The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(S...The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(SiC_(nws))/SiC composites are fabricated with in-situ SiC interface on one-dimensional oriented SiC_(nws)skeleton,which collaborative configuration by 3D printing and freeze casting assembly.The con-structed porous structure optimizes the impedance matching degree and scattering intensity,the maximum effective absorption bandwidth(EAB_(max))of 5.9 GHz and the minimum reflection loss(RL_(min))of−41.4 dB can be realized.Considering the inherent oxidation resistance of SiC,the composites present well-maintained absorption performance at 600℃.Even at 1100℃,the EAB_(max)of 4.9 GHz and RLmin of−30.4 dB also demonstrate the high-temperature absorption stability of the composites,indicating exceptional wave absorption properties and thermal stability.The slight attenuation can be attributed to the decrease in impedance matching capability accompanying the elevated dielectric constant.This work clarifies the impact of structure and component synergy on wave absorption behavior,and offers a novel approach to producing high-performance and high-temperature resistance ceramic-based electromagnetic wave absorption materials suitable for extreme environments.展开更多
To further improve the performance of binders,a SiHfBCN-based high-temperature resistant adhesive was successfully synthesized by Polymer-Derived Ceramics(PDC)route using TiB2,Polysiloxane(PSO)and short SiC nanowires ...To further improve the performance of binders,a SiHfBCN-based high-temperature resistant adhesive was successfully synthesized by Polymer-Derived Ceramics(PDC)route using TiB2,Polysiloxane(PSO)and short SiC nanowires as fillers.The effect of short SiC nanowires on the adhesive strength at room temperature and high temperature,as well as the reinforcing mechanism was studied.Compared with the adhesive without SiC nanowires,after curing(at 170℃)and pyrolysis(at 1000℃)in air,the appropriate adding of SiC nanowires upgrades the room temperature and high temperature(at 1000℃ in air)adhesive strength to(12.50±0.67)MPa(up by about 32%)and(13.11±0.79)MPa(up by about 106%),respectively.Attractively,under the synergistic impact of the nanowire bridging,nanowire breaking,nanowire drawing and crack deflection,the optimized adhesive exhibits multi-stage fracture,causing the increscent fracture displacement.展开更多
The structures and electronic properties of ZnO nanowires（NWs） of different diameters are investigated by employing the first-principles density functional theory. The results indicate that the oxygen vacancy（VO） ...The structures and electronic properties of ZnO nanowires（NWs） of different diameters are investigated by employing the first-principles density functional theory. The results indicate that the oxygen vacancy（VO） exerts a more evident influence on the band gap of the ZnO NWs. However, the effect will be weakened with the increase of the diameter. In addition, the energy band shifts downward due to the existence of VOand the offset decreases with the reduction of the VOconcentration. As the concentration of surface Zn atoms decreases, the conduction band shifts downward, while 2p electrons are lost in the oxygen vacancy, resulting in the split of valence band and the formation of an impurity level. Our findings agree well with the previous observations and will be of great importance for theoretical research based on ZnO NWs.展开更多
Anti-phase domain defects easily form in the in-plane GaAs nanowires(NWs)grown on CMOS-compatiblegroup IV substrates,which makes it difficult to obtain GaAs NWs with a designed length and also leads to asignificant li...Anti-phase domain defects easily form in the in-plane GaAs nanowires(NWs)grown on CMOS-compatiblegroup IV substrates,which makes it difficult to obtain GaAs NWs with a designed length and also leads to asignificant limitation in the growth of high-quality in-plane GaAs NW networks on such substrates.Here,wereport on the selective area growth of anti-phase domain-free in-plane GaAs NWs and NW networks on Ge(111)substrates.Detailed structural studies confirm that the GaAs NW grown using a large pattern period and GaAsNW networks grown by adding the Sb are both high-quality pure zinc-blende single crystals free of stackingfaults,twin defects,and anti-phase domain defects.Room-temperature photoluminescence measurements show asubstantial improvement in crystal quality and good consistency and uniformity of the GaAs NW networks.Ourwork provides useful insights into the controlled growth of high-quality anti-phase domain-defects-free in-planeIII-V NWs and NW networks.展开更多
Silicon-air batteries(SABs),a new type of semiconductor air battery,have a high energy density.However,some side reactions in SABs cause Si anodes to be covered by a passivation layer to prevent continuous discharge,a...Silicon-air batteries(SABs),a new type of semiconductor air battery,have a high energy density.However,some side reactions in SABs cause Si anodes to be covered by a passivation layer to prevent continuous discharge,and the anode utilization rate is low.In this work,reduced graphene oxide(RGO)fabricated via high-temperature annealing or L-ascorbic acid(L.AA)reduction was first used to obtain Si nanowires/RGO-1000(Si NWs/RGO-1000)and Si nanowires/RGO-L.AA(Si NWs/RGO-L.AA)composite anodes for SABs.It was found that RGO suppressed the passivation and self-corrosion reactions and that SABs using Si NWs/RGO-L.AA as the anode can discharge for more than 700 h,breaking the previous performance of SABs,and that the specific capacity was increased by 90.8%compared to bare Si.This work provides a new solution for the design of high specific capacity SABs with nanostructures and anode protective layers.展开更多
Highly active and robust electrocatalysts for methanol oxidation reaction(MOR)are of great significance to the commercial availability of alkaline direct methanol fuel cells(ADMFC).Pd-based nanostructures have receive...Highly active and robust electrocatalysts for methanol oxidation reaction(MOR)are of great significance to the commercial availability of alkaline direct methanol fuel cells(ADMFC).Pd-based nanostructures have received considerable attention in ADMFCs among non-platinum catalysts due to their high activity and tolerance against CO poisoning,which is strongly determined by their composition and structure.Herein,a one-spot hydrothermal method to synthesize Cu-doped Pd_(7)Te_(3)ultrathin nanowires was proposed.The density functional theory calculations show that the Cu doping simultaneously facilitates the desorption of CO^(*)and adsorption of OH,which refreshes the active sites quickly and thus enhances the electroactivity for MOR.Benefiting from their ultrathin architecture and the modified bonding and anti-bonding d states of Pd,Cu-doped Pd_(7)Te_(3)nanowires show about twofold and threefold mass activity promotion and enhanced durability for MOR when compared to the pure Pd_(7)Te_(3)nanowires and commercial Pd/C catalysts.This work not only provides a simple one-step synthesis strategy for Pd-based nanowire catalysts,but also helps to inspire the catalyst design in ADMFC.展开更多
Organometallic halide perovskite materials have triggered global attention in recent years due to their exciting and optimistic high performance energy conversion properties(high luminescence efficiency and tremendous...Organometallic halide perovskite materials have triggered global attention in recent years due to their exciting and optimistic high performance energy conversion properties(high luminescence efficiency and tremendous optical absorption ability[1,2]).These interesting photovoltaic properties together make them a promising candidate for high performance optoelectronic展开更多
The Mahabad rhyolitic complex,mostly composed of rhyolite but also including granite and granodiorite,is exposed in NW Iran as a part of the Central Iran Block.Porphyritic,hyalo-porphyritic and spheroidal are the main...The Mahabad rhyolitic complex,mostly composed of rhyolite but also including granite and granodiorite,is exposed in NW Iran as a part of the Central Iran Block.Porphyritic,hyalo-porphyritic and spheroidal are the main textures of the studied samples of rhyolite.U-Pb zircon chronology on three samples of Mahabad rhyolitic complex yielded Cambrian to Ediacaran ages of 537.6±6.6 Ma,547.4±6.5 Ma and 556.2±7.1 Ma.Based on geochemical analyses,the original magma was high potassium calc-alkaline to shoshonitic.The rocks are enriched in LREEs relative to HREEs.Trace element patterns of Mahabad rhyolite normalized to chondrites show negative anomalies of high-fi eld-strength elements(Ti,Nb,Ta,Hf,Yb,Y and Zr)and high LREEs and large ion lithophile element contents(Rb,K,Th and Ba).^(208)Pb/^(204) Pb(36.7219–39.0367),^(207) Pb/^(204) Pb(15.4963–15.7669)and ^(206) Pb/^(204) Pb(16.9405–19.9567)ratios indicate an EM-II enriched mantle source for the rhyolite magma.Large variation ofεHf(t)from−5.2 to+4.5 points to a mantle source with crustal material contribution in the magma genesis.The rhyolitic magma erupted in an active continental margin.The formation of calc-alkaline high potassium magma was probably related to metasomatism of the mantle because of the north to south subduction of Proto-Tethys oceanic crust beneath the northern margin of Gondwana continental crust.展开更多
The lack of a comprehensive whole-rock geochemical and mineralogical dataset for the Archean granitoids of the Aravalli-Banded Gneissic Complex(BGC),northwest India,results in significant challenges for their correct ...The lack of a comprehensive whole-rock geochemical and mineralogical dataset for the Archean granitoids of the Aravalli-Banded Gneissic Complex(BGC),northwest India,results in significant challenges for their correct characterization and assessment of their antiquity.The new field,mineralogical and geochemical data classify the Jaisamand granitoids into sanukitoids,TTGs,and transitional TTGs,which are most likely coeval in nature.The obtained results,in conjuncture with the previously published geochemical and geochronological results of the Aravalli-BGC granitoids,unveil the Neoarchean affinity of the Jaisamand pluton.The TTGs were generated by the melting of a subducting slab(metabasite)at shallow(high-HREE-Y TTGs)to moderate depths(medium-HREE-Y TTGs)above the garnet-in line but still within the plagioclase stability field,with garnet-poor residue.The ascending TTG melts were transformed into sanukitoids through differential interaction with the overlying mantle wedge peridotite.The TTG melts,generated at different pressures,interacted with older TTGs at lower and middle crustal levels to form the transitional TTGs.The coexistence of high-HREE-Y and medium-HREE-Y TTGs and sanukitoids suggests a subduction-related setting for the Jaisamand granitoids.The heat required for simultaneous melting at shallow and deeper depths during the Neoarchean was provided by the upwelling asthenosphere due to slab break-off.The study also revealed the occurrence of altered granitoids in the Jaisamand pluton,showing evidence of albitization and silicification.These rocks do not represent the pristine mineralogy and should be carefully examined to avoid misleading interpretations,particularly for the Archean granitoids.展开更多
The Kashmir Basin,shaped by the collision of the Indian and Eurasian tectonic plates,features prominent faults,including the Balapur fault and other fault zones.This study focuses on the Gulmarg fault within the North...The Kashmir Basin,shaped by the collision of the Indian and Eurasian tectonic plates,features prominent faults,including the Balapur fault and other fault zones.This study focuses on the Gulmarg fault within the Northwestern Himalaya,using advanced geomagnetic techniques for delineation.Geomagnetic measurements reveal the characteristics of the newly identified Gulmarg fault.Ground magnetic surveys with Proton Precession Magnetometers along linear profiles and a magnetic grid highlight fault-related anomalies.The results indicate a fault running through the Gulmarg meadows,approximately 1.6 km from the Balapur fault,suggesting a potential coupling between the two.Three profiles across the fault exhibit distinctive magnetic variations,highlighting the intricate nature of the fault structure.Gridding methods also reveal anomalies associated with subsurface water and hydraulic activities,underscoring the importance of advanced geophysical techniques.This study emphasizes the significance of detailed investigations to unravel the complex geological processes shaping the Kashmir Basin.The study provides valuable insights into the tectonic activity in the Gulmarg region,underscoring the role of geophysical studies in enhancing our understanding of dynamic geological structures like the Gulmarg fault zone.展开更多
基金supported by the National Key R&D Program of China(No.2022YFB3707700)National Natural Science Foundation of China(No.52302121)+3 种基金Shanghai Sailing Program(No.23YF1454700)Shanghai Natural Science Foundation(No.23ZR1472700)Shanghai Post-doctoral Excellent Program(No.2022664)Shanghai Science and Technology Innovation Action Plan(No.21511104800).
文摘The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(SiC_(nws))/SiC composites are fabricated with in-situ SiC interface on one-dimensional oriented SiC_(nws)skeleton,which collaborative configuration by 3D printing and freeze casting assembly.The con-structed porous structure optimizes the impedance matching degree and scattering intensity,the maximum effective absorption bandwidth(EAB_(max))of 5.9 GHz and the minimum reflection loss(RL_(min))of−41.4 dB can be realized.Considering the inherent oxidation resistance of SiC,the composites present well-maintained absorption performance at 600℃.Even at 1100℃,the EAB_(max)of 4.9 GHz and RLmin of−30.4 dB also demonstrate the high-temperature absorption stability of the composites,indicating exceptional wave absorption properties and thermal stability.The slight attenuation can be attributed to the decrease in impedance matching capability accompanying the elevated dielectric constant.This work clarifies the impact of structure and component synergy on wave absorption behavior,and offers a novel approach to producing high-performance and high-temperature resistance ceramic-based electromagnetic wave absorption materials suitable for extreme environments.
基金co-supported by the National Natural Science Foundation of China (No. 52061135102)the Innovation Training Foundation for College Students of Northwestern Polytechnical University, China (No. 202310699180)the Creative Research Foundation of the Science and Technology on Thermostructural Composite Materials Laboratory
文摘To further improve the performance of binders,a SiHfBCN-based high-temperature resistant adhesive was successfully synthesized by Polymer-Derived Ceramics(PDC)route using TiB2,Polysiloxane(PSO)and short SiC nanowires as fillers.The effect of short SiC nanowires on the adhesive strength at room temperature and high temperature,as well as the reinforcing mechanism was studied.Compared with the adhesive without SiC nanowires,after curing(at 170℃)and pyrolysis(at 1000℃)in air,the appropriate adding of SiC nanowires upgrades the room temperature and high temperature(at 1000℃ in air)adhesive strength to(12.50±0.67)MPa(up by about 32%)and(13.11±0.79)MPa(up by about 106%),respectively.Attractively,under the synergistic impact of the nanowire bridging,nanowire breaking,nanowire drawing and crack deflection,the optimized adhesive exhibits multi-stage fracture,causing the increscent fracture displacement.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51132002 and 11574261)the Natural Science Foundation of Hebei ProvinceChina(Grant No.A2015203261)
文摘The structures and electronic properties of ZnO nanowires（NWs） of different diameters are investigated by employing the first-principles density functional theory. The results indicate that the oxygen vacancy（VO） exerts a more evident influence on the band gap of the ZnO NWs. However, the effect will be weakened with the increase of the diameter. In addition, the energy band shifts downward due to the existence of VOand the offset decreases with the reduction of the VOconcentration. As the concentration of surface Zn atoms decreases, the conduction band shifts downward, while 2p electrons are lost in the oxygen vacancy, resulting in the split of valence band and the formation of an impurity level. Our findings agree well with the previous observations and will be of great importance for theoretical research based on ZnO NWs.
基金supported by the National Natural Science Foundation of China(Grant Nos.12374459,61974138,and 92065106)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302400)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB0460000)the support from the Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant Nos.2017156 and Y2021043)。
文摘Anti-phase domain defects easily form in the in-plane GaAs nanowires(NWs)grown on CMOS-compatiblegroup IV substrates,which makes it difficult to obtain GaAs NWs with a designed length and also leads to asignificant limitation in the growth of high-quality in-plane GaAs NW networks on such substrates.Here,wereport on the selective area growth of anti-phase domain-free in-plane GaAs NWs and NW networks on Ge(111)substrates.Detailed structural studies confirm that the GaAs NW grown using a large pattern period and GaAsNW networks grown by adding the Sb are both high-quality pure zinc-blende single crystals free of stackingfaults,twin defects,and anti-phase domain defects.Room-temperature photoluminescence measurements show asubstantial improvement in crystal quality and good consistency and uniformity of the GaAs NW networks.Ourwork provides useful insights into the controlled growth of high-quality anti-phase domain-defects-free in-planeIII-V NWs and NW networks.
基金supported by the National Natural Science Foundation of China(No.61904073)Spring City Plan-Special Program for Young Talents(No.K202005007)+4 种基金Yunnan Talents Support Plan for Yong Talents(No.XDYC-QNRC-20220482)Yunnan Local Colleges Applied Basic Research Projects(No.202101BA070001-138)Scientific Research Fund of Yunnan Education Department(No.2023Y0883)Frontier Research Team of Kunming University 2023Key Laboratory of Artificial Microstructures in Yunnan Higher Education。
文摘Silicon-air batteries(SABs),a new type of semiconductor air battery,have a high energy density.However,some side reactions in SABs cause Si anodes to be covered by a passivation layer to prevent continuous discharge,and the anode utilization rate is low.In this work,reduced graphene oxide(RGO)fabricated via high-temperature annealing or L-ascorbic acid(L.AA)reduction was first used to obtain Si nanowires/RGO-1000(Si NWs/RGO-1000)and Si nanowires/RGO-L.AA(Si NWs/RGO-L.AA)composite anodes for SABs.It was found that RGO suppressed the passivation and self-corrosion reactions and that SABs using Si NWs/RGO-L.AA as the anode can discharge for more than 700 h,breaking the previous performance of SABs,and that the specific capacity was increased by 90.8%compared to bare Si.This work provides a new solution for the design of high specific capacity SABs with nanostructures and anode protective layers.
基金supported by the National Natural Science Foundation of China(Nos.22275178 and 22005285)the Fundamental Research Funds for the Central Universities(Nos.JUSRP123013 and JUSRP123015)+1 种基金performed on Hefei advanced computing centerSupercomputing USTC and National Supercomputing Center in Shenzhen are acknowledged for computational support.
文摘Highly active and robust electrocatalysts for methanol oxidation reaction(MOR)are of great significance to the commercial availability of alkaline direct methanol fuel cells(ADMFC).Pd-based nanostructures have received considerable attention in ADMFCs among non-platinum catalysts due to their high activity and tolerance against CO poisoning,which is strongly determined by their composition and structure.Herein,a one-spot hydrothermal method to synthesize Cu-doped Pd_(7)Te_(3)ultrathin nanowires was proposed.The density functional theory calculations show that the Cu doping simultaneously facilitates the desorption of CO^(*)and adsorption of OH,which refreshes the active sites quickly and thus enhances the electroactivity for MOR.Benefiting from their ultrathin architecture and the modified bonding and anti-bonding d states of Pd,Cu-doped Pd_(7)Te_(3)nanowires show about twofold and threefold mass activity promotion and enhanced durability for MOR when compared to the pure Pd_(7)Te_(3)nanowires and commercial Pd/C catalysts.This work not only provides a simple one-step synthesis strategy for Pd-based nanowire catalysts,but also helps to inspire the catalyst design in ADMFC.
文摘Organometallic halide perovskite materials have triggered global attention in recent years due to their exciting and optimistic high performance energy conversion properties(high luminescence efficiency and tremendous optical absorption ability[1,2]).These interesting photovoltaic properties together make them a promising candidate for high performance optoelectronic
文摘The Mahabad rhyolitic complex,mostly composed of rhyolite but also including granite and granodiorite,is exposed in NW Iran as a part of the Central Iran Block.Porphyritic,hyalo-porphyritic and spheroidal are the main textures of the studied samples of rhyolite.U-Pb zircon chronology on three samples of Mahabad rhyolitic complex yielded Cambrian to Ediacaran ages of 537.6±6.6 Ma,547.4±6.5 Ma and 556.2±7.1 Ma.Based on geochemical analyses,the original magma was high potassium calc-alkaline to shoshonitic.The rocks are enriched in LREEs relative to HREEs.Trace element patterns of Mahabad rhyolite normalized to chondrites show negative anomalies of high-fi eld-strength elements(Ti,Nb,Ta,Hf,Yb,Y and Zr)and high LREEs and large ion lithophile element contents(Rb,K,Th and Ba).^(208)Pb/^(204) Pb(36.7219–39.0367),^(207) Pb/^(204) Pb(15.4963–15.7669)and ^(206) Pb/^(204) Pb(16.9405–19.9567)ratios indicate an EM-II enriched mantle source for the rhyolite magma.Large variation ofεHf(t)from−5.2 to+4.5 points to a mantle source with crustal material contribution in the magma genesis.The rhyolitic magma erupted in an active continental margin.The formation of calc-alkaline high potassium magma was probably related to metasomatism of the mantle because of the north to south subduction of Proto-Tethys oceanic crust beneath the northern margin of Gondwana continental crust.
基金the Ministry of Earth Sciences,New Delhi(MoES/P.O/(Geo)/100(2)/2017).
文摘The lack of a comprehensive whole-rock geochemical and mineralogical dataset for the Archean granitoids of the Aravalli-Banded Gneissic Complex(BGC),northwest India,results in significant challenges for their correct characterization and assessment of their antiquity.The new field,mineralogical and geochemical data classify the Jaisamand granitoids into sanukitoids,TTGs,and transitional TTGs,which are most likely coeval in nature.The obtained results,in conjuncture with the previously published geochemical and geochronological results of the Aravalli-BGC granitoids,unveil the Neoarchean affinity of the Jaisamand pluton.The TTGs were generated by the melting of a subducting slab(metabasite)at shallow(high-HREE-Y TTGs)to moderate depths(medium-HREE-Y TTGs)above the garnet-in line but still within the plagioclase stability field,with garnet-poor residue.The ascending TTG melts were transformed into sanukitoids through differential interaction with the overlying mantle wedge peridotite.The TTG melts,generated at different pressures,interacted with older TTGs at lower and middle crustal levels to form the transitional TTGs.The coexistence of high-HREE-Y and medium-HREE-Y TTGs and sanukitoids suggests a subduction-related setting for the Jaisamand granitoids.The heat required for simultaneous melting at shallow and deeper depths during the Neoarchean was provided by the upwelling asthenosphere due to slab break-off.The study also revealed the occurrence of altered granitoids in the Jaisamand pluton,showing evidence of albitization and silicification.These rocks do not represent the pristine mineralogy and should be carefully examined to avoid misleading interpretations,particularly for the Archean granitoids.
文摘The Kashmir Basin,shaped by the collision of the Indian and Eurasian tectonic plates,features prominent faults,including the Balapur fault and other fault zones.This study focuses on the Gulmarg fault within the Northwestern Himalaya,using advanced geomagnetic techniques for delineation.Geomagnetic measurements reveal the characteristics of the newly identified Gulmarg fault.Ground magnetic surveys with Proton Precession Magnetometers along linear profiles and a magnetic grid highlight fault-related anomalies.The results indicate a fault running through the Gulmarg meadows,approximately 1.6 km from the Balapur fault,suggesting a potential coupling between the two.Three profiles across the fault exhibit distinctive magnetic variations,highlighting the intricate nature of the fault structure.Gridding methods also reveal anomalies associated with subsurface water and hydraulic activities,underscoring the importance of advanced geophysical techniques.This study emphasizes the significance of detailed investigations to unravel the complex geological processes shaping the Kashmir Basin.The study provides valuable insights into the tectonic activity in the Gulmarg region,underscoring the role of geophysical studies in enhancing our understanding of dynamic geological structures like the Gulmarg fault zone.
