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
This paper reports that amorphous magnetic microwires (Fe79Si16Bs) have been fabricated by a melt-extraction technique and have been annealed at 600℃ and 750℃ respectively. Differential scanning calorimeter measur...This paper reports that amorphous magnetic microwires (Fe79Si16Bs) have been fabricated by a melt-extraction technique and have been annealed at 600℃ and 750℃ respectively. Differential scanning calorimeter measurements show that nanocrystalline magnetic phase (α-Fe) has been formed in the amorphous matrix when it was annealed at 600℃. Hard magnetic phase (Fe2B) was formed in the microwires annealed at 750℃, which increases the magnetic coercivity. Microwave permittivity and permeability are found to be dependent on the microstruetures. The permittivity fitting results show that multi Lorentzian dispersion processes exist. For microwires annealed at 750℃, their resonance peaks due to the domain wall movements and natural resonance are found higher than those of microwires annealed at 600℃. The microwave absorption performance of microwires annealed at 600℃ is found better than microwires annealed at 750℃.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
The amorphous FeCuNbSiB microwires are fabricated by using the melt extraction method and annealed separately at temperatures T = 573, 673, 723 and 773K for lh. The effect of annealing treatment on the microwaw electr...The amorphous FeCuNbSiB microwires are fabricated by using the melt extraction method and annealed separately at temperatures T = 573, 673, 723 and 773K for lh. The effect of annealing treatment on the microwaw electromagnetic properties of FeCuNbSiB wires/wax composites has been investigated for the first time. It is found that in a frequency range of 0.5-4.0 GHz, the complex permittivity, permeability, magnetic and electric loss tangents of FeCuNbSiB wires/wax composites are strongly dependent on the annealing temperature and frequency. For T = 573, 723 and 773K, two resonance peaks are found at frequency f = 1.2 and 3.3GHz. However, for T = 673K, only one resonance peak occurs at f = 3.3 GHz. The resonance peak at f = 1.2 GHz is believed to be due to the stress-induced anisotropy, while the resonance peak at f = 3.3 GHz is attributed to the random anisotropy.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 rnicrowire automatically according to their stable dielectrophoretic and electric characterisations.展开更多
One-dimensional(1D)micro/nanowires of wide band gap semiconductors have become one of the most promising blocks of high-performance photodetectors.However,in the axial direction of micro/nanowires,the carriers can tra...One-dimensional(1D)micro/nanowires of wide band gap semiconductors have become one of the most promising blocks of high-performance photodetectors.However,in the axial direction of micro/nanowires,the carriers can transport freely driven by an external electric field,which usually produces large dark current and low detectivity.Here,an UV photodetector built from three cross-intersecting ZnO microwires with double homo-interfaces is demonstrated by the chemical vapor deposition and physical transfer techniques.Compared with the reference device without interface,the dark current of this ZnO double-interface photodetector is significantly reduced by nearly 5 orders of magnitude,while the responsivity decreases slightly,thereby greatly improving the normalized photocurrent-to-dark current ratio.In addition,ZnO double-interface photodetector exhibits a much faster response speed(~0.65 s)than the no-interface device(~95 s).The improved performance is attributed to the potential barriers at the microwire-microwire homo-interfaces,which can regulate the carrier transport.Our findings in this work provide a promising approach for the design and development of high-performance photodetectors.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
ZrO_2 nanodots are successfully prepared on LaAlO_3(LAO)(100) substrates by photo-assisted metal-organic chemical vapor deposition(MOCVD). It is indicated that the sizes and densities of ZrO_2 nanodots are contr...ZrO_2 nanodots are successfully prepared on LaAlO_3(LAO)(100) substrates by photo-assisted metal-organic chemical vapor deposition(MOCVD). It is indicated that the sizes and densities of ZrO_2 nanodots are controllable by modulating the growth temperature, oxygen partial pressure, and growth time. Meanwhile, the microwires are observed on the surfaces of substrates. It is found that there is an obvious competitive relationship between the nanodots and the microwires. In a growth temperature range from 500℃ to 660℃, the microwires turn longest and widest at 600℃, but in contrast, the nanodots grow into the smallest diameter at 600℃. This phenomenon could be illustrated by the energy barrier, decomposition rate of Zr(tmhd)_4, and mobility of atoms. In addition, growth time or oxygen partial pressure also affects the competitive relationship between the nanodots and the microwires. With increasing oxygen partial pressure from 451 Pa to 75_2 Pa,the microwires gradually grow larger while the nanodots become smaller. To further achieve the controllable growth, the coarsening effect of ZrO_2 is modified by varying the growth time, and the experimental results show that the coarsening effect of microwires is higher than that of nanodots by increasing the growth time to quickly minimize ZrO_2 energy density.展开更多
A method of fabricating selenium(Se) microwire is demonstrated.A multimaterial fiber with amorphous selenium(a-Se) core and multicomponent phosphate glass cladding is drawn by using a conventional optical fiber dr...A method of fabricating selenium(Se) microwire is demonstrated.A multimaterial fiber with amorphous selenium(a-Se) core and multicomponent phosphate glass cladding is drawn by using a conventional optical fiber drawing technique.Then the a-Se core of the fiber is crystallized by a post thermal process at 150 ℃.After the multicomponent phosphate glass cladding is stripped from the multimaterial fiber by marinating the fiber in HF acid solution,a crystalline selenium(c-Se)microwire with high uniformity and smooth surface is obtained.Based on microstructure measurements,the c-Se microwire is identified to consist of most hexagonal state particles and very few trigonal state whiskers.The good photoconduction property of c-Se microwire with high quality and longer continuous length makes it possible to apply to functional devices and arrays.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 te...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 magnetostriction of Co-rich amorphous materials, the examined microwires have a circumferential magnetic anisotropy. In consequence, there are the near-surface 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
The effects of different masks and patterns on the top stripping of GaAs microwire arrays fabricated by inductively coupled plasma etching for 20min and 40min are investigated. The results show that the mask layer is ...The effects of different masks and patterns on the top stripping of GaAs microwire arrays fabricated by inductively coupled plasma etching for 20min and 40min are investigated. The results show that the mask layer is the main affect of the top stripping of the GaAs microwires in 40min. Increasing the mask layers and reducing the photoresist layers can prevent top stripping and result in a suitable GaAs microwire array.展开更多
The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20(Ni20Cr) were studied at strain rates from 4.8×10^(–4)s^(–1) to 1.1×10^(–1)s^(–1). Specimens were prepared throug...The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20(Ni20Cr) were studied at strain rates from 4.8×10^(–4)s^(–1) to 1.1×10^(–1)s^(–1). Specimens were prepared through cold drawing with abnormal plastic deformation. The texture of the specimen was characterized using electron backscatter diffraction. Results revealed that the ultimate tensile strength and ductility of the pre-strained Ni20Cr microwires simultaneously increased with increasing strain rate. Twinning-induced negative strain rate sensitivity was discovered. Positive strain rate sensitivity was present in fracture flow stress, whereas negative strain rate sensitivity was detected in flow stress values of σ_(0.5%) and σ_(1%). Tensile test of the pre-strained Ni20Cr showed that twinning deformation predominated, whereas dislocation slip deformation dominated when twinning deformation reached saturation. The trends observed in the fractions of 2°-5°, 5°-15°, and 15°-180° grain boundaries confirmed that twinning deformation dominated the first stage.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
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supported by the National Natural Science Foundation of China (Grant No 60701016)the Science Foundation for Young Faculties of UESTC (Grant Nos L08010301JX0618 and L08010301JX05013)
文摘This paper reports that amorphous magnetic microwires (Fe79Si16Bs) have been fabricated by a melt-extraction technique and have been annealed at 600℃ and 750℃ respectively. Differential scanning calorimeter measurements show that nanocrystalline magnetic phase (α-Fe) has been formed in the amorphous matrix when it was annealed at 600℃. Hard magnetic phase (Fe2B) was formed in the microwires annealed at 750℃, which increases the magnetic coercivity. Microwave permittivity and permeability are found to be dependent on the microstruetures. The permittivity fitting results show that multi Lorentzian dispersion processes exist. For microwires annealed at 750℃, their resonance peaks due to the domain wall movements and natural resonance are found higher than those of microwires annealed at 600℃. The microwave absorption performance of microwires annealed at 600℃ is found better than microwires annealed at 750℃.
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.
文摘The amorphous FeCuNbSiB microwires are fabricated by using the melt extraction method and annealed separately at temperatures T = 573, 673, 723 and 773K for lh. The effect of annealing treatment on the microwaw electromagnetic properties of FeCuNbSiB wires/wax composites has been investigated for the first time. It is found that in a frequency range of 0.5-4.0 GHz, the complex permittivity, permeability, magnetic and electric loss tangents of FeCuNbSiB wires/wax composites are strongly dependent on the annealing temperature and frequency. For T = 573, 723 and 773K, two resonance peaks are found at frequency f = 1.2 and 3.3GHz. However, for T = 673K, only one resonance peak occurs at f = 3.3 GHz. The resonance peak at f = 1.2 GHz is believed to be due to the stress-induced anisotropy, while the resonance peak at f = 3.3 GHz is attributed to the random anisotropy.
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 rnicrowire automatically according to their stable dielectrophoretic and electric characterisations.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62074148,61875194,11727902,12074372,11774341,11974344,61975204,and 11804335)the National Ten Thousand Talent Program for Young Topnotch Talents,the Key Research and Development Program of Changchun City(Grant No.21ZY05)+2 种基金the 100 Talents Program of the Chinese Academy of Sciences,Youth Innovation Promotion Association,CAS(Grant No.2020225)Jilin Province Science Fund(Grant No.20210101145JC)XuGuang Talents Plan of CIOMP。
文摘One-dimensional(1D)micro/nanowires of wide band gap semiconductors have become one of the most promising blocks of high-performance photodetectors.However,in the axial direction of micro/nanowires,the carriers can transport freely driven by an external electric field,which usually produces large dark current and low detectivity.Here,an UV photodetector built from three cross-intersecting ZnO microwires with double homo-interfaces is demonstrated by the chemical vapor deposition and physical transfer techniques.Compared with the reference device without interface,the dark current of this ZnO double-interface photodetector is significantly reduced by nearly 5 orders of magnitude,while the responsivity decreases slightly,thereby greatly improving the normalized photocurrent-to-dark current ratio.In addition,ZnO double-interface photodetector exhibits a much faster response speed(~0.65 s)than the no-interface device(~95 s).The improved performance is attributed to the potential barriers at the microwire-microwire homo-interfaces,which can regulate the carrier transport.Our findings in this work provide a promising approach for the design and development of high-performance photodetectors.
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Project supported by the National Natural Science Foundation of China(Grant No.51002063)the International Science and Technology Cooperation Program of Science and Technology Bureau of Changchun City,China(Grant No.12ZX68)
文摘ZrO_2 nanodots are successfully prepared on LaAlO_3(LAO)(100) substrates by photo-assisted metal-organic chemical vapor deposition(MOCVD). It is indicated that the sizes and densities of ZrO_2 nanodots are controllable by modulating the growth temperature, oxygen partial pressure, and growth time. Meanwhile, the microwires are observed on the surfaces of substrates. It is found that there is an obvious competitive relationship between the nanodots and the microwires. In a growth temperature range from 500℃ to 660℃, the microwires turn longest and widest at 600℃, but in contrast, the nanodots grow into the smallest diameter at 600℃. This phenomenon could be illustrated by the energy barrier, decomposition rate of Zr(tmhd)_4, and mobility of atoms. In addition, growth time or oxygen partial pressure also affects the competitive relationship between the nanodots and the microwires. With increasing oxygen partial pressure from 451 Pa to 75_2 Pa,the microwires gradually grow larger while the nanodots become smaller. To further achieve the controllable growth, the coarsening effect of ZrO_2 is modified by varying the growth time, and the experimental results show that the coarsening effect of microwires is higher than that of nanodots by increasing the growth time to quickly minimize ZrO_2 energy density.
基金Project supported by the National Natural Science Foundation for Distinguished Young Scientists,China(Grant No.61325024)the High-Level Personnel Special Support Program of Guangdong Province,China(Grant No.2014TX01C087)+3 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.2015ZP019)the National High Technology and Development Program of China(Grant Nos.2013AA031502 and 2014AA041902)the National Natural Science Foundation of China(Grant Nos.51472088,61535014,and 51302086)the Fund of Guangdong Provincial Cooperation of Producing,Studying and Researching,China(Grant No.2012B091100140)
文摘A method of fabricating selenium(Se) microwire is demonstrated.A multimaterial fiber with amorphous selenium(a-Se) core and multicomponent phosphate glass cladding is drawn by using a conventional optical fiber drawing technique.Then the a-Se core of the fiber is crystallized by a post thermal process at 150 ℃.After the multicomponent phosphate glass cladding is stripped from the multimaterial fiber by marinating the fiber in HF acid solution,a crystalline selenium(c-Se)microwire with high uniformity and smooth surface is obtained.Based on microstructure measurements,the c-Se microwire is identified to consist of most hexagonal state particles and very few trigonal state whiskers.The good photoconduction property of c-Se microwire with high quality and longer continuous length makes it possible to apply to functional devices and arrays.
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 magnetostriction of Co-rich amorphous materials, the examined microwires have a circumferential magnetic anisotropy. In consequence, there are the near-surface 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Supported by the National Natural Science Foundation of China under Grant Nos 61261009 and 61067001the Key Program of Science and Technology Research of the Ministry of Education of China under Grant No 212090+1 种基金the Natural Science Foundation of Jiangxi Province under Grant No 20133ACB20005the Foundation of Training Academic and Technical Leaders for Main Majors of Jiangxi Province under Grant No 20142BCB22006
文摘The effects of different masks and patterns on the top stripping of GaAs microwire arrays fabricated by inductively coupled plasma etching for 20min and 40min are investigated. The results show that the mask layer is the main affect of the top stripping of the GaAs microwires in 40min. Increasing the mask layers and reducing the photoresist layers can prevent top stripping and result in a suitable GaAs microwire array.
基金Funded by the National Natural Science Foundation of China(No.11135007)
文摘The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20(Ni20Cr) were studied at strain rates from 4.8×10^(–4)s^(–1) to 1.1×10^(–1)s^(–1). Specimens were prepared through cold drawing with abnormal plastic deformation. The texture of the specimen was characterized using electron backscatter diffraction. Results revealed that the ultimate tensile strength and ductility of the pre-strained Ni20Cr microwires simultaneously increased with increasing strain rate. Twinning-induced negative strain rate sensitivity was discovered. Positive strain rate sensitivity was present in fracture flow stress, whereas negative strain rate sensitivity was detected in flow stress values of σ_(0.5%) and σ_(1%). Tensile test of the pre-strained Ni20Cr showed that twinning deformation predominated, whereas dislocation slip deformation dominated when twinning deformation reached saturation. The trends observed in the fractions of 2°-5°, 5°-15°, and 15°-180° grain boundaries confirmed that twinning deformation dominated the first stage.
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.