Y_(2.80)Pr_(0.20)Fe_(5)O_(12)/Ba_(0.6)Sr_(0.4)TiO_(3)thin film heterostructure was claimed by Jiao et al.in Journal of Materials Science&Technology 202(2024)174 as a tunable dielectric material with superior perfo...Y_(2.80)Pr_(0.20)Fe_(5)O_(12)/Ba_(0.6)Sr_(0.4)TiO_(3)thin film heterostructure was claimed by Jiao et al.in Journal of Materials Science&Technology 202(2024)174 as a tunable dielectric material with superior performance achieved under simultaneous application of the electric and magnetic fields at a particular frequency of 1.44 MHz.However,here we express concerns regarding the real presence of the phenomenon at 1.44 MHz in the studied structures based on the literature and dielectric spectroscopy principles.We also note that the presented dielectric results and their interpretations are contradictory.展开更多
A wide terahertz tuning range from 0.96 THz to 7.01 THz has been demonstrated based on ring-cavity THz wave parametric oscillator with a KTiOPO_(4)(KTP)crystal.The tuning range was observed intermittently from 0.96 TH...A wide terahertz tuning range from 0.96 THz to 7.01 THz has been demonstrated based on ring-cavity THz wave parametric oscillator with a KTiOPO_(4)(KTP)crystal.The tuning range was observed intermittently from 0.96 THz to 1.87 THz,from 3.04 THz to 3.33 THz,from 4.17 THz to 4.48 THz,from 4.78 THz to 4.97 THz,from 5.125 THz to 5.168 THz,from5.44 THz to 5.97 THz,and from 6.74 THz to 7.01 THz.The dual-Stokes wavelengths resonance phenomena were observed in some certain tuning angle ranges.Through the theoretical analysis of the dispersion curve of the KTP crystal,the intermittent THz wave tuning range and dual-wavelength Stokes waves operation during angle tuning process were explained.The theoretical analysis was in good agreement with the experiment results.The maximum THz output voltage detected by Golay cell was 1.7 V at 5.7 THz under the pump energy of 210 mJ,corresponding to the THz wave output energy of5.47μJ and conversion efficiency of 2.6×10^(-5).展开更多
The optical properties of cylindrical core–shell nanorods(CCSNs)are theoretically investigated in this paper.The results show that Fano resonance can be generated in CCSNs,and the wavelength and the intensity at Fano...The optical properties of cylindrical core–shell nanorods(CCSNs)are theoretically investigated in this paper.The results show that Fano resonance can be generated in CCSNs,and the wavelength and the intensity at Fano dip can be tuned respectively by adjusting the field coupling of cavity mode inside and near field on gold surface.The high tuning sensitivity which is about 400 nm per refractive-index unit can be obtained,and an easy-to-realize tunable parameter is also proposed.A two-oscillator model is also introduced to describe the generation of Fano resonance in CCSNs,and the results from this model are in good agreement with theoretical results.The CCSNs investigated in this work may have promising applications in optical devices.展开更多
A composite ceramic with nominal composition of 45.0 wt%（Ba0.5Sr0.5）TiO3–55.0 wt%MgO（acronym is BST–MgO） is sintered for fabricating a frequency reconfigurable aperture-coupled microstrip antenna. The calcined ...A composite ceramic with nominal composition of 45.0 wt%（Ba0.5Sr0.5）TiO3–55.0 wt%MgO（acronym is BST–MgO） is sintered for fabricating a frequency reconfigurable aperture-coupled microstrip antenna. The calcined BST–Mg O composite ceramic exhibits good microwave dielectric properties at X-band with appropriate dielectric constant εr around85, lower dielectric loss tan δ about 0.01, and higher permittivity tunability 14.8% at 8.33 k V/cm. An ultrahigh E-field tunability of working frequency up to 11.0%（i.e., from 9.1 GHz to 10.1 GHz with a large frequency shift of 1000 MHz）at a DC bias field from 0 to 8.33 k V/cm and a considerably large center gain over 7.5 d B are obtained in the designed frequency reconfigurable microstrip antenna. These results demonstrate that BST materials are promising for the frequency reconfigurable antenna.展开更多
The electric-field tunability of dielectric constant （ε-E） in Sr1-xMnxTiO3 films （x = 0, 0.005, 0.010, 0.020 and 0.030） prepared by the metal organic decomposition method on Pt/Ti/SiO2/Si substrates is studied in...The electric-field tunability of dielectric constant （ε-E） in Sr1-xMnxTiO3 films （x = 0, 0.005, 0.010, 0.020 and 0.030） prepared by the metal organic decomposition method on Pt/Ti/SiO2/Si substrates is studied in the frequency range from 100Hz to 1MHz with different Mn contents at different temperatures. The frequencyindependent tunability increases strongly with decreasing the temperature from 300 K to 150K. The tunability （-31%） in thin films （x = 0.005） at 150K is obtained and the temperature for the same tunability in ceramics is about 60 K lower than the present one. This tunability is comparable with that in one of ferroelectric Sr1-1.sxBixTiO3 thin films. Similarly, the well-defined P（E） hysteresis 10013 and 2Pr （1.2 μC/cm^2） can be obtained at 300 K in Sr1-xMnxTiO3 films with z = 0.005. Both the existence of electric dipole or poled micro domain introduced by the doped Mn2＋ located in the off-center position at Sr sites and the strain between the thin film and the substrate are the origins of the tunable and polar behavior in Sr1-xMnxTiO3 films.展开更多
It is hard to simultaneously realize the high dielectric tunability and low loss for the single Ba_(0.6)Sr_(0.4)TiO_(3)(BST)dielectric film made through chemical method.Garnet structured Y_(2.80)Pr_(0.20)Fe_(5)O_(12)(...It is hard to simultaneously realize the high dielectric tunability and low loss for the single Ba_(0.6)Sr_(0.4)TiO_(3)(BST)dielectric film made through chemical method.Garnet structured Y_(2.80)Pr_(0.20)Fe_(5)O_(12)(YPrIG)ex-hibits the merits of high saturation magnetization and a much high resistivity,which are helpful for realizing magnetoelectric double tuning and suppressing the dielectric loss of BST film.In this work,Y_(2.80)Pr_(0.20)Fe_(5)O_(12)/Ba_(0.6)Sr_(0.4)TiO_(3)(YPrIG/BST)composite films were fabricated by sol-gel method.The com-posite films exhibited a low dielectric loss(0.0087),and got a magnetic tunability of 11.73%at 10 kOe and 1.44 MHz.Compared with BST film,the tunability of YPrIG/BST film was enhanced from 56.25%to 73.24%under the bias electric field of 800 kV/cm.Additionally,YPrIG/BST films exhibited an electromag-netic double adjustability.The electromagnetic tunability of YPrIG/BST composite films was as high as 80.40%at 1.44 MHz,under the DC bias electric field of 800 kV/cm and magnetic field of 10 kOe.This phenomenon can be explained in terms of the superposition effect of electric field and magnetic field.展开更多
We report a direct blue-diode-pumped wavelength tunable Kerr-lens mode-locked Ti: sapphire laser.Central wavelength tunability as broad as 89 nm(736-825 nm) is achieved by adjusting the insertion of the prism.Pulses a...We report a direct blue-diode-pumped wavelength tunable Kerr-lens mode-locked Ti: sapphire laser.Central wavelength tunability as broad as 89 nm(736-825 nm) is achieved by adjusting the insertion of the prism.Pulses as short as 17 fs are generated at a central wavelength of 736 nm with an average output power of 31 mW.The maximum output power is 46.8 mW at a central wavelength of 797 nm with a pulse duration of 46 fs.展开更多
Lead-halide perovskite nanocrystals(PNCs)exhibit exceptional optical properties with size-and dimensiontunable optical bandgaps,making them promising for diverse optoelectronic applications.The dimensionality of PNCs ...Lead-halide perovskite nanocrystals(PNCs)exhibit exceptional optical properties with size-and dimensiontunable optical bandgaps,making them promising for diverse optoelectronic applications.The dimensionality of PNCs has been controlled by tuning the oleic acid(OA)/oleylamine(OLA)feed ratio in conventional injection-based synthesis.Although the emerging bimolecular nucleophilic substitution(S_(N)2)-based heatup synthesis enables the production of high-quality and monodisperse PNCs,achieving dimensional tunability by altering the OA/OLA feed ratio remains challenging in this approach.Herein,we present an integrated strategy for controlling the dimensionality and surface properties of CsPbI_(3)-PNCs based on the S_(N)2-based heat-up method.Our approach focuses on the regulation of OLA protonation and oleylammonium(OAM^(+))latticeforming behavior.Using chemical analysis,we identify the protonation routes of OLA in S_(N)2 reactions and demonstrate that adjusting the acid–base and S_(N)2 reactions involving OA and OLA can reduce OLA protonation and the subsequent formation of OAM^(+).Furthermore,by enhancing the competitive lattice-forming behavior of Cs^(+)over OAM+,we suppress excessive surface termination by OAM^(+).These approaches achieve dimensional tunability between two-dimensional(2D)nanoplatelets and three-dimensional(3D)nanocubes in the S_(N)2-based heat-up synthesis,along with subsequent spectral control of optical features.To independently optimize their surface passivation,we employ a post-synthetic passivation(PSP)strategy using OAM^(+)–I−pairs,which increases the photoluminescence quantum yield of PNCs from 71.9%to 81.7%by reducing surface defects.展开更多
Integration of graphene in silicon-based micro-/nanoelectromechanical systems(MEMS/NEMS)marries the robustness of silicon-based materials with the exceptional physical properties of graphene,drastically enhancing the ...Integration of graphene in silicon-based micro-/nanoelectromechanical systems(MEMS/NEMS)marries the robustness of silicon-based materials with the exceptional physical properties of graphene,drastically enhancing the system’s regulation performance which now is key for many advanced applications in nanotechnology.Here,we experimentally demonstrate and theoretically analyze a powerful on-chip integration principle consisting of a hybrid graphene/silicon nitride membrane with metallic leads on top that enables an extremely large static and dynamic parameter regulation.When a static voltage is applied to the leads of the integrated structure,a spatially confined localized electrothermomechanical(ETM)effect results in ultra-wide frequency tuning,deformation(buckling transition)and regulation of the mechanical properties.Moreover,by injecting an alternating voltage to the leads,we can excite the resonator vibrating even far beyond its linear regime without a complex and space consuming actuation system.Our results prove that the scheme provides a compact integrated system possessing mechanical robustness,high controllability,and fast response.It not only expands the limit of the application range of MEMS/NEMS devices,but also enables the further miniaturization of the device.展开更多
A symmetrical one-dimensional(1D)photonic crystal structure with a Dirac-emimetal-defected layer is proposed.The material properties of the Dirac semimetal are governed by three key parameters:Fermi level,Fermi veloci...A symmetrical one-dimensional(1D)photonic crystal structure with a Dirac-emimetal-defected layer is proposed.The material properties of the Dirac semimetal are governed by three key parameters:Fermi level,Fermi velocity,and degeneracy factor.Simulation results demonstrate that the proposed structure generates multiple photonic bandgaps within the THz frequency range.In the low-THz region,pronounced resonant transmission peaks emerge,enabling near-perfect filtering performance.The positions of these defect modes can be dynamically tuned by adjusting the Fermi level and degeneracy factor.In mid-and high-THz frequency bands,the Dirac semimetal begins to exhibit metallic behavior,leading to attenuation of the transmission peaks and the appearance of absorption.The elevation of the Fermi level delays the critical threshold for the transition from the dielectric state to the metallic state,while an increase in Fermi velocity suppresses metallic behavior.Therefore,enhancing both the Fermi level and Fermi velocity contributes to strengthening the defect peak intensity.Conversely,increasing the degeneracy factor strengthens the metallic characteristics,thereby disrupting the high-frequency photonic bandgap.Notably,the defect layer thickness and incident angle exert significant influence on the transmission behavior:a larger incident angle causes the defect peak to shift toward higher frequencies and reduces its intensity,whereas a thicker defect layer shifts the defect peak toward lower frequencies.The modulation effects of both parameters become more pronounced as frequency increases.Compared with conventional photonic crystals,our work can provide a tunable structure over transmission properties,offering novel strategies for designing tunable filters and optical sensors.展开更多
We suggest a low cross-talk plasmonic cross-connector based on a metal/insulator/metal cavity and waveguides.We separately investigate the isolated cavity mode, the waveguide mode, and the combination of cavity and wa...We suggest a low cross-talk plasmonic cross-connector based on a metal/insulator/metal cavity and waveguides.We separately investigate the isolated cavity mode, the waveguide mode, and the combination of cavity and waveguide modes using a finite-different time-domain method. Due to resonant tunneling and the cutoff frequency of the odd waveguide mode, our proposed structure achieves a high throughput transmission ratio and eliminates cross-talk. Furthermore, the proposed structure has a broadband tunability of 587 nm, which can be achieved by modulating the cavity air gap thickness. This structure enables the miniaturization of photonic integrated circuits and sensing applications.展开更多
MXene-based films have been intensively explored for construction of piezoresistive flexible pressure sensors owing to their excellent mechanical and electrical properties.High pressure sensitivity relies on pre-moldi...MXene-based films have been intensively explored for construction of piezoresistive flexible pressure sensors owing to their excellent mechanical and electrical properties.High pressure sensitivity relies on pre-molding a flexible substrate,or regulating the micromorphology of MXene sheets,to obtain a micro-structured surface.However,the two avenues usually require complicated and time-consuming microfabrication or wet chemical processing,and are limited to non-adjustable topographicelectrical(topo-electro)properties.Herein,we propose a lithographic printing inspired in-situ transfer(LIPIT)strategy to fabricate MXene-ink films(MIFs).In LIPIT,MIFs not only inherit ridge-and-valley microstructure from paper substrate,but also achieve localized topo-electro tunability by programming ink-writing patterns and cycles.The MIF-based flexible pressure sensor with periodical topo-electro gradient exhibits remarkably boosted sensitivity in a wide sensing range(low detection limit of 0.29 Pa and working range of 100 kPa).The MIF sensor demonstrates versatile applicability in both subtle and vigorous pressuresensing fields,ranging from pulse wave extraction and machine learning-assisted surface texture recognition to piano-training glove(PT-glove)for piano learning.The LIPIT is quick,low-cost,and compatible with free ink/substrate combinations,which promises a versatile toolbox for designing functional MXene films with tailored morphological-mechanical-electrical properties for extended application scenarios.展开更多
All-inorganic zero-dimensional(0D)tetrahedrite(Cu12Sb4S13,CAS)quantum dots(QDs)have attracted extensive attention due to their excellent optical properties,bandgap tunability,and carrier mobility.In this paper,various...All-inorganic zero-dimensional(0D)tetrahedrite(Cu12Sb4S13,CAS)quantum dots(QDs)have attracted extensive attention due to their excellent optical properties,bandgap tunability,and carrier mobility.In this paper,various sized CAS QDs(5.1,6.7,and 7.9 nm)are applied as a switching layer with the structure F:Sn O2(FTO)/CAS QDs/Au,and in doing so,the nonvolatile resistive-switching behavior of electronics based on CAS QDs is reported.The SET/RESET voltage tunability with size dependency is observed for memory devices based on CAS QDs for the first time.Results suggest that differently sized CAS QDs result in different band structures and the regulation of the SET/RESET voltage occurs simply and effectively due to the uniform size of the CAS QDs.Moreover,the presented memory devices have reliable bipolar resistive-switching properties,a resistance(ON/OFF)ratio larger than 104,high reproducibility,and good data retention ability.After 1.4×10^6s of stability testing and 104cycles of quick read tests,the change rate of the ON/OFF ratio is smaller than 0.1%.Furthermore,resistiveswitching stability can be improved by ensuring a uniform particle size for the CAS QDs.The theoretical calculations suggest that the space-charge-limited currents(SCLCs),which are functioned by Cu 3d,Cu 3p and S 3p to act as electron selftrapping centers due to their quantum confinement and form conduction pathways under an electric field,are responsible for the resistive-switching effect.This paper demonstrates that CAS QDs are promising as a novel resistive-switching material in memory devices and can be used to facilitate the application of next-generation nonvolatile memory.展开更多
Organic electrochemical transistor(OECT)devices demonstrate great promising potential for reservoir computing(RC)systems,but their lack of tunable dynamic characteristics limits their application in multi-temporal sca...Organic electrochemical transistor(OECT)devices demonstrate great promising potential for reservoir computing(RC)systems,but their lack of tunable dynamic characteristics limits their application in multi-temporal scale tasks.In this study,we report an OECT-based neuromorphic device with tunable relaxation time(τ)by introducing an additional vertical back-gate electrode into a planar structure.The dual-gate design enablesτreconfiguration from 93 to 541 ms.The tunable relaxation behaviors can be attributed to the combined effects of planar-gate induced electrochemical doping and back-gateinduced electrostatic coupling,as verified by electrochemical impedance spectroscopy analysis.Furthermore,we used theτ-tunable OECT devices as physical reservoirs in the RC system for intelligent driving trajectory prediction,achieving a significant improvement in prediction accuracy from below 69%to 99%.The results demonstrate that theτ-tunable OECT shows a promising candidate for multi-temporal scale neuromorphic computing applications.展开更多
The luminescence modulation behaviour under the in-situ electric field of rare-earth doped KSr_(2)Nb_(5)O_(15) ceramics opened a new door for the development of dielectric materials.Where the understanding the effect ...The luminescence modulation behaviour under the in-situ electric field of rare-earth doped KSr_(2)Nb_(5)O_(15) ceramics opened a new door for the development of dielectric materials.Where the understanding the effect of rare-earth doping on the electric properties of host,especially at the similar doping concentration with luminescence researches(low concentrations)is very important for the exploration of mechanism of electric-luminescent coupling effect.In this work,Nd^(3+)-doped KSr_(2)Nb_(5)O_(15)(KSN-xNd)ceramics were synthesized,and the electric properties were investigated systematically.Our results suggest that the Nd^(3+) doping slightly increased the phase transition temperatures and improved the piezoelectric response of KSr_(2)Nb_(5)O_(15).Most importantly,a bidirectional dielectric tunability is revealed in KSr_(2)Nb_(5)O_(15).The dielectric permittivity can be adjusted by the DC electric bias,with tunability ranging from12.3% to 21.9%.The related mechanism and relationship between the bidirectional dielectric tunability and ferroelectricity are revealed by temperature-dependent dielectric and ferroelectric characterization.The researches of electric properties and bidirectional dielectric tunability of KSN-based ceramics paved the way to further exploration of electric-luminescent coupling mechanism.展开更多
Hospital wastewater contains complex pollutants,including residual organic dyes and antibiotic-resistant pathogens,posing severe risks to ecosystems and human health.Conventional adsorbents,constrained by monopolar fu...Hospital wastewater contains complex pollutants,including residual organic dyes and antibiotic-resistant pathogens,posing severe risks to ecosystems and human health.Conventional adsorbents,constrained by monopolar functional groups and limited surface sites,fail to remove both pollutants simultaneously.Here,we report an intelligent responsive polyurethane microsphere adsorbent doped with diallyl dimethylammonium chloride modified carbon nanotubes,termed as PUCD microspheres.The PUCD integrates bipolar adsorption sites,tunable micrometer-scale pores,and a near-infrared(NIR)-triggered in situ capture mechanism within a single platform,which achieves up to 98.3%dye removal,maintains strong adsorption performance across a wide pH range and retains 83.3%efficiency for rhodamine B after five cycles.Notably,the PUCD employs a temperature-responsive phase transition:under NIR irradiation,the microspheres undergo shrinkage,reducing the pore size to generate a‘polymer trap',enabling in situ capture of bacteria with>99%efficiencies for both Staphylococcus aureus and Escherichia coli.By immobilizing live bacteria,the PUCD microspheres substantially reduces the risk of pathogen desorption and toxin release.This promising platform offers a safe,efficient,and single-stage strategy for hospital wastewater purification,enabling the simultaneous elimination of dyes and pathogenic bacteria.展开更多
Hydrogen peroxide(H_(2)O_(2)) has been recognized as a green and nonpolluting multifunctional oxidant with extensive applications in environmental protection,metal etching,textile printing and dyeing,chemical synthesi...Hydrogen peroxide(H_(2)O_(2)) has been recognized as a green and nonpolluting multifunctional oxidant with extensive applications in environmental protection,metal etching,textile printing and dyeing,chemical synthesis and food processing.However,over 90 % of industrial H_(2)O_(2) is currently produced through the multi-step anthraquinone oxidation process,which suffers from a process with some drawbacks such as complex,high-energy consumption,and toxic byproducts emissions.Compared to the traditional anthraquinone method,artificial photosynthesis of H_(2)O_(2) using semiconductor photocatalysts has emerged as a sustainable alternative due to its use of water and O_(2) as the clean reactants and sole energy as the driving force.In recent years,metal-free photocatalysts mainly including covalent organic frameworks(COFs),covalent triazine frameworks(CTFs) and carbon nitrile(g-C_(3)N_(4)) have garnered significant interest due to their superior thermal and chemical stability,diverse synthesis methods,tunable functionality,light weight nature and non-toxicity.These materials also exhibit adjustable band structure and unique photoelectric properties.Sustainable efforts have been made to advance metal-free photocatalysts for artificial photosynthesis of H_(2)O_(2),however,a comprehensive summary of current research status on metalfree-based photocatalytic overall H_(2)O_(2) production remain scarce.This review outlines recent process in overall H_(2)O_(2) photosynthesis based on metal-free photocatalysts.First,we introduced the fundamental concepts of photocatalytic overall H_(2)O_(2) production.Then,we analyze representative studies on photocatalytic overall H_(2)O_(2) synthesis using metal-free materials.Finally,we discuss the challenges and future perspectives in this field to guide the design and synthesis of metal-free systems for H_(2)O_(2) generation.展开更多
Tunable mid-infrared and far-infrared laser output was demonstrated based on BaGa_(4)Se_(7)crystals and an optical parametric oscillator(OPO).With a 1.06μm Nd:YAG laser and a double-pass singly resonant OPO cavity,a ...Tunable mid-infrared and far-infrared laser output was demonstrated based on BaGa_(4)Se_(7)crystals and an optical parametric oscillator(OPO).With a 1.06μm Nd:YAG laser and a double-pass singly resonant OPO cavity,a laser energy output of 2.2 mJ at 10μm was obtained.By tuning the angle and temperature,a tunable laser output covering the wavelength range from 6μm to 17μm was obtained with a tuning precision better than 3 nm.The corresponding optical-to-optical conversion efficiency was 2.8%,and the slope efficiency was 4.4%.The damage effect of the output laser on detectors was also investigated,and point damage to the detector occurred at an output energy of 16.4μJ.The laser system has the advantages of miniaturization,a wide tuning range,high energy and high tuning resolution.Its broadband laser characteristics make it highly valuable for applications in atmospheric detection,infrared spectroscopy and electro-optical countermeasures.展开更多
Co_(3)S_(4)electrocatalysts with mixed valences of Co ions and excellent structural stability possess favorable oxygen evolution reaction(OER)activity,yet challenges remain in fabricating rechargeable lithiumoxygen ba...Co_(3)S_(4)electrocatalysts with mixed valences of Co ions and excellent structural stability possess favorable oxygen evolution reaction(OER)activity,yet challenges remain in fabricating rechargeable lithiumoxygen batteries(LOBs)due to their poor OER performance,resulting from poor electrical conductivity and overly strong intermediate adsorption.In this work,fancy double heterojunctions on 1T/2H-MoS_(2)@Co_(3)S_(4)(1T/2H-MCS)were constructed derived from the charge donation from Co to Mo ions,thus inducing the phase transformation of Mo S_(2)from 2H to 1T.The unique features of these double heterojunctions endow the1T/2H-MCS with complementary catalysis during charging and discharging processes.It is worth noting that 1T-Mo S2@Co3S4could provide fast Co-S-Mo electron transport channels to promote ORR/OER kinetics,and 2H-MoS_(2)@Co_(3)S_(4)contributed to enabling moderate egorbital occupancy when adsorbed with oxygen-containing intermediates.On the basis,the Li_(2)O_(2)nucleation route was changed to solution and surface dual pathways,improving reversible deposition and decomposition kinetics.As a result,1T/2H-MCS cathodes exhibit an improved electrocatalytic performance compared with those of Co_(3)S_(4)and Mo S2cathodes.This innovative heterostructure design provides a reliable strategy to construct efficient transition metal sulfide catalysts by improving electrical conductivity and modulating adsorption toward oxygenated intermediates for LOBs.展开更多
A simple configuration dual-wavelength fiber laser,by combining the first-order Brillouin laser and the residual pump laser,is proposed and experimentally demonstrated.A 1 km long single-mode fiber is used as the stim...A simple configuration dual-wavelength fiber laser,by combining the first-order Brillouin laser and the residual pump laser,is proposed and experimentally demonstrated.A 1 km long single-mode fiber is used as the stimulated Brillouin scattering gain medium pumped by a narrow linewidth tunable laser source（TLS）.Through simply adjusting the TLS output power,power-equalized dual-wavelength lasing can be achieved with a high optical signal to noise ratio（OSNR） of 〉80 d B.With the good tunability of the TLS,the dual-wavelength fiber laser has a tunable range of -130 nm,and simultaneously the beat frequency of the two lasing wavelengths can be tuned from 10.1875 to 11.0815 GHz with the tunable range of 0.8940 GHz.The high stability of the dualwavelength operation is experimentally verified by the measured beat frequency fluctuation of ≤6 MHz in 1 h and power fluctuation of ≤0.03 d B in 2 h.The temporal characteristics of the fiber laser are also investigated experimentally.The fiber laser will find good applications in fiber sensing and microwave photonics areas.展开更多
基金the FCT/MEC(PIDDAC)within FCT independent researcher grant 2021.02284.CEECIND/CP1659/CT0018(DOI 10.54499/2021.02284.CEECIND/CP1659/CT0018)+1 种基金supported by national funds,through FCT in the scope of the framework contract foreseen in numbers 4,5,and 6 of article 23 of the Decree Law 57/2016,of 29 August,UIDB/00481/2020 and UIDP/00481/2020,DOI 10.54499/UIDB/00481/2020 and DOI 10.54499/UIDP/00481/2020CENTRO-01-0145-FEDER-022083-Centro Portugal Regional Operational Programme(Centro2020),under the PORTUGAL 2020 Partnership Agreement,through the European Regional Develop-ment Fund.
文摘Y_(2.80)Pr_(0.20)Fe_(5)O_(12)/Ba_(0.6)Sr_(0.4)TiO_(3)thin film heterostructure was claimed by Jiao et al.in Journal of Materials Science&Technology 202(2024)174 as a tunable dielectric material with superior performance achieved under simultaneous application of the electric and magnetic fields at a particular frequency of 1.44 MHz.However,here we express concerns regarding the real presence of the phenomenon at 1.44 MHz in the studied structures based on the literature and dielectric spectroscopy principles.We also note that the presented dielectric results and their interpretations are contradictory.
基金Project supported by the National Basic Research Program of China(Grant Nos.2015CB755403 and 2014CB339802)the National Key Research and Development Program of China(Grant No.2016YFC0101001)+2 种基金the National Natural Science Foundation of China(Grant Nos.61775160,61771332,and 61471257)China Postdoctoral Science Foundation(Grant No.2016M602954)Postdoctoral Science Foundation of Chongqing,China(Grant No.Xm2016021)
文摘A wide terahertz tuning range from 0.96 THz to 7.01 THz has been demonstrated based on ring-cavity THz wave parametric oscillator with a KTiOPO_(4)(KTP)crystal.The tuning range was observed intermittently from 0.96 THz to 1.87 THz,from 3.04 THz to 3.33 THz,from 4.17 THz to 4.48 THz,from 4.78 THz to 4.97 THz,from 5.125 THz to 5.168 THz,from5.44 THz to 5.97 THz,and from 6.74 THz to 7.01 THz.The dual-Stokes wavelengths resonance phenomena were observed in some certain tuning angle ranges.Through the theoretical analysis of the dispersion curve of the KTP crystal,the intermittent THz wave tuning range and dual-wavelength Stokes waves operation during angle tuning process were explained.The theoretical analysis was in good agreement with the experiment results.The maximum THz output voltage detected by Golay cell was 1.7 V at 5.7 THz under the pump energy of 210 mJ,corresponding to the THz wave output energy of5.47μJ and conversion efficiency of 2.6×10^(-5).
基金Project supported by the National Natural Science Foundation of China(Grant No.11647021)。
文摘The optical properties of cylindrical core–shell nanorods(CCSNs)are theoretically investigated in this paper.The results show that Fano resonance can be generated in CCSNs,and the wavelength and the intensity at Fano dip can be tuned respectively by adjusting the field coupling of cavity mode inside and near field on gold surface.The high tuning sensitivity which is about 400 nm per refractive-index unit can be obtained,and an easy-to-realize tunable parameter is also proposed.A two-oscillator model is also introduced to describe the generation of Fano resonance in CCSNs,and the results from this model are in good agreement with theoretical results.The CCSNs investigated in this work may have promising applications in optical devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.11074040)the Key Project of Shandong Provincial Department of Science and TechnologyChina(Grant No.ZR2012FZ006)
文摘A composite ceramic with nominal composition of 45.0 wt%（Ba0.5Sr0.5）TiO3–55.0 wt%MgO（acronym is BST–MgO） is sintered for fabricating a frequency reconfigurable aperture-coupled microstrip antenna. The calcined BST–Mg O composite ceramic exhibits good microwave dielectric properties at X-band with appropriate dielectric constant εr around85, lower dielectric loss tan δ about 0.01, and higher permittivity tunability 14.8% at 8.33 k V/cm. An ultrahigh E-field tunability of working frequency up to 11.0%（i.e., from 9.1 GHz to 10.1 GHz with a large frequency shift of 1000 MHz）at a DC bias field from 0 to 8.33 k V/cm and a considerably large center gain over 7.5 d B are obtained in the designed frequency reconfigurable microstrip antenna. These results demonstrate that BST materials are promising for the frequency reconfigurable antenna.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51225201,61271078,and 51102133the National Basic Research Program of China under Grant No 2015CB921201+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Fundamental Research Funds for the Central Universities
文摘The electric-field tunability of dielectric constant （ε-E） in Sr1-xMnxTiO3 films （x = 0, 0.005, 0.010, 0.020 and 0.030） prepared by the metal organic decomposition method on Pt/Ti/SiO2/Si substrates is studied in the frequency range from 100Hz to 1MHz with different Mn contents at different temperatures. The frequencyindependent tunability increases strongly with decreasing the temperature from 300 K to 150K. The tunability （-31%） in thin films （x = 0.005） at 150K is obtained and the temperature for the same tunability in ceramics is about 60 K lower than the present one. This tunability is comparable with that in one of ferroelectric Sr1-1.sxBixTiO3 thin films. Similarly, the well-defined P（E） hysteresis 10013 and 2Pr （1.2 μC/cm^2） can be obtained at 300 K in Sr1-xMnxTiO3 films with z = 0.005. Both the existence of electric dipole or poled micro domain introduced by the doped Mn2＋ located in the off-center position at Sr sites and the strain between the thin film and the substrate are the origins of the tunable and polar behavior in Sr1-xMnxTiO3 films.
基金supported by the National Natural Science Foundation of China(Nos.52171191,52371198)Shaanxi Key Program for International Science and Technology Coopera-tion Projects(No.2021KWZ-12)the Youth Innovation Team of Shaanxi Universities.
文摘It is hard to simultaneously realize the high dielectric tunability and low loss for the single Ba_(0.6)Sr_(0.4)TiO_(3)(BST)dielectric film made through chemical method.Garnet structured Y_(2.80)Pr_(0.20)Fe_(5)O_(12)(YPrIG)ex-hibits the merits of high saturation magnetization and a much high resistivity,which are helpful for realizing magnetoelectric double tuning and suppressing the dielectric loss of BST film.In this work,Y_(2.80)Pr_(0.20)Fe_(5)O_(12)/Ba_(0.6)Sr_(0.4)TiO_(3)(YPrIG/BST)composite films were fabricated by sol-gel method.The com-posite films exhibited a low dielectric loss(0.0087),and got a magnetic tunability of 11.73%at 10 kOe and 1.44 MHz.Compared with BST film,the tunability of YPrIG/BST film was enhanced from 56.25%to 73.24%under the bias electric field of 800 kV/cm.Additionally,YPrIG/BST films exhibited an electromag-netic double adjustability.The electromagnetic tunability of YPrIG/BST composite films was as high as 80.40%at 1.44 MHz,under the DC bias electric field of 800 kV/cm and magnetic field of 10 kOe.This phenomenon can be explained in terms of the superposition effect of electric field and magnetic field.
基金Project supported by the National Key R&D Program of China(Grant No.2016YFB0402105)
文摘We report a direct blue-diode-pumped wavelength tunable Kerr-lens mode-locked Ti: sapphire laser.Central wavelength tunability as broad as 89 nm(736-825 nm) is achieved by adjusting the insertion of the prism.Pulses as short as 17 fs are generated at a central wavelength of 736 nm with an average output power of 31 mW.The maximum output power is 46.8 mW at a central wavelength of 797 nm with a pulse duration of 46 fs.
基金supported by the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(Nos.RS-2023-00207907 and RS-2024-00444458).
文摘Lead-halide perovskite nanocrystals(PNCs)exhibit exceptional optical properties with size-and dimensiontunable optical bandgaps,making them promising for diverse optoelectronic applications.The dimensionality of PNCs has been controlled by tuning the oleic acid(OA)/oleylamine(OLA)feed ratio in conventional injection-based synthesis.Although the emerging bimolecular nucleophilic substitution(S_(N)2)-based heatup synthesis enables the production of high-quality and monodisperse PNCs,achieving dimensional tunability by altering the OA/OLA feed ratio remains challenging in this approach.Herein,we present an integrated strategy for controlling the dimensionality and surface properties of CsPbI_(3)-PNCs based on the S_(N)2-based heat-up method.Our approach focuses on the regulation of OLA protonation and oleylammonium(OAM^(+))latticeforming behavior.Using chemical analysis,we identify the protonation routes of OLA in S_(N)2 reactions and demonstrate that adjusting the acid–base and S_(N)2 reactions involving OA and OLA can reduce OLA protonation and the subsequent formation of OAM^(+).Furthermore,by enhancing the competitive lattice-forming behavior of Cs^(+)over OAM+,we suppress excessive surface termination by OAM^(+).These approaches achieve dimensional tunability between two-dimensional(2D)nanoplatelets and three-dimensional(3D)nanocubes in the S_(N)2-based heat-up synthesis,along with subsequent spectral control of optical features.To independently optimize their surface passivation,we employ a post-synthetic passivation(PSP)strategy using OAM^(+)–I−pairs,which increases the photoluminescence quantum yield of PNCs from 71.9%to 81.7%by reducing surface defects.
基金financial support from the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)through Project-ID 425217212(SFB 1432)and project 510766045the major program in digital intelligence,Shapingba,Chongqing(Grant No.20240204)the Wisconsin Alumni Research Foundation(WARF)via the Accelerator Program.
文摘Integration of graphene in silicon-based micro-/nanoelectromechanical systems(MEMS/NEMS)marries the robustness of silicon-based materials with the exceptional physical properties of graphene,drastically enhancing the system’s regulation performance which now is key for many advanced applications in nanotechnology.Here,we experimentally demonstrate and theoretically analyze a powerful on-chip integration principle consisting of a hybrid graphene/silicon nitride membrane with metallic leads on top that enables an extremely large static and dynamic parameter regulation.When a static voltage is applied to the leads of the integrated structure,a spatially confined localized electrothermomechanical(ETM)effect results in ultra-wide frequency tuning,deformation(buckling transition)and regulation of the mechanical properties.Moreover,by injecting an alternating voltage to the leads,we can excite the resonator vibrating even far beyond its linear regime without a complex and space consuming actuation system.Our results prove that the scheme provides a compact integrated system possessing mechanical robustness,high controllability,and fast response.It not only expands the limit of the application range of MEMS/NEMS devices,but also enables the further miniaturization of the device.
文摘A symmetrical one-dimensional(1D)photonic crystal structure with a Dirac-emimetal-defected layer is proposed.The material properties of the Dirac semimetal are governed by three key parameters:Fermi level,Fermi velocity,and degeneracy factor.Simulation results demonstrate that the proposed structure generates multiple photonic bandgaps within the THz frequency range.In the low-THz region,pronounced resonant transmission peaks emerge,enabling near-perfect filtering performance.The positions of these defect modes can be dynamically tuned by adjusting the Fermi level and degeneracy factor.In mid-and high-THz frequency bands,the Dirac semimetal begins to exhibit metallic behavior,leading to attenuation of the transmission peaks and the appearance of absorption.The elevation of the Fermi level delays the critical threshold for the transition from the dielectric state to the metallic state,while an increase in Fermi velocity suppresses metallic behavior.Therefore,enhancing both the Fermi level and Fermi velocity contributes to strengthening the defect peak intensity.Conversely,increasing the degeneracy factor strengthens the metallic characteristics,thereby disrupting the high-frequency photonic bandgap.Notably,the defect layer thickness and incident angle exert significant influence on the transmission behavior:a larger incident angle causes the defect peak to shift toward higher frequencies and reduces its intensity,whereas a thicker defect layer shifts the defect peak toward lower frequencies.The modulation effects of both parameters become more pronounced as frequency increases.Compared with conventional photonic crystals,our work can provide a tunable structure over transmission properties,offering novel strategies for designing tunable filters and optical sensors.
基金National Research Foundation of Korea(NRF)(NRF-2015R1A2A1A15055998,NRF-2013M3C1A3065051,NRF-2016R1C1B2007007)
文摘We suggest a low cross-talk plasmonic cross-connector based on a metal/insulator/metal cavity and waveguides.We separately investigate the isolated cavity mode, the waveguide mode, and the combination of cavity and waveguide modes using a finite-different time-domain method. Due to resonant tunneling and the cutoff frequency of the odd waveguide mode, our proposed structure achieves a high throughput transmission ratio and eliminates cross-talk. Furthermore, the proposed structure has a broadband tunability of 587 nm, which can be achieved by modulating the cavity air gap thickness. This structure enables the miniaturization of photonic integrated circuits and sensing applications.
基金supported by the National Natural Science Foundation of China(Nos.62122080,62261136551,and 52203365)the Natural Science Foundation of Shanghai(Nos.22ZR1481700 and 22dz1205000)the Shanghai Pujiang Program(No.21PJ1414800).
文摘MXene-based films have been intensively explored for construction of piezoresistive flexible pressure sensors owing to their excellent mechanical and electrical properties.High pressure sensitivity relies on pre-molding a flexible substrate,or regulating the micromorphology of MXene sheets,to obtain a micro-structured surface.However,the two avenues usually require complicated and time-consuming microfabrication or wet chemical processing,and are limited to non-adjustable topographicelectrical(topo-electro)properties.Herein,we propose a lithographic printing inspired in-situ transfer(LIPIT)strategy to fabricate MXene-ink films(MIFs).In LIPIT,MIFs not only inherit ridge-and-valley microstructure from paper substrate,but also achieve localized topo-electro tunability by programming ink-writing patterns and cycles.The MIF-based flexible pressure sensor with periodical topo-electro gradient exhibits remarkably boosted sensitivity in a wide sensing range(low detection limit of 0.29 Pa and working range of 100 kPa).The MIF sensor demonstrates versatile applicability in both subtle and vigorous pressuresensing fields,ranging from pulse wave extraction and machine learning-assisted surface texture recognition to piano-training glove(PT-glove)for piano learning.The LIPIT is quick,low-cost,and compatible with free ink/substrate combinations,which promises a versatile toolbox for designing functional MXene films with tailored morphological-mechanical-electrical properties for extended application scenarios.
基金supported by the National Natural Science Foundation of China(51572205,11674258 and 51802093)the Joint Fund of Ministry of Education for Equipment Pre-research the Fundamental Research(6141A02022262)+1 种基金the Excellent Dissertation Cultivation Funds of Wuhan University of Technology(2018-YS-001)the Fundamental Research Funds for the Central Universities(2019zy-007)。
文摘All-inorganic zero-dimensional(0D)tetrahedrite(Cu12Sb4S13,CAS)quantum dots(QDs)have attracted extensive attention due to their excellent optical properties,bandgap tunability,and carrier mobility.In this paper,various sized CAS QDs(5.1,6.7,and 7.9 nm)are applied as a switching layer with the structure F:Sn O2(FTO)/CAS QDs/Au,and in doing so,the nonvolatile resistive-switching behavior of electronics based on CAS QDs is reported.The SET/RESET voltage tunability with size dependency is observed for memory devices based on CAS QDs for the first time.Results suggest that differently sized CAS QDs result in different band structures and the regulation of the SET/RESET voltage occurs simply and effectively due to the uniform size of the CAS QDs.Moreover,the presented memory devices have reliable bipolar resistive-switching properties,a resistance(ON/OFF)ratio larger than 104,high reproducibility,and good data retention ability.After 1.4×10^6s of stability testing and 104cycles of quick read tests,the change rate of the ON/OFF ratio is smaller than 0.1%.Furthermore,resistiveswitching stability can be improved by ensuring a uniform particle size for the CAS QDs.The theoretical calculations suggest that the space-charge-limited currents(SCLCs),which are functioned by Cu 3d,Cu 3p and S 3p to act as electron selftrapping centers due to their quantum confinement and form conduction pathways under an electric field,are responsible for the resistive-switching effect.This paper demonstrates that CAS QDs are promising as a novel resistive-switching material in memory devices and can be used to facilitate the application of next-generation nonvolatile memory.
基金supported by the National Key Research and Development Program of China under Grant 2022YFB3608300in part by the National Nature Science Foundation of China(NSFC)under Grants 62404050,U2341218,62574056,62204052。
文摘Organic electrochemical transistor(OECT)devices demonstrate great promising potential for reservoir computing(RC)systems,but their lack of tunable dynamic characteristics limits their application in multi-temporal scale tasks.In this study,we report an OECT-based neuromorphic device with tunable relaxation time(τ)by introducing an additional vertical back-gate electrode into a planar structure.The dual-gate design enablesτreconfiguration from 93 to 541 ms.The tunable relaxation behaviors can be attributed to the combined effects of planar-gate induced electrochemical doping and back-gateinduced electrostatic coupling,as verified by electrochemical impedance spectroscopy analysis.Furthermore,we used theτ-tunable OECT devices as physical reservoirs in the RC system for intelligent driving trajectory prediction,achieving a significant improvement in prediction accuracy from below 69%to 99%.The results demonstrate that theτ-tunable OECT shows a promising candidate for multi-temporal scale neuromorphic computing applications.
基金This work was supported by the China-Poland International Collaboration Fund of National Natural Science Foundation of China(No.51961135301)National Natural Science Foundation of China(No.51702259)+2 种基金the National Key R&D Foundation of the Ministry of Science and Technology(No.2018YFB1107405)the Basic Research Program of Shenzhen(No.JCYJ20170306155944271)the Fundamental Research Funds for the Central Universities(No.06450-G2019KY0601,3102019MS0406).
文摘The luminescence modulation behaviour under the in-situ electric field of rare-earth doped KSr_(2)Nb_(5)O_(15) ceramics opened a new door for the development of dielectric materials.Where the understanding the effect of rare-earth doping on the electric properties of host,especially at the similar doping concentration with luminescence researches(low concentrations)is very important for the exploration of mechanism of electric-luminescent coupling effect.In this work,Nd^(3+)-doped KSr_(2)Nb_(5)O_(15)(KSN-xNd)ceramics were synthesized,and the electric properties were investigated systematically.Our results suggest that the Nd^(3+) doping slightly increased the phase transition temperatures and improved the piezoelectric response of KSr_(2)Nb_(5)O_(15).Most importantly,a bidirectional dielectric tunability is revealed in KSr_(2)Nb_(5)O_(15).The dielectric permittivity can be adjusted by the DC electric bias,with tunability ranging from12.3% to 21.9%.The related mechanism and relationship between the bidirectional dielectric tunability and ferroelectricity are revealed by temperature-dependent dielectric and ferroelectric characterization.The researches of electric properties and bidirectional dielectric tunability of KSN-based ceramics paved the way to further exploration of electric-luminescent coupling mechanism.
基金financially supported by the National Natural Science Foundation of China(Nos.52473139 and U21A2098)。
文摘Hospital wastewater contains complex pollutants,including residual organic dyes and antibiotic-resistant pathogens,posing severe risks to ecosystems and human health.Conventional adsorbents,constrained by monopolar functional groups and limited surface sites,fail to remove both pollutants simultaneously.Here,we report an intelligent responsive polyurethane microsphere adsorbent doped with diallyl dimethylammonium chloride modified carbon nanotubes,termed as PUCD microspheres.The PUCD integrates bipolar adsorption sites,tunable micrometer-scale pores,and a near-infrared(NIR)-triggered in situ capture mechanism within a single platform,which achieves up to 98.3%dye removal,maintains strong adsorption performance across a wide pH range and retains 83.3%efficiency for rhodamine B after five cycles.Notably,the PUCD employs a temperature-responsive phase transition:under NIR irradiation,the microspheres undergo shrinkage,reducing the pore size to generate a‘polymer trap',enabling in situ capture of bacteria with>99%efficiencies for both Staphylococcus aureus and Escherichia coli.By immobilizing live bacteria,the PUCD microspheres substantially reduces the risk of pathogen desorption and toxin release.This promising platform offers a safe,efficient,and single-stage strategy for hospital wastewater purification,enabling the simultaneous elimination of dyes and pathogenic bacteria.
基金supported by the National Natural Science Foundation of China (No.22409038,52473221)Zhejiang Province Postdoctoral Science Foundation (No.ZJ2024021)+2 种基金Hubei Provincial Natural Science Foundation of China (Nos.2024DJC032,2025AFB889)Key Project of Science and Technology Research of Hubei Provincial Department of Education (Nos.D20232701,D20232702)the research grant funded by the Research,Development,and Innovation Authority (RDIA)-Kingdom of Saudi Arabia (No.12615-iu-2023-IU-R-2-1-EI-)。
文摘Hydrogen peroxide(H_(2)O_(2)) has been recognized as a green and nonpolluting multifunctional oxidant with extensive applications in environmental protection,metal etching,textile printing and dyeing,chemical synthesis and food processing.However,over 90 % of industrial H_(2)O_(2) is currently produced through the multi-step anthraquinone oxidation process,which suffers from a process with some drawbacks such as complex,high-energy consumption,and toxic byproducts emissions.Compared to the traditional anthraquinone method,artificial photosynthesis of H_(2)O_(2) using semiconductor photocatalysts has emerged as a sustainable alternative due to its use of water and O_(2) as the clean reactants and sole energy as the driving force.In recent years,metal-free photocatalysts mainly including covalent organic frameworks(COFs),covalent triazine frameworks(CTFs) and carbon nitrile(g-C_(3)N_(4)) have garnered significant interest due to their superior thermal and chemical stability,diverse synthesis methods,tunable functionality,light weight nature and non-toxicity.These materials also exhibit adjustable band structure and unique photoelectric properties.Sustainable efforts have been made to advance metal-free photocatalysts for artificial photosynthesis of H_(2)O_(2),however,a comprehensive summary of current research status on metalfree-based photocatalytic overall H_(2)O_(2) production remain scarce.This review outlines recent process in overall H_(2)O_(2) photosynthesis based on metal-free photocatalysts.First,we introduced the fundamental concepts of photocatalytic overall H_(2)O_(2) production.Then,we analyze representative studies on photocatalytic overall H_(2)O_(2) synthesis using metal-free materials.Finally,we discuss the challenges and future perspectives in this field to guide the design and synthesis of metal-free systems for H_(2)O_(2) generation.
基金supported by Independent Innovation Science Foundation of National University of Defense Technology(Grant No.23-ZZCX-JDZ-44)。
文摘Tunable mid-infrared and far-infrared laser output was demonstrated based on BaGa_(4)Se_(7)crystals and an optical parametric oscillator(OPO).With a 1.06μm Nd:YAG laser and a double-pass singly resonant OPO cavity,a laser energy output of 2.2 mJ at 10μm was obtained.By tuning the angle and temperature,a tunable laser output covering the wavelength range from 6μm to 17μm was obtained with a tuning precision better than 3 nm.The corresponding optical-to-optical conversion efficiency was 2.8%,and the slope efficiency was 4.4%.The damage effect of the output laser on detectors was also investigated,and point damage to the detector occurred at an output energy of 16.4μJ.The laser system has the advantages of miniaturization,a wide tuning range,high energy and high tuning resolution.Its broadband laser characteristics make it highly valuable for applications in atmospheric detection,infrared spectroscopy and electro-optical countermeasures.
基金financially supported by the National Natural Science Foundation of China(U21A20311,U24A2040,52171141,52272117)the Natural Science Foundation of Shandong Province(ZR2022JQ19)+3 种基金the Key Technology Research Project of Shandong Province(2023CXGC010202)the Taishan Industrial Experts Program(TSCX202306142)the Core Facility Sharing Platform of Shandong Universitythe Foundation of Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education),Nankai University。
文摘Co_(3)S_(4)electrocatalysts with mixed valences of Co ions and excellent structural stability possess favorable oxygen evolution reaction(OER)activity,yet challenges remain in fabricating rechargeable lithiumoxygen batteries(LOBs)due to their poor OER performance,resulting from poor electrical conductivity and overly strong intermediate adsorption.In this work,fancy double heterojunctions on 1T/2H-MoS_(2)@Co_(3)S_(4)(1T/2H-MCS)were constructed derived from the charge donation from Co to Mo ions,thus inducing the phase transformation of Mo S_(2)from 2H to 1T.The unique features of these double heterojunctions endow the1T/2H-MCS with complementary catalysis during charging and discharging processes.It is worth noting that 1T-Mo S2@Co3S4could provide fast Co-S-Mo electron transport channels to promote ORR/OER kinetics,and 2H-MoS_(2)@Co_(3)S_(4)contributed to enabling moderate egorbital occupancy when adsorbed with oxygen-containing intermediates.On the basis,the Li_(2)O_(2)nucleation route was changed to solution and surface dual pathways,improving reversible deposition and decomposition kinetics.As a result,1T/2H-MCS cathodes exhibit an improved electrocatalytic performance compared with those of Co_(3)S_(4)and Mo S2cathodes.This innovative heterostructure design provides a reliable strategy to construct efficient transition metal sulfide catalysts by improving electrical conductivity and modulating adsorption toward oxygenated intermediates for LOBs.
基金supported by the Natural Science Foundation of Hebei Province(No.F2016201023)the Technology Foundation for Selected Overseas Chinese Scholar of MOHRSS(No.CG2015003006)+1 种基金the Advanced Talents Program of Hebei Educational Committee(No.GCC2014020)the International Science and Technology Cooperation Program of China(No.2014DFA12930)
文摘A simple configuration dual-wavelength fiber laser,by combining the first-order Brillouin laser and the residual pump laser,is proposed and experimentally demonstrated.A 1 km long single-mode fiber is used as the stimulated Brillouin scattering gain medium pumped by a narrow linewidth tunable laser source（TLS）.Through simply adjusting the TLS output power,power-equalized dual-wavelength lasing can be achieved with a high optical signal to noise ratio（OSNR） of 〉80 d B.With the good tunability of the TLS,the dual-wavelength fiber laser has a tunable range of -130 nm,and simultaneously the beat frequency of the two lasing wavelengths can be tuned from 10.1875 to 11.0815 GHz with the tunable range of 0.8940 GHz.The high stability of the dualwavelength operation is experimentally verified by the measured beat frequency fluctuation of ≤6 MHz in 1 h and power fluctuation of ≤0.03 d B in 2 h.The temporal characteristics of the fiber laser are also investigated experimentally.The fiber laser will find good applications in fiber sensing and microwave photonics areas.
