Tetradymite-structured chalcogenides,such as Bi_(2)Te_(3) and Sb_(2)Te_(3),are quasi-two-dimensional(2D)layered compounds,which are significant thermoelectric materials applied near room temperature.The intercalation ...Tetradymite-structured chalcogenides,such as Bi_(2)Te_(3) and Sb_(2)Te_(3),are quasi-two-dimensional(2D)layered compounds,which are significant thermoelectric materials applied near room temperature.The intercalation of guest species in van der Waals(vdW)gap implemented for tunning properties has attracted much attention in recent years.We attempt to insert Ga atoms in the vdW gap between the Te layers in p-type Bi_(0.3)Sb_(1.7)Te_(3)(BST)for further improving thermoelectrics.The vdW-related defects(including extrinsic interstitial and intrinsic defects)induced by Ga intercalation can not only modulate the carrier concentration but also enhance the texture,thereby yielding excellent electrical properties,which are reflected in the power factor PF~4.43 mW·m^(-1)·K^(-2).Furthermore,the intercalation of Ga produces multi-scale lattice imperfections such as point defects,Te precipitations,and nanopores,realizing the low lattice thermal conductivity in BST-Ga samples.Ultimately,a peak zT~1.1 at 373 K is achieved in the BST-1%Ga sample and greatly improved by~22%compared to the pristine BST.The weak bonding of vdW interlayer interaction can boost the synergistic effect for advancing BST-based or other layered thermoelectrics.展开更多
The maximum velocity of a mobile vortex in movement is generally limited by the phenomenon of flux-flow instability(FFI),which necessitates weak vortex pinning and fast heat removal from non-equilibrium electrons.We h...The maximum velocity of a mobile vortex in movement is generally limited by the phenomenon of flux-flow instability(FFI),which necessitates weak vortex pinning and fast heat removal from non-equilibrium electrons.We here demonstrate exfoliations and nano-fabrications of Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ) crystalline nanostrips,which possess a rather weak pinning volume of vortices,relatively low resistivity,and large normal electron diffusion coefficient.The deduced vortex velocity in Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ) crystalline nanostrips can be up to 300 km/s near the superconducting transition temperature,well above the speed of sound.The observed vortex velocity is an order of magnitude faster than that of conventional superconducting systems,representing a perfect platform for exploration of ultra-fast vortex matter and a good candidate for fabrications of superconducting nanowire single photon detectors or superconducting THz modulator.展开更多
2,2'-Arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) 4l-s produced from reaction between dimedone with various aldehydes in acetonitrile using ZnO as a catalyst;whereas in the presence of ZnO-acetyl ...2,2'-Arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) 4l-s produced from reaction between dimedone with various aldehydes in acetonitrile using ZnO as a catalyst;whereas in the presence of ZnO-acetyl chloride catalysts the reaction is limited to give only 1,8-dioxo-octahydroxanthenes 3a-k in very good yields.展开更多
In this manuscript a comparative study on Bi<sub>2</sub>O<sub>3</sub>/polystyrene and Bi<sub>2</sub>O<sub>3</sub>/PVDF composites has been executed via analysis of struc...In this manuscript a comparative study on Bi<sub>2</sub>O<sub>3</sub>/polystyrene and Bi<sub>2</sub>O<sub>3</sub>/PVDF composites has been executed via analysis of structural, bonding, surface morphology and dielectric response of composites for energy storage. The composites have been synthesized using solution cast method by varying concentrations of Bi<sub>2</sub>O<sub>3</sub> (BO = 1 - 5 mw%) into polystyrene (PS) and polyvinylidene fluoride (PVDF) polymers respectively. X-ray diffraction confirms the generation of crystallinity, Fourier transform infrared (FT-IR) spectroscopy confirms bonding behavior and scanning electron microscopy (SEM) confirms uniform distribution of Bi<sub>2</sub>O<sub>3</sub> (BO) in PS and PVDF polymers. Impedance spectroscopy has been employed for determination of dielectric response of the fabricated composites. The dielectric constant has been found to be increased as 1.4 times of pristine PS to BO<sub>5%</sub>PS<sub>95%</sub> composites and 1.8 times of pristine PVDF to BO<sub>5%</sub>PVDF<sub>95%</sub> composites respectively. These high dielectric composite electrodes are useful for flexible energy storage devices.展开更多
BaO-Sm2O3-TiO2 microwave dielectric ceramics doped with Bi and Zn was studied. The experiment was based on BST microwave dielectric ceramics doped with Bi2O3, which is shown by Ba4(Sm1-yBiy )28/3Ti18O54. When y =0.15,...BaO-Sm2O3-TiO2 microwave dielectric ceramics doped with Bi and Zn was studied. The experiment was based on BST microwave dielectric ceramics doped with Bi2O3, which is shown by Ba4(Sm1-yBiy )28/3Ti18O54. When y =0.15, ZnO was added and the effects of ZnO on this system were studied. The result shows that the dielectric characteristics of BST microwave dielectric ceramics are the most excellent when the content of ZnO is 3% , and the optimal sintering temperature is 1200℃.展开更多
2,3-Bis（hydroxymethyl）-2,3-dinitro-1,4-butanediol（C6H12N2O8） was synthesized by condensation,cyclization,oxidative dimerization and deketalization of nitromethane with a total yield of 42.4%.The structure of the t...2,3-Bis（hydroxymethyl）-2,3-dinitro-1,4-butanediol（C6H12N2O8） was synthesized by condensation,cyclization,oxidative dimerization and deketalization of nitromethane with a total yield of 42.4%.The structure of the title compound was characterized by 1H NMR,13C NMR,FT-IR,elementary analysis,and X-ray single-crystal diffraction analysis,which reveals that the title compound crystallizes in triclinic,space group P with a = 0.6324（2）,b = 0.6454（3）,c = 0.7062（3） nm,α= 111.550（4）,β= 95.505（4）,γ= 113.395（4）°,V = 0.23595（16） nm3,Z = 1,Mr = 240.18,Dc = 1.690 g·cm-3,μ = 0.159 mm-1,F（000） = 126,R = 0.0304 and wR = 0.0907.展开更多
Nine 3,3’-(arylmethylene)bis(2-hydroxynaphthalene-1,4-dione) derivatives were synthesized through the reaction between 2-hydroxy-1,4-naphthalen-1,4-dione and different aromatic alde-hydes in water applying ultrasonic...Nine 3,3’-(arylmethylene)bis(2-hydroxynaphthalene-1,4-dione) derivatives were synthesized through the reaction between 2-hydroxy-1,4-naphthalen-1,4-dione and different aromatic alde-hydes in water applying ultrasonic irradiation for 5 min at room temperature and microwave irradiation for 15 min at 70°;C. Two of the nine derivatives, compounds 3-e and 3-i, obtained from 3-bromo-hydroxybenzaldehyde and 5-methylfuran-2-carbaldehyde, respectively, are previously unpublished. The structures of all compounds were established on the basis of their spectral data and mass analysis. The attractive features of this synthesis protocol include mild conditions, high atom-economy and excellent yields with the elimination of water as the only by-product.展开更多
3,3＇-Bis（5-（N-（4-hydroxylphenyl）imidomethyl）pyrrol-2-yl）pentane 1 has been synthesized and characterized. The crystal of its methanol complex, 1·（CH3OH）2, belongs to the orthorhombic system, space group ...3,3＇-Bis（5-（N-（4-hydroxylphenyl）imidomethyl）pyrrol-2-yl）pentane 1 has been synthesized and characterized. The crystal of its methanol complex, 1·（CH3OH）2, belongs to the orthorhombic system, space group Pccn with a = 18.094（2）, b = 11.6890（16）, c = 13.3629（19） , V = 2826.3（7） 3, Z = 8, C14.5H18N2O2, Mr = 252.31, Dc = 1.186 g/cm3, F（000） = 1080 and μ（MoKα） = 0.080 mm-1. The final R = 0.0662 and wR = 0.1801 for 1908 observed reflections with I 2σ（I）, and R = 0.0800 and wR = 0.1948 for all reflections. In the solid state, bridged by included methanol molecules, the molecules of compound 1 form interpenetrated grid structure through N–H···O and O–H···O hydrogen bonds.展开更多
The title compound,2,6-bis（2-pyridinylmethyl）-3,5-bis（2-hydroxyl-5-chlorophe nyl）-pyrazine（C26H12Cl2N4O2C2H8O2,Mr=551.41）,has been synthesized and characterized by LC-ESIMS,NMR,UV and IR spectroscopy as well as ...The title compound,2,6-bis（2-pyridinylmethyl）-3,5-bis（2-hydroxyl-5-chlorophe nyl）-pyrazine（C26H12Cl2N4O2C2H8O2,Mr=551.41）,has been synthesized and characterized by LC-ESIMS,NMR,UV and IR spectroscopy as well as by X-ray single-crystal diffraction.The compound behaves as a substituted pyrazine.The hydrogen atoms on C（2） and C（3） are substituted by 2-pyridinyl,whereas those on C（1） and C（4） are substituted by 2-hydroxyl-5-chlorophenyl.It crystallizes in the monoclinic system,space group P21/c with a=8.9433（12）,b=32.003（4）,c=10.5209（18）,β=111.199（2）°,V=2807.5（7）3,Z=4,Dc=1.305 mg/m3,F（000）=1144 and μ=0.094 mm-1.A total of 13235 reflections were collected in the range of 2.17～25.01o by using a phi and omega scan mode,of which 4923 were unique（Rint=0.0692） and 2872 observed reflections with Ⅰ 〉2σ（Ⅰ） were used in the structure solution and refinement.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2022YFB3803900 and 2018YFA0702100)the Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences’Large-Scale Scientific Facility(Grant No.U1932106)the Sichuan University Innovation Research Program of China(Grant No.2020SCUNL112)。
文摘Tetradymite-structured chalcogenides,such as Bi_(2)Te_(3) and Sb_(2)Te_(3),are quasi-two-dimensional(2D)layered compounds,which are significant thermoelectric materials applied near room temperature.The intercalation of guest species in van der Waals(vdW)gap implemented for tunning properties has attracted much attention in recent years.We attempt to insert Ga atoms in the vdW gap between the Te layers in p-type Bi_(0.3)Sb_(1.7)Te_(3)(BST)for further improving thermoelectrics.The vdW-related defects(including extrinsic interstitial and intrinsic defects)induced by Ga intercalation can not only modulate the carrier concentration but also enhance the texture,thereby yielding excellent electrical properties,which are reflected in the power factor PF~4.43 mW·m^(-1)·K^(-2).Furthermore,the intercalation of Ga produces multi-scale lattice imperfections such as point defects,Te precipitations,and nanopores,realizing the low lattice thermal conductivity in BST-Ga samples.Ultimately,a peak zT~1.1 at 373 K is achieved in the BST-1%Ga sample and greatly improved by~22%compared to the pristine BST.The weak bonding of vdW interlayer interaction can boost the synergistic effect for advancing BST-based or other layered thermoelectrics.
基金supporting high quality of post growth treatment Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ)single crystalssupported by the National Key Research and Development Program of China(Grant No.2017YFA0304000)+4 种基金the National Natural Science Foundation of China(Grant Nos.61971408 and 61827823)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Shanghai Rising-Star Program(Grant No.20QA1410900)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant Nos.2020241 and 2021230)the Natural Science Foundation of Shanghai(Grant No.19ZR1467400)。
文摘The maximum velocity of a mobile vortex in movement is generally limited by the phenomenon of flux-flow instability(FFI),which necessitates weak vortex pinning and fast heat removal from non-equilibrium electrons.We here demonstrate exfoliations and nano-fabrications of Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ) crystalline nanostrips,which possess a rather weak pinning volume of vortices,relatively low resistivity,and large normal electron diffusion coefficient.The deduced vortex velocity in Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ) crystalline nanostrips can be up to 300 km/s near the superconducting transition temperature,well above the speed of sound.The observed vortex velocity is an order of magnitude faster than that of conventional superconducting systems,representing a perfect platform for exploration of ultra-fast vortex matter and a good candidate for fabrications of superconducting nanowire single photon detectors or superconducting THz modulator.
基金support from the Research Council of University of Sistan and Baluchestan, Iran
文摘2,2'-Arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) 4l-s produced from reaction between dimedone with various aldehydes in acetonitrile using ZnO as a catalyst;whereas in the presence of ZnO-acetyl chloride catalysts the reaction is limited to give only 1,8-dioxo-octahydroxanthenes 3a-k in very good yields.
文摘In this manuscript a comparative study on Bi<sub>2</sub>O<sub>3</sub>/polystyrene and Bi<sub>2</sub>O<sub>3</sub>/PVDF composites has been executed via analysis of structural, bonding, surface morphology and dielectric response of composites for energy storage. The composites have been synthesized using solution cast method by varying concentrations of Bi<sub>2</sub>O<sub>3</sub> (BO = 1 - 5 mw%) into polystyrene (PS) and polyvinylidene fluoride (PVDF) polymers respectively. X-ray diffraction confirms the generation of crystallinity, Fourier transform infrared (FT-IR) spectroscopy confirms bonding behavior and scanning electron microscopy (SEM) confirms uniform distribution of Bi<sub>2</sub>O<sub>3</sub> (BO) in PS and PVDF polymers. Impedance spectroscopy has been employed for determination of dielectric response of the fabricated composites. The dielectric constant has been found to be increased as 1.4 times of pristine PS to BO<sub>5%</sub>PS<sub>95%</sub> composites and 1.8 times of pristine PVDF to BO<sub>5%</sub>PVDF<sub>95%</sub> composites respectively. These high dielectric composite electrodes are useful for flexible energy storage devices.
文摘BaO-Sm2O3-TiO2 microwave dielectric ceramics doped with Bi and Zn was studied. The experiment was based on BST microwave dielectric ceramics doped with Bi2O3, which is shown by Ba4(Sm1-yBiy )28/3Ti18O54. When y =0.15, ZnO was added and the effects of ZnO on this system were studied. The result shows that the dielectric characteristics of BST microwave dielectric ceramics are the most excellent when the content of ZnO is 3% , and the optimal sintering temperature is 1200℃.
基金Supported by the National "973" project (No. 613740102)
文摘2,3-Bis（hydroxymethyl）-2,3-dinitro-1,4-butanediol（C6H12N2O8） was synthesized by condensation,cyclization,oxidative dimerization and deketalization of nitromethane with a total yield of 42.4%.The structure of the title compound was characterized by 1H NMR,13C NMR,FT-IR,elementary analysis,and X-ray single-crystal diffraction analysis,which reveals that the title compound crystallizes in triclinic,space group P with a = 0.6324（2）,b = 0.6454（3）,c = 0.7062（3） nm,α= 111.550（4）,β= 95.505（4）,γ= 113.395（4）°,V = 0.23595（16） nm3,Z = 1,Mr = 240.18,Dc = 1.690 g·cm-3,μ = 0.159 mm-1,F（000） = 126,R = 0.0304 and wR = 0.0907.
文摘Nine 3,3’-(arylmethylene)bis(2-hydroxynaphthalene-1,4-dione) derivatives were synthesized through the reaction between 2-hydroxy-1,4-naphthalen-1,4-dione and different aromatic alde-hydes in water applying ultrasonic irradiation for 5 min at room temperature and microwave irradiation for 15 min at 70°;C. Two of the nine derivatives, compounds 3-e and 3-i, obtained from 3-bromo-hydroxybenzaldehyde and 5-methylfuran-2-carbaldehyde, respectively, are previously unpublished. The structures of all compounds were established on the basis of their spectral data and mass analysis. The attractive features of this synthesis protocol include mild conditions, high atom-economy and excellent yields with the elimination of water as the only by-product.
基金supported by the National Natural Science Foundation of China (No. 20702038)
文摘3,3＇-Bis（5-（N-（4-hydroxylphenyl）imidomethyl）pyrrol-2-yl）pentane 1 has been synthesized and characterized. The crystal of its methanol complex, 1·（CH3OH）2, belongs to the orthorhombic system, space group Pccn with a = 18.094（2）, b = 11.6890（16）, c = 13.3629（19） , V = 2826.3（7） 3, Z = 8, C14.5H18N2O2, Mr = 252.31, Dc = 1.186 g/cm3, F（000） = 1080 and μ（MoKα） = 0.080 mm-1. The final R = 0.0662 and wR = 0.1801 for 1908 observed reflections with I 2σ（I）, and R = 0.0800 and wR = 0.1948 for all reflections. In the solid state, bridged by included methanol molecules, the molecules of compound 1 form interpenetrated grid structure through N–H···O and O–H···O hydrogen bonds.
基金supported by the research grant of Phytochemistry Key Laboratory of Shaanxi Province (No. 02js40)
文摘The title compound,2,6-bis（2-pyridinylmethyl）-3,5-bis（2-hydroxyl-5-chlorophe nyl）-pyrazine（C26H12Cl2N4O2C2H8O2,Mr=551.41）,has been synthesized and characterized by LC-ESIMS,NMR,UV and IR spectroscopy as well as by X-ray single-crystal diffraction.The compound behaves as a substituted pyrazine.The hydrogen atoms on C（2） and C（3） are substituted by 2-pyridinyl,whereas those on C（1） and C（4） are substituted by 2-hydroxyl-5-chlorophenyl.It crystallizes in the monoclinic system,space group P21/c with a=8.9433（12）,b=32.003（4）,c=10.5209（18）,β=111.199（2）°,V=2807.5（7）3,Z=4,Dc=1.305 mg/m3,F（000）=1144 and μ=0.094 mm-1.A total of 13235 reflections were collected in the range of 2.17～25.01o by using a phi and omega scan mode,of which 4923 were unique（Rint=0.0692） and 2872 observed reflections with Ⅰ 〉2σ（Ⅰ） were used in the structure solution and refinement.
