Conventional gas sensing materials(e.g.,metal oxides)suffer from deficient sensitivity and serve cross-sensitivity issues due to the lack of efficient adsorption sites.Herein,the heteroatom atomically doping strategy ...Conventional gas sensing materials(e.g.,metal oxides)suffer from deficient sensitivity and serve cross-sensitivity issues due to the lack of efficient adsorption sites.Herein,the heteroatom atomically doping strategy is demonstrated to significantly enhance the sensing performance of metal oxides-based gas sensing materials.Specifically,the Sn atoms were incorporated into porous Fe_(2)O_(3)in the form of atomically dispersed sites.As revealed by X-ray absorption spectroscopy and atomic-resolution scanning transmission electron microscopy,these Sn atoms successfully occupy the Fe sites in the Fe_(2)O_(3)lattice,forming the unique Sn-O-Fe sites.Compared to Fe-O-Fe sites(from bare Fe_(2)O_(3))and Sn-O-Sn sites(from SnO_(2)/Fe_(2)O_(3)with high Sn loading),the Sn-O-Fe sites on porous Fe_(2)O_(3)exhibit a superior sensitivity(Rg/Ra=2646.6)to 1 ppm NO_(2),along with dramatically increased selectivity and ultra-low limits of detection(10 ppb).Further theoretical calculations suggest that the strong adsorption of NO_(2)on Sn-O-Fe sites(N atom on Sn site,O atom on Fe site)contributes a more efficient gas response,compared to NO_(2)on Fe-O-Fe sites and other gases on Sn-O-Fe sites.Moreover,the incorporated Sn atoms reduce the bandgap of Fe_(2)O_(3),not only facilitating the electron release but also increasing the NO_(2)adsorption at a low working temperature(150°C).This work introduces an effective strategy to construct effective adsorption sites that show a unique response to specific gas molecules,potentially promoting the rational design of atomically modified gas sensing materials with high sensitivity and high selectivity.展开更多
Herein,we report the synthesis of a Dy-Gd co-doped cubic phase-stabilized Bi_(2)O_(3) solid electrolyte system via solid-state processing under atmospheric conditions.Doping with Dy^(3+) and Gd^(3+) has been observed ...Herein,we report the synthesis of a Dy-Gd co-doped cubic phase-stabilized Bi_(2)O_(3) solid electrolyte system via solid-state processing under atmospheric conditions.Doping with Dy^(3+) and Gd^(3+) has been observed to significantly enhance the densification process during sintering for stabilization purposes,thereby improving the electrical properties of δ-Bi_(2)O_(3)-type polymorphs.The synthesized ceramics were characterized using X-ray diffraction(XRD),field emission scanning electron microscopy-energy dispersive X-ray spectroscopy(FESEM-EDX),thermal gravimetry/differential thermal analysis(TG/DTA),and the four-point probe technique(4PPT).XRD analysis reveals that the samples Bi_(1-x-y)Gd_(x)Dy_(y)O_(1.5)(y=0.05/x=0.05,0.10,0,15,and 0.20,and x=0.05/y=0.10,0.15,and 0.20) exhibit a stable face-centered cubic δ-phase and a mixed-phase crystallographic structure.The XRD analysis of the stabilized δ-phase suggests that the prepared oxides show a face-centered cubic(FCC) structure with a space group of Fm-3m.FESEM micrographs reveal that the composition Bi_(0.90)Gd_(0.05)Dy_(0.05)O_(1.5) has no significant holes.Nevertheless,an evident increase in the pore formation is observed as the amount of Gd_(2)O_(3) increases until it reaches 20%.This finding suggests that dense pellets are formed during the sintering process at 900-1000℃.The DTA analyses were performed to verify the phase stability,which agrees with the XRD results.The electrochemical performance of the synthesized Dy-Gd co-doped Bi_(2)O_(3)solid electrolyte system was evaluated and analyzed in detail by using the electrochemical impedance spectroscopy(EIS) technique,Based on EIS and conductivity measurements,Bi_(0.75)Gd_(0.20)Dy_(0.05)O_(1.5) exhibits the lowest activation energy of 0.519 eV and the highest conductivity value of 0.398 S/cm at 627℃compared to the other samples;this composition can be used as a solid electrolyte for intermediatetemperature solid oxide fuel cells(SOFCs).展开更多
Considering the serious electromagnetic wave(EMW)pollution problems and complex application condition,there is a pressing need to amalgamate multiple functionalities within a single substance.However,the effective int...Considering the serious electromagnetic wave(EMW)pollution problems and complex application condition,there is a pressing need to amalgamate multiple functionalities within a single substance.However,the effective integration of diverse functions into designed EMW absorption materials still faces the huge challenges.Herein,reduced graphene oxide/carbon foams(RGO/CFs)with two-dimensional/three-dimensional(2D/3D)van der Waals(vdWs)heterostructures were meticulously engineered and synthesized utilizing an efficient methodology involving freeze-drying,immersing absorption,secondary freeze-drying,followed by carbonization treatment.Thanks to their excellent linkage effect of amplified dielectric loss and optimized impedance matching,the designed 2D/3D RGO/CFs vdWs heterostructures demonstrated commendable EMW absorption performances,achieving a broad absorption bandwidth of 6.2 GHz and a reflection loss of-50.58 dB with the low matching thicknesses.Furthermore,the obtained 2D/3D RGO/CFs vdWs heterostructures also displayed the significant radar stealth properties,good corrosion resistance performances as well as outstanding thermal insulation capabilities,displaying the great potential in complex and variable environments.Accordingly,this work not only demonstrated a straightforward method for fabricating 2D/3D vdWs heterostructures,but also outlined a powerful mixeddimensional assembly strategy for engineering multifunctional foams for electromagnetic protection,aerospace and other complex conditions.展开更多
The efficient photo-response mechanism is one of the key factors in the commercialization of dye-sensitized solar cells in a bid to satisfy renewable energy demands. Progress in green technology has put solar energy o...The efficient photo-response mechanism is one of the key factors in the commercialization of dye-sensitized solar cells in a bid to satisfy renewable energy demands. Progress in green technology has put solar energy on the front burner as a provider of clean and affordable energy for a sustainable society. We report the synthesis of a novel Schiff base with optical transparency in the visible and near IR region of the solar spectrum that can find application in the DSSCs photo-response mechanism. The synthesized crystal exhibited features that could handle some of the shortcomings of dye-sensitized solar cells which include wide band solar spectrum absorption and capability for swift charge transfer within the photoelectrodes. The synthesized Schiff base was characterized using x-ray diffractometer, UV/Visible spectrometer, Frontier transmission infrared spectrometer and conductometer. XRD data revealed the grown crystal to have an average crystallite size of 2.08 nm with average microstrain value of about 269.43. The FT-IR recorded transmission wave ѵ (CO) at 1207.7 cm<sup>−1</sup> while dominant wave occurred at ѵ1654.9 and ѵ1592.3 cm<sup>−1</sup> relating to ѵ (CN) stretching and ѵ (NH) bending respectively were observed. The IR spectrum revealed the bonding species and a probable molecular structure of 2,6-bis(benzyloxy)pyridine. The UV/Visible spectra convoluted to maximum peak within the near IR region suggesting that 2,6-bis(benzyloxy)pyridine can absorb both the visible and near IR region while its electrical conductivity was determined to be 4.58 µS/cm. The obtained result of the present study revealed promising characteristics of a photosensitizer that can find application in the photo-response mechanism of DSSCs.展开更多
ZnO and In203 films were prepared by thermal oxidation of vacuum deposited zinc and indium films, respec- tively onto the glass substrate at 30 ℃. The fabricated films have been irradiated with 100-MeV Ni7＋ ions at ...ZnO and In203 films were prepared by thermal oxidation of vacuum deposited zinc and indium films, respec- tively onto the glass substrate at 30 ℃. The fabricated films have been irradiated with 100-MeV Ni7＋ ions at different fluences ranging from 5×1011 to 5×1013 ions/cm2. The structural and gas sensing properties of pristine and irradiated films have been discussed. X-ray diffraction （XRD） pattern of pristine and irradiated films reveal that the films are polycrystalline in nature and crystallinity increases after irradiation. In this study, highly porous In203 nanorods evolved when being irradiated at a fluence of 5×1013 ions/cm2 while ZnO film shows decrease in number of nanowires. The ammonia sensing performance of the Ni^7＋ irradiated In203 films shows an improvement as compared to its pristine counterpart.展开更多
Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination...Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination and annealing was used for modifying morphological and structural properties that lead to changes of the optical properties.The resulting films show morphology of tilted nanocolumn,fissures among columns,and structural changes.The as-deposited films are structurally disordered with an amorphous component and the annealed films are crystallized and more ordered and the film diffractograms correspond to the cubic structure of In2O3.The refractive index could be modified up to 0.3 in as-deposited films and up to 0.15 in annealed films as functions of the inclination angle of the nanocolumns.Similarly,the band gap energy increases up to about 0.4 eV due to the reduction of the microstrain distribution.It is found that the microstrain distribution,which is related to lattice distortions,defects and the presence of fissures in the films,is the main feature that can be engineered through morphological modifications for achieving the adjustment of the optical properties.展开更多
Ceramic thermal barrier coatings （TBCs） are a very important technology for protecting the hot parts of gas turbines （GTs） from a high-temperature environment. The coating stress generated in the operation of GTs ...Ceramic thermal barrier coatings （TBCs） are a very important technology for protecting the hot parts of gas turbines （GTs） from a high-temperature environment. The coating stress generated in the operation of GTs brings cracking and peeling damage to the TBCs. Thus, it is necessary to evaluate precisely such coating stress in a TBC system. We have obtained a stress-strain curve for a freestanding ceramic coat specimen peeled from a TBC coated substrate by conducting the bending test. The test results have revealed that the ceramic coating deforms nonlinearly with the applied loading. In this study, an inelastic constitutive equation for the ceramic thermal barrier coatings deposited by APS is developed. The obtained results are as follows： （1） the micromechanics-based constitutive equation was formulated with micro crack density formed at splat boundary, and （2） it was shown that the numerical results for a nonlinearly deformed beam simulated by the developed constitutive equation agreed with the experimental results obtained by cantilever bending tests.展开更多
We demonstrated a unique synthesis approach of graphene（GR）-wrapped AgPO/LaCOOH（APO/LCO）heterostructures by an in-situ wet chemical method. FESEM analysis reveals the formation of rhombic dodecahedrons of APO deco...We demonstrated a unique synthesis approach of graphene（GR）-wrapped AgPO/LaCOOH（APO/LCO）heterostructures by an in-situ wet chemical method. FESEM analysis reveals the formation of rhombic dodecahedrons of APO decorated with LCO and later wrapped with GR flakes. Optical studies shows two absorption edges corresponding to the band gap energies of APO（2.41 eV） and LCO（4.1 eV）. Considering the absorption edge of the heterostructures in the visible region, the photocatalytic activities of photocatalysts containing different APO/LCO mass ratios were evaluated by the degradation of MB. GR-decorated composite with 20% LCO（APO/LCO20/GR） exhibited the highest photocatalytic activity for MB degradation, with a rate constant, k of 0.541 min. The photocatalytic activity of APO/LCO20/GR more greatly enhanced than those of the individual constituents（APO, LCO, APO/LCO20）. The enhanced photocatalytic activity of the heterostructure can be attributed to the co-catalytic effect of LCO as well as intriguing physicochemical properties of GR. To understand the enhanced photocatalytic activity of the heterostructures the photocatalytic reaction mechanism is proposed in detail. The recyclability of the APO/LCO/GR composite photocatalyst is further evaluated by reusing the catalyst in replicate photocatalytic experiments which shows consistent photocatalytic activity thereby confirms the stability and reusability of heterostructure photocatalyst.展开更多
A layer of graphene(GR)particles was successfully deposited at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes,aiming to improve the photoelectrochemical performance of the large-bandgap semiconductor T...A layer of graphene(GR)particles was successfully deposited at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes,aiming to improve the photoelectrochemical performance of the large-bandgap semiconductor TiO2.The obtained Co(OH)2/GR/TiO2 was extensively characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),UV–vis absorption spectra and photoluminescence(PL)emission spectra.Electrochemical impedance spectra,photogenerated potential-time(E-t),photocurrent density-time(i-t)and i-E curves and open circuit potential(OCP)curves were measured to investigate the photoelectrochemical activities and photogenerated cathodic protection properties.The results revealed that Co(OH)2/GR/TiO2 exhibits excellent photoelectrochemical and photogenerated cathodic performance due to synergistic effect between Co(OH)2 and graphene.Co(OH)2 and graphene co-modified TiO2 photoanode could provide an effective protection for 304 stainless steel(304 SS)in 3.5 wt%Na Cl solution for 12 h,which would be promising for future practical applications in the field of marine corrosion protection.展开更多
The effect of hydrochloric acid concentration on stainless steel (Fe6956) at temperature range 303 - 333 ± 1 K has been studied using weight loss, thermometric and electrochemical polarization techniques. The cor...The effect of hydrochloric acid concentration on stainless steel (Fe6956) at temperature range 303 - 333 ± 1 K has been studied using weight loss, thermometric and electrochemical polarization techniques. The corrosion rate of the stainless steel was found to be dependent on both temperature variation and acid concentration. The potentiostatic study showed that the active passive transition depends strongly on acid concentration while the weight loss measurements revealed that 2 M HCl at temperature 333 K had an appreciable corrosion rate which corresponds to 14.04 × 10﹣3 reaction number (RN) got from thermometric monitoring. Arrhenius equation and transition state theory were used to calculate kinetic and thermodynamic parameter such as Ea, ΔH* and ΔS*. Results obtained showed that corrosion reaction of Fe6956 in HCl is spontaneous and there is good agreement between the data got from the techniques employed.展开更多
The G?ksun(Kahramanmaras)ophiolite(GKO),cropping out in a tectonic window bounded by the Malatya metamorphic unit on both the north and south,is located in the EW-trending lower nappe zone of the southeast Anatolian o...The G?ksun(Kahramanmaras)ophiolite(GKO),cropping out in a tectonic window bounded by the Malatya metamorphic unit on both the north and south,is located in the EW-trending lower nappe zone of the southeast Anatolian orogenic belt(Turkey).It exhibits a complete oceanic lithospheric section and overlies the Middle Eocene Maden Group/Complex with a tectonic contact at its base.The ophiolitic rocks and the tectonically overlying Malatya metamorphic(continental)unit were intruded by I-type calc-alkaline Late Cretaceous granitoid(~81-84 Ma).The ultramafic to cumulates in the GKO are represented by wehrlite,plagioclase wehrlite,olivine gabbro and gabbro.The crystallization order for the cumulate rocks is as follows:olivine±chromian spinel→clinopyroxene→plagioclase.The major and trace element geochemistry as well as the mineral chemistry of the ultramafic to mafic cumulate rocks suggest that the primary magma generating the GKO is compositionally similar to that observed in the modern island-arc tholeiitic sequences.The mineral chemistry of the ultramafic to mafic cumulates indicates that they were derived from a mantle source that was previously depleted by earlier partial melting events.The highly magnesian olivine(Fo77-83),clinopyroxene(Mg#of 82-90)and the highly Ca-plagioclase(An81-89)exhibit a close similarity to those,which formed in a supra-subduction zone(SSZ)setting.The field and the geochemical evidence suggest that the GKO formed as part of a much larger sheet of oceanic lithosphere,which accreted to the base of the Tauride active continental margin,including the ispendere,K?mürhan and the Guleman ophiolites.The latter were contemporaneous and genetically/tectonically related within the same SSZ setting during the closure of the Neotethyan oceanic basin(Berit Ocean)between the Taurides to the north and the Bitlis-Pütürge massif to the south during the Late Cretaceous.展开更多
In this work, we present a theoretical study of a vertical parallel junction silicon solar cell under monochromatic illumination. The internal quantum efficiency (IQE) and the photovoltaic conversion efficiency are ca...In this work, we present a theoretical study of a vertical parallel junction silicon solar cell under monochromatic illumination. The internal quantum efficiency (IQE) and the photovoltaic conversion efficiency are calculated, taking into account the base doping density and illumination wave-length. The main purpose of this work is to show how conversion efficiency depends on internal quantum efficiency and the dependence of the later on the base doping density.展开更多
Hierarchically mesoporous titanosilicate Ti-SBA-1 was synthesized with organic mesomorphous complexes of polyelectrolyte（poly（acrylic acid）（PAA）） and cationic surfactant（hexadecyl pyridinium chloride（CPC）） a...Hierarchically mesoporous titanosilicate Ti-SBA-1 was synthesized with organic mesomorphous complexes of polyelectrolyte（poly（acrylic acid）（PAA）） and cationic surfactant（hexadecyl pyridinium chloride（CPC）） as template, tetraethylsiloxane as silica source and titanium ethoxide as titanium source.By adjusting the amount of titanium ethoxide in the synthesis, a series of Ti-SBA-1 particles with different Si/Ti ratio（79–180） were prepared. After incorporation of Ti into the silica framework the wellordered cubic Pm3n mesostructure remained, as well as the morphology, particle size. UV–vis DR spectra of the Ti-SBA-1 materials indicated that incorporated titanium species existed in a highly dispersed state and exhibited tetrahedral and octahedral coordination in the silica framework.展开更多
In this study we report the effect of laser parameters such as laser energy, laser wavelength as well as focusing condition of laser beam on the size and morphology of the gold nanoparticles (GNPs) prepared in deionis...In this study we report the effect of laser parameters such as laser energy, laser wavelength as well as focusing condition of laser beam on the size and morphology of the gold nanoparticles (GNPs) prepared in deionised water by pulsed laser ablation. The optimum conditions at which gold nanoparticles obtained with controllable average size have been reported as these parameters affected on the size, distribution and absorbance spectrum. Effect of energy was studied. The laser energy was divided into three regions (low, middle and high). A noteworthy change was observed at each region, as the average size changed from 5.9 nm at low energy to 14.4 nm at high energy and the gold nanoparticles reached a critical size of 8 nm at 100 mJ. The Effect of the wavelength on the particle size was examined at 1064 nm, 532 nm. It was found that, the optimum ablation laser wavelength was 1064 nm. Finally, significant results obtained when the effect of focusing conditions studied.展开更多
Strength of welded joints of high chromium steels is one of the important concerns for fabricators and operators of ultra supercritical thermal power plants. A number of creep as well as creep-fatigue tests with tensi...Strength of welded joints of high chromium steels is one of the important concerns for fabricators and operators of ultra supercritical thermal power plants. A number of creep as well as creep-fatigue tests with tensile hold have been carried out on the welded joints of two types of high chromium steels widely used in Japan, i.e. Grade 91 and 122 steels. It was found that failure occurred in fine grain heat-affected zone in all the creep-fatigue tests, even at a relatively low temperature and fairly short time where failure occurred in plain base metal region in simple creep testing. Four procedures were used to predict failure lives and their results were compared with the test results. A newly proposed energy-based approach gave the best estimation of failure life, without respect of the material and temperature.展开更多
Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augment...Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augmented plane wave （FP-LAPW） method. The exchange correlation effects are included through the local density approximation （LDA ）, generalized gradient approximation （GGA） and modified Becke-Johnson （mBJ） exchange potential The calculated lattice constant is in good agreement with the experimental result. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young＇s modulus and Poisson＇s ratio are calculated. KCdF3 is ductile and elastically anisotropic. The calculations of the electronic band structure, density of states （DOS） and charge density show that this compound has an indirect energy band gap （M-F） with a mixed ionic and covalent bonding. The contribution of the different bands is analyzed from the total and partial density of states curves. Optical response of the dielectric functions, optical reflectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of O-40eV. The compound KCdF3 can be used for high-frequency optical and optoelectronic devices.展开更多
Ceramics usually have irregular grains, cracking, or porosity, which result in their lightproof.Y2Mo3O12 ceramics have more porosity due to the heavy hygroscopicity.Introducing ZnLi to Y2Mo3O12 could form regular grai...Ceramics usually have irregular grains, cracking, or porosity, which result in their lightproof.Y2Mo3O12 ceramics have more porosity due to the heavy hygroscopicity.Introducing ZnLi to Y2Mo3O12 could form regular grains, reduce cracking and porosity.With increasing the content of ZnLi, the grain shapes self-assembly gradually and then the laser scattering and transmittance improve.The laser scattering property and transmittance of diverging rays become the best in ceramics Y2-x(ZnLi)xMo3O12(x = 1.0 and 1.2) with regular grains and low thermal expansion.The formation mechanism of regular grains is ascribed to the substitutions of Zn^2+ and Li+for Y^3+ in Y2Mo3O12 resulting in the preferential growth.The investigation in laser scattering, transmittance and low thermal expansion behaviors of Y2-x(ZnLi)xMo3O12 could pave a way to weaken the strong-laser attack from the high-power laser weapon and the other.展开更多
Electronic,structural and optical properties of the cubic perovskite CsCaF_(3) are calculated by using the full potential linearized augmented plane wave(FP-LAPW)plus local orbitals method with generalized gradient ap...Electronic,structural and optical properties of the cubic perovskite CsCaF_(3) are calculated by using the full potential linearized augmented plane wave(FP-LAPW)plus local orbitals method with generalized gradient approximation(GGA)in the framework of the density functional theory.The calculated lattice constant is in good agreement with the experimental result.The electronic band structure shows that the fundamental band gap is wide and indirect at(Γ–R)point.The contribution of the different bands is analyzed from the total and partial density of states curves.The charge density plots show strong ionic bonding in Cs-F,and ionic and weak covalent bonding between Ca and F.Calculations of the optical spectra,viz.,the dielectric function,optical reflectivity,absorption coefficient,real part of optical conductivity,refractive index,extinction coefficient and electron energy loss,are performed for the energy range 0–30 eV.展开更多
AD = 1 position-dependent mass approach to constructing nonlinear quantum states for a modified Coulomb potential is used to generate Gazeau–Klauder coherent states. It appears that their energy eigenvalues are scale...AD = 1 position-dependent mass approach to constructing nonlinear quantum states for a modified Coulomb potential is used to generate Gazeau–Klauder coherent states. It appears that their energy eigenvalues are scaled down by the quantum number and the nonlinearity coefficient. We study the basic properties of these states, which are found to be undefined on the whole complex plane, and some details of their revival structure are discussed.展开更多
基金supported by the National Key Research and Development Project of China(Grant No.2022YFB3205500)the National Natural Science Foundation of China(Grant No.12275190,12105201)+2 种基金Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant No.2024ZB723)the Shenzhen Research Funding Program(JCYJ20230807154402004)supported by the Collaborative Innovation Center of Suzhou Nano Science&Technology,the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),the 111 Project,the Joint International Research Laboratory of Carbon-Based Functional Materials and Devices,and the Suzhou Key Laboratory of Functional Nano&Soft Materials and Soochow University-Western University Centre for Synchrotron Radiation Research.
文摘Conventional gas sensing materials(e.g.,metal oxides)suffer from deficient sensitivity and serve cross-sensitivity issues due to the lack of efficient adsorption sites.Herein,the heteroatom atomically doping strategy is demonstrated to significantly enhance the sensing performance of metal oxides-based gas sensing materials.Specifically,the Sn atoms were incorporated into porous Fe_(2)O_(3)in the form of atomically dispersed sites.As revealed by X-ray absorption spectroscopy and atomic-resolution scanning transmission electron microscopy,these Sn atoms successfully occupy the Fe sites in the Fe_(2)O_(3)lattice,forming the unique Sn-O-Fe sites.Compared to Fe-O-Fe sites(from bare Fe_(2)O_(3))and Sn-O-Sn sites(from SnO_(2)/Fe_(2)O_(3)with high Sn loading),the Sn-O-Fe sites on porous Fe_(2)O_(3)exhibit a superior sensitivity(Rg/Ra=2646.6)to 1 ppm NO_(2),along with dramatically increased selectivity and ultra-low limits of detection(10 ppb).Further theoretical calculations suggest that the strong adsorption of NO_(2)on Sn-O-Fe sites(N atom on Sn site,O atom on Fe site)contributes a more efficient gas response,compared to NO_(2)on Fe-O-Fe sites and other gases on Sn-O-Fe sites.Moreover,the incorporated Sn atoms reduce the bandgap of Fe_(2)O_(3),not only facilitating the electron release but also increasing the NO_(2)adsorption at a low working temperature(150°C).This work introduces an effective strategy to construct effective adsorption sites that show a unique response to specific gas molecules,potentially promoting the rational design of atomically modified gas sensing materials with high sensitivity and high selectivity.
文摘Herein,we report the synthesis of a Dy-Gd co-doped cubic phase-stabilized Bi_(2)O_(3) solid electrolyte system via solid-state processing under atmospheric conditions.Doping with Dy^(3+) and Gd^(3+) has been observed to significantly enhance the densification process during sintering for stabilization purposes,thereby improving the electrical properties of δ-Bi_(2)O_(3)-type polymorphs.The synthesized ceramics were characterized using X-ray diffraction(XRD),field emission scanning electron microscopy-energy dispersive X-ray spectroscopy(FESEM-EDX),thermal gravimetry/differential thermal analysis(TG/DTA),and the four-point probe technique(4PPT).XRD analysis reveals that the samples Bi_(1-x-y)Gd_(x)Dy_(y)O_(1.5)(y=0.05/x=0.05,0.10,0,15,and 0.20,and x=0.05/y=0.10,0.15,and 0.20) exhibit a stable face-centered cubic δ-phase and a mixed-phase crystallographic structure.The XRD analysis of the stabilized δ-phase suggests that the prepared oxides show a face-centered cubic(FCC) structure with a space group of Fm-3m.FESEM micrographs reveal that the composition Bi_(0.90)Gd_(0.05)Dy_(0.05)O_(1.5) has no significant holes.Nevertheless,an evident increase in the pore formation is observed as the amount of Gd_(2)O_(3) increases until it reaches 20%.This finding suggests that dense pellets are formed during the sintering process at 900-1000℃.The DTA analyses were performed to verify the phase stability,which agrees with the XRD results.The electrochemical performance of the synthesized Dy-Gd co-doped Bi_(2)O_(3)solid electrolyte system was evaluated and analyzed in detail by using the electrochemical impedance spectroscopy(EIS) technique,Based on EIS and conductivity measurements,Bi_(0.75)Gd_(0.20)Dy_(0.05)O_(1.5) exhibits the lowest activation energy of 0.519 eV and the highest conductivity value of 0.398 S/cm at 627℃compared to the other samples;this composition can be used as a solid electrolyte for intermediatetemperature solid oxide fuel cells(SOFCs).
基金provided by Guizhou Provincial Science and Technology Projects for Platform and Talent Team Plan(GCC[2023]007)Fok Ying Tung Education Foundation(171095)National Natural Science Foundation of China(11964006).
文摘Considering the serious electromagnetic wave(EMW)pollution problems and complex application condition,there is a pressing need to amalgamate multiple functionalities within a single substance.However,the effective integration of diverse functions into designed EMW absorption materials still faces the huge challenges.Herein,reduced graphene oxide/carbon foams(RGO/CFs)with two-dimensional/three-dimensional(2D/3D)van der Waals(vdWs)heterostructures were meticulously engineered and synthesized utilizing an efficient methodology involving freeze-drying,immersing absorption,secondary freeze-drying,followed by carbonization treatment.Thanks to their excellent linkage effect of amplified dielectric loss and optimized impedance matching,the designed 2D/3D RGO/CFs vdWs heterostructures demonstrated commendable EMW absorption performances,achieving a broad absorption bandwidth of 6.2 GHz and a reflection loss of-50.58 dB with the low matching thicknesses.Furthermore,the obtained 2D/3D RGO/CFs vdWs heterostructures also displayed the significant radar stealth properties,good corrosion resistance performances as well as outstanding thermal insulation capabilities,displaying the great potential in complex and variable environments.Accordingly,this work not only demonstrated a straightforward method for fabricating 2D/3D vdWs heterostructures,but also outlined a powerful mixeddimensional assembly strategy for engineering multifunctional foams for electromagnetic protection,aerospace and other complex conditions.
文摘The efficient photo-response mechanism is one of the key factors in the commercialization of dye-sensitized solar cells in a bid to satisfy renewable energy demands. Progress in green technology has put solar energy on the front burner as a provider of clean and affordable energy for a sustainable society. We report the synthesis of a novel Schiff base with optical transparency in the visible and near IR region of the solar spectrum that can find application in the DSSCs photo-response mechanism. The synthesized crystal exhibited features that could handle some of the shortcomings of dye-sensitized solar cells which include wide band solar spectrum absorption and capability for swift charge transfer within the photoelectrodes. The synthesized Schiff base was characterized using x-ray diffractometer, UV/Visible spectrometer, Frontier transmission infrared spectrometer and conductometer. XRD data revealed the grown crystal to have an average crystallite size of 2.08 nm with average microstrain value of about 269.43. The FT-IR recorded transmission wave ѵ (CO) at 1207.7 cm<sup>−1</sup> while dominant wave occurred at ѵ1654.9 and ѵ1592.3 cm<sup>−1</sup> relating to ѵ (CN) stretching and ѵ (NH) bending respectively were observed. The IR spectrum revealed the bonding species and a probable molecular structure of 2,6-bis(benzyloxy)pyridine. The UV/Visible spectra convoluted to maximum peak within the near IR region suggesting that 2,6-bis(benzyloxy)pyridine can absorb both the visible and near IR region while its electrical conductivity was determined to be 4.58 µS/cm. The obtained result of the present study revealed promising characteristics of a photosensitizer that can find application in the photo-response mechanism of DSSCs.
文摘ZnO and In203 films were prepared by thermal oxidation of vacuum deposited zinc and indium films, respec- tively onto the glass substrate at 30 ℃. The fabricated films have been irradiated with 100-MeV Ni7＋ ions at different fluences ranging from 5×1011 to 5×1013 ions/cm2. The structural and gas sensing properties of pristine and irradiated films have been discussed. X-ray diffraction （XRD） pattern of pristine and irradiated films reveal that the films are polycrystalline in nature and crystallinity increases after irradiation. In this study, highly porous In203 nanorods evolved when being irradiated at a fluence of 5×1013 ions/cm2 while ZnO film shows decrease in number of nanowires. The ammonia sensing performance of the Ni^7＋ irradiated In203 films shows an improvement as compared to its pristine counterpart.
基金supported by the Project No.CB/2012/178748 CONACYT/México
文摘Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination and annealing was used for modifying morphological and structural properties that lead to changes of the optical properties.The resulting films show morphology of tilted nanocolumn,fissures among columns,and structural changes.The as-deposited films are structurally disordered with an amorphous component and the annealed films are crystallized and more ordered and the film diffractograms correspond to the cubic structure of In2O3.The refractive index could be modified up to 0.3 in as-deposited films and up to 0.15 in annealed films as functions of the inclination angle of the nanocolumns.Similarly,the band gap energy increases up to about 0.4 eV due to the reduction of the microstrain distribution.It is found that the microstrain distribution,which is related to lattice distortions,defects and the presence of fissures in the films,is the main feature that can be engineered through morphological modifications for achieving the adjustment of the optical properties.
文摘Ceramic thermal barrier coatings （TBCs） are a very important technology for protecting the hot parts of gas turbines （GTs） from a high-temperature environment. The coating stress generated in the operation of GTs brings cracking and peeling damage to the TBCs. Thus, it is necessary to evaluate precisely such coating stress in a TBC system. We have obtained a stress-strain curve for a freestanding ceramic coat specimen peeled from a TBC coated substrate by conducting the bending test. The test results have revealed that the ceramic coating deforms nonlinearly with the applied loading. In this study, an inelastic constitutive equation for the ceramic thermal barrier coatings deposited by APS is developed. The obtained results are as follows： （1） the micromechanics-based constitutive equation was formulated with micro crack density formed at splat boundary, and （2） it was shown that the numerical results for a nonlinearly deformed beam simulated by the developed constitutive equation agreed with the experimental results obtained by cantilever bending tests.
基金Department of Electronics and Information Technology (Deit Y, New Delhi) for financial supportUGC-SAP, DST-FIST Department of Chemistry, Shivaji University Kolhapursupported by the Commercialization Promotion Agency for R&D Outcomes (COMPA) funded by the Ministry of Science, ICT and Future Planning (MISP) and NRF-2013R1A2A2A05005589
文摘We demonstrated a unique synthesis approach of graphene（GR）-wrapped AgPO/LaCOOH（APO/LCO）heterostructures by an in-situ wet chemical method. FESEM analysis reveals the formation of rhombic dodecahedrons of APO decorated with LCO and later wrapped with GR flakes. Optical studies shows two absorption edges corresponding to the band gap energies of APO（2.41 eV） and LCO（4.1 eV）. Considering the absorption edge of the heterostructures in the visible region, the photocatalytic activities of photocatalysts containing different APO/LCO mass ratios were evaluated by the degradation of MB. GR-decorated composite with 20% LCO（APO/LCO20/GR） exhibited the highest photocatalytic activity for MB degradation, with a rate constant, k of 0.541 min. The photocatalytic activity of APO/LCO20/GR more greatly enhanced than those of the individual constituents（APO, LCO, APO/LCO20）. The enhanced photocatalytic activity of the heterostructure can be attributed to the co-catalytic effect of LCO as well as intriguing physicochemical properties of GR. To understand the enhanced photocatalytic activity of the heterostructures the photocatalytic reaction mechanism is proposed in detail. The recyclability of the APO/LCO/GR composite photocatalyst is further evaluated by reusing the catalyst in replicate photocatalytic experiments which shows consistent photocatalytic activity thereby confirms the stability and reusability of heterostructure photocatalyst.
基金supported financially by the National Natural Science Foundation of China(Nos.51622106 and 51871049)the Fundamental Research Funds for the Central Universities(No.160708001).
文摘A layer of graphene(GR)particles was successfully deposited at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes,aiming to improve the photoelectrochemical performance of the large-bandgap semiconductor TiO2.The obtained Co(OH)2/GR/TiO2 was extensively characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),UV–vis absorption spectra and photoluminescence(PL)emission spectra.Electrochemical impedance spectra,photogenerated potential-time(E-t),photocurrent density-time(i-t)and i-E curves and open circuit potential(OCP)curves were measured to investigate the photoelectrochemical activities and photogenerated cathodic protection properties.The results revealed that Co(OH)2/GR/TiO2 exhibits excellent photoelectrochemical and photogenerated cathodic performance due to synergistic effect between Co(OH)2 and graphene.Co(OH)2 and graphene co-modified TiO2 photoanode could provide an effective protection for 304 stainless steel(304 SS)in 3.5 wt%Na Cl solution for 12 h,which would be promising for future practical applications in the field of marine corrosion protection.
文摘The effect of hydrochloric acid concentration on stainless steel (Fe6956) at temperature range 303 - 333 ± 1 K has been studied using weight loss, thermometric and electrochemical polarization techniques. The corrosion rate of the stainless steel was found to be dependent on both temperature variation and acid concentration. The potentiostatic study showed that the active passive transition depends strongly on acid concentration while the weight loss measurements revealed that 2 M HCl at temperature 333 K had an appreciable corrosion rate which corresponds to 14.04 × 10﹣3 reaction number (RN) got from thermometric monitoring. Arrhenius equation and transition state theory were used to calculate kinetic and thermodynamic parameter such as Ea, ΔH* and ΔS*. Results obtained showed that corrosion reaction of Fe6956 in HCl is spontaneous and there is good agreement between the data got from the techniques employed.
基金supported by TüBITAK (YDABCAG199Y011) and the Cukurova University Scientific Research Projects (MMF2002BAP41)the Open Fund (GPMR201702) of State Key Lab of Geological Processes and Mineral Resources,China University of Geosciences,Wuhansubsidy by the Russian Government to support the Program of competitive growth of Kazan Federal University
文摘The G?ksun(Kahramanmaras)ophiolite(GKO),cropping out in a tectonic window bounded by the Malatya metamorphic unit on both the north and south,is located in the EW-trending lower nappe zone of the southeast Anatolian orogenic belt(Turkey).It exhibits a complete oceanic lithospheric section and overlies the Middle Eocene Maden Group/Complex with a tectonic contact at its base.The ophiolitic rocks and the tectonically overlying Malatya metamorphic(continental)unit were intruded by I-type calc-alkaline Late Cretaceous granitoid(~81-84 Ma).The ultramafic to cumulates in the GKO are represented by wehrlite,plagioclase wehrlite,olivine gabbro and gabbro.The crystallization order for the cumulate rocks is as follows:olivine±chromian spinel→clinopyroxene→plagioclase.The major and trace element geochemistry as well as the mineral chemistry of the ultramafic to mafic cumulate rocks suggest that the primary magma generating the GKO is compositionally similar to that observed in the modern island-arc tholeiitic sequences.The mineral chemistry of the ultramafic to mafic cumulates indicates that they were derived from a mantle source that was previously depleted by earlier partial melting events.The highly magnesian olivine(Fo77-83),clinopyroxene(Mg#of 82-90)and the highly Ca-plagioclase(An81-89)exhibit a close similarity to those,which formed in a supra-subduction zone(SSZ)setting.The field and the geochemical evidence suggest that the GKO formed as part of a much larger sheet of oceanic lithosphere,which accreted to the base of the Tauride active continental margin,including the ispendere,K?mürhan and the Guleman ophiolites.The latter were contemporaneous and genetically/tectonically related within the same SSZ setting during the closure of the Neotethyan oceanic basin(Berit Ocean)between the Taurides to the north and the Bitlis-Pütürge massif to the south during the Late Cretaceous.
文摘In this work, we present a theoretical study of a vertical parallel junction silicon solar cell under monochromatic illumination. The internal quantum efficiency (IQE) and the photovoltaic conversion efficiency are calculated, taking into account the base doping density and illumination wave-length. The main purpose of this work is to show how conversion efficiency depends on internal quantum efficiency and the dependence of the later on the base doping density.
基金supported by National Science Foundation of China (Nos. 21373116 and 21421001)Tianjin Natural Science Research Fund (No. 13JCYBJC18300)+3 种基金RFDP (No. 20120031110005)the Technology Planning Project of Hunan Province (No. 2014SK2019)National Science Foundation for Post-doctoral Scientists of China (No. 2014T70774)the Scientific Research Fund of Hunan Provincial Education Department (No. 14C0343)
文摘Hierarchically mesoporous titanosilicate Ti-SBA-1 was synthesized with organic mesomorphous complexes of polyelectrolyte（poly（acrylic acid）（PAA）） and cationic surfactant（hexadecyl pyridinium chloride（CPC）） as template, tetraethylsiloxane as silica source and titanium ethoxide as titanium source.By adjusting the amount of titanium ethoxide in the synthesis, a series of Ti-SBA-1 particles with different Si/Ti ratio（79–180） were prepared. After incorporation of Ti into the silica framework the wellordered cubic Pm3n mesostructure remained, as well as the morphology, particle size. UV–vis DR spectra of the Ti-SBA-1 materials indicated that incorporated titanium species existed in a highly dispersed state and exhibited tetrahedral and octahedral coordination in the silica framework.
文摘In this study we report the effect of laser parameters such as laser energy, laser wavelength as well as focusing condition of laser beam on the size and morphology of the gold nanoparticles (GNPs) prepared in deionised water by pulsed laser ablation. The optimum conditions at which gold nanoparticles obtained with controllable average size have been reported as these parameters affected on the size, distribution and absorbance spectrum. Effect of energy was studied. The laser energy was divided into three regions (low, middle and high). A noteworthy change was observed at each region, as the average size changed from 5.9 nm at low energy to 14.4 nm at high energy and the gold nanoparticles reached a critical size of 8 nm at 100 mJ. The Effect of the wavelength on the particle size was examined at 1064 nm, 532 nm. It was found that, the optimum ablation laser wavelength was 1064 nm. Finally, significant results obtained when the effect of focusing conditions studied.
文摘Strength of welded joints of high chromium steels is one of the important concerns for fabricators and operators of ultra supercritical thermal power plants. A number of creep as well as creep-fatigue tests with tensile hold have been carried out on the welded joints of two types of high chromium steels widely used in Japan, i.e. Grade 91 and 122 steels. It was found that failure occurred in fine grain heat-affected zone in all the creep-fatigue tests, even at a relatively low temperature and fairly short time where failure occurred in plain base metal region in simple creep testing. Four procedures were used to predict failure lives and their results were compared with the test results. A newly proposed energy-based approach gave the best estimation of failure life, without respect of the material and temperature.
基金Supported by UGC,New Delhi through UGC-BSR(JRF)fellowships
文摘Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augmented plane wave （FP-LAPW） method. The exchange correlation effects are included through the local density approximation （LDA ）, generalized gradient approximation （GGA） and modified Becke-Johnson （mBJ） exchange potential The calculated lattice constant is in good agreement with the experimental result. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young＇s modulus and Poisson＇s ratio are calculated. KCdF3 is ductile and elastically anisotropic. The calculations of the electronic band structure, density of states （DOS） and charge density show that this compound has an indirect energy band gap （M-F） with a mixed ionic and covalent bonding. The contribution of the different bands is analyzed from the total and partial density of states curves. Optical response of the dielectric functions, optical reflectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of O-40eV. The compound KCdF3 can be used for high-frequency optical and optoelectronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60976016,61350012,and 11574276)the Key Scientific Research Projects of Henan Province,China(Grant No.15B140004)+2 种基金Henan Science and Technology Development Project,China(Grant No.182102210241)Key Projects of Science and Technology Research of Henan Provincial Department of Education,China(Grant No.18A140014)Industrial Science and Technology Research Projects of Kaifeng,Henan Province,China(Grant No.1501049)
文摘Ceramics usually have irregular grains, cracking, or porosity, which result in their lightproof.Y2Mo3O12 ceramics have more porosity due to the heavy hygroscopicity.Introducing ZnLi to Y2Mo3O12 could form regular grains, reduce cracking and porosity.With increasing the content of ZnLi, the grain shapes self-assembly gradually and then the laser scattering and transmittance improve.The laser scattering property and transmittance of diverging rays become the best in ceramics Y2-x(ZnLi)xMo3O12(x = 1.0 and 1.2) with regular grains and low thermal expansion.The formation mechanism of regular grains is ascribed to the substitutions of Zn^2+ and Li+for Y^3+ in Y2Mo3O12 resulting in the preferential growth.The investigation in laser scattering, transmittance and low thermal expansion behaviors of Y2-x(ZnLi)xMo3O12 could pave a way to weaken the strong-laser attack from the high-power laser weapon and the other.
文摘Electronic,structural and optical properties of the cubic perovskite CsCaF_(3) are calculated by using the full potential linearized augmented plane wave(FP-LAPW)plus local orbitals method with generalized gradient approximation(GGA)in the framework of the density functional theory.The calculated lattice constant is in good agreement with the experimental result.The electronic band structure shows that the fundamental band gap is wide and indirect at(Γ–R)point.The contribution of the different bands is analyzed from the total and partial density of states curves.The charge density plots show strong ionic bonding in Cs-F,and ionic and weak covalent bonding between Ca and F.Calculations of the optical spectra,viz.,the dielectric function,optical reflectivity,absorption coefficient,real part of optical conductivity,refractive index,extinction coefficient and electron energy loss,are performed for the energy range 0–30 eV.
文摘AD = 1 position-dependent mass approach to constructing nonlinear quantum states for a modified Coulomb potential is used to generate Gazeau–Klauder coherent states. It appears that their energy eigenvalues are scaled down by the quantum number and the nonlinearity coefficient. We study the basic properties of these states, which are found to be undefined on the whole complex plane, and some details of their revival structure are discussed.
