanof ilms to electromagnetic wave field was suggested. Reflectance, transmittance in infrared region and carrier density of the films was measured. With the carrier density of the films, the dependence of their plasma frequencies on the film thickness was obtained. On the other hand, the dependence of absorptance on the frequency of electromagnetic wave field was set up by using the measured reflectance and transmittance, which provided plasma frequency-film thickness relation as well. Similarity of both plasma frequency-film thickness relations proved plasma resonance as a mode of electromagnetic response in Al nanofilms.
基金Supported by the National Natural Science Foundation of China under Grant No 11474173the Natural Science Foundation of Zhejiang Province under Grant Nos LY14A040006 and LQ14F040002+1 种基金the Ningbo Natural Science Foundation under Grant Nos2014A610202 and 2014A610149the K.C.Wong Magna Fund in Ningbo University
文摘The assessment of nanomechanical properties of a single amyloid fibril in a confined space provides important information for understanding the role of fibrils in a cell microenvironment. In this study, the structure and nanomechanical properties of different fibrils formed in water nanofilms on mica surface are carefully investigated by using the new atomic force microscopy imaging mode-peak force quantitative nanomechanics （PF-QNM）. We find that two types of fibrils with different morphologies are formed in water nanofilm on mica. The compression elasticities of these two types of fibrils are 3.9±0.9 and 2.5±0.6 GPa, respectively. The remarkable difference is possibly due to the structural discrepancy in two types of fibrils.
基金National Nature Science Foundation of China(50705094)
文摘A transparent phase-pure anatase TiO_(2)nanofilm was prepared through magnetron sputtering method,and a subsequent annealing treatment awarded it the superhydrophilic characteristic.To make clear the mechanism of the heat-induced superhydrophilicity,the chemical composition and surface morphology of the film were investigated in detail and compared before and after the annealing treatment mainly by field emission scanning electron microscopy(FESEM),X-ray diffraction method(XRD),Raman spectroscopy,and X-ray photoelectron spectroscope(XPS).The results suggest that the probable mechanism is in accordance with the UV-induced mechanism,where the heat-induced surface oxygen vacancies and hydroxyl radicals play important roles for achieving the superhydrophilicity.
基金Project supported by the Natural Science Foundation of Shanxi Province,China(Grant No.201901D111316)the National Natural Science Foundation of China(Grant No.11874245)+1 种基金the Teaching Reform and Innovation Pproject of Colleges and Universities in Shanxi Province,China(Grant No.J2021508)the Natural Science Foundation of Inner Mongolia Autonomous Region,China(Grant No.2020MS06007)。
文摘A continuum theoretical scheme for self-rolling nanotubes from bilayers by mismatch is obtained by considering surface elasticity,surface stress,and symmetry lowering effects.For an ultrathin nanofilm with only several nanometers in thickness,isotropic mismatch,and isotropic surface stress usually induce anisotropic rolling behavior.The isotropic Timoshenko formula should be modified anisotropically to explain the mechanical behavior of anisotropic rolling structure of nanotubes accurately.The nanofilm rolls up in tangential direction while remaining straight in cylindrical direction theoretically.Therefore,in this paper the anisotropic shape of nanotubes is taken into consideration.Along the cylindrical direction,although it maintains straight and its residual strain is uniform,the stress varies in the radial direction due to the Poisson's effect of tangential strain.The results of the current theory applied to Si-Si nanotube,InAs-GaAs nanotube,and InGaAs-Cr nanotube systems show good agreement with the experimental data.Beside the surface elasticity effect and surface stress effect,the symmetry breaking and the anisotropic rolling structure are of great importance in theoretically describing the mechanical behavior of rolling-up of nanotubes.
