Ferroelectric materials are widely applied in the ferroelectronic devices,photovoltaics,and so on.Ultrathin ferroelectric thin films are highly desired for their applications,which still remain a challenge.In this wor...Ferroelectric materials are widely applied in the ferroelectronic devices,photovoltaics,and so on.Ultrathin ferroelectric thin films are highly desired for their applications,which still remain a challenge.In this work,the ultrathin barium titanate(BaTiO_(3),BTO)films are deposited directly on the fluorine-doped tin oxide glass(SnO_(2):F,FTO)substrates by radio frequency magnetron sputtering method at different temperatures.All BTO ultrathin films exhibit strong ferroelectric properties.Interestingly,BTO thin films deposited at room temperature(RT)also exhibit robust ferroelectricity.The polar domains are switched reversibly with a phase degree of~180°by piezoelectric force microscopy for the BTO thin films deposited at room temperature,attributing to the strain and ion migration.展开更多
Ising superconductivity has garnered much attention in recent years due to its extremely high in-plane upper critical field (B_(c2)).Here,we fabricated 14 multilayer Pb_(1-x)Bi_(x) (0%≤x≤40%) thin films on Si (111)-...Ising superconductivity has garnered much attention in recent years due to its extremely high in-plane upper critical field (B_(c2)).Here,we fabricated 14 multilayer Pb_(1-x)Bi_(x) (0%≤x≤40%) thin films on Si (111)-7×7 reconstructed surface by molecular beam epitaxy.Large B_(c2) beyond the Pauli limit is observed in all the Pb_(1-x)Bi_(x) films,indicating that they may exhibit characteristics of Ising superconductivity.Moreover,the introduction of Bi doping can significantly enhance and effectively tune the in-plane B_(c2) of Pb_(1-x)Bi_(x) films,which will help us better understand Ising superconductivity and provide a new platform for the development of tunable Ising superconductors.展开更多
Because of their low electrical conductivity,sluggish ion diffusion,and poor stability,conventional electrode materials are not able to meet the growing demands of energy storage and portable devices.Graphene assemble...Because of their low electrical conductivity,sluggish ion diffusion,and poor stability,conventional electrode materials are not able to meet the growing demands of energy storage and portable devices.Graphene assembled films(GAFs)formed from graphene nanosheets have an ultrahigh conductivity,a unique 2D network structure,and exceptional mechanical strength,which give them the potential to solve these problems.However,a systematic understanding of GAFs as an advanced electrode material is lacking.This review focuses on the use of GAFs in electrochemistry,providing a comprehensive analysis of their synthesis methods,surface/structural characteristics,and physical properties,and thus understand their structure-property relationships.Their advantages in batteries,supercapacitors,and electrochemical sensors are systematically evaluated,with an emphasis on their excellent electrical conductivity,ion transport kinetics,and interfacial stability.The existing problems in these devices,such as chemical inertness and mechanical brittleness,are discussed and potential solutions are proposed,including defect engineering and hybrid structures.This review should deepen our mechanistic understanding of the use of GAFs in electrochemical systems and provide actionable strategies for developing stable,high-performance electrode materials.展开更多
[Background and purposes]Proton exchange membrane fuel cells(PEMFCs),which convert hydrogen energy directly into electrical energy and water,have received overwhelming attention,owing to their potential to significant...[Background and purposes]Proton exchange membrane fuel cells(PEMFCs),which convert hydrogen energy directly into electrical energy and water,have received overwhelming attention,owing to their potential to significantly reduce energy consumption,pollution emissions and reliance on fossil fuels.Bipolar plates are the major part and key component of PEMFCs stack,which provide mechanical strength,collect and conduct current segregate oxidants and reduce agents.They contribute 70-80%weight and 20-30%cost of a whole stack,while significantly affecting the power density.There are three types plates,including metal bipolar plate,graphite bipolar plate and composite bipolar plate.Stainless steel bipolar plates,as one of metal bipolar plate,exhibit promising manufacturability,competitive cost and durability among various metal materials.However,stainless steel would be corroded in the harsh acid(pH 2-5)and humid PEMFCs environment,whereas the leached ions will contaminate the membrane.In addition,the passivated film formed on the surface will increase the interfacial contact resistance(ICR).In order to improve the corrosion resistance and electrical conductivity of steel bipolar plates,surface coatings are essential.Metal nitride coatings,metal carbide coatings,polymer coatings and carbon-based coatings have been introduced in recent years.Carbon-based coatings,mainly including a-C(amorphous Carbon),Ta-C(Tetrahedral amorphous carbon)and DLC(diamond-like carbon),have attracted considerable attention from both academia and industry,owing to their superior performance,such as chemical inertness,mechanical hardness and electrical conductivity.However,Ta-C films as protective coating of PEMFCs have been rarely reported,due to the difficulty in production for industrial application.In this paper,multi-layer Ta-C composite films were produced by using customized industrial-scale vacuum equipment to address those issues.[Methods]Multiple layered Ta-C coatings were prepared by using PIS624 equipment,which assembled filtered cathodic arc evaporation,ion beam and magnetron sputtering into one equipment,while SS304 and silicon specimens were used as substrate for testing and analysis.Adhesion layer and intermediate layer were deposited by using magnetron sputtering at deposition temperature of 150℃and pressure of 3×10^(−1) Pa,while the sputtering current was set to be 5 A and bias power to be 300 V.The Ta-C layer was coated at arc current of 80-100 A,bias voltage of 1500 V and gas flow of 75 sccm.A scanning electron microscope(CIQTEK SEM3200)was used to characterize surface morphology,coating structure and cross-section profile of the coatings.Raman spectrometer(LabRam HR Evolution,HORIBA JOBIN YVON)was used to identify the bonding valence states.Electrochemical tests were performed by using an electrochemical work station(CHI760,Shanghai Chenhua Instrument Co.,Ltd.),with the traditional three electrode system,where saturated Ag/AgCl and platinum mesh were used as the reference electrode and counter electrode,respectively.All samples were mounted in plastic tube and sealed with epoxy resin,with an exposure area of 2.25 cm^(2),serving as the working electrode.Electrochemical measurements were carried out in simulated PEMFCs cathode environment in 0.5 mol·L^(−1) H_(2)SO_(4)+5 ppm F−solution,at operating temperature of 70℃.As the cathode environment was harsher than the anode environment,all the samples are stabilized at the open-circuit potential(OCP)for approximately 30 min before the EIS measurements.ICR between bipolar plates and GDL was a key parameter affecting performance of the PEMFCs stack.The test sample sandwiched between 2 pieces of carbon paper(simulate gas diffusion layer,GDL)was placed between 2 gold-plated copper electrodes at a compaction pressure of 1.4 MPa,which was considered to be the conventional compaction pressure in the PEMFCs.Under the same conditions,the resistance of a single carbon paper was measured as well.The ICR was calculated according to the formula ICR=1/2(R2−R1)×S,where S was the contact area between GDL and coated stainless steel BPPs.All data of ICR were measured three times for averaging.[Results]The coatings deposited by filtered cathodic arc technology were compact and smooth,which reduced coating porosity and favorable to corrosion resistance.The coating thickness of adhesion and intermediate layers were 180 nm,while the protective Ta-C coating thickness was about 300 nm,forming multiple coating to provide stronger protection for metal bipolar plates.Cr,Ti,Nb and Ta coatings were selected as adhesion layers for comparison.According to electrochemical test,Ta and Nb coatings have higher corrosion resistance.However,Ta and Nb materials would be costly when they are used for mass production.Relatively,Cr and Ti materials were cost effective.Hence,a comprehensive assessment was indispensable to decide the materials to be selected as adhesion layer.Ta-TiN and Ti-TiN combined adhesion and intermediate layer exhibited stronger corrosion resistance,with the corrosion current to be less than 10^(−6) A·cm^(−2).Ta-C protective coating deposited by using filtered cathodic arc technology indicated displayed higher corrosion resistance,with the average corrosion density to be about 1.26×10^(−7) A·cm^(−2).Ta-C coating also shown larger contact angle,with the highest hydrophobicity,which was one of the important advantages for Ta-C,in terms of corrosion resistance.According to Raman spectroscopy,the I(D)/I(G)=549.8/1126.7=0.487,with the estimated fraction of sp^(3) bonding to be in the range of 5154%.The intermediate layer TiN has higher conductivity than the CrN layer.Considering cost,corrosion performance and ICR result,the Ti-TiN layer combination is recommended for industrial scale application.[Conclusions]Multiple layer coating structure of Ta-C film had stronger corrosion resistance;with more than 50%sp^(3) content,while it also had larger water contact angle and higher corrosion resistance than DLC film.The filtered arcing deposition technology was able to make the film to be more consistent and stable than normal arcing technology in terms of the preparation of Ta-C.The coating displayed corrosion density of 1.26×10^(−7) A·cm^(−2) and ICR of less than 5 mΩ·cm^(2),far beyond technical target of 2025 DOE(US Department of Energy).This indicated that the mass-production scale coating technology for PEMFC bipolar plates is highly possible.展开更多
The periodic [Ti/TiB2]n （n=l, 2, 3） multilayered films were prepared on the substrate of AISI 316L stainless steel by magnetron sputtering to enhance the adhesion of TiB2 films based on the remarkable mechanical per...The periodic [Ti/TiB2]n （n=l, 2, 3） multilayered films were prepared on the substrate of AISI 316L stainless steel by magnetron sputtering to enhance the adhesion of TiB2 films based on the remarkable mechanical performance of layered films. The influence of periods on microstructure, adhesion and hardness of [Ti/TiB2]n multilayered films was studied. X-ray diffraction （XRD） analysis shows that the monolayer TiB2 films exhibit （001） preferred orientation, and the preferred orientation of [Ti/TiB2], multilayered films transfers from （001） to （100） with the increase of periods. The cross-sectional morphology of each film displays homogeneity by field emission scanning electron microscopy （FESEM）. The hardness of the films measured via nanoindention changes from 20 to 26 GPa with the increase of periods. These values of hardness are a bit lower than that of the monolayer TiB2 films which is up to 33 GPa. However, the [Ti/TiB2]n multilayered films present a considerably good adhesion, which reaches a maximum of 24 N, in comparison with the monolayer TiB2 films according to the experimental results.展开更多
The discovery of high-temperature superconductivity in bilayer nickelate La_(3)Ni_(2)O_(7)under high-pressure conditions has spurred extensive efforts to stabilize superconductivity at ambient pressure.Recently,the re...The discovery of high-temperature superconductivity in bilayer nickelate La_(3)Ni_(2)O_(7)under high-pressure conditions has spurred extensive efforts to stabilize superconductivity at ambient pressure.Recently,the realization of superconductivity in compressively strained La_(3)Ni_(2)O_(7)thin films grown on the SrLaAlO_(4)substrates,with a T_(c)exceeding 40 K,represents a significant step toward this goal.Here,we investigate the influence of film thickness and carrier doping on the electronic structure of La_(3)Ni_(2)O_(7)thin films,ranging from 0.5 to 3 unit cells,using first-principles calculations.For a 2 unit-cell film with an optimal doping concentration of 0.3 hole per formula unit(0.15 hole/Ni),the Ni-d_(z^(2))interlayer bonding state crosses the Fermi level,resulting in the formation ofγpockets at the Fermi surface.These findings align with angle-resolved photoemission spectroscopy experimental data.Our results provide theoretical validation for the recent experimental discovery of ambient-pressure superconductivity in La_(3)Ni_(2)O_(7)thin films and underscore the significant impact of film thickness and carrier doping on electronic property modulation.展开更多
Polymer adsorption at solid interfaces plays an important role in the dynamics of nanoscale polymer films.We investigated the influence of the interfacial chain adsorption on the glass transition temperature(Tg)and de...Polymer adsorption at solid interfaces plays an important role in the dynamics of nanoscale polymer films.We investigated the influence of the interfacial chain adsorption on the glass transition temperature(Tg)and dewetting of polystyrene(PS)thin films on a graphene substrate that has strong interaction with PS.We found that the Tgs of PS films show a non-monotonic trend with increasing amount of polymer adsorption at the interface—first increasing and then decreasing,and this change in Tg is accompanied by a wetting-dewetting transition of the PS films.Film morphological analysis showed that the PS films dewet from the interfacially adsorbed layers rather than from the substrate,i.e.,autophobic dewetting,indicating the presence of an unfavorable interaction between the adsorbed and free PS chains.We ascribed the repulsive interaction to the formation of a dense adsorbed layer on graphene due to the π-π interaction between PS and graphene,which prevents the nonadsorbed PS chain from penetrating into the adsorbed layer.This may lead to drops in Tg at high adsorption extent.展开更多
FeCoCrMnNiN_(x)high entropy nitride ceramics thin films were prepared using the magnetron sputtering method,and the effects of nitrogen content on the thin films’properties were later examined.The addition of N_(2)af...FeCoCrMnNiN_(x)high entropy nitride ceramics thin films were prepared using the magnetron sputtering method,and the effects of nitrogen content on the thin films’properties were later examined.The addition of N_(2)affected the microstructures of the thin films and their mechanical and corrosion properties.Compared with the FeCoCrMnNi thin films with 1-sccm N_(2),the addition of 2 and 3 sccm of N_(2)by as much as 5.45at%and 6.34at%changed the solid solution’s crystalline structure into an amorphous structure.The addition of nitro-gen caused drastic changes to the surface morphology,creating a smoother and more uniform surface without cauliflower units.The atomic force microscopy image analysis indicated that the addition of nitrogen reduced the surface roughness from 5.58 to 1.82 nm.Adding N_(2)to the CoCrFeMnNi thin film helped increase its mechanical properties,such as hardness and strength,while the Young’s modulus decreased.The hardness of(8.75±0.5)GPa and the reduced Young’s modulus of(257.37±11.4)GPa of the FeCoCrMnNi thin film reached(12.67±1.2)and(194.39±12.4)GPa,respectively,with 1 sccm N_(2).The applied coating of the CoCrFeMnNi thin film on 304SUS increased the corrosion resistance,whereas the addition of nitrogen to the CoCrFeMnNi thin film also improved its corrosion res-istance compared with that of the CoCrFeMnNi thin film without nitrogen.展开更多
Polymeric materials,known for their lightweight and strength,are widely used today.However,their non-biodegradable nature poses significant environmental challenges.This research aimed to develop biodegradable films f...Polymeric materials,known for their lightweight and strength,are widely used today.However,their non-biodegradable nature poses significant environmental challenges.This research aimed to develop biodegradable films from fruits and vegetables,using alginate as a binding agent.Using a completely randomized design,seven experimental sets were prepared with carrots,Kimju guava,and Namwa banana peel fibers as the primary materials and alginate as the secondary material at three levels:1.2,1.8,and 2.4 by weight.The solution technique was employed to create the samples.Upon testing mechanical and physical properties,experimental set 3,consisting of 60%guava and 1.8%alginate,emerged as the optimal ratio.This combination exhibited favorable physical properties,including a thickness of 0.26±0.02 mm,meeting the standards for food packaging films.Additionally,the tensile strength was 0.50±0.01 N/m²,and the elongation at break was 55.60±0.44%.Regarding chemical properties,the moisture content of 5.64±0.03%fell within the acceptable range for dried food.Furthermore,a 30-day soil burial test revealed that the sample from experimental set 3 exhibited the highest degradation rate.In conclusion,these findings suggest that guava can be a promising raw material for producing biodegradable plastics suitable for packaging applications.展开更多
Photovoltaic(PV)technology plays a pivotal role in energy transformation processes,especially for sustainable energy systems.However,the conversion efficiency of the PV cells is adversely affected by increasing temper...Photovoltaic(PV)technology plays a pivotal role in energy transformation processes,especially for sustainable energy systems.However,the conversion efficiency of the PV cells is adversely affected by increasing temperature,leading to a reduction in their overall performance.In this study,a self-hygroscopic polyvinyl alcohol/graphene(SPG)cooling film,comprising a graphene layer and a polyvinyl alcohol(PVA)hydrogel layer with lithium bromide(LiBr),is introduced to passively reduce the working temperature of the PV cells.The graphene layer,as a heat-conducting layer,can efficiently conduct heat from the heat source to the self-hygroscopic PVA hydrogel layer used as an evaporation cooling layer.In addition,the introduction of LiBr endows the PVA hydrogel with an excellent self-hygroscopic property.The SPG cooling film demonstrates an outstanding cooling performance under the synergistic effect of the graphene film and the self-hygroscopic PVA hydrogel.In the outdoor experiments,the SPG cooling film can reduce the temperature of the PV cells by 20.6℃and increase its average output power from 74 to 93 W/m^(2),about a 25.7%increase.This cooling film demonstrates significant potential for enhancing cooling performance in electronic devices and could be widely used in the thermal management of PV cells.展开更多
Dye-based color films are increasingly considered as viable alternatives to pigment-based color films in complementary metal-oxide-semiconductor(CMOS) image sensors.Herein,a series of azo dyes utilizing 5-methyl-2-phe...Dye-based color films are increasingly considered as viable alternatives to pigment-based color films in complementary metal-oxide-semiconductor(CMOS) image sensors.Herein,a series of azo dyes utilizing 5-methyl-2-phenyl-4-(2-phenylhydrazono)-2,4-dihydro-3H-pyrazol-3-one as the coupling component and aromatic amines with various electron-withdrawing groups(NO_(2),CN,Br) as diazo components were designed and synthesized.The presence of intermolecular hydrogen bonding between the hydrogen atom on the N-H group and the oxygen atom of the C=O group of the hydrazo structure facilitates the formation of a stable six-membered ring.Additionally,the electron-withdrawing groups in the diazo component further stabilize this hydrogen-bonded structure.As a result,these azo dyes(P-2,P-3,P-4,P-5)exhibit not only excellent light stability but also ultra-highly thermal stability(T_(d)> 260℃).Therein,the synthesized dyes P-2 and P-3 with great bright yellow color(~400 nm),proper solubility(~6.00g/100 g)were selected to make for color films.And their dye-based color films displayed ultra-highly thermal and light stability(color difference ΔE<3).Notably,the increased planarity of the molecular structure by hydrogen bonding for the novel dyes ensures a balance between high transmittance(>90%) in the 550-780 nm wavelength range and the solvent resistance of the dye-based color films.This work contributes to the advancement of next-generation smart CMOS devices and offers valuable insights into the design of azo dyes for applications in the field of organic electronics.展开更多
Doped gallium oxide-based thin films are a class of wide-band semiconductor materials with the ad-vantages of chemically stable,tunable bandgap,and offer the benefit of ultraviolet response.In order to obtain photodet...Doped gallium oxide-based thin films are a class of wide-band semiconductor materials with the ad-vantages of chemically stable,tunable bandgap,and offer the benefit of ultraviolet response.In order to obtain photodetectors(PDs)with superior response,higher demands are placed on the quality of growth and processing of doped films.In this work,Zn-doped ternary metal oxide ZnGaO(ZGO)thin films were grown using the atomic layer deposition technique and annealed at different temperatures under an oxy-gen atmosphere.The results showed that the high-quality ZGO films with good uniformity,high visible light transmittance,low roughness,and significant reduction of oxygen vacancies were obtained after an-nealing.Subsequently,metal-semiconductor-metal PDs were prepared based on the studied ZGO films.The responsivity(R),detectivity(D^(∗)),and external quantum efficiency(EQE)of the optimized device are 61.8 A W^(-1),1.2×10^(12) Jones,and 255.9%,respectively.Compared to the unannealed device,the an-nealed ZGO PD achieves a maximum 309-fold increase in responsivity.This thermal engineering work may provide a strong reference for the development of low-cost,large-area,high-performance ultraviolet detection.And it also broadens the application of ternary metal oxides in optoelectronics.展开更多
The Casimir pressure plays an important role in the adhesion stability of nanofilms at submicro scales.In this work,the Casimir pressure of peptide films deposited on a layered substrate is investigated.Three types of...The Casimir pressure plays an important role in the adhesion stability of nanofilms at submicro scales.In this work,the Casimir pressure of peptide films deposited on a layered substrate is investigated.Three types of semi-infinite substrates,i.e.,silica,silicon and gold,are considered.The buffer layer between the peptide film and substrate consists of silicon or silica.The switching sign of the Casimir pressure can be controlled in a region ranging from about 130 nm to 1000 nm,depending on the thickness of the buffer layer and the substrate.The results suggest that the critical thickness of peptide films for Casimir equilibrium increases(or decreases)by increasing the thickness of the silicon(or silica)buffer film.The influences of wetting and electrolyte screening on the Casimir pressure are also investigated.Our finding provides a theoretical guide for the adhesion stability of peptide films in organic electronics.展开更多
T-carbon is a new allotrope of carbon materials,and it displays high hardness and low density.Nevertheless,the hardening mechanisms of T-carbon thin films under nanoindentation remain elusive.This work utilizes molecu...T-carbon is a new allotrope of carbon materials,and it displays high hardness and low density.Nevertheless,the hardening mechanisms of T-carbon thin films under nanoindentation remain elusive.This work utilizes molecular dynamics simulation to explore the hardening mechanisms of T-carbon thin films under nanoindentation with variations of loading velocities and temperatures.The results reveal that a loading velocity increase at a given temperature raises the nanoindentation force.The increase in nanoindentation force is due to graphitization,which is related to the fracture of tetrahedral structures in T-carbon thin films.However,increased graphitization caused by an increased temperature lowers the nanoindentation force at a given loading velocity.The increased graphitization is influenced by both the fractured tetrahedrons and the deformation of inter-tetrahedron bond angles.This is attributed to the loss of thermal stability and the lower density of T-carbon thin films as the temperature increases.These findings have significant implications for the design of nanodevices for specific application requirements.展开更多
The development of low-energy consumption and environmentally friendly electrodeposition of metal/alloy films or coatings is presently one of the primary topics for the research community.For this purpose,deep eutecti...The development of low-energy consumption and environmentally friendly electrodeposition of metal/alloy films or coatings is presently one of the primary topics for the research community.For this purpose,deep eutectic solvents(DESs)are valued as electrolytes for their advantages of low operating temperature and wide electrochemical windows.At present,there is large amount of literature on this emerging field,but there are no specialized reviews of these studies.Here,after a brief introduction of DESs’concept and history,we comprehensively reviewed the lastest progress on the metal/alloy electrodeposition in DESs.Additionally,we discussed the key influence factors of the electrodeposition process and analyzed the corresponding mechanisms.Based on these,we emphasized the importance of the establishment of predictive models for dealing with the challenges in large-scale applications.展开更多
The microelectronics industry is increasingly seeking freestanding multiferroic materials for the next generation of devices.Bismuth ferrite(BiFeO_(3)),known for its remarkable ferroelectric and antiferromagnetic prop...The microelectronics industry is increasingly seeking freestanding multiferroic materials for the next generation of devices.Bismuth ferrite(BiFeO_(3)),known for its remarkable ferroelectric and antiferromagnetic properties at room temperature,holds great promise for multifunctional applications.However,current fabrication methods depend on Sr_(3)Al_(2)O_(6)sacrificial layers that deteriorate under ambient conditions,which limits their practical use.In this study,we showcase the exceptional qualities of strontium cobalt oxide(SrCoO_(2.5))as an innovative sacrificial layer for BiFeO_(3).We successfully fabricated highquality films of both BiFeO_(3)and SrCoO_(2.5)using pulsed laser deposition(PLD),and we achieved freestanding BiFeO_(3)films through a careful chemical etching process that ensures precise quality control.Our investigation into the solubility and stability of SrCoO_(2.5)reveals its advantages over Sr_(3)Al_(2)O_(6),demonstrating enhanced durability while allowing long-term preservation of SrCoO_(2.5).The resulting freestanding films exhibit excellent crystallinity and surface smoothness,paving the way for their integration into next-generation electronic devices.This research not only advances the preparation of high-quality freestanding BiFeO_(3)but also highlights the potential of using SrCoO_(2.5)as a sacrificial layer in various perovskite oxide thin films,which are suitable for sensors,actuators,and memory devices.展开更多
Homogeneous films with tailored microporous structures are crucial for several applications;however,fabricating such films presents significant challenges.This is primarily because most microporous materials have crys...Homogeneous films with tailored microporous structures are crucial for several applications;however,fabricating such films presents significant challenges.This is primarily because most microporous materials have crystal sizes in the nanoand micrometer ranges,which inevitably generates intergranular spaces in the films,thereby complicating the fabrication of these thin films.In this study,functionalized metal–organic polyhedra(MOPs)are used as discrete microporous units and assembled into homogenous microporous films.The generation of intergranular spaces is avoided while controlling packing parameters and film thicknesses.Initially,the MOP units,influenced by van der Waals forces between carbon chains of functionalized adipic acids,display an affinity to form spindle-shaped blocks and islands.As the MOP concentration increases,these structures self-assembled into a hexagonally packed structure with an in-plane orientation and a maximum stacking of two layers of MOPs.By contrast,un-functionalized MOPs form a disordered film structure owing to random agglomeration.Evidently,functionalized adipic acid influences the orientation of the MOP network films with uniformly distributed micropores,effectively preventing the formation of intergranular spaces.Additionally,formaldehyde adsorption and desorption experiments revealed that the MOP network films possess superior adsorption and desorption capacities.The proposed approach signifies a breakthrough in the fabrication of homogenous microporous films.展开更多
In antiferromagnets,dipolar coupling is often disregarded due to the cancellation of magnetic moments between the two sublattices,so that the spin-wave dispersion is predominantly determined by exchange interactions.H...In antiferromagnets,dipolar coupling is often disregarded due to the cancellation of magnetic moments between the two sublattices,so that the spin-wave dispersion is predominantly determined by exchange interactions.However,antiferromagnetic spin waves typically involve a slight misalignment of the magnetic moments on the sublattices,which gives rise to a small net magnetization enabling long-range dipolar coupling.In this paper,we investigate the role of dipolar coupling in spin-wave excitations and its influence on the resulting dispersion.Our findings show that:(i)when the Néel vector is perpendicular to the film plane or lies within the film plane and parallel to the wave vector,the dispersion branches can be divided into two groups:those unaffected by the dipolar field and those influenced by it.In these cases,the total magnetic moment remains linearly polarized,but the polarization directions differ between the two types of branches;(ii)when the Néel vector lies in the film plane and is perpendicular to the wave vector,the dipolar interactions affect both types of dispersion branches,leading to their hybridization.This hybridization alters the polarization of the magnetic moment,resulting in elliptical polarization.展开更多
YBa_(2)Cu_(3)O_(7-x)(YBCO)films with low microwave surface resistance(RS)are essential for high temperature superconducting microwave devices.The oxygen pressure during deposition has been found to influence RS signif...YBa_(2)Cu_(3)O_(7-x)(YBCO)films with low microwave surface resistance(RS)are essential for high temperature superconducting microwave devices.The oxygen pressure during deposition has been found to influence RS significantly.In this work,we deposited highly c-axis aligned YBCO films on single crystal MgO(001)substrates under different oxygen pressures via pulsed laser ablation.Their detailed microstructure was characterized with three-dimensional reciprocal space mapping(3D-RSM)method and their microwave surface resistance was also measured with resonant cavity perturbation method.We found that the variation of oxygen pressure can affect film microstructure,including grain orientation distribution and the concentration of crystal defects.The microstructure modulation can explain RS dependence on the oxygen pressure.展开更多
Type-II Dirac semimetal PtTe2is a promising candidate for various electronic device applications due to its high carrier mobility,high conductivity,and air stability.In this work,we report on the growth of large-scale...Type-II Dirac semimetal PtTe2is a promising candidate for various electronic device applications due to its high carrier mobility,high conductivity,and air stability.In this work,we report on the growth of large-scale PtTe_(2)films by the pulsed laser deposition(PLD)and the comparison of the magnetotransport properties with the PtTe2films grown by the chemical vapor deposition(CVD).The low-temperature Hall curves of the PLD-grown films exhibit a linear behavior,in contrast with the nonlinear characteristic of the Hall behavior observed in CVD-grown films,in which a defect gradient is introduced.Meanwhile,both PtTe2films show weak antilocalization at low temperatures,which is attributed to the strong spin–orbit coupling.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2019YFB1503500)
文摘Ferroelectric materials are widely applied in the ferroelectronic devices,photovoltaics,and so on.Ultrathin ferroelectric thin films are highly desired for their applications,which still remain a challenge.In this work,the ultrathin barium titanate(BaTiO_(3),BTO)films are deposited directly on the fluorine-doped tin oxide glass(SnO_(2):F,FTO)substrates by radio frequency magnetron sputtering method at different temperatures.All BTO ultrathin films exhibit strong ferroelectric properties.Interestingly,BTO thin films deposited at room temperature(RT)also exhibit robust ferroelectricity.The polar domains are switched reversibly with a phase degree of~180°by piezoelectric force microscopy for the BTO thin films deposited at room temperature,attributing to the strain and ion migration.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12374196, 92165201, and 11634011)the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302800)+2 种基金the Chinese Academy of Sciences Project for Young Scientists in Basic Research (Grant No. YSBR-046)the Fundamental Research Funds for the Central Universities (Grant Nos. WK3510000006 and WK3430000003)Anhui Initiative in Quantum Information Technologies (Grant No. AHY170000)。
文摘Ising superconductivity has garnered much attention in recent years due to its extremely high in-plane upper critical field (B_(c2)).Here,we fabricated 14 multilayer Pb_(1-x)Bi_(x) (0%≤x≤40%) thin films on Si (111)-7×7 reconstructed surface by molecular beam epitaxy.Large B_(c2) beyond the Pauli limit is observed in all the Pb_(1-x)Bi_(x) films,indicating that they may exhibit characteristics of Ising superconductivity.Moreover,the introduction of Bi doping can significantly enhance and effectively tune the in-plane B_(c2) of Pb_(1-x)Bi_(x) films,which will help us better understand Ising superconductivity and provide a new platform for the development of tunable Ising superconductors.
基金the National Natural Science Foundation of China(22279097)the Key R&D Program of Hubei Province(2023BAB103)the PhD Scientific Research and Innovation Foundation of The Education Department of Hainan Province Joint Project of Sanya Yazhou Bay Science and Technology City(HSPHDSRF-2024-03-022)。
文摘Because of their low electrical conductivity,sluggish ion diffusion,and poor stability,conventional electrode materials are not able to meet the growing demands of energy storage and portable devices.Graphene assembled films(GAFs)formed from graphene nanosheets have an ultrahigh conductivity,a unique 2D network structure,and exceptional mechanical strength,which give them the potential to solve these problems.However,a systematic understanding of GAFs as an advanced electrode material is lacking.This review focuses on the use of GAFs in electrochemistry,providing a comprehensive analysis of their synthesis methods,surface/structural characteristics,and physical properties,and thus understand their structure-property relationships.Their advantages in batteries,supercapacitors,and electrochemical sensors are systematically evaluated,with an emphasis on their excellent electrical conductivity,ion transport kinetics,and interfacial stability.The existing problems in these devices,such as chemical inertness and mechanical brittleness,are discussed and potential solutions are proposed,including defect engineering and hybrid structures.This review should deepen our mechanistic understanding of the use of GAFs in electrochemical systems and provide actionable strategies for developing stable,high-performance electrode materials.
基金Major Science and technology projects of Anhui Province (202103a05020003)。
文摘[Background and purposes]Proton exchange membrane fuel cells(PEMFCs),which convert hydrogen energy directly into electrical energy and water,have received overwhelming attention,owing to their potential to significantly reduce energy consumption,pollution emissions and reliance on fossil fuels.Bipolar plates are the major part and key component of PEMFCs stack,which provide mechanical strength,collect and conduct current segregate oxidants and reduce agents.They contribute 70-80%weight and 20-30%cost of a whole stack,while significantly affecting the power density.There are three types plates,including metal bipolar plate,graphite bipolar plate and composite bipolar plate.Stainless steel bipolar plates,as one of metal bipolar plate,exhibit promising manufacturability,competitive cost and durability among various metal materials.However,stainless steel would be corroded in the harsh acid(pH 2-5)and humid PEMFCs environment,whereas the leached ions will contaminate the membrane.In addition,the passivated film formed on the surface will increase the interfacial contact resistance(ICR).In order to improve the corrosion resistance and electrical conductivity of steel bipolar plates,surface coatings are essential.Metal nitride coatings,metal carbide coatings,polymer coatings and carbon-based coatings have been introduced in recent years.Carbon-based coatings,mainly including a-C(amorphous Carbon),Ta-C(Tetrahedral amorphous carbon)and DLC(diamond-like carbon),have attracted considerable attention from both academia and industry,owing to their superior performance,such as chemical inertness,mechanical hardness and electrical conductivity.However,Ta-C films as protective coating of PEMFCs have been rarely reported,due to the difficulty in production for industrial application.In this paper,multi-layer Ta-C composite films were produced by using customized industrial-scale vacuum equipment to address those issues.[Methods]Multiple layered Ta-C coatings were prepared by using PIS624 equipment,which assembled filtered cathodic arc evaporation,ion beam and magnetron sputtering into one equipment,while SS304 and silicon specimens were used as substrate for testing and analysis.Adhesion layer and intermediate layer were deposited by using magnetron sputtering at deposition temperature of 150℃and pressure of 3×10^(−1) Pa,while the sputtering current was set to be 5 A and bias power to be 300 V.The Ta-C layer was coated at arc current of 80-100 A,bias voltage of 1500 V and gas flow of 75 sccm.A scanning electron microscope(CIQTEK SEM3200)was used to characterize surface morphology,coating structure and cross-section profile of the coatings.Raman spectrometer(LabRam HR Evolution,HORIBA JOBIN YVON)was used to identify the bonding valence states.Electrochemical tests were performed by using an electrochemical work station(CHI760,Shanghai Chenhua Instrument Co.,Ltd.),with the traditional three electrode system,where saturated Ag/AgCl and platinum mesh were used as the reference electrode and counter electrode,respectively.All samples were mounted in plastic tube and sealed with epoxy resin,with an exposure area of 2.25 cm^(2),serving as the working electrode.Electrochemical measurements were carried out in simulated PEMFCs cathode environment in 0.5 mol·L^(−1) H_(2)SO_(4)+5 ppm F−solution,at operating temperature of 70℃.As the cathode environment was harsher than the anode environment,all the samples are stabilized at the open-circuit potential(OCP)for approximately 30 min before the EIS measurements.ICR between bipolar plates and GDL was a key parameter affecting performance of the PEMFCs stack.The test sample sandwiched between 2 pieces of carbon paper(simulate gas diffusion layer,GDL)was placed between 2 gold-plated copper electrodes at a compaction pressure of 1.4 MPa,which was considered to be the conventional compaction pressure in the PEMFCs.Under the same conditions,the resistance of a single carbon paper was measured as well.The ICR was calculated according to the formula ICR=1/2(R2−R1)×S,where S was the contact area between GDL and coated stainless steel BPPs.All data of ICR were measured three times for averaging.[Results]The coatings deposited by filtered cathodic arc technology were compact and smooth,which reduced coating porosity and favorable to corrosion resistance.The coating thickness of adhesion and intermediate layers were 180 nm,while the protective Ta-C coating thickness was about 300 nm,forming multiple coating to provide stronger protection for metal bipolar plates.Cr,Ti,Nb and Ta coatings were selected as adhesion layers for comparison.According to electrochemical test,Ta and Nb coatings have higher corrosion resistance.However,Ta and Nb materials would be costly when they are used for mass production.Relatively,Cr and Ti materials were cost effective.Hence,a comprehensive assessment was indispensable to decide the materials to be selected as adhesion layer.Ta-TiN and Ti-TiN combined adhesion and intermediate layer exhibited stronger corrosion resistance,with the corrosion current to be less than 10^(−6) A·cm^(−2).Ta-C protective coating deposited by using filtered cathodic arc technology indicated displayed higher corrosion resistance,with the average corrosion density to be about 1.26×10^(−7) A·cm^(−2).Ta-C coating also shown larger contact angle,with the highest hydrophobicity,which was one of the important advantages for Ta-C,in terms of corrosion resistance.According to Raman spectroscopy,the I(D)/I(G)=549.8/1126.7=0.487,with the estimated fraction of sp^(3) bonding to be in the range of 5154%.The intermediate layer TiN has higher conductivity than the CrN layer.Considering cost,corrosion performance and ICR result,the Ti-TiN layer combination is recommended for industrial scale application.[Conclusions]Multiple layer coating structure of Ta-C film had stronger corrosion resistance;with more than 50%sp^(3) content,while it also had larger water contact angle and higher corrosion resistance than DLC film.The filtered arcing deposition technology was able to make the film to be more consistent and stable than normal arcing technology in terms of the preparation of Ta-C.The coating displayed corrosion density of 1.26×10^(−7) A·cm^(−2) and ICR of less than 5 mΩ·cm^(2),far beyond technical target of 2025 DOE(US Department of Energy).This indicated that the mass-production scale coating technology for PEMFC bipolar plates is highly possible.
基金Project(51175212)supported by the National Natural Science Foundation of China
文摘The periodic [Ti/TiB2]n （n=l, 2, 3） multilayered films were prepared on the substrate of AISI 316L stainless steel by magnetron sputtering to enhance the adhesion of TiB2 films based on the remarkable mechanical performance of layered films. The influence of periods on microstructure, adhesion and hardness of [Ti/TiB2]n multilayered films was studied. X-ray diffraction （XRD） analysis shows that the monolayer TiB2 films exhibit （001） preferred orientation, and the preferred orientation of [Ti/TiB2], multilayered films transfers from （001） to （100） with the increase of periods. The cross-sectional morphology of each film displays homogeneity by field emission scanning electron microscopy （FESEM）. The hardness of the films measured via nanoindention changes from 20 to 26 GPa with the increase of periods. These values of hardness are a bit lower than that of the monolayer TiB2 films which is up to 33 GPa. However, the [Ti/TiB2]n multilayered films present a considerably good adhesion, which reaches a maximum of 24 N, in comparison with the monolayer TiB2 films according to the experimental results.
基金supported by the National Key R&D Program of China(Gran Nos.2022YFA1402304 and 2022YFA1402802)the National Natural Science Foundation of China(Grant Nos.12494591,12122405,12274169,and 92165204)+4 种基金Program for Science and Technology Innovation Team in Zhejiang(Grant No.2021R01004)Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)Guangdong Fundamental Research Center for Magnetoelectric Physics(2024B0303390001)Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2401010)the Fundamental Research Funds for the Central Universities。
文摘The discovery of high-temperature superconductivity in bilayer nickelate La_(3)Ni_(2)O_(7)under high-pressure conditions has spurred extensive efforts to stabilize superconductivity at ambient pressure.Recently,the realization of superconductivity in compressively strained La_(3)Ni_(2)O_(7)thin films grown on the SrLaAlO_(4)substrates,with a T_(c)exceeding 40 K,represents a significant step toward this goal.Here,we investigate the influence of film thickness and carrier doping on the electronic structure of La_(3)Ni_(2)O_(7)thin films,ranging from 0.5 to 3 unit cells,using first-principles calculations.For a 2 unit-cell film with an optimal doping concentration of 0.3 hole per formula unit(0.15 hole/Ni),the Ni-d_(z^(2))interlayer bonding state crosses the Fermi level,resulting in the formation ofγpockets at the Fermi surface.These findings align with angle-resolved photoemission spectroscopy experimental data.Our results provide theoretical validation for the recent experimental discovery of ambient-pressure superconductivity in La_(3)Ni_(2)O_(7)thin films and underscore the significant impact of film thickness and carrier doping on electronic property modulation.
基金supported by the National Natural Science Foundation of China(Nos.22122306,22303084 and 52373025)。
文摘Polymer adsorption at solid interfaces plays an important role in the dynamics of nanoscale polymer films.We investigated the influence of the interfacial chain adsorption on the glass transition temperature(Tg)and dewetting of polystyrene(PS)thin films on a graphene substrate that has strong interaction with PS.We found that the Tgs of PS films show a non-monotonic trend with increasing amount of polymer adsorption at the interface—first increasing and then decreasing,and this change in Tg is accompanied by a wetting-dewetting transition of the PS films.Film morphological analysis showed that the PS films dewet from the interfacially adsorbed layers rather than from the substrate,i.e.,autophobic dewetting,indicating the presence of an unfavorable interaction between the adsorbed and free PS chains.We ascribed the repulsive interaction to the formation of a dense adsorbed layer on graphene due to the π-π interaction between PS and graphene,which prevents the nonadsorbed PS chain from penetrating into the adsorbed layer.This may lead to drops in Tg at high adsorption extent.
基金the Ahvaz Branch, Islamic Azad University for the financial support
文摘FeCoCrMnNiN_(x)high entropy nitride ceramics thin films were prepared using the magnetron sputtering method,and the effects of nitrogen content on the thin films’properties were later examined.The addition of N_(2)affected the microstructures of the thin films and their mechanical and corrosion properties.Compared with the FeCoCrMnNi thin films with 1-sccm N_(2),the addition of 2 and 3 sccm of N_(2)by as much as 5.45at%and 6.34at%changed the solid solution’s crystalline structure into an amorphous structure.The addition of nitro-gen caused drastic changes to the surface morphology,creating a smoother and more uniform surface without cauliflower units.The atomic force microscopy image analysis indicated that the addition of nitrogen reduced the surface roughness from 5.58 to 1.82 nm.Adding N_(2)to the CoCrFeMnNi thin film helped increase its mechanical properties,such as hardness and strength,while the Young’s modulus decreased.The hardness of(8.75±0.5)GPa and the reduced Young’s modulus of(257.37±11.4)GPa of the FeCoCrMnNi thin film reached(12.67±1.2)and(194.39±12.4)GPa,respectively,with 1 sccm N_(2).The applied coating of the CoCrFeMnNi thin film on 304SUS increased the corrosion resistance,whereas the addition of nitrogen to the CoCrFeMnNi thin film also improved its corrosion res-istance compared with that of the CoCrFeMnNi thin film without nitrogen.
基金funding from the Environmental Science Program for Academic Excellence and Community Research for Fiscal Year 2024,a financial resource of the Environmental Science and Technology Program,Faculty of Science,Buriram Rajabhat University.Additionally,Buriram Rajabhat University provided a publication budget.
文摘Polymeric materials,known for their lightweight and strength,are widely used today.However,their non-biodegradable nature poses significant environmental challenges.This research aimed to develop biodegradable films from fruits and vegetables,using alginate as a binding agent.Using a completely randomized design,seven experimental sets were prepared with carrots,Kimju guava,and Namwa banana peel fibers as the primary materials and alginate as the secondary material at three levels:1.2,1.8,and 2.4 by weight.The solution technique was employed to create the samples.Upon testing mechanical and physical properties,experimental set 3,consisting of 60%guava and 1.8%alginate,emerged as the optimal ratio.This combination exhibited favorable physical properties,including a thickness of 0.26±0.02 mm,meeting the standards for food packaging films.Additionally,the tensile strength was 0.50±0.01 N/m²,and the elongation at break was 55.60±0.44%.Regarding chemical properties,the moisture content of 5.64±0.03%fell within the acceptable range for dried food.Furthermore,a 30-day soil burial test revealed that the sample from experimental set 3 exhibited the highest degradation rate.In conclusion,these findings suggest that guava can be a promising raw material for producing biodegradable plastics suitable for packaging applications.
基金supported by the Key Research and Development Program of Jiangsu Province(BE2023009)the Natural Science Foundation of Chongqing(2022NSCQ-MSX2366)+1 种基金the Open Research Fund of Key Laboratory of MEMS of Ministry of Education,Southeast Universitysupported by Shanghai Pilot Program for Basic Research and the Fundamental Research Funds for the Central Universities.
文摘Photovoltaic(PV)technology plays a pivotal role in energy transformation processes,especially for sustainable energy systems.However,the conversion efficiency of the PV cells is adversely affected by increasing temperature,leading to a reduction in their overall performance.In this study,a self-hygroscopic polyvinyl alcohol/graphene(SPG)cooling film,comprising a graphene layer and a polyvinyl alcohol(PVA)hydrogel layer with lithium bromide(LiBr),is introduced to passively reduce the working temperature of the PV cells.The graphene layer,as a heat-conducting layer,can efficiently conduct heat from the heat source to the self-hygroscopic PVA hydrogel layer used as an evaporation cooling layer.In addition,the introduction of LiBr endows the PVA hydrogel with an excellent self-hygroscopic property.The SPG cooling film demonstrates an outstanding cooling performance under the synergistic effect of the graphene film and the self-hygroscopic PVA hydrogel.In the outdoor experiments,the SPG cooling film can reduce the temperature of the PV cells by 20.6℃and increase its average output power from 74 to 93 W/m^(2),about a 25.7%increase.This cooling film demonstrates significant potential for enhancing cooling performance in electronic devices and could be widely used in the thermal management of PV cells.
基金supported by the Program of the National Natural Science Foundation of China(No.22238002)the Fundamental Research Funds for the Central Universities(No.DUT22LAB610)+1 种基金Research and Innovation Team Project of Dalian University of Technology(No.DUT2022TB10)China Postdoctoral Science Foundation(No.2022M720639)。
文摘Dye-based color films are increasingly considered as viable alternatives to pigment-based color films in complementary metal-oxide-semiconductor(CMOS) image sensors.Herein,a series of azo dyes utilizing 5-methyl-2-phenyl-4-(2-phenylhydrazono)-2,4-dihydro-3H-pyrazol-3-one as the coupling component and aromatic amines with various electron-withdrawing groups(NO_(2),CN,Br) as diazo components were designed and synthesized.The presence of intermolecular hydrogen bonding between the hydrogen atom on the N-H group and the oxygen atom of the C=O group of the hydrazo structure facilitates the formation of a stable six-membered ring.Additionally,the electron-withdrawing groups in the diazo component further stabilize this hydrogen-bonded structure.As a result,these azo dyes(P-2,P-3,P-4,P-5)exhibit not only excellent light stability but also ultra-highly thermal stability(T_(d)> 260℃).Therein,the synthesized dyes P-2 and P-3 with great bright yellow color(~400 nm),proper solubility(~6.00g/100 g)were selected to make for color films.And their dye-based color films displayed ultra-highly thermal and light stability(color difference ΔE<3).Notably,the increased planarity of the molecular structure by hydrogen bonding for the novel dyes ensures a balance between high transmittance(>90%) in the 550-780 nm wavelength range and the solvent resistance of the dye-based color films.This work contributes to the advancement of next-generation smart CMOS devices and offers valuable insights into the design of azo dyes for applications in the field of organic electronics.
基金supported by the National Natural Science Foundation of China(Nos.62027818,61874034,11974320)the National Key R&D Program of China(No.2021YFB3202500)+1 种基金the Key R&D Program of Shanxi Province(No.202102030201008)the International Science and Technology Cooperation Program of Shanghai Science and Technology Innovation Action Plan(No.21520713300).
文摘Doped gallium oxide-based thin films are a class of wide-band semiconductor materials with the ad-vantages of chemically stable,tunable bandgap,and offer the benefit of ultraviolet response.In order to obtain photodetectors(PDs)with superior response,higher demands are placed on the quality of growth and processing of doped films.In this work,Zn-doped ternary metal oxide ZnGaO(ZGO)thin films were grown using the atomic layer deposition technique and annealed at different temperatures under an oxy-gen atmosphere.The results showed that the high-quality ZGO films with good uniformity,high visible light transmittance,low roughness,and significant reduction of oxygen vacancies were obtained after an-nealing.Subsequently,metal-semiconductor-metal PDs were prepared based on the studied ZGO films.The responsivity(R),detectivity(D^(∗)),and external quantum efficiency(EQE)of the optimized device are 61.8 A W^(-1),1.2×10^(12) Jones,and 255.9%,respectively.Compared to the unannealed device,the an-nealed ZGO PD achieves a maximum 309-fold increase in responsivity.This thermal engineering work may provide a strong reference for the development of low-cost,large-area,high-performance ultraviolet detection.And it also broadens the application of ternary metal oxides in optoelectronics.
基金supported by the National Natural Science Foundation of China(Grant No.11804288)the Natural Science Foundation of Henan(Grant No.232300420120)。
文摘The Casimir pressure plays an important role in the adhesion stability of nanofilms at submicro scales.In this work,the Casimir pressure of peptide films deposited on a layered substrate is investigated.Three types of semi-infinite substrates,i.e.,silica,silicon and gold,are considered.The buffer layer between the peptide film and substrate consists of silicon or silica.The switching sign of the Casimir pressure can be controlled in a region ranging from about 130 nm to 1000 nm,depending on the thickness of the buffer layer and the substrate.The results suggest that the critical thickness of peptide films for Casimir equilibrium increases(or decreases)by increasing the thickness of the silicon(or silica)buffer film.The influences of wetting and electrolyte screening on the Casimir pressure are also investigated.Our finding provides a theoretical guide for the adhesion stability of peptide films in organic electronics.
文摘T-carbon is a new allotrope of carbon materials,and it displays high hardness and low density.Nevertheless,the hardening mechanisms of T-carbon thin films under nanoindentation remain elusive.This work utilizes molecular dynamics simulation to explore the hardening mechanisms of T-carbon thin films under nanoindentation with variations of loading velocities and temperatures.The results reveal that a loading velocity increase at a given temperature raises the nanoindentation force.The increase in nanoindentation force is due to graphitization,which is related to the fracture of tetrahedral structures in T-carbon thin films.However,increased graphitization caused by an increased temperature lowers the nanoindentation force at a given loading velocity.The increased graphitization is influenced by both the fractured tetrahedrons and the deformation of inter-tetrahedron bond angles.This is attributed to the loss of thermal stability and the lower density of T-carbon thin films as the temperature increases.These findings have significant implications for the design of nanodevices for specific application requirements.
基金financially supported from the National Natural Science Foundation of China(Nos.52274291,52204305)Beijing Institute of Technology Research Fund Program for Young Scholars,China(No.1740011182102).
文摘The development of low-energy consumption and environmentally friendly electrodeposition of metal/alloy films or coatings is presently one of the primary topics for the research community.For this purpose,deep eutectic solvents(DESs)are valued as electrolytes for their advantages of low operating temperature and wide electrochemical windows.At present,there is large amount of literature on this emerging field,but there are no specialized reviews of these studies.Here,after a brief introduction of DESs’concept and history,we comprehensively reviewed the lastest progress on the metal/alloy electrodeposition in DESs.Additionally,we discussed the key influence factors of the electrodeposition process and analyzed the corresponding mechanisms.Based on these,we emphasized the importance of the establishment of predictive models for dealing with the challenges in large-scale applications.
基金financially supported by the Key Research and Development Program from the Ministry of Science and Technology(No.2023YFA1406301)the National Natural Science Foundation of China(Nos.12274061 and 12204090)+4 种基金Sichuan Science and Technology Program(No.2024ZYD0164)the Technology Department of Sichuan Province(No.2023NSFSC1336)the Young Scientists Fund of the National Natural Science Foundation of China(No.52403297)the National Natural Science Foundation of Jiangsu Province(No.BK20241426)the Young Elite Scientists Sponsorship Program of Jiangsu Association for Science and Technology(No.JSTJ-2024-010)
文摘The microelectronics industry is increasingly seeking freestanding multiferroic materials for the next generation of devices.Bismuth ferrite(BiFeO_(3)),known for its remarkable ferroelectric and antiferromagnetic properties at room temperature,holds great promise for multifunctional applications.However,current fabrication methods depend on Sr_(3)Al_(2)O_(6)sacrificial layers that deteriorate under ambient conditions,which limits their practical use.In this study,we showcase the exceptional qualities of strontium cobalt oxide(SrCoO_(2.5))as an innovative sacrificial layer for BiFeO_(3).We successfully fabricated highquality films of both BiFeO_(3)and SrCoO_(2.5)using pulsed laser deposition(PLD),and we achieved freestanding BiFeO_(3)films through a careful chemical etching process that ensures precise quality control.Our investigation into the solubility and stability of SrCoO_(2.5)reveals its advantages over Sr_(3)Al_(2)O_(6),demonstrating enhanced durability while allowing long-term preservation of SrCoO_(2.5).The resulting freestanding films exhibit excellent crystallinity and surface smoothness,paving the way for their integration into next-generation electronic devices.This research not only advances the preparation of high-quality freestanding BiFeO_(3)but also highlights the potential of using SrCoO_(2.5)as a sacrificial layer in various perovskite oxide thin films,which are suitable for sensors,actuators,and memory devices.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean Government(MSIT)(Nos.NRF-2021R1C1C2012825,2022R1A2B5B01001826,2022R1A5A2021216,and No.RS-2023-00218255)。
文摘Homogeneous films with tailored microporous structures are crucial for several applications;however,fabricating such films presents significant challenges.This is primarily because most microporous materials have crystal sizes in the nanoand micrometer ranges,which inevitably generates intergranular spaces in the films,thereby complicating the fabrication of these thin films.In this study,functionalized metal–organic polyhedra(MOPs)are used as discrete microporous units and assembled into homogenous microporous films.The generation of intergranular spaces is avoided while controlling packing parameters and film thicknesses.Initially,the MOP units,influenced by van der Waals forces between carbon chains of functionalized adipic acids,display an affinity to form spindle-shaped blocks and islands.As the MOP concentration increases,these structures self-assembled into a hexagonally packed structure with an in-plane orientation and a maximum stacking of two layers of MOPs.By contrast,un-functionalized MOPs form a disordered film structure owing to random agglomeration.Evidently,functionalized adipic acid influences the orientation of the MOP network films with uniformly distributed micropores,effectively preventing the formation of intergranular spaces.Additionally,formaldehyde adsorption and desorption experiments revealed that the MOP network films possess superior adsorption and desorption capacities.The proposed approach signifies a breakthrough in the fabrication of homogenous microporous films.
基金supported by the National Natural Science Foundation of China(Grant No.12474110)the National Key Research and Development Program of China(Grant No.2022YFA1403300)+1 种基金the Innovation Program for Quantum Science and Technology(Grant No.2024ZD0300103)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)。
文摘In antiferromagnets,dipolar coupling is often disregarded due to the cancellation of magnetic moments between the two sublattices,so that the spin-wave dispersion is predominantly determined by exchange interactions.However,antiferromagnetic spin waves typically involve a slight misalignment of the magnetic moments on the sublattices,which gives rise to a small net magnetization enabling long-range dipolar coupling.In this paper,we investigate the role of dipolar coupling in spin-wave excitations and its influence on the resulting dispersion.Our findings show that:(i)when the Néel vector is perpendicular to the film plane or lies within the film plane and parallel to the wave vector,the dispersion branches can be divided into two groups:those unaffected by the dipolar field and those influenced by it.In these cases,the total magnetic moment remains linearly polarized,but the polarization directions differ between the two types of branches;(ii)when the Néel vector lies in the film plane and is perpendicular to the wave vector,the dipolar interactions affect both types of dispersion branches,leading to their hybridization.This hybridization alters the polarization of the magnetic moment,resulting in elliptical polarization.
基金Project support by the National Key Research and Development Program of China(Grant No.2022YFA1603900)the National Natural Science Foundation of China–Beijing Joint Fund(Grant No.U23A6015)+1 种基金Central University Basic Research Fund of China(Grant No.E1E40207X2)the Funds from University of Chinese Academy of Sciences(Grant Nos.E1EG0210X2 and 118900M018).
文摘YBa_(2)Cu_(3)O_(7-x)(YBCO)films with low microwave surface resistance(RS)are essential for high temperature superconducting microwave devices.The oxygen pressure during deposition has been found to influence RS significantly.In this work,we deposited highly c-axis aligned YBCO films on single crystal MgO(001)substrates under different oxygen pressures via pulsed laser ablation.Their detailed microstructure was characterized with three-dimensional reciprocal space mapping(3D-RSM)method and their microwave surface resistance was also measured with resonant cavity perturbation method.We found that the variation of oxygen pressure can affect film microstructure,including grain orientation distribution and the concentration of crystal defects.The microstructure modulation can explain RS dependence on the oxygen pressure.
基金Project supported by the National Key R&D Program of China(Grant No.2022YFA1402404)the National Natural Science Foundation of China(Grant Nos.T2394473,624B2070,and 62274085)。
文摘Type-II Dirac semimetal PtTe2is a promising candidate for various electronic device applications due to its high carrier mobility,high conductivity,and air stability.In this work,we report on the growth of large-scale PtTe_(2)films by the pulsed laser deposition(PLD)and the comparison of the magnetotransport properties with the PtTe2films grown by the chemical vapor deposition(CVD).The low-temperature Hall curves of the PLD-grown films exhibit a linear behavior,in contrast with the nonlinear characteristic of the Hall behavior observed in CVD-grown films,in which a defect gradient is introduced.Meanwhile,both PtTe2films show weak antilocalization at low temperatures,which is attributed to the strong spin–orbit coupling.
