Recently,the two-dimensional(2D)form of Ruddlesden-Popper perovskite(RPP)has been widely studied.However,the synthesis of one-dimensional(1D)RPP is rarely reported.Here,we fabricated a photodetector based on RPP micro...Recently,the two-dimensional(2D)form of Ruddlesden-Popper perovskite(RPP)has been widely studied.However,the synthesis of one-dimensional(1D)RPP is rarely reported.Here,we fabricated a photodetector based on RPP microwires(RPP-MWs)and compared it with a 2D-RPP photodetector.The results show that the RPP-MWs photodetector possesses a wider photoresponse range and higher responsivities of 233 A/W in the visible band and 30 A/W in the near-infrared(NIR)band.The analyses show that the synthesized RPP-MWs have a multi-layer,heterogeneous core-shell structure.This structure gives RPP-MWs a unique band structure,as well as abundant trap states and defect levels,which enable them to acquire better photoresponse performance.This configuration of RPP-MWs provides a new idea for the design and application of novel heterostructures.展开更多
Ultrawide band gap semiconductors are promising solar-blind ultraviolet(UV)photodetector materials due to their suitable bandgap,strong absorption and high sensitivity.Here,β-Ga_(2)O_(3)microwires with high crystal q...Ultrawide band gap semiconductors are promising solar-blind ultraviolet(UV)photodetector materials due to their suitable bandgap,strong absorption and high sensitivity.Here,β-Ga_(2)O_(3)microwires with high crystal quality and large size were grown by the chemical vapor deposition(CVD)method.The microwires reach up to 1 cm in length and were single crystalline with low defect density.Owing to its high crystal quality,a metal–semiconductor–metal photodetector fabricated from a Ga_(2)O_(3)microwire showed a responsivity of 1.2 A/W at 240 nm with an ultrahigh UV/visible rejection ratio(R_(peak)/R_(400 nm))of 5.8×10^(5),indicating that the device has excellent spectral selectivity.In addition,no obvious persistent photoconductivity was observed in the test.The rise and decay time constants of the device were 0.13 and 0.14 s,respectively.This work not only provides a growth method for high-quality Ga_(2)O_(3)microwires,but also demonstrates the excellent performance of Ga_(2)O_(3)microwires in solar-blind ultraviolet detection.展开更多
Results on the magneto-optical investigation of near-surface micromagnetic structure (MMS) of Co69Fe4Si12B15 amorphous wires 10-50 μm in diameter are presented. The wires were prepared by the rapid solidification t...Results on the magneto-optical investigation of near-surface micromagnetic structure (MMS) of Co69Fe4Si12B15 amorphous wires 10-50 μm in diameter are presented. The wires were prepared by the rapid solidification technique. The magnetic field H was applied along or perpendicular to the wire length. By scanning the light spot of 1 μm-diameter along the wire length, distributions of magnetization components (both parallel and perpendicular to the applied magnetic field) and also local hysteresis characteristics of the wires were measured. It was experimentally established that owing to the compressive stresses from quenching coupled with negative netostriction of Co-rich amorphous materials, the examined microwires have a circumferential magnetic anisotropy. In consequence, there are the near-sudece alternate left-and right-handled circular domains in these samples. The dependencies of the circular domain width on the wire diameter and length were found. It was discovered that in the axial magnetic field local hysteresis loops are unhysteretic. It was proved that in this case the dominant mechanism of the wire magnetization reversal is rotation of local magnetization vectors in circular domains.展开更多
Ni50Mn25Ga20Fe5 ferromagnetic shape memory alloy microwires with diameters of^30-50μm and grain sizes of^2-5μm were prepared by melt-extraction technique.A step-wise chemical ordering annealing was carried out to im...Ni50Mn25Ga20Fe5 ferromagnetic shape memory alloy microwires with diameters of^30-50μm and grain sizes of^2-5μm were prepared by melt-extraction technique.A step-wise chemical ordering annealing was carried out to improve the superelasticity strain and recovery ratio which were hampered by the internal stress,compositional inhomogeneity,and high-density defects in the as-extracted Ni50Mn25Ga20Fe5 microwires.The annealed microwires exhibited enhanced atomic ordering degree,narrow thermal hysteresis,and high saturation magnetization under a low magnetic field.As a result,the annealed microwire showed decreased superelastic critical stress,improved reversibility,and a high superelastic strain(1.9%)with a large recovery ratio(>96%).This kind of filamentous material with superior superelastic effects may be promising materials for minor-devices.展开更多
Chiral two-dimensional(2D) perovskites offer numerous attractive features for optoelectronics owing to their soft, deformable lattices and a high degree of chemical tunability. While tremendous advances have been made...Chiral two-dimensional(2D) perovskites offer numerous attractive features for optoelectronics owing to their soft, deformable lattices and a high degree of chemical tunability. While tremendous advances have been made in perovskite-based direct circularly polarized light(CPL) detection, the low circular polarization anisotropy factor and sensitivity of those photodetectors arising from large lattice distortion still limit practical applications. Herein, chiral 2D perovskite-based single-crystalline microwire arrays with enhanced circular dichroism(CD) absorption are fabricated with the synergy of the capillary-bridgeconfined assembly method and chlorine-substituted phenethylamine(Cl-MBA). Compared with phenethylamine(MBA)-inserted perovskites, the smaller lattice distortion and increased halogen–halogen interaction within Cl–MBA-inserted perovskites strengthen lattice rigidity and weaken electron–phonon coupling to improve carrier transport and thermal stability, resulting in high-performance CPL photodetectors with an anisotropy factor of 0.25, responsivity exceeding 95.7±9.3 A W^(-1)and detectivity exceeding(3.05±0.30)×10^(13)Jones. This work opens a new perspective to modulate circular polarization sensitivity and will be helpful to realize promising implementations in quantum computation and communication.展开更多
Ga_(2)O_(3)has been regarded as a promising material for solar-blind detection due to its ultrawide bandgap and low growth cost.Although semiconductor microwires(MWs)possess unique optical and electronic characteristi...Ga_(2)O_(3)has been regarded as a promising material for solar-blind detection due to its ultrawide bandgap and low growth cost.Although semiconductor microwires(MWs)possess unique optical and electronic characteristics,the performances of photodetectors developed from Ga_(2)O_(3)MWs are still less than satisfactory.Herein,we demonstrate high-performance solar-blind photodetectors based on Sn-doped Ga_(2)O_(3)MWs,possessing a light/dark current ratio of 107 and a responsivity of 2,409 A/W at 40 V.Moreover,a 1×10 solar-blind photodetector linear array is developed based on the Sn-doped Ga_(2)O_(3)MWs via a patternedelectrodes method.And clear solar-blind images are obtained by using the photodetector array as the imaging unit of a solarblind imaging system.The results provide a convenient way to construct high-performance solar-blind photodetector arrays based on Ga_(2)O_(3)MWs,and thus may push forward their future applications.展开更多
Highly efficient second-harmonic generation(SHG)has facilitated the development of nanophotonics and sustained promising applications,ranging from electro-optical modulation,frequency conversion,and optical frequency ...Highly efficient second-harmonic generation(SHG)has facilitated the development of nanophotonics and sustained promising applications,ranging from electro-optical modulation,frequency conversion,and optical frequency combs to pulse characterization.Although controllable SHG switching has been observed in nanophotonics structures and molecule systems,the relatively small SHG switching contrast impedes its application in switchable nonlinear optics.Herein,reversible phase transitions between glassy and crystalline states without material degradation are demonstrated based on solution-processed chiral perovskite microwire arrays.Breaking of lattice inversion symmetry and high crystallinity support efficient SHG in microwire arrays.By synergy of high-performance SHG and reversible phase transitions between glassy and crystalline states,reversible switching of SHG is demonstrated under facile conditions.The high SHG switching performances,together with a small footprint,pave the way toward the integration of switchable nonlinear devices based on microwire arrays.展开更多
Hall-Petch relation was widely applied to evaluate the grain size effect on mechanical properties of metallic material. However, the sample size effect on the Hall-Petch relation was always ignored. In the present stu...Hall-Petch relation was widely applied to evaluate the grain size effect on mechanical properties of metallic material. However, the sample size effect on the Hall-Petch relation was always ignored. In the present study, the mechanical test and microstructure observation were performed to investigate the combined effects of grain and sample sizes on the deformation behaviors of gold microwires. The polycrystalline gold microwires with diameter of 16 ?m were annealed at temperatures from 100°C to 600°C, leading to different ratios(t/d) of wire diameter(t) to grain size(d) from 0.9 to 16.7. When the t/d was lower than 10, the yield stress dropped fast and deviated from the Hall-Petch relation. The free-surface grains played key role in the yield stress softening, and the volume fraction of free-surface grains increased with the t/d decreasing. Furthermore, the effects of t/d on work-hardening behaviors and fracture modes were also studied. With t/d value decreasing from 17 to 3.4, the samples exhibited necking fracture and the dislocation pile-ups induced work-hardening stage was gradually activated.With the t/d value further decreasing(t/d < 3.4), the fracture mode turned into shear failure, and the work-hardening capability lost. As the gold microwire for wire bonding is commonly applied in the packaging of integrated circuit chips, and the fabrication of microwire suffers multi-pass cold-drawing and annealing treatments to control the grain size. The present study could provide instructive suggestion for gold microwire fabrication and bonding processes.展开更多
Pure ZnO hexagonal microwires and Fe(Ⅲ)-doped ZnO microwires(MWs)with a novel rectangular cross section were synthesized in a confined chamber by a convenient one-step thermal evaporation method.An oriented attachmen...Pure ZnO hexagonal microwires and Fe(Ⅲ)-doped ZnO microwires(MWs)with a novel rectangular cross section were synthesized in a confined chamber by a convenient one-step thermal evaporation method.An oriented attachment mechanism is consistent with a vapor-solid growth process.Photoluminescence(PL)and Raman spectroscopy of the Fe(Ⅲ)-doped ZnO MWs and in situ spectral mappings indicate a quasi-periodic distribution of Fe(Ⅲ)along a one-dimensional(1-D)superlattice ZnO:ZnFe_(2)O_(4) wire,while PL mapping shows the presence of optical multicavities and related multimodes.The PL spectra at room temperature show weak near-edge doublets(376 nm and 383 nm)and a broad band(450-650 nm)composed of strong discrete lines,due to a 1-D photonic crystal structure.Such a 1-D coupled optical cavity material may find many applications in future photonic and spintronic devices.展开更多
Low-dimensional halide perovskites(HPs)have received considerable attention in recent years due to their novel physical properties such as compositional flexibility,high quantum yield,quantum size effects and superior...Low-dimensional halide perovskites(HPs)have received considerable attention in recent years due to their novel physical properties such as compositional flexibility,high quantum yield,quantum size effects and superior charge transport.Here we show room temperature solution synthesis of 1D organic-inorganic lead bromide perovskite microwires(MWs).Our method uses acetone as a reactant,and when CH3NH3PbBr3 is immersed,acetone reacts with CH3NH3+cations in the CH3NH3PbBr3 single crystal by the dehydration condensation.The reaction generates a large(CH3)2C=NHCH3+A-site which cannot be accommodated by the cuboctahedron formed by the corner-sharing[PbBr6]4−octahedral,leading to the transition of corner-sharing octahedra to face-sharing triangular prism and the crystal structure transformation from 3D to 1D.The formation process of(CH3)2C=NHCH3PbBr3 MWs does not involve any ligands,templates or catalysts.A two-terminal memory device was constructed using the(CH3)2C=NHCH3PbBr3 MWs,showing great potential of the method in fabrication of electronic and optoelectronic devices.展开更多
This paper presents a systematic investigation of the microstructure and magnetocaloric properties of melt-extracted Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)high-entropy microwires.The fabricated wires exhibited an amorpho...This paper presents a systematic investigation of the microstructure and magnetocaloric properties of melt-extracted Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)high-entropy microwires.The fabricated wires exhibited an amorphous structure,and the temperature interval of the undercooled liquid AT was 45 K.The microwires underwent a second-order magnetic transition from a ferromagnetic to a paramagnetic state near the Curie temperature(T_(C)=52 K),The maximum magnetic entropy change(-ΔS_M^(max)),the relative cooling power and the refrigeration capacity reached 6.34 J·kg^(-1)·K^(-1).422.09 J·kg^(-1)and 332.94 J·kg^(-1),respectively,under a magnetic field change of 5 T.In addition,the temperature-averaged entropy changes with two temperature lifts(3 and 10 K)were 6.32 and 6.27 J·kg^(-1)·K^(-1),respectively.The good magnetocalorie performance highlights the significant potential for the Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)microwires to be used as magnetic refrigerant materials in low-temperature region applications.This work will serve as a valuable reference for future investigations on low-temperature high-entropy magnetocaloric materials.展开更多
An electromagnetic shielding metacomposite based on the absorbing mechanism was prepared by weaving ferromagnetic microwires into the three-dimensional(3D)fabric.The influence of the ferromagnetic microwire spacing on...An electromagnetic shielding metacomposite based on the absorbing mechanism was prepared by weaving ferromagnetic microwires into the three-dimensional(3D)fabric.The influence of the ferromagnetic microwire spacing on electromagnetic shielding performance and the electromagnetic shielding mechanism of 3D metacomposites were studied.The total electromagnetic shielding performance increases with the increase of electromagnetic wave frequency.3D metacomposites based on the absorbing mechanism can avoid the secondary pollution of electromagnetic waves,and have great potential in military,civil,aerospace and other fields.展开更多
In this paper,ultra-long and large-scaled ZnO microwire arrays are grown by the chemical vapor deposition method,and a single ZnO microwire-based non-balanced electric bridge ethanol gas sensor is fabricated.The exper...In this paper,ultra-long and large-scaled ZnO microwire arrays are grown by the chemical vapor deposition method,and a single ZnO microwire-based non-balanced electric bridge ethanol gas sensor is fabricated.The experimental results show that the gas sensor has good repeatability,high response rate,short response,and recovery time at room temperature(25℃).The response rate of the gas sensor exposed to 90-ppm ethanol is about 93%,with a response time and recovery time are 0.3 s and 0.7 s respectively.As a contrast,the traditional resistive gas sensor of a single ZnO microwire shows very small gas response rate.Therefore,ethanol gas sensor based on non-balanced electric bridge can obviously enhance gas sensing characteristics,which provides a feasible method of developing the high performance ZnO-based gas sensor.展开更多
Microspheres coated with a perfectly conductive surface have many advantages in the applications of biosensors and micro-electromechanical systems.Polystyrene microspheres with the diameter of 10 μm were coated with ...Microspheres coated with a perfectly conductive surface have many advantages in the applications of biosensors and micro-electromechanical systems.Polystyrene microspheres with the diameter of 10 μm were coated with a 50 nmthick gold layer using an electroless gold plating approach.Dielectrophoresis(DEP) for bare microspheres and shelled microspheres was theoretically analysed and the real part of the Clausius-Mossotti factor was calculated for the two kinds of microspheres.The experiments on the dielectrophoretic characterisation of the uncoated polystyrene microspheres and gold coated polystyrene microspheres(GCPMs) were carried out.Experimental results showed that the gold coated polystyrene microspheres were only acted by a positive dielectrophoretic force when the frequency was below 40M Hz,while the uncoated polystyrene microspheres were governed by a negative dielectrophoretic force in this frequency range.The gold coated polystyrene microspheres were exploited to form the microwire automatically according to their stable dielectrophoretic and electric characterisations.展开更多
基金This work was supported by the National Science Foundation of China(NSFC),(Grant No.62022079)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2020115).
文摘Recently,the two-dimensional(2D)form of Ruddlesden-Popper perovskite(RPP)has been widely studied.However,the synthesis of one-dimensional(1D)RPP is rarely reported.Here,we fabricated a photodetector based on RPP microwires(RPP-MWs)and compared it with a 2D-RPP photodetector.The results show that the RPP-MWs photodetector possesses a wider photoresponse range and higher responsivities of 233 A/W in the visible band and 30 A/W in the near-infrared(NIR)band.The analyses show that the synthesized RPP-MWs have a multi-layer,heterogeneous core-shell structure.This structure gives RPP-MWs a unique band structure,as well as abundant trap states and defect levels,which enable them to acquire better photoresponse performance.This configuration of RPP-MWs provides a new idea for the design and application of novel heterostructures.
基金supported by the National Key R&D Program of China(Grant No.2019YFA0705202)the National Natural Science Foundation of China(Grant Nos.62274027 and 31701296)。
文摘Ultrawide band gap semiconductors are promising solar-blind ultraviolet(UV)photodetector materials due to their suitable bandgap,strong absorption and high sensitivity.Here,β-Ga_(2)O_(3)microwires with high crystal quality and large size were grown by the chemical vapor deposition(CVD)method.The microwires reach up to 1 cm in length and were single crystalline with low defect density.Owing to its high crystal quality,a metal–semiconductor–metal photodetector fabricated from a Ga_(2)O_(3)microwire showed a responsivity of 1.2 A/W at 240 nm with an ultrahigh UV/visible rejection ratio(R_(peak)/R_(400 nm))of 5.8×10^(5),indicating that the device has excellent spectral selectivity.In addition,no obvious persistent photoconductivity was observed in the test.The rise and decay time constants of the device were 0.13 and 0.14 s,respectively.This work not only provides a growth method for high-quality Ga_(2)O_(3)microwires,but also demonstrates the excellent performance of Ga_(2)O_(3)microwires in solar-blind ultraviolet detection.
基金scientific Korea-Russia Manpower exchange programScience & Technology Policy instituteRussian Fund of Fundamental invest
文摘Results on the magneto-optical investigation of near-surface micromagnetic structure (MMS) of Co69Fe4Si12B15 amorphous wires 10-50 μm in diameter are presented. The wires were prepared by the rapid solidification technique. The magnetic field H was applied along or perpendicular to the wire length. By scanning the light spot of 1 μm-diameter along the wire length, distributions of magnetization components (both parallel and perpendicular to the applied magnetic field) and also local hysteresis characteristics of the wires were measured. It was experimentally established that owing to the compressive stresses from quenching coupled with negative netostriction of Co-rich amorphous materials, the examined microwires have a circumferential magnetic anisotropy. In consequence, there are the near-sudece alternate left-and right-handled circular domains in these samples. The dependencies of the circular domain width on the wire diameter and length were found. It was discovered that in the axial magnetic field local hysteresis loops are unhysteretic. It was proved that in this case the dominant mechanism of the wire magnetization reversal is rotation of local magnetization vectors in circular domains.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 51701099,51801044,and 51671071)the Natural Science Foundation of Heilongjiang Province of China (Grant No. LH2019E091)+1 种基金Fundamental Research Funds in Heilongjiang Provincial Universities,China (Grant No. 135409320)the help of Technology Innovation Center of Agricultural Multi-Dimensional Sensor Information Perception,Heilongjiang Province.
文摘Ni50Mn25Ga20Fe5 ferromagnetic shape memory alloy microwires with diameters of^30-50μm and grain sizes of^2-5μm were prepared by melt-extraction technique.A step-wise chemical ordering annealing was carried out to improve the superelasticity strain and recovery ratio which were hampered by the internal stress,compositional inhomogeneity,and high-density defects in the as-extracted Ni50Mn25Ga20Fe5 microwires.The annealed microwires exhibited enhanced atomic ordering degree,narrow thermal hysteresis,and high saturation magnetization under a low magnetic field.As a result,the annealed microwire showed decreased superelastic critical stress,improved reversibility,and a high superelastic strain(1.9%)with a large recovery ratio(>96%).This kind of filamentous material with superior superelastic effects may be promising materials for minor-devices.
基金supported by the National Natural Science Foundation of China (21988102, 52173190, and 52303257)the Ministry of Science and Technology of China (2018YFA0704803 and 2018YFA0208502)+2 种基金Youth Innovation Promotion Association CAS (2018034)Shanxi Province Science Foundation for Youths (202203021222297)project funded by China Postdoctoral Science Foundation (2023TQ0300 and 2022M721331)。
文摘Chiral two-dimensional(2D) perovskites offer numerous attractive features for optoelectronics owing to their soft, deformable lattices and a high degree of chemical tunability. While tremendous advances have been made in perovskite-based direct circularly polarized light(CPL) detection, the low circular polarization anisotropy factor and sensitivity of those photodetectors arising from large lattice distortion still limit practical applications. Herein, chiral 2D perovskite-based single-crystalline microwire arrays with enhanced circular dichroism(CD) absorption are fabricated with the synergy of the capillary-bridgeconfined assembly method and chlorine-substituted phenethylamine(Cl-MBA). Compared with phenethylamine(MBA)-inserted perovskites, the smaller lattice distortion and increased halogen–halogen interaction within Cl–MBA-inserted perovskites strengthen lattice rigidity and weaken electron–phonon coupling to improve carrier transport and thermal stability, resulting in high-performance CPL photodetectors with an anisotropy factor of 0.25, responsivity exceeding 95.7±9.3 A W^(-1)and detectivity exceeding(3.05±0.30)×10^(13)Jones. This work opens a new perspective to modulate circular polarization sensitivity and will be helpful to realize promising implementations in quantum computation and communication.
基金the National Natural Science Foundation of China(Nos.61804136,U1804155,and 62027816).
文摘Ga_(2)O_(3)has been regarded as a promising material for solar-blind detection due to its ultrawide bandgap and low growth cost.Although semiconductor microwires(MWs)possess unique optical and electronic characteristics,the performances of photodetectors developed from Ga_(2)O_(3)MWs are still less than satisfactory.Herein,we demonstrate high-performance solar-blind photodetectors based on Sn-doped Ga_(2)O_(3)MWs,possessing a light/dark current ratio of 107 and a responsivity of 2,409 A/W at 40 V.Moreover,a 1×10 solar-blind photodetector linear array is developed based on the Sn-doped Ga_(2)O_(3)MWs via a patternedelectrodes method.And clear solar-blind images are obtained by using the photodetector array as the imaging unit of a solarblind imaging system.The results provide a convenient way to construct high-performance solar-blind photodetector arrays based on Ga_(2)O_(3)MWs,and thus may push forward their future applications.
基金National Science and Technology Major Project,Grant/Award Numbers:2017YFA0204504,2018YFA0208502,2018YFA0704803JiHua Laboratory Science Program,Grant/Award Number:X190251UZ190+1 种基金Youth Innovation Promotion Association of the Chinese Academy of Sciences,Grant/Award Number:2018034National Natural Science Foundation of China,Grant/Award Numbers:52173190,21633014,21703268,51922012。
文摘Highly efficient second-harmonic generation(SHG)has facilitated the development of nanophotonics and sustained promising applications,ranging from electro-optical modulation,frequency conversion,and optical frequency combs to pulse characterization.Although controllable SHG switching has been observed in nanophotonics structures and molecule systems,the relatively small SHG switching contrast impedes its application in switchable nonlinear optics.Herein,reversible phase transitions between glassy and crystalline states without material degradation are demonstrated based on solution-processed chiral perovskite microwire arrays.Breaking of lattice inversion symmetry and high crystallinity support efficient SHG in microwire arrays.By synergy of high-performance SHG and reversible phase transitions between glassy and crystalline states,reversible switching of SHG is demonstrated under facile conditions.The high SHG switching performances,together with a small footprint,pave the way toward the integration of switchable nonlinear devices based on microwire arrays.
基金financially supported by the National Key R&D Program of China(Project No.2017YFA0204403)the Shenzhen Virtual University Park(R-IND1710)+5 种基金the Innovation and Technology Commission via the Hong Kong Branch of National Precious Metals Material Engineering Research Centersupported by the Research Grants Council of the Hong Kong Special Administrative Region,China(No.CityU 11209914)General Research Fund of Hong Kong(No.CityU 11247516)the National Natural Science Foundation of China(No.51301147)supported by Province-Institute/Province-College Cooperation Project underGrant No.2017IB016The financial support from SZSTI(Ref:JSGG20141020103826038)
文摘Hall-Petch relation was widely applied to evaluate the grain size effect on mechanical properties of metallic material. However, the sample size effect on the Hall-Petch relation was always ignored. In the present study, the mechanical test and microstructure observation were performed to investigate the combined effects of grain and sample sizes on the deformation behaviors of gold microwires. The polycrystalline gold microwires with diameter of 16 ?m were annealed at temperatures from 100°C to 600°C, leading to different ratios(t/d) of wire diameter(t) to grain size(d) from 0.9 to 16.7. When the t/d was lower than 10, the yield stress dropped fast and deviated from the Hall-Petch relation. The free-surface grains played key role in the yield stress softening, and the volume fraction of free-surface grains increased with the t/d decreasing. Furthermore, the effects of t/d on work-hardening behaviors and fracture modes were also studied. With t/d value decreasing from 17 to 3.4, the samples exhibited necking fracture and the dislocation pile-ups induced work-hardening stage was gradually activated.With the t/d value further decreasing(t/d < 3.4), the fracture mode turned into shear failure, and the work-hardening capability lost. As the gold microwire for wire bonding is commonly applied in the packaging of integrated circuit chips, and the fabrication of microwire suffers multi-pass cold-drawing and annealing treatments to control the grain size. The present study could provide instructive suggestion for gold microwire fabrication and bonding processes.
基金The authors thank the National Natural Science Foundation of China(NSFC)of China(Nos.90606001,20873039,and 90406024)for financial support.
文摘Pure ZnO hexagonal microwires and Fe(Ⅲ)-doped ZnO microwires(MWs)with a novel rectangular cross section were synthesized in a confined chamber by a convenient one-step thermal evaporation method.An oriented attachment mechanism is consistent with a vapor-solid growth process.Photoluminescence(PL)and Raman spectroscopy of the Fe(Ⅲ)-doped ZnO MWs and in situ spectral mappings indicate a quasi-periodic distribution of Fe(Ⅲ)along a one-dimensional(1-D)superlattice ZnO:ZnFe_(2)O_(4) wire,while PL mapping shows the presence of optical multicavities and related multimodes.The PL spectra at room temperature show weak near-edge doublets(376 nm and 383 nm)and a broad band(450-650 nm)composed of strong discrete lines,due to a 1-D photonic crystal structure.Such a 1-D coupled optical cavity material may find many applications in future photonic and spintronic devices.
基金This work was supported by the National Key Research and Development Program of China (Grant No. 2018YFB0406704)the National Natural Science Foundation of China (Grant No. 61964011)+1 种基金the Natural Science Foundation of Jiangxi Province (Grant Nos. 20165BCB18004 and 20171BCB23005)the Nanchang University Graduate Innovation Special Funding (Grant No. CX2019054).
文摘Low-dimensional halide perovskites(HPs)have received considerable attention in recent years due to their novel physical properties such as compositional flexibility,high quantum yield,quantum size effects and superior charge transport.Here we show room temperature solution synthesis of 1D organic-inorganic lead bromide perovskite microwires(MWs).Our method uses acetone as a reactant,and when CH3NH3PbBr3 is immersed,acetone reacts with CH3NH3+cations in the CH3NH3PbBr3 single crystal by the dehydration condensation.The reaction generates a large(CH3)2C=NHCH3+A-site which cannot be accommodated by the cuboctahedron formed by the corner-sharing[PbBr6]4−octahedral,leading to the transition of corner-sharing octahedra to face-sharing triangular prism and the crystal structure transformation from 3D to 1D.The formation process of(CH3)2C=NHCH3PbBr3 MWs does not involve any ligands,templates or catalysts.A two-terminal memory device was constructed using the(CH3)2C=NHCH3PbBr3 MWs,showing great potential of the method in fabrication of electronic and optoelectronic devices.
基金financially supported by the National Natural Science Foundation of China(No.51827801)the support by the Overseas Visiting Study Program of Harbin Institute of Technology。
文摘This paper presents a systematic investigation of the microstructure and magnetocaloric properties of melt-extracted Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)high-entropy microwires.The fabricated wires exhibited an amorphous structure,and the temperature interval of the undercooled liquid AT was 45 K.The microwires underwent a second-order magnetic transition from a ferromagnetic to a paramagnetic state near the Curie temperature(T_(C)=52 K),The maximum magnetic entropy change(-ΔS_M^(max)),the relative cooling power and the refrigeration capacity reached 6.34 J·kg^(-1)·K^(-1).422.09 J·kg^(-1)and 332.94 J·kg^(-1),respectively,under a magnetic field change of 5 T.In addition,the temperature-averaged entropy changes with two temperature lifts(3 and 10 K)were 6.32 and 6.27 J·kg^(-1)·K^(-1),respectively.The good magnetocalorie performance highlights the significant potential for the Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)microwires to be used as magnetic refrigerant materials in low-temperature region applications.This work will serve as a valuable reference for future investigations on low-temperature high-entropy magnetocaloric materials.
基金Open Project Program of Key Laboratory of Yarn Materials Forming and Composite Processing Technology of Zhejiang Province,China(No.MTC2021-02)。
文摘An electromagnetic shielding metacomposite based on the absorbing mechanism was prepared by weaving ferromagnetic microwires into the three-dimensional(3D)fabric.The influence of the ferromagnetic microwire spacing on electromagnetic shielding performance and the electromagnetic shielding mechanism of 3D metacomposites were studied.The total electromagnetic shielding performance increases with the increase of electromagnetic wave frequency.3D metacomposites based on the absorbing mechanism can avoid the secondary pollution of electromagnetic waves,and have great potential in military,civil,aerospace and other fields.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61574026 and 11405017)the Liaoning Provincial Natural Science Foundation,China(Grant No.201602453)
文摘In this paper,ultra-long and large-scaled ZnO microwire arrays are grown by the chemical vapor deposition method,and a single ZnO microwire-based non-balanced electric bridge ethanol gas sensor is fabricated.The experimental results show that the gas sensor has good repeatability,high response rate,short response,and recovery time at room temperature(25℃).The response rate of the gas sensor exposed to 90-ppm ethanol is about 93%,with a response time and recovery time are 0.3 s and 0.7 s respectively.As a contrast,the traditional resistive gas sensor of a single ZnO microwire shows very small gas response rate.Therefore,ethanol gas sensor based on non-balanced electric bridge can obviously enhance gas sensing characteristics,which provides a feasible method of developing the high performance ZnO-based gas sensor.
基金Project supported by the National Natural Science Foundation of China (Grant No. 51075087)the State Key Laboratory of Fluid Power Transmission and Control,ZheJiang University of China (Grnat No. GZKF-201004)the China Scholarship Council(Grant No. 2009612129)
文摘Microspheres coated with a perfectly conductive surface have many advantages in the applications of biosensors and micro-electromechanical systems.Polystyrene microspheres with the diameter of 10 μm were coated with a 50 nmthick gold layer using an electroless gold plating approach.Dielectrophoresis(DEP) for bare microspheres and shelled microspheres was theoretically analysed and the real part of the Clausius-Mossotti factor was calculated for the two kinds of microspheres.The experiments on the dielectrophoretic characterisation of the uncoated polystyrene microspheres and gold coated polystyrene microspheres(GCPMs) were carried out.Experimental results showed that the gold coated polystyrene microspheres were only acted by a positive dielectrophoretic force when the frequency was below 40M Hz,while the uncoated polystyrene microspheres were governed by a negative dielectrophoretic force in this frequency range.The gold coated polystyrene microspheres were exploited to form the microwire automatically according to their stable dielectrophoretic and electric characterisations.