The detailed theoretical studies of electronic,optical,and mechanical properties of γ-Bi2Sn2O7 are carried out by using first-principle density functional theory calculations.Our calculated results indicate that γ-B...The detailed theoretical studies of electronic,optical,and mechanical properties of γ-Bi2Sn2O7 are carried out by using first-principle density functional theory calculations.Our calculated results indicate that γ-Bi2Sn2O7 is the p-type semiconductor with an indirect band gap of about 2.72 e V.The flat electronic bands close to the valence band maximum are mainly composed of Bi-6s and O-2p states and play a key role in determining the electrical properties of γ-Bi2Sn2O7.The calculated complex dielectric function and macroscopic optical constants including refractive index,extinction coefficient,absorption coefficients,reflectivity,and electron energy-loss function show that γ-Bi2Sn2O7 is an excellent light absorbing material.The analysis on mechanical properties shows that γ-Bi2Sn2O7 is mechanically stable and highly isotropic.展开更多
The magneto-caloric effect （MCE） of a Gd55Co25Al18Sn2 bulk metallic glass （BMG） is investigated. The Gd55Co25AllsSn2 as-cast rod prepared by a water-cooled copper mold suction casting method exhibits typi- cal amo...The magneto-caloric effect （MCE） of a Gd55Co25Al18Sn2 bulk metallic glass （BMG） is investigated. The Gd55Co25AllsSn2 as-cast rod prepared by a water-cooled copper mold suction casting method exhibits typi- cal amorphous characteristics. The maximum magnetic entropy change （--ASPmeak） and the magnetic refrigerant capacity （Re） of the BMG under a field of 5 T are about 9.32 J.kg-X.K 1 and 832 J.kg-1, respectively, both of which are larger than the values of the Gd55 Co25A120 BMG. The mechanism for the improved MCE by minor Sn addition is studied and the field dependence of - magneto-caloric behaviors of Gd55Co25Al18Sn2 BMG ASPmeak is investigated for a better understanding on the展开更多
Yolk-shell ternary composites composed of a Ni sphere core and a SnO2（Ni3Sn2） shell were successfully prepared by a facile two-step method. The size, morphology, microstructure, and phase purity of the resulting com...Yolk-shell ternary composites composed of a Ni sphere core and a SnO2（Ni3Sn2） shell were successfully prepared by a facile two-step method. The size, morphology, microstructure, and phase purity of the resulting composites were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy （TEM）, high-resolution TEM, selected-area electron diffraction, and powder X-ray diffraction. The core sizes, interstitial void volumes, and constituents of the yolk-shell structures varied by varying the reaction time. A mechanism based on the time-dependent experiments was proposed for the formation of the yolk-shell structures. The yolk-shell structures were formed by a synergistic combination of an etching reaction, a galvanic replacement reaction, and the Kirkendall effect. The yolk-shell ternary SnO2 （Ni3Sn2）@Ni composites synthesized at a reaction time of 15 h showed excellent microwave absorption properties. The reflection loss was found to be as low as -43 dB at 6.1 GHz. The enhanced microwave absorption properties may be attributed to the good impedance match, multiple reflections, the scattering owing to the voids between the core and the shell, and the effective complementarities between the dielectric loss and the magnetic loss. Thus, the yolk-shell ternary composites are expected to be promising candidates for microwave absorption applications, lithium ion batteries, and photocatalysis.展开更多
Two-dimensional Sn2Ta2O7 nanosheets with a thickness of^10 nm were successfully prepared through a novel tantalic acid-based solid-state reaction method at reduced temperature.The as-obtained samples were characterize...Two-dimensional Sn2Ta2O7 nanosheets with a thickness of^10 nm were successfully prepared through a novel tantalic acid-based solid-state reaction method at reduced temperature.The as-obtained samples were characterized by powder X-ray diffraction(XRD),ultraviolet–visible(UV–Vis)diffuse reflectance spectra,scanning electron microscopy(SEM),transmission electron microscopy(TEM)and Brunauer–Emmett–Teller(BET)analysis.The photocatalytic performance of Sn2 Ta2 O7 nanosheets was evaluated by photocatalytic water splitting for hydrogen evolution under visible light irradiation(k C 400 nm).The Sn2Ta2O7 nanosheets with a large surface area of 25.9 m^2·g^-1 showed higher H2 production activity,which was about 4.4 times higher than that of bulk Sn2 Ta2O7 in lactic acid aqueous solutions using Pt as a cocatalyst.The improved photocatalytic performance mainly benefited from the nanosheet structure,which provided abundant surface active sites and facilitated the photogenerated charge carrier separation efficiently.This workmay open up new opportunity to develop novel nanostructured tantalum-based semiconductors with improved catalytic performance for solar energy conversion.展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2014CB643703)the National Natural Science Foundation of China(Grant Nos.11164005,11464008,and 51401060)+1 种基金the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China(Grant Nos.2014GXNSFGA118001 and 2012GXNSFGA060002)the Fund from Guangxi Provincial Key Laboratory of Information Materials of Guangxi Zhuang Autonomous Region,China(Grant Nos.1210908-215-Z and 131022-Z)
文摘The detailed theoretical studies of electronic,optical,and mechanical properties of γ-Bi2Sn2O7 are carried out by using first-principle density functional theory calculations.Our calculated results indicate that γ-Bi2Sn2O7 is the p-type semiconductor with an indirect band gap of about 2.72 e V.The flat electronic bands close to the valence band maximum are mainly composed of Bi-6s and O-2p states and play a key role in determining the electrical properties of γ-Bi2Sn2O7.The calculated complex dielectric function and macroscopic optical constants including refractive index,extinction coefficient,absorption coefficients,reflectivity,and electron energy-loss function show that γ-Bi2Sn2O7 is an excellent light absorbing material.The analysis on mechanical properties shows that γ-Bi2Sn2O7 is mechanically stable and highly isotropic.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51171100 and 51271103
文摘The magneto-caloric effect （MCE） of a Gd55Co25Al18Sn2 bulk metallic glass （BMG） is investigated. The Gd55Co25AllsSn2 as-cast rod prepared by a water-cooled copper mold suction casting method exhibits typi- cal amorphous characteristics. The maximum magnetic entropy change （--ASPmeak） and the magnetic refrigerant capacity （Re） of the BMG under a field of 5 T are about 9.32 J.kg-X.K 1 and 832 J.kg-1, respectively, both of which are larger than the values of the Gd55 Co25A120 BMG. The mechanism for the improved MCE by minor Sn addition is studied and the field dependence of - magneto-caloric behaviors of Gd55Co25Al18Sn2 BMG ASPmeak is investigated for a better understanding on the
基金Acknowledgements The authors appreciate the financial support from the National Natural Science Foundation of China （No. 51402264）, and China Postdoctoral Science Foundation （No. 2014M561996）.
文摘Yolk-shell ternary composites composed of a Ni sphere core and a SnO2（Ni3Sn2） shell were successfully prepared by a facile two-step method. The size, morphology, microstructure, and phase purity of the resulting composites were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy （TEM）, high-resolution TEM, selected-area electron diffraction, and powder X-ray diffraction. The core sizes, interstitial void volumes, and constituents of the yolk-shell structures varied by varying the reaction time. A mechanism based on the time-dependent experiments was proposed for the formation of the yolk-shell structures. The yolk-shell structures were formed by a synergistic combination of an etching reaction, a galvanic replacement reaction, and the Kirkendall effect. The yolk-shell ternary SnO2 （Ni3Sn2）@Ni composites synthesized at a reaction time of 15 h showed excellent microwave absorption properties. The reflection loss was found to be as low as -43 dB at 6.1 GHz. The enhanced microwave absorption properties may be attributed to the good impedance match, multiple reflections, the scattering owing to the voids between the core and the shell, and the effective complementarities between the dielectric loss and the magnetic loss. Thus, the yolk-shell ternary composites are expected to be promising candidates for microwave absorption applications, lithium ion batteries, and photocatalysis.
基金financially supported by the National Key R&D Program of China (Nos. 2017YFA0206904, 2017YFA0206900 and 2016YFB0600901)the National Natural Science Foundation of China (Nos. 51825205, U1662118, 51772305, 51572270, 21871279 and 21802154)+4 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB17000000)the Beijing Natural Science Foundation (No. 2182078), the Beijing Municipal Science and Technology Project (No. Z181100005118007)the Royal Society-Newton Advanced Fellowship (No. NA170422)the International Partnership Program of Chinese Academy of Sciences (No. GJHZ1819)the K. C. Wong Education Foundation
文摘Two-dimensional Sn2Ta2O7 nanosheets with a thickness of^10 nm were successfully prepared through a novel tantalic acid-based solid-state reaction method at reduced temperature.The as-obtained samples were characterized by powder X-ray diffraction(XRD),ultraviolet–visible(UV–Vis)diffuse reflectance spectra,scanning electron microscopy(SEM),transmission electron microscopy(TEM)and Brunauer–Emmett–Teller(BET)analysis.The photocatalytic performance of Sn2 Ta2 O7 nanosheets was evaluated by photocatalytic water splitting for hydrogen evolution under visible light irradiation(k C 400 nm).The Sn2Ta2O7 nanosheets with a large surface area of 25.9 m^2·g^-1 showed higher H2 production activity,which was about 4.4 times higher than that of bulk Sn2 Ta2O7 in lactic acid aqueous solutions using Pt as a cocatalyst.The improved photocatalytic performance mainly benefited from the nanosheet structure,which provided abundant surface active sites and facilitated the photogenerated charge carrier separation efficiently.This workmay open up new opportunity to develop novel nanostructured tantalum-based semiconductors with improved catalytic performance for solar energy conversion.
