A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)...A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)∶Eu^(3+)can produce red mechanoluminescence,and importantly,it shows good repeatability.The mechanoluminescence of Ca_(5)Ga_(6)O_(14)∶Eu^(3+) results from the piezoelectric field generated inside the material under stress,rather than the charge carriers stored in the traps,which can be confirmed by the multiple cycles of mechanoluminescence tests and heat treatment tests.The mechanoluminescence color can be turned from red to green by co-doping varied concentrations of Tb^(3+),which may be meaningful for encrypted letter writing.The encryption scheme for secure communication was devised by harnessing mechanoluminescence patterns in diverse shapes and ASCII codes,which shows good encryption performance.The results suggest that the mechanoluminescence phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+),Tb^(3+)may be applied to the optical information encryption.展开更多
The authors regret that the printed version of the above article contained an error reference.We hope to correct it here.[14]B.J.M.Christophe Legein,Franck Fayon,Angew.Chem.Int.Ed.,132(2020)19409–19415.
Due to the advantages of aluminum in abundance in the earth’s crust and safety,how to exploit these advantages to develop high-performance rechargeable aluminum batteries to replace traditional batteries has become a...Due to the advantages of aluminum in abundance in the earth’s crust and safety,how to exploit these advantages to develop high-performance rechargeable aluminum batteries to replace traditional batteries has become an urgent issue.The key to solving this problem is to find suitable materials as cathode for aluminum batteries.Here,we propose a strategy in which Ti_(3)C_(2)(MXene)is used as a loaded structure for the organic anthraquinone derivative Benzo[1,2-b:4,5-b’]dithiophene-4,8-dione(BDTO).This strategy enables the self-stacking of monolayer MXene into a layered structure while embedding organics into it.The unique structure enables efficient and reversible intercalation/deintercalation of Al^(3+).At the same time,it exhibits excellent electrochemical performance,and its reversible capacity reaches229.8 mAh g^(-1).Moreover,it can still maintain a capacity of 134.9 mAh g^(-1)after 500 cycles.In addition.compared with BDTO,the rate performance of MXene@BDTO has also been greatly improved.Meanwhile,this unique layered structure also brings better electro nic co nductivity and ionic diffusion coefficient.We also demonstrate that the battery mechanism is a reaction between three C=O and one Al^(3+) through multiple characterization methods and density functional calculations(DFT).The advantages of MXene@BDTO provide a better research basis for the study of rechargeable Aluminum-Organic batteries,and provide a good idea to explore the development of Aluminum-Organic batteries.展开更多
In recent years,aqueous aluminum ion batteries have been widely studied owing to their abundant energy storage and high theo retical capacity.An in-depth study of vanadium oxide materials is necessary to address the p...In recent years,aqueous aluminum ion batteries have been widely studied owing to their abundant energy storage and high theo retical capacity.An in-depth study of vanadium oxide materials is necessary to address the precipitation of insoluble products covered cathode surface and the slow reaction kinetics.Therefore,a method using a simple one-step hydrothermal preparation and oxalic acid to regulate oxygen vacancies has been reported.A high starting capacity(400 mAh g^(-1))can be achieved by Ov-V2O5,and it is capable of undergoing 200 cycles at 0.4 A g^(-1),with a termination discharge capacity of103 mAh g^(-1).Mechanism analysis demonstrated that metastable structures(AlxV2O5and HxV2O5)were constructed through the insertion of Al^(3+)/H^(+)during discharging,which existed in the lattice intercalation with V2O5.The incorporation of oxygen vacancies lowers the reaction energy barrier while improving the ion transport efficiency.In addition,the metastable structure allows the electrostatic interaction between Al3+and the main backbone to establish protection and optimize the transport channel.In parallel,this work exploits ex-situ characterization and DFT to obtain a profound insight into the instrumental effect of oxygen vacancies in the construction of metastable structures during in-situ electrochemical activation,with a view to better understanding the mechanism of the synergistic participation of Al3+and H+in the reaction.This work not only reports a method for cathode materials to modulate oxygen vacancies,but also lays the foundation for a deeper understanding of the metastable structure of vanadium oxides.展开更多
The trivalent lanthanides have been broadly utilized as emitting centers in persistent luminescence(PersL)materials due to their wide emitting spectral range,which thus attract considerable attention over decades.Howe...The trivalent lanthanides have been broadly utilized as emitting centers in persistent luminescence(PersL)materials due to their wide emitting spectral range,which thus attract considerable attention over decades.However,the origin of the trivalent lanthanides’PersL is still an open question,hindering the development of excellent PersL phosphors and their broad applications.Here,the PersL of 12 kinds of the trivalent lanthanides with the exception of La^(3+),Lu^(3+),and Pm^(3+) is reported,and a mechanism of the PersL of the trivalent lanthanides in wide bandgap hosts is proposed.According to the mechanism,the excitons in wide bandgap materials transfer their recombination energy to the trivalent lanthanides that bind the excitons,followed by the generation of PersL.During the PersL process,the trivalent lanthanides as isoelectronic traps bind excitons,and the binding ability is not only related to the inherent arrangement of the 4f electrons of the trivalent lanthanides,but also to the extrinsic ligand field including anion coordination and cation substitution.Our work is believed to be a guidance for designing high-performance PersL phosphors.展开更多
Thermoelectric（TE）materials have been considered as a strong candidate for recovering the waste heat from industry and vehicles due to the ability to convert heat directly into electricity.Recently,multinary diamond...Thermoelectric（TE）materials have been considered as a strong candidate for recovering the waste heat from industry and vehicles due to the ability to convert heat directly into electricity.Recently,multinary diamond-like chalcogenides（MDLCs）,such as Cu In Te2,Cu2Sn Se3,Cu3Sb Se4,Cu2ZnSnSe4,etc.,are eco-friendly Pb-free TE materials with relatively large Seebeck coefficient and low thermal conductivity and have aroused intensive research as a popular theme in the TE field.In this review,we summarize the TE performance and device development of MDLCs.The features of crystalline and electronic structure are first analyzed,and then the strategies that have emerged to enhance the TE figure of merits of these materials are illustrated in detail.The final part of this review describes the advance in TE device research for MDLCs.In the outlook,the challenges and future directions are also discussed to promote the further development of MDLCs TE materials.展开更多
We propose a method of complex-amplitude Fourier single-pixel imaging(CFSI)with coherent structured illumination to acquire both the amplitude and phase of an object.In the proposed method,an object is illustrated by ...We propose a method of complex-amplitude Fourier single-pixel imaging(CFSI)with coherent structured illumination to acquire both the amplitude and phase of an object.In the proposed method,an object is illustrated by a series of coherent structured light fields,which are generated by a phase-only spatial light modulator,the complex Fourier spectrum of the object can be acquired sequentially by a single-pixel photodetector.Then the desired complex-amplitude image can be retrieved directly by applying an inverse Fourier transform.We experimentally implemented this CFSI with several different types of objects.The experimental results show that the proposed method provides a promising complex-amplitude imaging approach with high quality and a stable configuration.Thus,it might find broad applications in optical metrology and biomedical science.展开更多
Herein,we focused on the development of the V_(4)C_(3) MXene composite bimetallic selenide heterostruc-ture(V_(4)C_(3)@CuSe_(2)/CoSe_(2))as a cathode material for aluminum batteries.This heterostructure was pre-pared ...Herein,we focused on the development of the V_(4)C_(3) MXene composite bimetallic selenide heterostruc-ture(V_(4)C_(3)@CuSe_(2)/CoSe_(2))as a cathode material for aluminum batteries.This heterostructure was pre-pared through a Lewis melt salt etching and selenization process.By capitalizing on the synergistic effect between the bimetallic selenide and V_(4)C_(3) MXene,V_(4)C_(3)@CuSe_(2)/CoSe_(2) exhibited rapid charge transfer and demonstrated superior discharge specific capacity compared to V_(4)C_(3) composite monometallic selenide.Furthermore,the incorporation of V_(4)C_(3) improved the material's stability during charging/discharging.The initial discharge specific capacity of V_(4)C_(3)@CuSe_(2)/CoSe_(2) reached an impressive 809 mAh g^(-1) at 1 Ag^(-1).Even after nearly 3000 cycles,it retained a substantial capacity of 169.1 mAh g^(-1).Ex-situ XPS analysis confirmed the reversible valence transitions of Cu,Co,and Se elements as the main energy storage reac-tions taking place in the cathode material.Density functional theory analysis provided further insights,revealing that the strong metallic behavior of the heterostructure stemmed from the charge rearrange-ment facilitated by the bimetallic selenide structure and the optimization of the energy level structure.Additionally,the presence of the bimetallic selenide structure significantly improved the adsorption ef-ficiency of[AlCl4]^(-).Overall,this research contributes to the advancement of rechargeable aluminum ion batteries and presents a promising avenue for future developments in composite metal selenide struc-tures and MXene-based materials.展开更多
The thermoelectric performance of CdO ceramics was enhanced by simultaneously optimizing the electrical and thermal transport properties via a small amount of Zn doping （≤3%）. The introduction of Zn can obviously i...The thermoelectric performance of CdO ceramics was enhanced by simultaneously optimizing the electrical and thermal transport properties via a small amount of Zn doping （≤3%）. The introduction of Zn can obviously increase the electrical conductivity of CdO due to the simultaneous increase of carrier concentration and mobility, and eventually results in an improvement in power factor. Zn doping is also effective in suppressing the thermal conductivity of CdO because of stronger phonon scatterings from point defects, Zn-riched second phase, and grain boundaries. A best ZT of about 0.45 has been achieved in the Cd1-xZnxO systems at about 1000 K, which is comparable to the highest values reported for other n-type oxide TE materials.展开更多
A blue phosphor was obtained by doping Eu2＋ into a multi-cation host Sro.8Cao.2Al2Si208 through high tempera- ture solid state reaction. The emission spectra show a continuous red-shift behavior from 413 nm to 435 nm...A blue phosphor was obtained by doping Eu2＋ into a multi-cation host Sro.8Cao.2Al2Si208 through high tempera- ture solid state reaction. The emission spectra show a continuous red-shift behavior from 413 nm to 435 nm with Eu2＋ concentration increasing. The substitution priority of Eu2＋ in Sro.8Cao.2AI2Si208 was investigated via x-ray diffraction （XRD） and temperature properties in detail： the Ca2＋ ions are preferentially substituted by Eu2＋at lower doping, and with the Eu2＋ concentration increasing, the probability of substitution for Sr2＋ is greater than that of replacing Ca2＋. Accord- ingly, we propose the underlying method of thermal property to determine the substitution of Eu2＋ in the multi-cation hosts. Moreover, the abnormal increase of emission intensity with increasing temperature was studied by the thermolumi- nescence spectra. The energy transfer mechanism between the Eu2＋ ions occupying different cation sites was studied by the lifetime decay curves. A series of warm white light emitting diodes were successfully fabricated using the blue phos- phors Sro.gCao.2A12Si208： Eu2＋ with commercial red phosphor （Ca Sr）SJA1N3： lu2＋ and green phosphor （Y Lu）jA15Or2 ： Ce3＋, and the luminescent efficiency can reach 45 lm/W.展开更多
The electron-impact ionization of lithium-like ions C^(3+),N^(4+),O^(5+),Ne^(7+),and Fe2^(3+)is studied using a combination of two-potential distorted-wave and R-matrix methods with a relativistic correction.Total cro...The electron-impact ionization of lithium-like ions C^(3+),N^(4+),O^(5+),Ne^(7+),and Fe2^(3+)is studied using a combination of two-potential distorted-wave and R-matrix methods with a relativistic correction.Total cross sections are computed for incident energies from 1 to 10 times of ionization energy and better agreements with the experimental results are obtained in comparison with the theoretical data available.It is found that the indirect ionization processes become significant for the incident energy larger than about four times of the ionization energy.Contributions from the exchange effects along the isoelectronic sequence are also discussed and found to be important.The present method can be used to obtain systematic ionization cross sections for highly charged ions across a wide incident energy range.展开更多
Mechanoluminescent(ML)materials can directly convert external mechanical stimulation into light without the need for excitation from other forms of energy,such as light or electricity.This alluring characteristic make...Mechanoluminescent(ML)materials can directly convert external mechanical stimulation into light without the need for excitation from other forms of energy,such as light or electricity.This alluring characteristic makes ML materials potentially applicable in a wide range of areas,including dynamic imaging of force,advanced displays,information code,storage,and anti-counterfeiting encryption.However,current reproducible ML materials are restricted to sulfide-and oxide-based materials.In addition,most of the reported ML materials require pre-irradiation with ultraviolet(UV)lamps or other light sources,which seriously hinders their practical applications.Here,we report a novel ML material,MgF_(2):Mn^(2+),which emits bright red light under an external dynamic force without the need for pre-charging with UV light.The luminescence properties were systematically studied,and the piezophotonic application was demonstrated.More interestingly,unlike the well-known zinc sulfide ML complexes reported previously,a highly transparent ML film was successfully fabricated by incorporating MgF_(2):Mn^(2+)into polydimethylsiloxane(PDMS)matrices.This film is expected to find applications in advanced flexible optoelectronics such as integrated piezophotonics,artificial skin,athletic analytics in sports.展开更多
Aqueous aluminum ion batteries(AAIBs)have garnered extensive attention due to their environmental friendliness,high theoretical capacity,and low cost.However,the sluggish reaction kinetics and severe structural collap...Aqueous aluminum ion batteries(AAIBs)have garnered extensive attention due to their environmental friendliness,high theoretical capacity,and low cost.However,the sluggish reaction kinetics and severe structural collapse of the cathode material,especially manganese oxide,during the cycling process have hindered its further application.Herein,Cu^(2+)pre-interca la ted layeredδ-MnO_(2)was synthesized via a hydrothermal method.The pre-intercalated Cu^(2+)ions not only improve the conductivity of MnO_(2)cathode but also stabilize the structure to enhance stability.X-ray absorption fine structure(XAFS)combined with density functional theory(DFT)calculations confirm the formation of the covalent bond between Cu and O,increasing the electronegativity of O atoms and enhancing the H^(+)adsorption energy.Moreover,ex-situ measurements not only elucidate the Al^(3+)/H^(+)co-insertion energy storage mechanism but also demonstrate the high reversibility of the Cu-MnO_(2)cathode during cycling.This work provides a promising modification approach for the application of manganese oxides in AAIBs.展开更多
Cu(In,Ga)Se2(CIGS) based multilayer heterojunction, as one of the best high efficiency thin film solar cells, has attracted great interest due to its outstanding features. However, the present studies are primarily fo...Cu(In,Ga)Se2(CIGS) based multilayer heterojunction, as one of the best high efficiency thin film solar cells, has attracted great interest due to its outstanding features. However, the present studies are primarily focused on the structure optimization and modulation in order to enhance the photoelectric conversion efficiency. Here, we exploit another application of this multilayer heterostructure in photoresistance-modulated position sensitive detector by introducing lateral photoresistance effect.The lateral photoresistance measurements show that this multilayer heterojunction exhibits a wide spectral response(~330 to ~1150 nm) and excellent bipolar photoresistance performances(position sensitivity of ~63.26 X/mm and nonlinearity <4.5%), and a fast response speed(rise and fall time of ~14.46 and^14.42 ms, respectively). More importantly, based on the lateral photoresistance effect, the CIGS heterostructure may also be developed as a position-dependent resistance memory device, which can be modulated by changing laser intensity, wavelength, and bias voltage with excellent stability and repeatability, and the position resolution reaches up to 1 lm. These results can be well explained by considering the diffusion and the drift model of carriers in the CIGS multilayer heterojunction. This work provides a new approach of achieving novel photoelectric sensors and memory devices based on the traditional photovoltaic heterostructures.展开更多
A series of Y1_xPO4：xTb3＋ （x=0.005-0.1） phosphors were successfully fabricated by using co-precipitation method with NHzH2PO4 as phosphorus source. The structure and morphology characterization of the luminescent ...A series of Y1_xPO4：xTb3＋ （x=0.005-0.1） phosphors were successfully fabricated by using co-precipitation method with NHzH2PO4 as phosphorus source. The structure and morphology characterization of the luminescent material was investigated with X-ray powder diffraction （XRD） and field emission scanning electron microscopy （FESEM）. The XRD patterns indicated that the samples belonged to tetragonal phase. Luminescence properties were discussed by measuring the excitation and emission spectra. The phosphor could be excited by UV light （340-390 nm） and emitted green light, with the emission peaks located at 491 （5Da→7F6）, 550 （SD4→7Fs）, 589 （5D4→7F4） and 624 nm （SD4→TF3）. In addition, the pH value and activator concentration had great effects on the emission intensity. The results illuminated that this phosphor could be used for UV based white light emitting diodes and co-precipitation method could be used to prepare better appearance phosphor.展开更多
Rechargeable aluminum batteries(RABs)are a popular energy storage device because of its safety and environmental protection.As cathode materials of RABs,transition metal oxide,sulfide,and selenide have become the rese...Rechargeable aluminum batteries(RABs)are a popular energy storage device because of its safety and environmental protection.As cathode materials of RABs,transition metal oxide,sulfide,and selenide have become the research hotspot.In this work,we have successfully prepared CuO,Cu_(1.8)S,and Cu_(1.8)Se electrode materials.Among them,although Cu_(1.8)Se had a relatively higher initial discharge capacity,all of these products had severe capacity degradation in terms of cycling and rate performance.Furthermore,for solving the problem of capacity decline,CMK-3 modified separator was used to make the Cu_(1.8)Se cathode material more stable,thus improving cycling and rate performance.It can be confirmed by ex situ X-ray photoelectron spectroscopy(XPS)that both Cu and Se elements underwent reversible redox reactions during the charging/discharging process.Density functional theory was implemented to study the energy storage mechanism of CumX(X=O,S,Se).The results showed that Cu_(1.8)S and Cu_(1.8)Se mainly relied on AlCl4−for energy storage,and the intercalation/de-intercalation of Al3+occurred during the charge/discharge process in CuO material.Consequently,the optimized Cu_(1.8)Se/CMK-3@GF/C/Al revealed an outstanding rate capability(977.83 mAh·g^(−1)at 0.5 A·g^(−1))and long cyclic stability(retention of 478.77 mAh·g^(−1)after 500 cycles at 1.0 A·g^(−1)).Compared to previously reported cathode materials of RABs,this type of battery displays great superiority in terms of rate and cycling stability.This research also provides a novel approach to suppress the shuttle effect of active species for advanced clean energy devices.展开更多
This paper studies the effective polytropic index in the central plasma sheet （CPS） by using the method of Kartalev et al. （2006）, which adopts the denoising technique of Haar wavelet to identify the homogeneous M...This paper studies the effective polytropic index in the central plasma sheet （CPS） by using the method of Kartalev et al. （2006）, which adopts the denoising technique of Haar wavelet to identify the homogeneous MHD Bernoulli integral （MBI） and has been frequently used to study the polytropic relation in the solar wind. We chose the quiet CPS crossing by Cluster C1 during the interval 08：51：00-09：19：00 UT on 03 August 2001. In the central plasma sheet, thermal pressure energy per unit mass is the most important part in MBI, and kinetic energy of fluid motion and electromagnetic energy per unit mass are less important. In the MBI, there are many peaks, which correspond to isothermal or near isothermal processes. The interval lengths of homogenous MBI regions are generally less than 1 min. The polytropic indexes are calculated by linearly fitting the data of lnp and Inn within a 16 s window, which is shifted forward by 8 s step length. Those polytropic indexes with IRI ≥0.8 （R is the correlation coefficient between lnp and inn） and p-value≤0.1 in the homogeneous regions are almost all in the range of [0, 1]. The mean and median effective polytropic indexes with high R and low p-value in homogeneous regions are 0.34 and 0.32 respectively, which are much different from the polytropic index obtained by traditional method （αtrad=-0.15）. This result indicates that the CPS is not uniform even during quiet time and the blanket applications of polytropic law to plasma sheet may return misleading value of polytropic index. The polytropic indexes in homogeneous regions with a high correlation coefficient basically have good regression significance and are thus credible. These results are very important to understand the energy transport in magnetotail in the MHD frame.展开更多
We propose and demonstrate a novel single-longitudinal-mode(SLM) erbium-doped fiber laser(EDFL) capable of operating at fixed-wavelength lasing mode with a tunable range more than 54 nm, an ultra-narrow linewidth of 4...We propose and demonstrate a novel single-longitudinal-mode(SLM) erbium-doped fiber laser(EDFL) capable of operating at fixed-wavelength lasing mode with a tunable range more than 54 nm, an ultra-narrow linewidth of 473 Hz and an ultra-high optical signal-to-noise ratio(OSNR) more than 72 dB, or operating at wavelength-swept mode with tunable sweep rate of 10—200 Hz and a sweep range more than 50 nm. The excellent features mainly benefit from a triple-ring subring cavity constructed by three optical couplers nested one another and a fiber Fabry-Pérot tunable filter which can be driven by a constant voltage or a periodic sweep voltage for fixed or wavelength-swept operation, respectively. The proposed EDFL has potential applications in high-resolution spectroscopy and fiber optic sensing.展开更多
文摘A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)∶Eu^(3+)can produce red mechanoluminescence,and importantly,it shows good repeatability.The mechanoluminescence of Ca_(5)Ga_(6)O_(14)∶Eu^(3+) results from the piezoelectric field generated inside the material under stress,rather than the charge carriers stored in the traps,which can be confirmed by the multiple cycles of mechanoluminescence tests and heat treatment tests.The mechanoluminescence color can be turned from red to green by co-doping varied concentrations of Tb^(3+),which may be meaningful for encrypted letter writing.The encryption scheme for secure communication was devised by harnessing mechanoluminescence patterns in diverse shapes and ASCII codes,which shows good encryption performance.The results suggest that the mechanoluminescence phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+),Tb^(3+)may be applied to the optical information encryption.
文摘The authors regret that the printed version of the above article contained an error reference.We hope to correct it here.[14]B.J.M.Christophe Legein,Franck Fayon,Angew.Chem.Int.Ed.,132(2020)19409–19415.
基金financially supported by the National Natural Science Foundation of China(52102233 and 52102095)the Nature Science Foundation of Hebei Province(E2021201006)。
文摘Due to the advantages of aluminum in abundance in the earth’s crust and safety,how to exploit these advantages to develop high-performance rechargeable aluminum batteries to replace traditional batteries has become an urgent issue.The key to solving this problem is to find suitable materials as cathode for aluminum batteries.Here,we propose a strategy in which Ti_(3)C_(2)(MXene)is used as a loaded structure for the organic anthraquinone derivative Benzo[1,2-b:4,5-b’]dithiophene-4,8-dione(BDTO).This strategy enables the self-stacking of monolayer MXene into a layered structure while embedding organics into it.The unique structure enables efficient and reversible intercalation/deintercalation of Al^(3+).At the same time,it exhibits excellent electrochemical performance,and its reversible capacity reaches229.8 mAh g^(-1).Moreover,it can still maintain a capacity of 134.9 mAh g^(-1)after 500 cycles.In addition.compared with BDTO,the rate performance of MXene@BDTO has also been greatly improved.Meanwhile,this unique layered structure also brings better electro nic co nductivity and ionic diffusion coefficient.We also demonstrate that the battery mechanism is a reaction between three C=O and one Al^(3+) through multiple characterization methods and density functional calculations(DFT).The advantages of MXene@BDTO provide a better research basis for the study of rechargeable Aluminum-Organic batteries,and provide a good idea to explore the development of Aluminum-Organic batteries.
基金financially supported by the National Natural Science Foundation of China(52102233)Science and Technology Project of Hebei Education Department(QN2023019).
文摘In recent years,aqueous aluminum ion batteries have been widely studied owing to their abundant energy storage and high theo retical capacity.An in-depth study of vanadium oxide materials is necessary to address the precipitation of insoluble products covered cathode surface and the slow reaction kinetics.Therefore,a method using a simple one-step hydrothermal preparation and oxalic acid to regulate oxygen vacancies has been reported.A high starting capacity(400 mAh g^(-1))can be achieved by Ov-V2O5,and it is capable of undergoing 200 cycles at 0.4 A g^(-1),with a termination discharge capacity of103 mAh g^(-1).Mechanism analysis demonstrated that metastable structures(AlxV2O5and HxV2O5)were constructed through the insertion of Al^(3+)/H^(+)during discharging,which existed in the lattice intercalation with V2O5.The incorporation of oxygen vacancies lowers the reaction energy barrier while improving the ion transport efficiency.In addition,the metastable structure allows the electrostatic interaction between Al3+and the main backbone to establish protection and optimize the transport channel.In parallel,this work exploits ex-situ characterization and DFT to obtain a profound insight into the instrumental effect of oxygen vacancies in the construction of metastable structures during in-situ electrochemical activation,with a view to better understanding the mechanism of the synergistic participation of Al3+and H+in the reaction.This work not only reports a method for cathode materials to modulate oxygen vacancies,but also lays the foundation for a deeper understanding of the metastable structure of vanadium oxides.
基金L.L.thanks the support from the Advanced Talents Incubation Program of Hebei University(521100221006)Y.Y.acknowledges the financial support from the National Natural Science Foundation of China(11974097)+1 种基金the Natural Science Foundation of Hebei Province(A2019201073)J.Q.acknowledges the support from the National Natural Science Foundation of China(52161135109).
文摘The trivalent lanthanides have been broadly utilized as emitting centers in persistent luminescence(PersL)materials due to their wide emitting spectral range,which thus attract considerable attention over decades.However,the origin of the trivalent lanthanides’PersL is still an open question,hindering the development of excellent PersL phosphors and their broad applications.Here,the PersL of 12 kinds of the trivalent lanthanides with the exception of La^(3+),Lu^(3+),and Pm^(3+) is reported,and a mechanism of the PersL of the trivalent lanthanides in wide bandgap hosts is proposed.According to the mechanism,the excitons in wide bandgap materials transfer their recombination energy to the trivalent lanthanides that bind the excitons,followed by the generation of PersL.During the PersL process,the trivalent lanthanides as isoelectronic traps bind excitons,and the binding ability is not only related to the inherent arrangement of the 4f electrons of the trivalent lanthanides,but also to the extrinsic ligand field including anion coordination and cation substitution.Our work is believed to be a guidance for designing high-performance PersL phosphors.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51372064 and 61704044)the Key Project of the Natural Science Foundation of Hebei Province,China(Grant No.E2017201227)
文摘Thermoelectric（TE）materials have been considered as a strong candidate for recovering the waste heat from industry and vehicles due to the ability to convert heat directly into electricity.Recently,multinary diamond-like chalcogenides（MDLCs）,such as Cu In Te2,Cu2Sn Se3,Cu3Sb Se4,Cu2ZnSnSe4,etc.,are eco-friendly Pb-free TE materials with relatively large Seebeck coefficient and low thermal conductivity and have aroused intensive research as a popular theme in the TE field.In this review,we summarize the TE performance and device development of MDLCs.The features of crystalline and electronic structure are first analyzed,and then the strategies that have emerged to enhance the TE figure of merits of these materials are illustrated in detail.The final part of this review describes the advance in TE device research for MDLCs.In the outlook,the challenges and future directions are also discussed to promote the further development of MDLCs TE materials.
基金Project supported by the Natural Science Foundation of Hebei Province,China(Grant Nos.A2022201039 and F2019201446)the MultiYear Research Grant of University of Macao,China(Grant No.MYRG2020-00082-IAPME)+2 种基金the Science and Technology Development Fund from Macao SAR(FDCT),China(Grant No.0062/2020/AMJ)the Advanced Talents Incubation Program of the Hebei University(Grant No.8012605)the National Natural Science Foundation of China(Grant Nos.11204062,61774053,and 11674273)。
文摘We propose a method of complex-amplitude Fourier single-pixel imaging(CFSI)with coherent structured illumination to acquire both the amplitude and phase of an object.In the proposed method,an object is illustrated by a series of coherent structured light fields,which are generated by a phase-only spatial light modulator,the complex Fourier spectrum of the object can be acquired sequentially by a single-pixel photodetector.Then the desired complex-amplitude image can be retrieved directly by applying an inverse Fourier transform.We experimentally implemented this CFSI with several different types of objects.The experimental results show that the proposed method provides a promising complex-amplitude imaging approach with high quality and a stable configuration.Thus,it might find broad applications in optical metrology and biomedical science.
基金National Natural Science Foundation of China(No.52102233)Science and Technology Project of Hebei Education Department(No.QN2023019).
文摘Herein,we focused on the development of the V_(4)C_(3) MXene composite bimetallic selenide heterostruc-ture(V_(4)C_(3)@CuSe_(2)/CoSe_(2))as a cathode material for aluminum batteries.This heterostructure was pre-pared through a Lewis melt salt etching and selenization process.By capitalizing on the synergistic effect between the bimetallic selenide and V_(4)C_(3) MXene,V_(4)C_(3)@CuSe_(2)/CoSe_(2) exhibited rapid charge transfer and demonstrated superior discharge specific capacity compared to V_(4)C_(3) composite monometallic selenide.Furthermore,the incorporation of V_(4)C_(3) improved the material's stability during charging/discharging.The initial discharge specific capacity of V_(4)C_(3)@CuSe_(2)/CoSe_(2) reached an impressive 809 mAh g^(-1) at 1 Ag^(-1).Even after nearly 3000 cycles,it retained a substantial capacity of 169.1 mAh g^(-1).Ex-situ XPS analysis confirmed the reversible valence transitions of Cu,Co,and Se elements as the main energy storage reac-tions taking place in the cathode material.Density functional theory analysis provided further insights,revealing that the strong metallic behavior of the heterostructure stemmed from the charge rearrange-ment facilitated by the bimetallic selenide structure and the optimization of the energy level structure.Additionally,the presence of the bimetallic selenide structure significantly improved the adsorption ef-ficiency of[AlCl4]^(-).Overall,this research contributes to the advancement of rechargeable aluminum ion batteries and presents a promising avenue for future developments in composite metal selenide struc-tures and MXene-based materials.
基金supported by the National Natural Science Foundation of China(Grant No.51372064)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2014201176 and E2017201209)+1 种基金the Outstanding Doctoral Cultivation Project of Hebei University(Grant No.YB201502)the Hebei Province Universities Science and Technology Program funded by the Hebei Provincial Education Department,China(Grant Nos.ZD2014018 and QN2017017)
文摘The thermoelectric performance of CdO ceramics was enhanced by simultaneously optimizing the electrical and thermal transport properties via a small amount of Zn doping （≤3%）. The introduction of Zn can obviously increase the electrical conductivity of CdO due to the simultaneous increase of carrier concentration and mobility, and eventually results in an improvement in power factor. Zn doping is also effective in suppressing the thermal conductivity of CdO because of stronger phonon scatterings from point defects, Zn-riched second phase, and grain boundaries. A best ZT of about 0.45 has been achieved in the Cd1-xZnxO systems at about 1000 K, which is comparable to the highest values reported for other n-type oxide TE materials.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51672066 and 50902042)Funds for Distinguished Young Scientists of Hebei Province,China(Grant No.A2015201129)Personnel Training Project of Hebei Province,China(Grant No.A2016002013)
文摘A blue phosphor was obtained by doping Eu2＋ into a multi-cation host Sro.8Cao.2Al2Si208 through high tempera- ture solid state reaction. The emission spectra show a continuous red-shift behavior from 413 nm to 435 nm with Eu2＋ concentration increasing. The substitution priority of Eu2＋ in Sro.8Cao.2AI2Si208 was investigated via x-ray diffraction （XRD） and temperature properties in detail： the Ca2＋ ions are preferentially substituted by Eu2＋at lower doping, and with the Eu2＋ concentration increasing, the probability of substitution for Sr2＋ is greater than that of replacing Ca2＋. Accord- ingly, we propose the underlying method of thermal property to determine the substitution of Eu2＋ in the multi-cation hosts. Moreover, the abnormal increase of emission intensity with increasing temperature was studied by the thermolumi- nescence spectra. The energy transfer mechanism between the Eu2＋ ions occupying different cation sites was studied by the lifetime decay curves. A series of warm white light emitting diodes were successfully fabricated using the blue phos- phors Sro.gCao.2A12Si208： Eu2＋ with commercial red phosphor （Ca Sr）SJA1N3： lu2＋ and green phosphor （Y Lu）jA15Or2 ： Ce3＋, and the luminescent efficiency can reach 45 lm/W.
基金the National Natural Science Foundation of China(Grant Nos.11934004 and U1832201)the Science Challenge Project(Grant No.TZ2016005)the CAEP Foundation(Grant No.CX2019022).
文摘The electron-impact ionization of lithium-like ions C^(3+),N^(4+),O^(5+),Ne^(7+),and Fe2^(3+)is studied using a combination of two-potential distorted-wave and R-matrix methods with a relativistic correction.Total cross sections are computed for incident energies from 1 to 10 times of ionization energy and better agreements with the experimental results are obtained in comparison with the theoretical data available.It is found that the indirect ionization processes become significant for the incident energy larger than about four times of the ionization energy.Contributions from the exchange effects along the isoelectronic sequence are also discussed and found to be important.The present method can be used to obtain systematic ionization cross sections for highly charged ions across a wide incident energy range.
基金financial support from the Advanced Talents Incubation Program of Hebei University (521100221006)financial support from the National Natural Science Foundation of China (11974097)+2 种基金the Natural Science Foundation of Hebei Province (A2019201073)support from the National Natural Science Foundation of China (61875136)the Fundamental Research Project of Guangdong Province (2020A1515011315)
文摘Mechanoluminescent(ML)materials can directly convert external mechanical stimulation into light without the need for excitation from other forms of energy,such as light or electricity.This alluring characteristic makes ML materials potentially applicable in a wide range of areas,including dynamic imaging of force,advanced displays,information code,storage,and anti-counterfeiting encryption.However,current reproducible ML materials are restricted to sulfide-and oxide-based materials.In addition,most of the reported ML materials require pre-irradiation with ultraviolet(UV)lamps or other light sources,which seriously hinders their practical applications.Here,we report a novel ML material,MgF_(2):Mn^(2+),which emits bright red light under an external dynamic force without the need for pre-charging with UV light.The luminescence properties were systematically studied,and the piezophotonic application was demonstrated.More interestingly,unlike the well-known zinc sulfide ML complexes reported previously,a highly transparent ML film was successfully fabricated by incorporating MgF_(2):Mn^(2+)into polydimethylsiloxane(PDMS)matrices.This film is expected to find applications in advanced flexible optoelectronics such as integrated piezophotonics,artificial skin,athletic analytics in sports.
基金financially supported by the National Natural Science Foundation of China(52102233)Science and Technology Project of Hebei Education Department(QN2023019)。
文摘Aqueous aluminum ion batteries(AAIBs)have garnered extensive attention due to their environmental friendliness,high theoretical capacity,and low cost.However,the sluggish reaction kinetics and severe structural collapse of the cathode material,especially manganese oxide,during the cycling process have hindered its further application.Herein,Cu^(2+)pre-interca la ted layeredδ-MnO_(2)was synthesized via a hydrothermal method.The pre-intercalated Cu^(2+)ions not only improve the conductivity of MnO_(2)cathode but also stabilize the structure to enhance stability.X-ray absorption fine structure(XAFS)combined with density functional theory(DFT)calculations confirm the formation of the covalent bond between Cu and O,increasing the electronegativity of O atoms and enhancing the H^(+)adsorption energy.Moreover,ex-situ measurements not only elucidate the Al^(3+)/H^(+)co-insertion energy storage mechanism but also demonstrate the high reversibility of the Cu-MnO_(2)cathode during cycling.This work provides a promising modification approach for the application of manganese oxides in AAIBs.
基金supported by the National Natural Science Foundation of China (11704094, 11504076, 51372064, 61405040, 51622205, 61675027, 51432005, and 61505010)the Natural Science Foundation of Hebei Province (F2019201047, F2018201198, F2017201141, and E2017201227)the Natural Science Foundation for Distinguished Young Scholars of Hebei University (2015JQ03)。
文摘Cu(In,Ga)Se2(CIGS) based multilayer heterojunction, as one of the best high efficiency thin film solar cells, has attracted great interest due to its outstanding features. However, the present studies are primarily focused on the structure optimization and modulation in order to enhance the photoelectric conversion efficiency. Here, we exploit another application of this multilayer heterostructure in photoresistance-modulated position sensitive detector by introducing lateral photoresistance effect.The lateral photoresistance measurements show that this multilayer heterojunction exhibits a wide spectral response(~330 to ~1150 nm) and excellent bipolar photoresistance performances(position sensitivity of ~63.26 X/mm and nonlinearity <4.5%), and a fast response speed(rise and fall time of ~14.46 and^14.42 ms, respectively). More importantly, based on the lateral photoresistance effect, the CIGS heterostructure may also be developed as a position-dependent resistance memory device, which can be modulated by changing laser intensity, wavelength, and bias voltage with excellent stability and repeatability, and the position resolution reaches up to 1 lm. These results can be well explained by considering the diffusion and the drift model of carriers in the CIGS multilayer heterojunction. This work provides a new approach of achieving novel photoelectric sensors and memory devices based on the traditional photovoltaic heterostructures.
基金Project supported by the National Science Foundation of China(61205180)National Science Foundation for Distinguished Young Scholars of China(61125505)Natural Science Foundation of Hebei Province(E2012201087)
文摘A series of Y1_xPO4：xTb3＋ （x=0.005-0.1） phosphors were successfully fabricated by using co-precipitation method with NHzH2PO4 as phosphorus source. The structure and morphology characterization of the luminescent material was investigated with X-ray powder diffraction （XRD） and field emission scanning electron microscopy （FESEM）. The XRD patterns indicated that the samples belonged to tetragonal phase. Luminescence properties were discussed by measuring the excitation and emission spectra. The phosphor could be excited by UV light （340-390 nm） and emitted green light, with the emission peaks located at 491 （5Da→7F6）, 550 （SD4→7Fs）, 589 （5D4→7F4） and 624 nm （SD4→TF3）. In addition, the pH value and activator concentration had great effects on the emission intensity. The results illuminated that this phosphor could be used for UV based white light emitting diodes and co-precipitation method could be used to prepare better appearance phosphor.
基金the National Natural Science Foundation of China(No.52102233)Nature Science Foundation of Hebei Province(No.E2021201006).
文摘Rechargeable aluminum batteries(RABs)are a popular energy storage device because of its safety and environmental protection.As cathode materials of RABs,transition metal oxide,sulfide,and selenide have become the research hotspot.In this work,we have successfully prepared CuO,Cu_(1.8)S,and Cu_(1.8)Se electrode materials.Among them,although Cu_(1.8)Se had a relatively higher initial discharge capacity,all of these products had severe capacity degradation in terms of cycling and rate performance.Furthermore,for solving the problem of capacity decline,CMK-3 modified separator was used to make the Cu_(1.8)Se cathode material more stable,thus improving cycling and rate performance.It can be confirmed by ex situ X-ray photoelectron spectroscopy(XPS)that both Cu and Se elements underwent reversible redox reactions during the charging/discharging process.Density functional theory was implemented to study the energy storage mechanism of CumX(X=O,S,Se).The results showed that Cu_(1.8)S and Cu_(1.8)Se mainly relied on AlCl4−for energy storage,and the intercalation/de-intercalation of Al3+occurred during the charge/discharge process in CuO material.Consequently,the optimized Cu_(1.8)Se/CMK-3@GF/C/Al revealed an outstanding rate capability(977.83 mAh·g^(−1)at 0.5 A·g^(−1))and long cyclic stability(retention of 478.77 mAh·g^(−1)after 500 cycles at 1.0 A·g^(−1)).Compared to previously reported cathode materials of RABs,this type of battery displays great superiority in terms of rate and cycling stability.This research also provides a novel approach to suppress the shuttle effect of active species for advanced clean energy devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.41431071,41174141,41474124)the National Basic Research Program of China(Grant No.2011CB811404)
文摘This paper studies the effective polytropic index in the central plasma sheet （CPS） by using the method of Kartalev et al. （2006）, which adopts the denoising technique of Haar wavelet to identify the homogeneous MHD Bernoulli integral （MBI） and has been frequently used to study the polytropic relation in the solar wind. We chose the quiet CPS crossing by Cluster C1 during the interval 08：51：00-09：19：00 UT on 03 August 2001. In the central plasma sheet, thermal pressure energy per unit mass is the most important part in MBI, and kinetic energy of fluid motion and electromagnetic energy per unit mass are less important. In the MBI, there are many peaks, which correspond to isothermal or near isothermal processes. The interval lengths of homogenous MBI regions are generally less than 1 min. The polytropic indexes are calculated by linearly fitting the data of lnp and Inn within a 16 s window, which is shifted forward by 8 s step length. Those polytropic indexes with IRI ≥0.8 （R is the correlation coefficient between lnp and inn） and p-value≤0.1 in the homogeneous regions are almost all in the range of [0, 1]. The mean and median effective polytropic indexes with high R and low p-value in homogeneous regions are 0.34 and 0.32 respectively, which are much different from the polytropic index obtained by traditional method （αtrad=-0.15）. This result indicates that the CPS is not uniform even during quiet time and the blanket applications of polytropic law to plasma sheet may return misleading value of polytropic index. The polytropic indexes in homogeneous regions with a high correlation coefficient basically have good regression significance and are thus credible. These results are very important to understand the energy transport in magnetotail in the MHD frame.
基金financially supported by the National Natural Science Foundation of China(12104125,11974097,61875136,and 52002246)the Advanced Talents Incubation Program of Hebei University(521100221006)+3 种基金the Natural Science Foundation of Hebei Province(A2019201073)Guangdong Provincial Science Fund for Distinguished Yong Scholars(2022B1515020054)the Fundamental Research Project of Guangdong Province(2020A1515011315)the Scientific Research Foundation as PhaseⅡconstruction of High Level University for the Youth Scholars of Shenzhen University 2019(000002110223)。
基金supported by the National Natural Science Foundation of China(51972094 and 52002107)Hebei Provincial Department of Science and Technology(236Z4403G)+1 种基金Research Innovation Team Project of Hebei University(IT2023A04,150000321008)supported in part by the Micro-analysis Center and the High-Performance Computing Center of Hebei University。
基金supported by the Natural Science Foundation of Hebei Province(No.F2016201023)the Technology Foundation for Selected Overseas Chinese Scholar of Ministry of Human Resources and Social Security of China(No.CG2015003006)the Advanced Talents Program of Hebei Educational Committee(No.GCC2014020)
文摘We propose and demonstrate a novel single-longitudinal-mode(SLM) erbium-doped fiber laser(EDFL) capable of operating at fixed-wavelength lasing mode with a tunable range more than 54 nm, an ultra-narrow linewidth of 473 Hz and an ultra-high optical signal-to-noise ratio(OSNR) more than 72 dB, or operating at wavelength-swept mode with tunable sweep rate of 10—200 Hz and a sweep range more than 50 nm. The excellent features mainly benefit from a triple-ring subring cavity constructed by three optical couplers nested one another and a fiber Fabry-Pérot tunable filter which can be driven by a constant voltage or a periodic sweep voltage for fixed or wavelength-swept operation, respectively. The proposed EDFL has potential applications in high-resolution spectroscopy and fiber optic sensing.
