Tin dioxide (SnO2 ) nanobelts have been successfully synthesized in bulk quantity by the CVD process based on the thermal evaporation of tin powders. The x-ray diffraction analysis indicates that the nanobelts are t...Tin dioxide (SnO2 ) nanobelts have been successfully synthesized in bulk quantity by the CVD process based on the thermal evaporation of tin powders. The x-ray diffraction analysis indicates that the nanobelts are the tetragonal futile structure of SnO2. Scanning electron microscopy and transmission electron microscopy observations reveal that the nanobelts are uniform. The selected-area electron diffraction analysis demonstrates that the nanobelts are single crystals. The energy dispersive x-ray analysis of the nanobelt shows that the nanobelts are composed of Sn and O, Gas-sensing components have been manufactured with prepared SnO2 nanobelts. Their performance indicates that SnO2 nanobelts have high sensitivity and selectivity to liquefied petroleum gas with fairly good response-recovery characteristic and stability at 220℃.展开更多
TiO2 is a wide band gap semiconductor with important applications in photovoltaic cells. Vertically aligned Tit2 nanorod arrays (NRs) are grown on the fluorine-doped tin oxide (FTO) substrates by a multicycle hydr...TiO2 is a wide band gap semiconductor with important applications in photovoltaic cells. Vertically aligned Tit2 nanorod arrays (NRs) are grown on the fluorine-doped tin oxide (FTO) substrates by a multicycle hydrothermal synthesis process. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED). It is found that dye-sensitized solar cells (DSSCs) assembled by the as-prepared Tit2 single-crystal NRs exhibit different trends under the condition of different nucleation and growth concentrations. Optimum cell performance is obtained with high nucleation concentration and low growth cycle concentration. The efficiency enhancement is mainly attributed to the improved specific surface area of the nanorod.展开更多
Ta_(2)O_(5) and Nb_(2)O_(5) films are deposited by conventional e−beam method under different electron beam currents.The optical transmittance,chemical composition,absorption,scattering,surface topography and laser-in...Ta_(2)O_(5) and Nb_(2)O_(5) films are deposited by conventional e−beam method under different electron beam currents.The optical transmittance,chemical composition,absorption,scattering,surface topography and laser-induced damage threshold(LIDT)of the films are comparatively studied.It is shown that the increase of electron beam current results in a decrease of the optical transmittance and stoichiometry,whereas it increases the absorption,scattering and rms roughness for both Ta_(2)O_(5) and Nb_(2)O_(5) films.However,the LIDT increases first and then decreases with the increase of electron beam current.In addition,the annealing improves the optical transmittance,stoichiometry and LIDT for the two kinds of films.Both the effects of electron beam current and annealing on the LIDT can be mainly attributed to three factors:substoichiometric defects,structural defects and adhesive force.Furthermore,the comparative results indicate that the laser damage resistance of Ta_(2)O_(5) is lower than that of Nb_(2)O_(5).展开更多
Ta2O5 films are deposited on fused silica substrates by conventional e-beam evaporation. Surface topography and chemical composition are examined by atomic force microscopy (AFM) and x-ray photoelectron spectroscopy...Ta2O5 films are deposited on fused silica substrates by conventional e-beam evaporation. Surface topography and chemical composition are examined by atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). The calculation of electron structures of Ta2O5 and Ta2O5-x is attempted using a first-principle pseudopotential method within the local density approximation. The laser-induced damage threshold (LIDT) is performed at 1064, 532 and 355 nm in 1-on-1 regime, respectively. The results show that the LIDT increases with the wavelength increasing, which is in agreement with the wavelength effect. However, the LIDT results are not consistent with the empirical equation (I(λ)=aλm), which may be attributed to the intrinsic absorption of Ta2O5 at the wavelengths of 532 or/and 355 nm. Moreover, different damage morphologies are observed when the films are irradiated at different wavelengths. It is concluded that the laser damage at 1064 nm is the defect dominant mechanism and at 355 nm it is the intrinsic absorption dominant mechanism, whereas at 532 nm it is the combined defect and intrinsic absorption dominant mechanism.展开更多
Ta2O5 films are prepared by e-beam evaporation with varied deposition temperatures, annealing temperatures, and annealing times. The effects of temperature on the optical properties, chemical composition, structure, a...Ta2O5 films are prepared by e-beam evaporation with varied deposition temperatures, annealing temperatures, and annealing times. The effects of temperature on the optical properties, chemical composition, structure, and laser- induced damage threshold (LIDT) are systematically investigated. The results show that the increase of deposition temperature decreases the film transmittance slightly, yet annealing below 923 K is beneficial for the transmittance. The XRD analysis reveals that the film is in the amorphous phase when annealed below 873 K and in thehexagonal phase when annealed at 1073 K. While an interesting near-crystalline phase is found when annealed at 923 K. The LIDT increases with the deposition temperature increasing, whereas it increases firstly and then decreases as the annealing temperature increases. In addition, the increase of the annealing time from 4 h to 12 h is favourable to improving the LIDT, which is mainly due to the improvement of the O/Ta ratio. The highest LIDT film is obtained when annealed at 923 K, owing to the lowest density of defect.展开更多
Ta_(2)O_(5) films are deposited on fused silica substrates by electron beam evaporation method.The optical property,x-ray photoelectron spectroscopy,band gap and nanosecond laser-induced damage threshold(LIDT)of the f...Ta_(2)O_(5) films are deposited on fused silica substrates by electron beam evaporation method.The optical property,x-ray photoelectron spectroscopy,band gap and nanosecond laser-induced damage threshold(LIDT)of the films before and after annealing are studied.It is found that the existence of an oxygen vacancy results in the decrease of the transmittance,refractive index,both macroscopic band gap and microscopic band gap,and the LIDT of Ta_(2)O_(5) films.If the oxygen vacancy forms,the macroscopic band gap decreases 2%.However,when the oxygen vacancy forms the microscopic band gap decreases 73%for crystalline Ta_(2)O_(5) and 77%for amorphous Ta_(2)O_(5).The serious decrease of microscopic band gap may significantly increase the absorbance of the micro-area in Ta_(2)O_(5) films when irradiated by laser,thus the damage probability increases.It is consistent with our experimental results that the LIDT of the as-deposited Ta_(2)O_(5) films is 7.3 J/cm^(2),which increases 26%to 9.2 J/cm^(2) when the oxygen vacancy is eliminated after annealing.展开更多
Pouring temperature and time are the most important influencing factors on interfacial reaction during the centrifugal casting. When cast at high temperatures, the crucible becomes brittle and prone to cracking, and s...Pouring temperature and time are the most important influencing factors on interfacial reaction during the centrifugal casting. When cast at high temperatures, the crucible becomes brittle and prone to cracking, and shows a low stability. In this paper, we studied the centrifugal casting of Ti-47.5-Al-2.5V-1Cr alloy, and explored the effects of pouring temperature on the interfacial reaction. Castings at 1 600, 1 650, and 1 700 ℃ were obtained by controlling the other parameters constant in the experiments. The microstructure, elemental distribution, thickness of the reaction layer and phase composition of the castings at the interface were studied. The results show that the thickness at the interfacial reaction layer is increased by raising the pouring temperature. The elements in the mold and the matrix were double-diffused and reacted at the interface during the casting process, and formed solid solutions with the precipitation of many new phases such as AlOand TiO. The roughness of interface structure and layer thickness of reaction increase with the rise of temperature, and the interfacial reaction is more intense. There is a minimum layer thickness of the reaction layer that is 80 μm when the temperature is 1 600 ℃.展开更多
Sol-gel TiO2 films are prepared by the dip-coating method and the spin-coating method, and then annealing is performed at different temperatures. The structures, optical properties, surface morphologies, absorption an...Sol-gel TiO2 films are prepared by the dip-coating method and the spin-coating method, and then annealing is performed at different temperatures. The structures, optical properties, surface morphologies, absorption and laser-induced damage threshold (LIDT) at 1064 nm and 12 ns of the films are investigated. The results show that the dip-coating method can be used to obtain a higher LIDT than the spin-coating method. When the annealing temperature increases from 80℃ to 120℃, the dip-coated film obtains a higher LIDT, whereas the spin-coated film obtains a lower LIDT. In addition, the damage morphology is a spalling pit for the dip-coated film annealed at 80℃. When the annealing temperature increases to 120℃, it shows a melting area. For both the spin-coated films annealed at different temperatures, the damage morphologies are the combination of spelling and melting. The differences in LIDT and damage morphologies of the films are discussed.展开更多
In order to improve the corrosion resistance of NiFe2O4 ceramics as inert anode,additive V2O5 was added to raw materials NiO and Fe2O3.The inert anodes of nickel-ferrite ceramics were prepared by powder metallurgic me...In order to improve the corrosion resistance of NiFe2O4 ceramics as inert anode,additive V2O5 was added to raw materials NiO and Fe2O3.The inert anodes of nickel-ferrite ceramics were prepared by powder metallurgic method and the static corrosion rate in Na3AlF6-Al2O3 was determined by mass loss measurement.The effect of V2O5 on sintering property and corrosion resistance was studied.The results show that V2O5 can promote the grain to develop completely and improve sintering property.EDS results show the reaction product Ni2FeVO6 distributes along the grain boundary.The corrosion tests show that V2O5 is beneficial to improving corrosion resistance remarkably.The reasons that V2O5 can improve the corrosion resistance must be V2O5 promoting the gains to develop completely and Ni2FeVO6 distributes along the grain boundary.The stable structure can control the chemical dissolution of ceramics anode and the reinforced grain boundary can control the grain-boundary corrosion rate.展开更多
The oxidation behavior of molybdenum disilicide (MoSi2) powders at 400, 500, and 600℃ for 12 h in air were investigated by using X-ray diffraction (XRD) and transmission electron microscopic (TEM) techniques. S...The oxidation behavior of molybdenum disilicide (MoSi2) powders at 400, 500, and 600℃ for 12 h in air were investigated by using X-ray diffraction (XRD) and transmission electron microscopic (TEM) techniques. Significant changes were observed in volume, mass, and color. Especially at 500℃, the volume expansion was found to be as high as 7-8 times, the color changed from black to yellow-white, and the mass gain was about 169.34% after 8 h, with SiO2 and MoO3 as main reaction products. The gains in volume and mass were less at 400 and 600℃ compared with those at 500℃, probably due to the less reaction rate at 400℃ and the formation of silica glass scale at 600℃, which would protect the matrix and restrain the diffusion of oxygen and molybdenum. Thus, the accelerated oxidation behavior of MoSi2 powder appeared at 500℃ and the volume expansion was the sign of accelerated oxidation.展开更多
In this research,the effects of centrifugal radius and mould rotation speed on microstructure in centrifugal-cast Al-Cu alloy have been investigated.The results show that,with increase of the centrifugal radius or mou...In this research,the effects of centrifugal radius and mould rotation speed on microstructure in centrifugal-cast Al-Cu alloy have been investigated.The results show that,with increase of the centrifugal radius or mould rotation speed,the grain size of centrifugal-cast Al-Cu alloy decreases gradually,while the content of white phases containing the Al2Cu precipitated from α-phase,divorced eutectic and regular eutectic microstructure increases,leading to higher Cu macrosegregation.The variation level of microstructure in centrifugal-cast Al-Cu alloy at 600 rpm of mould rotation speed is greater than that at 300 rpm.展开更多
A novel method for preparing Ta-doped Ti02 via using Ta2 05 as the doping source is proposed. The preparation process combines the hydrothernlal fluorination of Ta2O5 and the subsequent formation of Ta-doped TiO2 sol....A novel method for preparing Ta-doped Ti02 via using Ta2 05 as the doping source is proposed. The preparation process combines the hydrothernlal fluorination of Ta2O5 and the subsequent formation of Ta-doped TiO2 sol. The results show that the doped sample annealed at 393 K generates an unstable intermediate NH4 TiOF3, which converts into anatase TiO2 with the increase of temperature. After annealing at ≥673K, the Ta-doped TiO2 nanocrystals with the grain size 〈20nm are obtained. Both the XRD and TG-DSC results confirm that Ta doping prevents the anatase-rutile crystal transition of TiO2. The band gap values of the doped samples, as obtained by UV-vis diffuse reflectance spectra, are smaller than that of pure anatase TiO2. The first-principle pseudopotential method calculations indicate that Ta5+ lies in the TiO2 lattice at the interstitial position.展开更多
Phosphorus sulfide cage molecule based on P4S3 was investigated for the first time as anode material for the storage of alkali metal ions(Li+, Na+, K+). Such P4S3 sample was obtained in a large scale by a simple heati...Phosphorus sulfide cage molecule based on P4S3 was investigated for the first time as anode material for the storage of alkali metal ions(Li+, Na+, K+). Such P4S3 sample was obtained in a large scale by a simple heating reaction of low-cost rep P and S. X-ray diffraction refinement analysis indicates that P4S3 sample possesses a defect rich molecule crystal structure with S/P atom ratio of 0.74. The P4S3 anode delivered a high reversible capacity of 1266 m Ah g-1 for lithium-ion batteries at 0.1 A g-1 and good cycling performance. Experimental results demonstrated that the P4S3 anode undergoes a reversible Listorage reaction of P4S3+ 11 Li++ 11 e-←→ 0.5 Li4P2S6+ 3 Li3P during cycling. It also exhibited a high capacity of 1002 and 378 mAh g-1 at 0.1 A g-1 for Na+and K+storage, respectively. These properties suggest the promising application of P4S3 anode in high energy batteries.展开更多
The β-Zn4Sb3, emerged as a compelling p-type thermoelectric material, is widely used in heat-electricity conversion in the 400-650 K range. In order to probe the effects of slight doping on the crystal structure and ...The β-Zn4Sb3, emerged as a compelling p-type thermoelectric material, is widely used in heat-electricity conversion in the 400-650 K range. In order to probe the effects of slight doping on the crystal structure and physical properties, we prepared the samples of Al-added Zn-Sb based alloys by spark plasma sintering and evaluated their microstructures and thermoelectric properties. After a limited A1 addition into the Zn-Sb based alloys we observed many phases in the alloys, which include a major phase β-Zn4Sb3, intermetallic phases ZnSb and A1Sb. The major β-Zn4Sb3 phase plays a fundamental role in controlling the thermoelectric performance, the precipitated phases ZnSb and AISb are of great importance to tailor the transport properties, such as the gradual enhancement of lattice thermal conductivity, in spite of an increased phonon scattering in additional grain boundaries. The highest thermoelectric figure of merit of 0.55 is obtained for the alloy with a limited A1 addition at 653 K, which is 0.08 higher than that of un-doped β-Zn4Sb3 at the corresponding temperature. Physical property experiments indicate that there is a potentiality for the improvement of thermoelectric properties if a proper elemental doping is carried out into the Zn-Sb based alloys, which was confirmed by A1 addition in the present work.展开更多
A broadband non-polarizing beam splitter (NPBS) operating in the telecommunication C+L band is designed by using the guided mode resonance effect of periodic silicon-on-insulator (SOI) elements. It is shown that ...A broadband non-polarizing beam splitter (NPBS) operating in the telecommunication C+L band is designed by using the guided mode resonance effect of periodic silicon-on-insulator (SOI) elements. It is shown that this double layer SOI structure can provide ~50/50 beam ratio with the maximum divergences between reflection and transmission being less than 8% over the spectrum of 1.4μm-l.7 μm and i% in the telecommunication band for both TE and TM polarizations. The physical basis of this broadband non-polarizing property is on the simultaneous excitation of the TE and TM strong modulation waveguide modes near the designed spectrum band. Meanwhile, the electric field distributions for both TE and TM polarizations verify the resonant origin of spectrum in the periodic SOI structure. Furthermore, it is demonstrated with our calculations that the beam splitter proposed here is tolerant to the deviations of incident angle and structure parameters, which make it very easy to be fabricated with current IC technology.展开更多
Photoelectrochemical hydrogen generation is a promising approach to address the environmental pollution and energy crisis.In this work,we present a hybridized mechanical and solar energy-driven selfpowered hydrogen pr...Photoelectrochemical hydrogen generation is a promising approach to address the environmental pollution and energy crisis.In this work,we present a hybridized mechanical and solar energy-driven selfpowered hydrogen production system.A rotatory disc-shaped triboelectric nanogenerator was employed to harvest mechanical energy from water and functions as a su cient external power source.WO3/BiVO4 heterojunction photoanode was synthesized in a PEC water-splitting cell to produce H2.After transformation and rectification,the peak current reaches 0.1 m A at the rotation speed of 60 rpm.In this case,the H2 evolution process only occurs with sunlight irradiation.When the rotation speed is over 130 rpm,the peak photocurrent and peak dark current have nearly equal value.Direct electrolysis of water is almost simultaneous with photoelectrocatalysis of water.It is worth noting that the hydrogen production rate increases to 5.45 and 7.27μL min-1 without or with light illumination at 160 rpm.The corresponding energy conversion e ciency is calculated to be 2.43%and 2.59%,respectively.All the results demonstrate such a self-powered system can successfully achieve the PEC hydrogen generation,exhibiting promising possibility of energy conversion.展开更多
This paper reports that carbon microcoils are grown through a chemical vapour deposit process, they are then embedded in silicone rubber, and manipulated to parallel with each other along their axes in the resulting c...This paper reports that carbon microcoils are grown through a chemical vapour deposit process, they are then embedded in silicone rubber, and manipulated to parallel with each other along their axes in the resulting composite. The impedance |Z| as well as phase angle 8 of both the original carbon microcoil sheets and the aligned carbon microcoil/silicone rubber composites are measured. The results illustrate that carbon microcoils in different forms show different alternating current electric properties. The aligned carbon microcoils in the composites show stable parameters for f 〈 104 Hz but a sharp decrease in both |Z| and θ for frequencies 〉 10^4 Hz, which will also change as the carbon microcoils are extended. But, the original sheets have a pure resistance with their parameters stable throughout the entire alternating current frequency range investigated.展开更多
Here in this paper, we demonstrate a facile technique for creating the mixed formamidinium(HN = CHNH_3~+, FA~+)and methylammonium(CH_3NH_3~+, MA~+) cations in the lead iodide perovskite. This technique entails...Here in this paper, we demonstrate a facile technique for creating the mixed formamidinium(HN = CHNH_3~+, FA~+)and methylammonium(CH_3NH_3~+, MA~+) cations in the lead iodide perovskite. This technique entails a facile drop-casting of formamidinium iodide(FAI) solutions on as-prepared MAPbI_3 perovskite thin films under the controlled conditions,which leads to controllable displacement of the MA~+ cations by FA~+ cations in the perovskite structure at room temperature. Uniform and controllable mixed organic cation perovskite thin films without a "bi-layered" or graded structure are achieved. By applying this approach to photovoltaic devices, we are able to improve the performances of devices through extending their optical-absorption onset further into the infrared region to enhance solar-light harvesting. Additionally,this work provides a simple and efficient technique to tune the structural, electrical, and optoelectronic properties of the light-harvesting materials for high-performance perovskite solar cells.展开更多
PVA-HA-Silk composite hydrogel was synthesized with polyvinyl alcohol (PVA), nano-hydroxyapatite (HA) and natural silk by using the method of repeated freezing and thawing. A series of tests were performed to stud...PVA-HA-Silk composite hydrogel was synthesized with polyvinyl alcohol (PVA), nano-hydroxyapatite (HA) and natural silk by using the method of repeated freezing and thawing. A series of tests were performed to study water content, stress relaxation behavior, elastic modulus, and creep characteristics of PVA-HA-Silk composite hydrogel. Orthogonal experimental design method was used to analyze the influence degree of PVA, HA and silk (three kinds of raw materials) on mechanical properties and water content of the PVA-HA-Silk composite hydrogel to select the best material ratio according to their overall performance. The results demonstrate that the mass percentage of PVA has the greatest impact on the water content, followed by HA and silk. Compression stress-strain variation of PVA-HA-Silk composite hydrogel presents a nonlinear relationship, which proves that it is a typical viscoelastic material. Comparing the mechanical properties of 16 formulas, the formula of PVA-HA-silk composite hydrogel with mass percentage of PVA 15%, HA 2.0% and silk 1.0% is the best.展开更多
In this paper, high density of dislocations, grain boundaries and nanometer-scale α precipitates were intro- duced to a metastable Ti-36Nb-5Zr alloy (wt%) through a thermo-mechanical approach including severe cold ...In this paper, high density of dislocations, grain boundaries and nanometer-scale α precipitates were intro- duced to a metastable Ti-36Nb-5Zr alloy (wt%) through a thermo-mechanical approach including severe cold rolling and short-time annealing treatment. The martensitic trans- formation was retarded, and the β phase with low content of β stabilizers was retained at room temperature after the thermo-mechanical treatment. As a result, both low mod- ulus (57 GPa) and high strength (950 MPa) are obtained. The results indicate that it is a feasible strategy to control martensitic transformation start temperature through microstructure optimization instead of composition design, with the aim of fabricating low modulus β-type Ti alloy.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 19974055.
文摘Tin dioxide (SnO2 ) nanobelts have been successfully synthesized in bulk quantity by the CVD process based on the thermal evaporation of tin powders. The x-ray diffraction analysis indicates that the nanobelts are the tetragonal futile structure of SnO2. Scanning electron microscopy and transmission electron microscopy observations reveal that the nanobelts are uniform. The selected-area electron diffraction analysis demonstrates that the nanobelts are single crystals. The energy dispersive x-ray analysis of the nanobelt shows that the nanobelts are composed of Sn and O, Gas-sensing components have been manufactured with prepared SnO2 nanobelts. Their performance indicates that SnO2 nanobelts have high sensitivity and selectivity to liquefied petroleum gas with fairly good response-recovery characteristic and stability at 220℃.
基金Project supported by the Fundamental Research Funds for the Central Universities,China(Grant No.2013XK07)
文摘TiO2 is a wide band gap semiconductor with important applications in photovoltaic cells. Vertically aligned Tit2 nanorod arrays (NRs) are grown on the fluorine-doped tin oxide (FTO) substrates by a multicycle hydrothermal synthesis process. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED). It is found that dye-sensitized solar cells (DSSCs) assembled by the as-prepared Tit2 single-crystal NRs exhibit different trends under the condition of different nucleation and growth concentrations. Optimum cell performance is obtained with high nucleation concentration and low growth cycle concentration. The efficiency enhancement is mainly attributed to the improved specific surface area of the nanorod.
基金by the Youth Science Research Foundation of China University of Mining and Technology(No 2009A058)the Fundamental Research Funds for the Central Universities(No 2010Qnb06).
文摘Ta_(2)O_(5) and Nb_(2)O_(5) films are deposited by conventional e−beam method under different electron beam currents.The optical transmittance,chemical composition,absorption,scattering,surface topography and laser-induced damage threshold(LIDT)of the films are comparatively studied.It is shown that the increase of electron beam current results in a decrease of the optical transmittance and stoichiometry,whereas it increases the absorption,scattering and rms roughness for both Ta_(2)O_(5) and Nb_(2)O_(5) films.However,the LIDT increases first and then decreases with the increase of electron beam current.In addition,the annealing improves the optical transmittance,stoichiometry and LIDT for the two kinds of films.Both the effects of electron beam current and annealing on the LIDT can be mainly attributed to three factors:substoichiometric defects,structural defects and adhesive force.Furthermore,the comparative results indicate that the laser damage resistance of Ta_(2)O_(5) is lower than that of Nb_(2)O_(5).
文摘Ta2O5 films are deposited on fused silica substrates by conventional e-beam evaporation. Surface topography and chemical composition are examined by atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). The calculation of electron structures of Ta2O5 and Ta2O5-x is attempted using a first-principle pseudopotential method within the local density approximation. The laser-induced damage threshold (LIDT) is performed at 1064, 532 and 355 nm in 1-on-1 regime, respectively. The results show that the LIDT increases with the wavelength increasing, which is in agreement with the wavelength effect. However, the LIDT results are not consistent with the empirical equation (I(λ)=aλm), which may be attributed to the intrinsic absorption of Ta2O5 at the wavelengths of 532 or/and 355 nm. Moreover, different damage morphologies are observed when the films are irradiated at different wavelengths. It is concluded that the laser damage at 1064 nm is the defect dominant mechanism and at 355 nm it is the intrinsic absorption dominant mechanism, whereas at 532 nm it is the combined defect and intrinsic absorption dominant mechanism.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61107080 and 50921002)the Natural Science Foundation of Jiangsu Province,China (Grant No. BK2011223)+2 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (New Teachers) (Grant No.20110095120018)the China Postdoctoral Science Foundation (Grant No. 20110491472)the Fundamental Research Funds for the Central Universities,China (Grant No. 2012QNA03)
文摘Ta2O5 films are prepared by e-beam evaporation with varied deposition temperatures, annealing temperatures, and annealing times. The effects of temperature on the optical properties, chemical composition, structure, and laser- induced damage threshold (LIDT) are systematically investigated. The results show that the increase of deposition temperature decreases the film transmittance slightly, yet annealing below 923 K is beneficial for the transmittance. The XRD analysis reveals that the film is in the amorphous phase when annealed below 873 K and in thehexagonal phase when annealed at 1073 K. While an interesting near-crystalline phase is found when annealed at 923 K. The LIDT increases with the deposition temperature increasing, whereas it increases firstly and then decreases as the annealing temperature increases. In addition, the increase of the annealing time from 4 h to 12 h is favourable to improving the LIDT, which is mainly due to the improvement of the O/Ta ratio. The highest LIDT film is obtained when annealed at 923 K, owing to the lowest density of defect.
基金Supported by the National Natural Science Foundation of China(Nos 61107080,50921002)the Natural Science Foundation of Jiangsu Province of China(No BK2011223)+3 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(New Teachers)(No 20110095120018)the China Postdoctoral Science Foundation(No 20110491472)the National Undergraduate Innovation Experiment Programs(No 2012106)the Fundamental Research Funds for the Central Universities(No 2012QNA03).
文摘Ta_(2)O_(5) films are deposited on fused silica substrates by electron beam evaporation method.The optical property,x-ray photoelectron spectroscopy,band gap and nanosecond laser-induced damage threshold(LIDT)of the films before and after annealing are studied.It is found that the existence of an oxygen vacancy results in the decrease of the transmittance,refractive index,both macroscopic band gap and microscopic band gap,and the LIDT of Ta_(2)O_(5) films.If the oxygen vacancy forms,the macroscopic band gap decreases 2%.However,when the oxygen vacancy forms the microscopic band gap decreases 73%for crystalline Ta_(2)O_(5) and 77%for amorphous Ta_(2)O_(5).The serious decrease of microscopic band gap may significantly increase the absorbance of the micro-area in Ta_(2)O_(5) films when irradiated by laser,thus the damage probability increases.It is consistent with our experimental results that the LIDT of the as-deposited Ta_(2)O_(5) films is 7.3 J/cm^(2),which increases 26%to 9.2 J/cm^(2) when the oxygen vacancy is eliminated after annealing.
基金Funded by the National Natural Science Foundation of China(No.51304198)Natural Science Foundation of Jiangsu Province(Nos.2013106,20141134 and 2014028-08)
文摘Pouring temperature and time are the most important influencing factors on interfacial reaction during the centrifugal casting. When cast at high temperatures, the crucible becomes brittle and prone to cracking, and shows a low stability. In this paper, we studied the centrifugal casting of Ti-47.5-Al-2.5V-1Cr alloy, and explored the effects of pouring temperature on the interfacial reaction. Castings at 1 600, 1 650, and 1 700 ℃ were obtained by controlling the other parameters constant in the experiments. The microstructure, elemental distribution, thickness of the reaction layer and phase composition of the castings at the interface were studied. The results show that the thickness at the interfacial reaction layer is increased by raising the pouring temperature. The elements in the mold and the matrix were double-diffused and reacted at the interface during the casting process, and formed solid solutions with the precipitation of many new phases such as AlOand TiO. The roughness of interface structure and layer thickness of reaction increase with the rise of temperature, and the interfacial reaction is more intense. There is a minimum layer thickness of the reaction layer that is 80 μm when the temperature is 1 600 ℃.
基金Supported by the National Natural Science Foundation of China under Grant No 61107080, the Natural Science Foundation of Jiangsu Province of China under Grant No BK2011223, the Jiangsu Overseas Research and Training Program for University Prominent Young and Middle-aged Teachers and Presidents, the Qing Lan Project of Jiangsu Province, the Specialized Research Fund for the Doctoral Program of Higher Education of China (New Teachers) under Grant No 20110095120018, the China Postdoctoral Science Foundation under Grant Nos 20110491472 and 2012T50523, and the Fundamental Research Funds for the Central Universities under Grant No 2012QNA03.
文摘Sol-gel TiO2 films are prepared by the dip-coating method and the spin-coating method, and then annealing is performed at different temperatures. The structures, optical properties, surface morphologies, absorption and laser-induced damage threshold (LIDT) at 1064 nm and 12 ns of the films are investigated. The results show that the dip-coating method can be used to obtain a higher LIDT than the spin-coating method. When the annealing temperature increases from 80℃ to 120℃, the dip-coated film obtains a higher LIDT, whereas the spin-coated film obtains a lower LIDT. In addition, the damage morphology is a spalling pit for the dip-coated film annealed at 80℃. When the annealing temperature increases to 120℃, it shows a melting area. For both the spin-coated films annealed at different temperatures, the damage morphologies are the combination of spelling and melting. The differences in LIDT and damage morphologies of the films are discussed.
基金Project(2006A050)supported by Science and Technology Foundation of China University of Mining and Technology,ChinaProject(0702058C)supported by Postdoctoral Scientific Research Foundation of Jiangsu Province,China
文摘In order to improve the corrosion resistance of NiFe2O4 ceramics as inert anode,additive V2O5 was added to raw materials NiO and Fe2O3.The inert anodes of nickel-ferrite ceramics were prepared by powder metallurgic method and the static corrosion rate in Na3AlF6-Al2O3 was determined by mass loss measurement.The effect of V2O5 on sintering property and corrosion resistance was studied.The results show that V2O5 can promote the grain to develop completely and improve sintering property.EDS results show the reaction product Ni2FeVO6 distributes along the grain boundary.The corrosion tests show that V2O5 is beneficial to improving corrosion resistance remarkably.The reasons that V2O5 can improve the corrosion resistance must be V2O5 promoting the gains to develop completely and Ni2FeVO6 distributes along the grain boundary.The stable structure can control the chemical dissolution of ceramics anode and the reinforced grain boundary can control the grain-boundary corrosion rate.
基金This work was financially supported by the National Natural Science Foundation of China (No.50025412)
文摘The oxidation behavior of molybdenum disilicide (MoSi2) powders at 400, 500, and 600℃ for 12 h in air were investigated by using X-ray diffraction (XRD) and transmission electron microscopic (TEM) techniques. Significant changes were observed in volume, mass, and color. Especially at 500℃, the volume expansion was found to be as high as 7-8 times, the color changed from black to yellow-white, and the mass gain was about 169.34% after 8 h, with SiO2 and MoO3 as main reaction products. The gains in volume and mass were less at 400 and 600℃ compared with those at 500℃, probably due to the less reaction rate at 400℃ and the formation of silica glass scale at 600℃, which would protect the matrix and restrain the diffusion of oxygen and molybdenum. Thus, the accelerated oxidation behavior of MoSi2 powder appeared at 500℃ and the volume expansion was the sign of accelerated oxidation.
基金supported by the China National Natural Science Foundation (grant no.50434030)
文摘In this research,the effects of centrifugal radius and mould rotation speed on microstructure in centrifugal-cast Al-Cu alloy have been investigated.The results show that,with increase of the centrifugal radius or mould rotation speed,the grain size of centrifugal-cast Al-Cu alloy decreases gradually,while the content of white phases containing the Al2Cu precipitated from α-phase,divorced eutectic and regular eutectic microstructure increases,leading to higher Cu macrosegregation.The variation level of microstructure in centrifugal-cast Al-Cu alloy at 600 rpm of mould rotation speed is greater than that at 300 rpm.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No 2012QNA03
文摘A novel method for preparing Ta-doped Ti02 via using Ta2 05 as the doping source is proposed. The preparation process combines the hydrothernlal fluorination of Ta2O5 and the subsequent formation of Ta-doped TiO2 sol. The results show that the doped sample annealed at 393 K generates an unstable intermediate NH4 TiOF3, which converts into anatase TiO2 with the increase of temperature. After annealing at ≥673K, the Ta-doped TiO2 nanocrystals with the grain size 〈20nm are obtained. Both the XRD and TG-DSC results confirm that Ta doping prevents the anatase-rutile crystal transition of TiO2. The band gap values of the doped samples, as obtained by UV-vis diffuse reflectance spectra, are smaller than that of pure anatase TiO2. The first-principle pseudopotential method calculations indicate that Ta5+ lies in the TiO2 lattice at the interstitial position.
基金the Natural Science Foundation of Shandong Province(ZR2017QB017)the Ph.D.Scientific Research Fund of Liaocheng University(No.318051406)+2 种基金the Natural Science Foundation of Shandong Province(ZR2016BQ41)the High Education Science and Technology Program of Shandong Province(J16LC03)the Cultivation Fund of Liaocheng University(318011615)。
文摘Phosphorus sulfide cage molecule based on P4S3 was investigated for the first time as anode material for the storage of alkali metal ions(Li+, Na+, K+). Such P4S3 sample was obtained in a large scale by a simple heating reaction of low-cost rep P and S. X-ray diffraction refinement analysis indicates that P4S3 sample possesses a defect rich molecule crystal structure with S/P atom ratio of 0.74. The P4S3 anode delivered a high reversible capacity of 1266 m Ah g-1 for lithium-ion batteries at 0.1 A g-1 and good cycling performance. Experimental results demonstrated that the P4S3 anode undergoes a reversible Listorage reaction of P4S3+ 11 Li++ 11 e-←→ 0.5 Li4P2S6+ 3 Li3P during cycling. It also exhibited a high capacity of 1002 and 378 mAh g-1 at 0.1 A g-1 for Na+and K+storage, respectively. These properties suggest the promising application of P4S3 anode in high energy batteries.
基金supported by National Natural Science Foundation of China (Grant No. 50871056)Ningbo Link Project with Israel- Academic Links with Israel Scheme (ALIS) (Grant No. 2007B10020)
文摘The β-Zn4Sb3, emerged as a compelling p-type thermoelectric material, is widely used in heat-electricity conversion in the 400-650 K range. In order to probe the effects of slight doping on the crystal structure and physical properties, we prepared the samples of Al-added Zn-Sb based alloys by spark plasma sintering and evaluated their microstructures and thermoelectric properties. After a limited A1 addition into the Zn-Sb based alloys we observed many phases in the alloys, which include a major phase β-Zn4Sb3, intermetallic phases ZnSb and A1Sb. The major β-Zn4Sb3 phase plays a fundamental role in controlling the thermoelectric performance, the precipitated phases ZnSb and AISb are of great importance to tailor the transport properties, such as the gradual enhancement of lattice thermal conductivity, in spite of an increased phonon scattering in additional grain boundaries. The highest thermoelectric figure of merit of 0.55 is obtained for the alloy with a limited A1 addition at 653 K, which is 0.08 higher than that of un-doped β-Zn4Sb3 at the corresponding temperature. Physical property experiments indicate that there is a potentiality for the improvement of thermoelectric properties if a proper elemental doping is carried out into the Zn-Sb based alloys, which was confirmed by A1 addition in the present work.
基金supported by the Youth Science Research Foundation of China University of Mining and Technology (Grant No. 2009A058)the Natural Science Foundation of Shanghai Committee of Science and Technology (Grant No. 10ZR1433500)
文摘A broadband non-polarizing beam splitter (NPBS) operating in the telecommunication C+L band is designed by using the guided mode resonance effect of periodic silicon-on-insulator (SOI) elements. It is shown that this double layer SOI structure can provide ~50/50 beam ratio with the maximum divergences between reflection and transmission being less than 8% over the spectrum of 1.4μm-l.7 μm and i% in the telecommunication band for both TE and TM polarizations. The physical basis of this broadband non-polarizing property is on the simultaneous excitation of the TE and TM strong modulation waveguide modes near the designed spectrum band. Meanwhile, the electric field distributions for both TE and TM polarizations verify the resonant origin of spectrum in the periodic SOI structure. Furthermore, it is demonstrated with our calculations that the beam splitter proposed here is tolerant to the deviations of incident angle and structure parameters, which make it very easy to be fabricated with current IC technology.
基金supported by National Natural Science Foundation of China(NSFC)(Nos.61804103,U1932124)the National Science and Technology Major Project from Minister of Science and Technology of China(Grant No.2018AAA0103104)+8 种基金Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.18KJA535001)Natural Science Foundation of Jiangsu Province of China(Nos.BK20170343,BK20180242)Jiangsu Key Laboratory for Carbon Based Functional Materials and Devices,Soochow University(KJS1803)the XJTLU Key Programme Special Fund(KSF-A-18)Jiangsu Province Engineering Laboratory of High Efficient Energy Storage Technology and Equipments,China University of Mining and Technology(CUMT)supported by Collaborative Innovation Center of Suzhou Nano Science and Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the 111 ProjectJoint International Research Laboratory of Carbon-Based Functional Materials and Devices.
文摘Photoelectrochemical hydrogen generation is a promising approach to address the environmental pollution and energy crisis.In this work,we present a hybridized mechanical and solar energy-driven selfpowered hydrogen production system.A rotatory disc-shaped triboelectric nanogenerator was employed to harvest mechanical energy from water and functions as a su cient external power source.WO3/BiVO4 heterojunction photoanode was synthesized in a PEC water-splitting cell to produce H2.After transformation and rectification,the peak current reaches 0.1 m A at the rotation speed of 60 rpm.In this case,the H2 evolution process only occurs with sunlight irradiation.When the rotation speed is over 130 rpm,the peak photocurrent and peak dark current have nearly equal value.Direct electrolysis of water is almost simultaneous with photoelectrocatalysis of water.It is worth noting that the hydrogen production rate increases to 5.45 and 7.27μL min-1 without or with light illumination at 160 rpm.The corresponding energy conversion e ciency is calculated to be 2.43%and 2.59%,respectively.All the results demonstrate such a self-powered system can successfully achieve the PEC hydrogen generation,exhibiting promising possibility of energy conversion.
基金Project supported by the Natural Science Foundation of Jiangsu Province of China (Grant No. BK2008129)
文摘This paper reports that carbon microcoils are grown through a chemical vapour deposit process, they are then embedded in silicone rubber, and manipulated to parallel with each other along their axes in the resulting composite. The impedance |Z| as well as phase angle 8 of both the original carbon microcoil sheets and the aligned carbon microcoil/silicone rubber composites are measured. The results illustrate that carbon microcoils in different forms show different alternating current electric properties. The aligned carbon microcoils in the composites show stable parameters for f 〈 104 Hz but a sharp decrease in both |Z| and θ for frequencies 〉 10^4 Hz, which will also change as the carbon microcoils are extended. But, the original sheets have a pure resistance with their parameters stable throughout the entire alternating current frequency range investigated.
基金Project supported by the Fundamental Research Funds for the Central Universities,China(Grant No.2015QNA09)
文摘Here in this paper, we demonstrate a facile technique for creating the mixed formamidinium(HN = CHNH_3~+, FA~+)and methylammonium(CH_3NH_3~+, MA~+) cations in the lead iodide perovskite. This technique entails a facile drop-casting of formamidinium iodide(FAI) solutions on as-prepared MAPbI_3 perovskite thin films under the controlled conditions,which leads to controllable displacement of the MA~+ cations by FA~+ cations in the perovskite structure at room temperature. Uniform and controllable mixed organic cation perovskite thin films without a "bi-layered" or graded structure are achieved. By applying this approach to photovoltaic devices, we are able to improve the performances of devices through extending their optical-absorption onset further into the infrared region to enhance solar-light harvesting. Additionally,this work provides a simple and efficient technique to tune the structural, electrical, and optoelectronic properties of the light-harvesting materials for high-performance perovskite solar cells.
文摘PVA-HA-Silk composite hydrogel was synthesized with polyvinyl alcohol (PVA), nano-hydroxyapatite (HA) and natural silk by using the method of repeated freezing and thawing. A series of tests were performed to study water content, stress relaxation behavior, elastic modulus, and creep characteristics of PVA-HA-Silk composite hydrogel. Orthogonal experimental design method was used to analyze the influence degree of PVA, HA and silk (three kinds of raw materials) on mechanical properties and water content of the PVA-HA-Silk composite hydrogel to select the best material ratio according to their overall performance. The results demonstrate that the mass percentage of PVA has the greatest impact on the water content, followed by HA and silk. Compression stress-strain variation of PVA-HA-Silk composite hydrogel presents a nonlinear relationship, which proves that it is a typical viscoelastic material. Comparing the mechanical properties of 16 formulas, the formula of PVA-HA-silk composite hydrogel with mass percentage of PVA 15%, HA 2.0% and silk 1.0% is the best.
基金financially supported by the National Natural Science Foundation of China (No.51601217)the Natural Science Foundation of Jiangsu Province (No.BK20160255)the Fundamental Research Funds for the Central Universities (No.2017QNA04)
文摘In this paper, high density of dislocations, grain boundaries and nanometer-scale α precipitates were intro- duced to a metastable Ti-36Nb-5Zr alloy (wt%) through a thermo-mechanical approach including severe cold rolling and short-time annealing treatment. The martensitic trans- formation was retarded, and the β phase with low content of β stabilizers was retained at room temperature after the thermo-mechanical treatment. As a result, both low mod- ulus (57 GPa) and high strength (950 MPa) are obtained. The results indicate that it is a feasible strategy to control martensitic transformation start temperature through microstructure optimization instead of composition design, with the aim of fabricating low modulus β-type Ti alloy.