Yb:GdYAl3 (B03)4 (Yb:GdYAB) is investigated as a new laser crystal for potential applications in self-frequency doubling. The emission and absorption properties of Yb:GdYAB crystal are studied, and the emission...Yb:GdYAl3 (B03)4 (Yb:GdYAB) is investigated as a new laser crystal for potential applications in self-frequency doubling. The emission and absorption properties of Yb:GdYAB crystal are studied, and the emission decay times of the upper laser level are measured. The emission cross sections are evaluated using the absorption cross section and principle of reciprocity. The other laser performance parameters, such as the minimum inversion fraction βmin, pump saturation intensity Isat and minimum pump intensity 1rain, are also calculated. The results are discussed in the framework of requirements for an effective diode-pumped Yb^3+ laser system. Yb:GdYAB is expected to exhibit the most useful laser properties and to be superior to Yb:YAB crystal that has been excellent self-frequency-doubling crystal at present in many key spectroscopic parameter values.展开更多
Using an external couple cavity and a pump beam compression system, efficient 1.5 μm eye-safe Raman laser is obtained based on BaWO4 crystal. The largest output energy is 8.5mJ, corresponding to an electric-optical c...Using an external couple cavity and a pump beam compression system, efficient 1.5 μm eye-safe Raman laser is obtained based on BaWO4 crystal. The largest output energy is 8.5mJ, corresponding to an electric-optical conversion efficiency of 47%.展开更多
Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor (HAuC14) to an electrolyzed aqueous solution of poly(N-vinylpyrrolidone) (PVP) and KN03, which indicates the good reducin...Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor (HAuC14) to an electrolyzed aqueous solution of poly(N-vinylpyrrolidone) (PVP) and KN03, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuC14,' respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H+ or OH- catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.展开更多
In this paper, the coupled extension and thickness- twist vibrations are studied for AT-cut quartz plates under Lateral Field Excitation (LFE) with variations along the x1- direction. Mindlin's two-dimensional equa...In this paper, the coupled extension and thickness- twist vibrations are studied for AT-cut quartz plates under Lateral Field Excitation (LFE) with variations along the x1- direction. Mindlin's two-dimensional equations are used for anisotropic crystal plates. Both free and electrically forced vibrations are considered. Important vibration characteristics are obtained, including dispersion relations, frequency spectra, and motional capacitances. It is shown that, to avoid the effects of the couplings between extension and thickness-twist vibrations, a series of discrete values of the length/thickness ratio of the crystal plate need to be excluded. The results are of fundamental significance for the design of LFE resonators and sensors.展开更多
Single phase crystalline cubic boron nitride (cBN) with high yield was prepared by hydrothermal route at low temperature, using hydrochloric acid (HCI) as the promoter. The promotion effect of HCI on the synthesis...Single phase crystalline cubic boron nitride (cBN) with high yield was prepared by hydrothermal route at low temperature, using hydrochloric acid (HCI) as the promoter. The promotion effect of HCI on the synthesis of cBN is briefly discussed.展开更多
Co2MnSi thin films are made by magnetron sputtering onto MgO (001) substrates. The crystalline quality is improved by increasing depositing temperature and/or annealing temperature. The sample deposited at 550℃ and...Co2MnSi thin films are made by magnetron sputtering onto MgO (001) substrates. The crystalline quality is improved by increasing depositing temperature and/or annealing temperature. The sample deposited at 550℃ and subsequently annealed at 550℃ (sample I) exhibits a pseudo-epitaxial growth with partially ordered L21 phase. Sample I shows a four-fold magnetic anisotropy, in addition to a relatively weak uniaxial anisotropy. The Gilbert damping factor of sample I is smaller than 0.001, much smaller than reported ones. The possible reasons responsible for the small Gilbert damping factor are discussed, including weak spin-orbit coupling, small density of states at Fermi level, and so on.展开更多
Metal-organic frameworks(MOFs)are favored in the fields of adsorption,separation,catalysis,electrochemistry,and magnetism due to their advantages of large specific surface area,high porosity,controllable pore size adj...Metal-organic frameworks(MOFs)are favored in the fields of adsorption,separation,catalysis,electrochemistry,and magnetism due to their advantages of large specific surface area,high porosity,controllable pore size adjustment,and dispersion of metal active sites.The application of MOFs involves multiple fields,which requires that MOFs have good water stability,as gaseous and liquid water inevitably exist in industrial processes.In this paper,the research status of the stability of MOFs in aqueous solutions was reviewed in recent years,including the design and synthesis,the influencing factors,and the applications of MOFs in water stability.展开更多
A diode-end-pumped Q-switched high-efficiency Nd, Cr:YAG laser with simultaneous dual-wavelength emission at 946nm and 1.3μm is demonstrated. The maximum output power of 1.93 W with simultaneous dual-wavelength oper...A diode-end-pumped Q-switched high-efficiency Nd, Cr:YAG laser with simultaneous dual-wavelength emission at 946nm and 1.3μm is demonstrated. The maximum output power of 1.93 W with simultaneous dual-wavelength operation is achieved at an absorbed pump power of 13.32 W and an absorbed slope efficiency of 15.15%. The maximum optical-optical efficiency is 14.49% with pulse widths of 16.38ns at 946nm and 26.65ns at 1.3μm. A maximum total repetition rate of 43.25 kHz is obtained.展开更多
Cubic boron nitride (cBN) and orthorhombic boron nitride (oBN) crystals have been prepared in hydrothermal solutions by reacting H3BO3+NaN3+P and H3BO3+NaN3+N2H4 respectively. The experimental results indicated that, ...Cubic boron nitride (cBN) and orthorhombic boron nitride (oBN) crystals have been prepared in hydrothermal solutions by reacting H3BO3+NaN3+P and H3BO3+NaN3+N2H4 respectively. The experimental results indicated that, if the temperature was increased rapidly, both the yield and perfectness of BN crystals became poor. On the contrast, the yield and perfectness of BN crystals can be improved very much by slowly increasing the temperature of the reaction mixture. The results of X-ray powder diffraction (XRD), Fourier transform infrared spectrum (FTIR) and high resolution transmission electron microscopy (HRTEM) proved that the samples were composed of oBN and cBN.展开更多
MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical...MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical conductivity restrict its potential realworld application.Herein,an alternately intercalated structure of MoS2 monolayer and N-doped porous carbon(NC)layer is grown on reduced graphene oxide(rGO)via a chemical intercalated strategy.The expanded interlayer distance of MoS2(0.96 nm),enlarged by the intercalation of N-doped porous carbon layers,can enhance ion diffusion mobility,provide additional reactive sites for ion storage and maintain the stability of electrode structure.In addition,the hierarchical structures between rGO substrate and intercalated N-doped carbon layers construct a three-dimensional(3D)conductive network,which can significantly improve the electrical conductivity and the structural stability.As a result,the rGO-supported MoS2/NC electrode exhibits an ultrahigh reversible capacity and remarkable long cycling stability for sodium-ion batteries(SIBs)and potassium-ion(PIBs).Meanwhile,the as-obtained MoS2/NC@rGO electrode also delivers a superior cycle performance of 250 mAh·g−1 after 160 cycles at 0.5 A·g−1 when employed as an anode for sodium-ion full cells.展开更多
As promising electrode materials,transition metal oxides have attracted considerable attention owing to their excellent performance in electrochemical energy storage.However,their poor conductivity and fragile structu...As promising electrode materials,transition metal oxides have attracted considerable attention owing to their excellent performance in electrochemical energy storage.However,their poor conductivity and fragile structure limit their practical application.In this study,a binder-free nickel oxide/oxynitride network(NiON WS)bifunctional electrodes with cation multivalent states that exhibit high energy storage performance were synthesized for the first time.The massive active sites,high specific surface areas,and multiple cation valence states of NiON WS were advantageous for electrochemical redox reaction during its application in supercapacitors(1283.5 mF cm^(-2))and lithium-ion batteries(1345.0 mA h g^(-1)).Particularly,the NiON WS based flexible asymmetric SCs exhibit excellent capacitance and energy densities.First-principle calculations were employed to study the mechanism of the electrochemical performance improvement of NiON WS.This study demonstrates the potential of transition metal oxides electrode with high capacity and activity for electrochemical energy storage and conversion.展开更多
Copper phthalocyanine junctions, fabricated by magnetron sputtering and evaporating methods, show multi-polar (unipolar and bipolar) resistance switching and the memory effect. The multi-polar resistance switching h...Copper phthalocyanine junctions, fabricated by magnetron sputtering and evaporating methods, show multi-polar (unipolar and bipolar) resistance switching and the memory effect. The multi-polar resistance switching has not been observed simultaneously in one organic material before. With both electrodes being cobalt, the unipolar resistance switching is universal. The high resistance state is switched to the low resistance state when the bias reaches the set voltage. Generally, the set voltage increases with the thickness of copper phthalocyanine and decreases with increasing dwell time of bias. Moreover, the low resistance state could be switched to the high resistance state by absorbing the phonon energy. The stability of the low resistance state could be tuned by different electrodes. In Au/copper phthalocyanine/Co system, the low resistance state is far more stable, and the bipolar resistance switching is found. Temperature dependence of electrical transport measurements demonstrates that there are no obvious differences in the electrical transport mechanism before and after the resistance switching. They fit quite well with Mott variable range hopping theory. The effect of A1203 on the resistance switching is excluded by control experiments. The holes trapping and detrapping in copper phthalocyanine layer are responsible for the resistance switching, and the interfacial effect between electrodes and copper phthalocyanine layer affects the memory effect.展开更多
KDP and its deuterated analog DKDP (K (D x H 1- x ) 2PO 4) are the first ch oice materials in the fabrication of optical switcher and frequency converter fo r inertial confinement fusion study.In the past years,the gr...KDP and its deuterated analog DKDP (K (D x H 1- x ) 2PO 4) are the first ch oice materials in the fabrication of optical switcher and frequency converter fo r inertial confinement fusion study.In the past years,the growth technique has b een d eveloped greatly.Large aperture crystals can be grown with various methods,such as,temperature decreasing,solution circular flow,and rapid growth method,which i ntend to reduce the cost of production and satisfy the requirement of ICF.As to rapid growth method,much attention has been paid to solution stability and the K DP crystal qualities of this method which has been proved that high speed can be obtained.LLNL has grown KDP crystal with dimension of 57mm×57mm×55mm,260 kil ogram in 59 days.This method is very different from conventional method for grow ing KDP crystal in three directions uniformly.In addition to the growth of the pyramidal faces,rapid crystallization from supersaturated solution results in si gnificant growth of prismatic faces.Inclusions of growth solution and incorporat ion of metal impurities will occur in the prism sector as prism extends very muc h by this method.Fast growth needs high supersaturation(10%—30%),so the grow th condition,such as ,raw materials,apparatus,temperature lowing proceed should be controlled very strictly.In order to improve the utilization of KDP crystal g rown by point seed method,we developed 4 vessels circular technique on the bas e of 3 vessels circular technique recently.展开更多
PbWO 4 crystal is a dense,fast and radiation hard scintillator which is being t ested to be used as a radiator of EM calorimeters.With a density of 8.2g/cm 3,t his crystal is having a decay time of less than 10nm for ...PbWO 4 crystal is a dense,fast and radiation hard scintillator which is being t ested to be used as a radiator of EM calorimeters.With a density of 8.2g/cm 3,t his crystal is having a decay time of less than 10nm for about 85% of light outp ut.Its unit radiation length, x 0 is shorter than any of the well establish ed scintillators. In order to improve the scintillating property,CeO 2(0.01wt%) and Ge 2O 3 add ed into PWO,Ce:Ge:PWO crystal was grown by Czochraski method.The growth technolo gy parameters were:the temperature gradient of 40℃/cm,the rotating rate of 30r/ m in and the growth speed of 1 2mm/h.The transmissibility of pure PWO crystal was 68%,where as that of Ce:Ge:PWO was 70%.The light yield of pure PWO and Ce:Ge:PWO was 9.5p.e./MeV and 14.6 p.e./MeV,respectively.展开更多
Weak ion diffusion and electron transport due to limited interlayer spacing and poor electrical conductivity have been identified as critical roadbacks for fast and abundant energy storage of both MoS2-based lithium i...Weak ion diffusion and electron transport due to limited interlayer spacing and poor electrical conductivity have been identified as critical roadbacks for fast and abundant energy storage of both MoS2-based lithium ion batteries (LIBs) and sodium ion batteries (SIBs). In this work, MoS2 porous-hollow nanorods (MoS2/m-C800) have been designed and synthesized via an annealing-followed chemistry-intercalated strategy to solve the two issues. They are uniformly assembled from ultrathin MoS2 nanosheets, deviated to the rod-axis direction, with expanded interlayer spacing due to alternate intercalation of N-doped carbon monolayers between the adjacent MoS2 monolayers. Electrochemical studies of the MoS2/m-C800 sample, as an anode of LIBs, demonstrate that the superstructure can deliver a reversible discharge capacity of 1,170 mAh·g^-1 after 100 cycles at 0.2 A·g^-1 and maintain a reversible capacity of 951 mAh·g^-1 at 1.25 A·g^-1 after 350 cycles. While for SIBs, the superstructure also delivers a reversible discharge capacity of 350 mAh·g^-1 at 0.5 A-g-1 after 500 cycles and exhibits superior rate capacity of 238 mAh·g^-1 at 15 A·g^-1 .The excellent electrochemical performance is closely related with the hierarchical superstructures, including expanded interlayer spacing, alternate intercalation of carbon monolayers and mesoporous feature, which effectively reduce ion diffusion barrier, shorten ion diffusion paths and improve electrical conductivity.展开更多
g-C3N4/TiO2 composite were prepared by hydrolysis of Ti(OC4Hn9) 4 and the precursors of g-C3N4 at room temperature and annealing in nitrogen atmosphere.X-ray diffraction results revealed that all the products were a...g-C3N4/TiO2 composite were prepared by hydrolysis of Ti(OC4Hn9) 4 and the precursors of g-C3N4 at room temperature and annealing in nitrogen atmosphere.X-ray diffraction results revealed that all the products were anatase structure.The chemical nature of O,N of the g-C 3N4/TiO2 were identified by X-ray photoelectron spectroscopy,presenting N-Ti-O and N-Ti-N doping status of the composite.The g-C3N4 /TiO2 composite showed better photocatalytic activity for the UV and visible-light degradation of Rhodamine B.展开更多
In order to improve the characteristics of the general broad-waveguide 808-nm semiconductor laser diode (LD), we design a new type quantum well LD with an asymmetric cladding structure. The structure is grown by met...In order to improve the characteristics of the general broad-waveguide 808-nm semiconductor laser diode (LD), we design a new type quantum well LD with an asymmetric cladding structure. The structure is grown by metal organic chemical vapor deposition (MOCVD). For the devices with 100-ttm-wide stripe and 1000-/zm-long cavity under continuous-wave (CW) operation condition, the typical threshold current is 190 mA, the slope efficiency is 1.31 W/A, the wall-plug efficiency reaches 63%, and the maximum output power reaches higher than 7 W. And the internal absorption value decreases to 1.5 cm^-1.展开更多
VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer s...VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer spacing(0.57 nm)of VS2 generally determines high ion diffusion barrier and large volume variation,resulting in unsatisfactory electrochemical performance of SIBs and PIBs.In this work,flower-like VS_(2)/N-doped carbon(VS_(2)/N-C)with expanded(001)plane is grown on reduced graphene oxide(rGO)via a solvothermal and subsequently carbonization strategy.In the VS_(2)/N-C@rGO nanohybrids,the ultrathin VS2"petals"are alternately intercalated by the N-doped porous carbon monolayers to achieve an expanded interlayer spacing(1.02 nm),which can effectively reduce ions diffusion barrier,expose abundant active sites for Na+/K+intercalation,and tolerate large volume variation.The N-C and rGO carbonous materials can significantly promote the electrical conductivity and structural stability.Benefited from the synergistic effect,the VS2/N-C@rGO electrode exhibits large reversible capacity(Na+:407 mAh·g^(-1) at 1 A·g^(-1);K^(+):334 mAh·g^(-1) at 0.2 A·g^(-1)),high rate capacity(Na+:273 mAh·g^(-1) at 8 A·g^(-1);K+:186 mAh·g^(-1) at 5 A·g^(-1)),and remarkable cycling stability(Na+:316 mAh·g^(-1) at 2 A·g^(-1) after 1,400 cycles;K^(+):216 mAh·g^(-1) at 1 A·g^(-1) after 500 cycles).展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 50323006, and the Excellent Middle-Young- Aged Foundation of Shandong Province under Grant No 2006BS04023.
文摘Yb:GdYAl3 (B03)4 (Yb:GdYAB) is investigated as a new laser crystal for potential applications in self-frequency doubling. The emission and absorption properties of Yb:GdYAB crystal are studied, and the emission decay times of the upper laser level are measured. The emission cross sections are evaluated using the absorption cross section and principle of reciprocity. The other laser performance parameters, such as the minimum inversion fraction βmin, pump saturation intensity Isat and minimum pump intensity 1rain, are also calculated. The results are discussed in the framework of requirements for an effective diode-pumped Yb^3+ laser system. Yb:GdYAB is expected to exhibit the most useful laser properties and to be superior to Yb:YAB crystal that has been excellent self-frequency-doubling crystal at present in many key spectroscopic parameter values.
基金This work was supported by the National Natural Science Foundation of China (NNSFC, No. 20473048, 50272036, 50302005, 90206042)Key Project of Science & Technology Research of Ministry of Education (KPSTR)Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP, No. 20020422057).
基金Supported by the National Natural Science Foundation of China under Grant Nos 60508010 and 50590401, the Natural Science Foundation of Shandong Province under Grant No Y2004F05, and the Programme for Taishan Scholar of Shandong Province.
文摘Using an external couple cavity and a pump beam compression system, efficient 1.5 μm eye-safe Raman laser is obtained based on BaWO4 crystal. The largest output energy is 8.5mJ, corresponding to an electric-optical conversion efficiency of 47%.
基金supported by the National Natural Science Foundation of China(No.21073111)the Natural Science Foundation of Shandong Province,China(No.ZR2010BQ029)
文摘Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor (HAuC14) to an electrolyzed aqueous solution of poly(N-vinylpyrrolidone) (PVP) and KN03, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuC14,' respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H+ or OH- catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.
基金supported by the National Natural Science Foundation of China(11372146)Research Fund for the Doctoral Program of Higher Education of China(20123305120007)+2 种基金Impact and Safety of Coastal Engineering Initiative,a COE Program of Zhejiang Provincial Government at Ningbo University(zj1110,zj1201,zj1229,and zj1203)Research Project Foundation of Zhejiang Educational Department(201327293)Young Doctoral Innovation Fund by Ningbo Polythchnic
文摘In this paper, the coupled extension and thickness- twist vibrations are studied for AT-cut quartz plates under Lateral Field Excitation (LFE) with variations along the x1- direction. Mindlin's two-dimensional equations are used for anisotropic crystal plates. Both free and electrically forced vibrations are considered. Important vibration characteristics are obtained, including dispersion relations, frequency spectra, and motional capacitances. It is shown that, to avoid the effects of the couplings between extension and thickness-twist vibrations, a series of discrete values of the length/thickness ratio of the crystal plate need to be excluded. The results are of fundamental significance for the design of LFE resonators and sensors.
基金This work was supported by the National Natural Science Foundation of China(No.20473048,90206042)Science&Technology Research Program of Ministry of Education(No.104110,305010)Natural Science Foundation of Shandong Province(Y2006B24).
文摘Single phase crystalline cubic boron nitride (cBN) with high yield was prepared by hydrothermal route at low temperature, using hydrochloric acid (HCI) as the promoter. The promotion effect of HCI on the synthesis of cBN is briefly discussed.
基金Supported by the National Basic Research Program of China under Grant No 2015CB921502the National Natural Science Foundation of China under Grant Nos 11474184 and 11174183+3 种基金the 111 Project under Grant No B13029the Natural Science Foundation of Shandong Province under Grant No JQ201201the Doctorate Foundation of Shandong Province under Grant No BS2013CL042the Young Scientists Fund of the National Natural Science Foundation of China under Grant No 11204164
文摘Co2MnSi thin films are made by magnetron sputtering onto MgO (001) substrates. The crystalline quality is improved by increasing depositing temperature and/or annealing temperature. The sample deposited at 550℃ and subsequently annealed at 550℃ (sample I) exhibits a pseudo-epitaxial growth with partially ordered L21 phase. Sample I shows a four-fold magnetic anisotropy, in addition to a relatively weak uniaxial anisotropy. The Gilbert damping factor of sample I is smaller than 0.001, much smaller than reported ones. The possible reasons responsible for the small Gilbert damping factor are discussed, including weak spin-orbit coupling, small density of states at Fermi level, and so on.
基金supported by the National Natural Science Foundation of China(22002136,U1904215)Natural Science Foundation of Jiangsu Province(20KJB150004 and BK20200044)+1 种基金Lvyangjinfeng Talent Program of YangzhouChangjiang Scholars’Program of the Ministry of Education(Q2018270)
文摘Metal-organic frameworks(MOFs)are favored in the fields of adsorption,separation,catalysis,electrochemistry,and magnetism due to their advantages of large specific surface area,high porosity,controllable pore size adjustment,and dispersion of metal active sites.The application of MOFs involves multiple fields,which requires that MOFs have good water stability,as gaseous and liquid water inevitably exist in industrial processes.In this paper,the research status of the stability of MOFs in aqueous solutions was reviewed in recent years,including the design and synthesis,the influencing factors,and the applications of MOFs in water stability.
基金Supported by the National Basic Research Program of China under Grant No 2013CB632704
文摘A diode-end-pumped Q-switched high-efficiency Nd, Cr:YAG laser with simultaneous dual-wavelength emission at 946nm and 1.3μm is demonstrated. The maximum output power of 1.93 W with simultaneous dual-wavelength operation is achieved at an absorbed pump power of 13.32 W and an absorbed slope efficiency of 15.15%. The maximum optical-optical efficiency is 14.49% with pulse widths of 16.38ns at 946nm and 26.65ns at 1.3μm. A maximum total repetition rate of 43.25 kHz is obtained.
基金Project supported by the Natural Science Foundation of China (Nos. 50272036 90101016 and 90206042) the Natural Science Foundation of Shan-dong Province and the Foundation of Doctorate Education Discipline by the Ministry of Education of China.
文摘Cubic boron nitride (cBN) and orthorhombic boron nitride (oBN) crystals have been prepared in hydrothermal solutions by reacting H3BO3+NaN3+P and H3BO3+NaN3+N2H4 respectively. The experimental results indicated that, if the temperature was increased rapidly, both the yield and perfectness of BN crystals became poor. On the contrast, the yield and perfectness of BN crystals can be improved very much by slowly increasing the temperature of the reaction mixture. The results of X-ray powder diffraction (XRD), Fourier transform infrared spectrum (FTIR) and high resolution transmission electron microscopy (HRTEM) proved that the samples were composed of oBN and cBN.
基金The authors are grateful to the National Key Research and Development Project(No.51890863)the National Natural Science Foundation of China(Nos.51872172 and 51972197)+1 种基金Natural Science Foundation of Shandong Province(Nos.ZR2019MEM021 and ZR2020QE067)Young Scholars Program of Shandong University.
文摘MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical conductivity restrict its potential realworld application.Herein,an alternately intercalated structure of MoS2 monolayer and N-doped porous carbon(NC)layer is grown on reduced graphene oxide(rGO)via a chemical intercalated strategy.The expanded interlayer distance of MoS2(0.96 nm),enlarged by the intercalation of N-doped porous carbon layers,can enhance ion diffusion mobility,provide additional reactive sites for ion storage and maintain the stability of electrode structure.In addition,the hierarchical structures between rGO substrate and intercalated N-doped carbon layers construct a three-dimensional(3D)conductive network,which can significantly improve the electrical conductivity and the structural stability.As a result,the rGO-supported MoS2/NC electrode exhibits an ultrahigh reversible capacity and remarkable long cycling stability for sodium-ion batteries(SIBs)and potassium-ion(PIBs).Meanwhile,the as-obtained MoS2/NC@rGO electrode also delivers a superior cycle performance of 250 mAh·g−1 after 160 cycles at 0.5 A·g−1 when employed as an anode for sodium-ion full cells.
基金supported by the National Natural Science Foundation of China,China(Contract 51872164)Natural Science Foundation of Shandong Province,China(Contract ZR2018MEM013)+1 种基金China Postdoctoral Science Foundation,China(Contract 2019TQ0172,2019M662349)Shandong Provincial Key Research and Development Program,China(Contract 2019GGX103010)。
文摘As promising electrode materials,transition metal oxides have attracted considerable attention owing to their excellent performance in electrochemical energy storage.However,their poor conductivity and fragile structure limit their practical application.In this study,a binder-free nickel oxide/oxynitride network(NiON WS)bifunctional electrodes with cation multivalent states that exhibit high energy storage performance were synthesized for the first time.The massive active sites,high specific surface areas,and multiple cation valence states of NiON WS were advantageous for electrochemical redox reaction during its application in supercapacitors(1283.5 mF cm^(-2))and lithium-ion batteries(1345.0 mA h g^(-1)).Particularly,the NiON WS based flexible asymmetric SCs exhibit excellent capacitance and energy densities.First-principle calculations were employed to study the mechanism of the electrochemical performance improvement of NiON WS.This study demonstrates the potential of transition metal oxides electrode with high capacity and activity for electrochemical energy storage and conversion.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.50971080,11174183,and 50901043)the Program for New Century Excellent Talents of China(Grant No.NCET-10-0541)+3 种基金the Scientific Research Foundation for Returned Overseas Chinese Scholars,111 Project(Grant No.B13029)the Natural Science Foundation of Shandong Province,China(Grant No.JQ201201)the Doctorate Foundation of Shandong Province,China(Grant No.BS2013CL042)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.11204164)
文摘Copper phthalocyanine junctions, fabricated by magnetron sputtering and evaporating methods, show multi-polar (unipolar and bipolar) resistance switching and the memory effect. The multi-polar resistance switching has not been observed simultaneously in one organic material before. With both electrodes being cobalt, the unipolar resistance switching is universal. The high resistance state is switched to the low resistance state when the bias reaches the set voltage. Generally, the set voltage increases with the thickness of copper phthalocyanine and decreases with increasing dwell time of bias. Moreover, the low resistance state could be switched to the high resistance state by absorbing the phonon energy. The stability of the low resistance state could be tuned by different electrodes. In Au/copper phthalocyanine/Co system, the low resistance state is far more stable, and the bipolar resistance switching is found. Temperature dependence of electrical transport measurements demonstrates that there are no obvious differences in the electrical transport mechanism before and after the resistance switching. They fit quite well with Mott variable range hopping theory. The effect of A1203 on the resistance switching is excluded by control experiments. The holes trapping and detrapping in copper phthalocyanine layer are responsible for the resistance switching, and the interfacial effect between electrodes and copper phthalocyanine layer affects the memory effect.
文摘KDP and its deuterated analog DKDP (K (D x H 1- x ) 2PO 4) are the first ch oice materials in the fabrication of optical switcher and frequency converter fo r inertial confinement fusion study.In the past years,the growth technique has b een d eveloped greatly.Large aperture crystals can be grown with various methods,such as,temperature decreasing,solution circular flow,and rapid growth method,which i ntend to reduce the cost of production and satisfy the requirement of ICF.As to rapid growth method,much attention has been paid to solution stability and the K DP crystal qualities of this method which has been proved that high speed can be obtained.LLNL has grown KDP crystal with dimension of 57mm×57mm×55mm,260 kil ogram in 59 days.This method is very different from conventional method for grow ing KDP crystal in three directions uniformly.In addition to the growth of the pyramidal faces,rapid crystallization from supersaturated solution results in si gnificant growth of prismatic faces.Inclusions of growth solution and incorporat ion of metal impurities will occur in the prism sector as prism extends very muc h by this method.Fast growth needs high supersaturation(10%—30%),so the grow th condition,such as ,raw materials,apparatus,temperature lowing proceed should be controlled very strictly.In order to improve the utilization of KDP crystal g rown by point seed method,we developed 4 vessels circular technique on the bas e of 3 vessels circular technique recently.
文摘PbWO 4 crystal is a dense,fast and radiation hard scintillator which is being t ested to be used as a radiator of EM calorimeters.With a density of 8.2g/cm 3,t his crystal is having a decay time of less than 10nm for about 85% of light outp ut.Its unit radiation length, x 0 is shorter than any of the well establish ed scintillators. In order to improve the scintillating property,CeO 2(0.01wt%) and Ge 2O 3 add ed into PWO,Ce:Ge:PWO crystal was grown by Czochraski method.The growth technolo gy parameters were:the temperature gradient of 40℃/cm,the rotating rate of 30r/ m in and the growth speed of 1 2mm/h.The transmissibility of pure PWO crystal was 68%,where as that of Ce:Ge:PWO was 70%.The light yield of pure PWO and Ce:Ge:PWO was 9.5p.e./MeV and 14.6 p.e./MeV,respectively.
基金supported by the National Natural Science Foundation of China (No.51872172)Natural Science Foundation of Shandong Province (Nos.ZR2018MEM010 and ZR2019MEM021)+1 种基金Major Research and Development Program for Public Welfare in Shandong (No.2018GGX102021)Young Scholars Program of Shandong University.
文摘Weak ion diffusion and electron transport due to limited interlayer spacing and poor electrical conductivity have been identified as critical roadbacks for fast and abundant energy storage of both MoS2-based lithium ion batteries (LIBs) and sodium ion batteries (SIBs). In this work, MoS2 porous-hollow nanorods (MoS2/m-C800) have been designed and synthesized via an annealing-followed chemistry-intercalated strategy to solve the two issues. They are uniformly assembled from ultrathin MoS2 nanosheets, deviated to the rod-axis direction, with expanded interlayer spacing due to alternate intercalation of N-doped carbon monolayers between the adjacent MoS2 monolayers. Electrochemical studies of the MoS2/m-C800 sample, as an anode of LIBs, demonstrate that the superstructure can deliver a reversible discharge capacity of 1,170 mAh·g^-1 after 100 cycles at 0.2 A·g^-1 and maintain a reversible capacity of 951 mAh·g^-1 at 1.25 A·g^-1 after 350 cycles. While for SIBs, the superstructure also delivers a reversible discharge capacity of 350 mAh·g^-1 at 0.5 A-g-1 after 500 cycles and exhibits superior rate capacity of 238 mAh·g^-1 at 15 A·g^-1 .The excellent electrochemical performance is closely related with the hierarchical superstructures, including expanded interlayer spacing, alternate intercalation of carbon monolayers and mesoporous feature, which effectively reduce ion diffusion barrier, shorten ion diffusion paths and improve electrical conductivity.
基金supported by the National Natural Science Foundation of China (NSFC,No.50990061,50721002)Ministry of Science and Technology,China(No. 2005CCA00900)
文摘g-C3N4/TiO2 composite were prepared by hydrolysis of Ti(OC4Hn9) 4 and the precursors of g-C3N4 at room temperature and annealing in nitrogen atmosphere.X-ray diffraction results revealed that all the products were anatase structure.The chemical nature of O,N of the g-C 3N4/TiO2 were identified by X-ray photoelectron spectroscopy,presenting N-Ti-O and N-Ti-N doping status of the composite.The g-C3N4 /TiO2 composite showed better photocatalytic activity for the UV and visible-light degradation of Rhodamine B.
基金supported by the National Natural Science Foundation of China (No.50472068)the Program for New Century Excellent Talents in University
文摘In order to improve the characteristics of the general broad-waveguide 808-nm semiconductor laser diode (LD), we design a new type quantum well LD with an asymmetric cladding structure. The structure is grown by metal organic chemical vapor deposition (MOCVD). For the devices with 100-ttm-wide stripe and 1000-/zm-long cavity under continuous-wave (CW) operation condition, the typical threshold current is 190 mA, the slope efficiency is 1.31 W/A, the wall-plug efficiency reaches 63%, and the maximum output power reaches higher than 7 W. And the internal absorption value decreases to 1.5 cm^-1.
基金The authors are grateful to the National Key Research and Development Project(No.51890863)the National Natural Science Foundation of China(NSFC,Nos.51872172 and 51972197)+2 种基金the Natural Science Foundation of Shandong Province(Nos.ZR2018MEM010 and ZR2019MEM021)Major Research and Development Program for Public Welfare in Shandong(No.2018GGX102021)Young Scholars Program of Shandong University.
文摘VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer spacing(0.57 nm)of VS2 generally determines high ion diffusion barrier and large volume variation,resulting in unsatisfactory electrochemical performance of SIBs and PIBs.In this work,flower-like VS_(2)/N-doped carbon(VS_(2)/N-C)with expanded(001)plane is grown on reduced graphene oxide(rGO)via a solvothermal and subsequently carbonization strategy.In the VS_(2)/N-C@rGO nanohybrids,the ultrathin VS2"petals"are alternately intercalated by the N-doped porous carbon monolayers to achieve an expanded interlayer spacing(1.02 nm),which can effectively reduce ions diffusion barrier,expose abundant active sites for Na+/K+intercalation,and tolerate large volume variation.The N-C and rGO carbonous materials can significantly promote the electrical conductivity and structural stability.Benefited from the synergistic effect,the VS2/N-C@rGO electrode exhibits large reversible capacity(Na+:407 mAh·g^(-1) at 1 A·g^(-1);K^(+):334 mAh·g^(-1) at 0.2 A·g^(-1)),high rate capacity(Na+:273 mAh·g^(-1) at 8 A·g^(-1);K+:186 mAh·g^(-1) at 5 A·g^(-1)),and remarkable cycling stability(Na+:316 mAh·g^(-1) at 2 A·g^(-1) after 1,400 cycles;K^(+):216 mAh·g^(-1) at 1 A·g^(-1) after 500 cycles).