共查询到20条相似文献,搜索用时 10 毫秒
1.
T. Xie G.S. Wu B.Y. Geng Z. Jiang X.Y. Yuan Y. Lin G.Z. Wang L.D. Zhang 《Applied Physics A: Materials Science & Processing》2005,80(5):1057-1059
Crystalline Si3N4 nanowires were simply prepared by heating a silicon wafer at 1250 °C in a flowing NH3 and N2 atmosphere. The obtained nanowires are straight and uniform with diameters of 30–100 nm and of lengths up to tens of microns. The possible reactions in the synthesis process are discussed. The growth mechanism of the nanowires is vapor-solid (VS) process. PACS 81.05.Je; 81.07.Bc; 81.10.Bk; 81.16.Be; 81.20.Ka 相似文献
2.
Min Xia Changchun Ge Qingzhi Yan Hongyan Guo Lina Yue 《Applied Physics A: Materials Science & Processing》2012,107(4):777-782
Large quantities of Ti-catalyzed β-SiC nanowhiskers were efficiently prepared via a SHS process by pyrolysis of poly (tetrafluoroethylene) (PTFE). The as-synthesized β-SiC whiskers appear to be structurally uniform with width from 50?nm to 2?μm and length of up to several hundred microns, and they are single crystalline in nature. Results demonstrated that Ti particles could significantly accelerate the absorption and dissolving of Si- and C-related fragments. A Ti–Si–C alloy droplet was detected at the end of an individual β-SiC whisker, which indicated that β-SiC whiskers were grown via the vapor–liquid–solid (VLS) growth mechanism. The elastic bending modulus of individual whiskers was measured by an in-situ transmission electron microscopy (TEM) process; the average value of the elastic bending modulus of individual as-synthesized whiskers was 554?GPa. 相似文献
3.
Guodong Wei Weiping Qin Ryongjin Kim Guofeng Wang Peifen Zhu Daisheng Zhang Kezhi Zheng Lili Wang 《Applied Physics A: Materials Science & Processing》2009,96(2):521-527
By using a novel and low-cost microwave method, three-dimensional SiC networks have been synthesized in large-scale. The composition
and structural features of the product were characterized by X-ray diffraction, field emission scanning electron microscopy,
and transmission electron microscopy. The results show that the SiC networks consist of nanocable X-junction and Y-junction.
Some nanocables are composed of 3C–SiC multicore encapsulated in single amorphous SiO2 shell. The SiC networks emitted stable violet–blue light around 380 nm under 325-nm excitation. Compared to the emission
peak of the SiC networks after etched and the reported results of 3C–SiC nanowires, the emission peak of the SiC networks
shows significant blueshift. The origin of the photoluminescence for the SiC networks could be due to two possible reasons:
the central crystalline SiC nanowires and amorphous SiO2 shell. A two-step growth mechanism of the SiC networks was proposed based on the experimental characterizations. The successful
synthesis of SiC networks is an important step in the development of SiC-based electronic devices and circuits. 相似文献
4.
Z.-Y. Yuan T.-Z. Ren G.-H. Du B.-L. Su 《Applied Physics A: Materials Science & Processing》2005,80(4):743-747
A facile method has been developed to synthesize single-crystalline manganese (oxyhydr)oxide nanowires. A pure phase of single-crystalline MnOOH nanowires with the lengths of several hundred nanometres to several micrometers and the diameters of 5–40 nm was synthesized by hydrothermal transformation of commercial granular - or MnO2 in water, and single-crystalline MnO2 and polycrystalline Mn2O3 nanowires formed after subsequent calcination at 300 and 600 °C of the as-prepared MnOOH nanostructures, respectively. These low-dimensional nanostructured materials may find novel properties and provide more possible applications in lithium batteries and catalysis. PACS 81.07.-b; 81.10.Dn; 81.16.Be 相似文献
5.
Shan Yukai Xiao Zhen Chuan Yongming Li Hongli Yuan Minglong Li Zhen Dou Shixue 《Journal of nanoparticle research》2014,16(5):1-11
A general hydrothermal method was developed to prepare colloidal gadolinium orthovanadate nanocrystals by using supercritical water as a green solvent. The spectacular properties of supercritical water is advantageous for synthesizing crystalline and surface-modified luminescent nanoparticles capped with long alkyl chains of organic modifiers on the surface of the particles to make them dispersible in nonpolar solvents. The size of the nanoparticles could be controlled within 10–15 nm. Characterization of the hydrothermal product was accomplished using X-ray diffraction, transmission electron microscopy (TEM), high-resolution TEM, Fourier transform infrared spectroscopy, thermo gravimetric analysis, and electron dispersive X-ray scattering. The photoluminescence characterization showed that there is a strong red emission under UV excitation, which broadens the material’s various applications. 相似文献
6.
《中国物理 B》2019,(2)
In this work, we prepared the β-Ga_2O_3@GaN nanowires(NWs) by oxidizing GaN NWs. High-quality hexagonal wurtzite GaN NWs were achieved and the conversion from GaN to β-Ga_2O_3 was confirmed by x-ray diffraction, Raman spectroscopy and transmission electron microscopy. The effect of the oxidation temperature and time on the oxidation degree of GaN NWs was investigated systematically. The oxidation rate of GaN NWs was estimated at different temperatures. 相似文献
7.
R. Q. Guo J. Nishimura M. Matsumoto D. Nakamura T. Okada 《Applied Physics A: Materials Science & Processing》2008,93(4):843-847
Vertically aligned ZnO nanowires have been successfully synthesized on c-cut sapphire substrates by a catalyst-free nanoparticle-assisted pulsed-laser ablation deposition (NAPLD) in Ar and N2 background gases. In NAPLD, the nanoparticles formed in the background gas by laser ablation are used for the growth of the
nanowires. The surface density of the nanowires can be controlled by varying the density of nanoparticles, which is in turn
achieved by varying ablation laser parameters such as the energy and the repetition rate. When single ZnO nanowire synthesized
in a N2 background gas was excited by 355 nm laser-pulse with a pulse-width of 8 ns, stimulated emission was clearly observed, indicating
high quality of the nanowire. 相似文献
8.
L. L. Liu M. K. Li D. Q. Yu J. Zhang H. Zhang C. Qian Z. Yang 《Applied Physics A: Materials Science & Processing》2010,98(4):831-835
Undoped and N-doped β-Ga2O3 nanowires (NWs), using NH3 as the dopant source, were successfully fabricated by the CVD method on Si substrates. The microstructure, morphology, element
composition and carrier concentration of the samples were characterized by XRD, SEM, TEM, and EDX. The results revealed that
well-aligned undoped NWs were perpendicular to the substrates. Comparing with undoped β-Ga2O3 NWs, the morphology of N-doped β-Ga2O3 NWs showed a significant change and they were randomly oriented relative to the substrates. As the NH3 flow was increased, the microstructure of the sample presented a lot of branched-like and trumpet-shaped structures. Simultaneously,
a rougher surface has been attained. PL spectrum measurements showed that N-doped β-Ga2O3 NWs had ultraviolet (UV), blue and green emission peaks because of the N-doped process. Furthermore, micro-scale undoped
β-Ga2O3/N-doped β-Ga2O3 homojunction structures were fabricated. The I–V property of the fabricated N-doped β-Ga2O3 microwire and β-Ga2O3/N-doped β-Ga2O3 microwire homojunction were compared. I–V results testified that N-doped β-Ga2O3 NWs showed p-type conductivity. 相似文献
9.
Li Li Heqing Yang Hua Zhao Jie Yu Junhu Ma Lijuan An Xuewen Wang 《Applied Physics A: Materials Science & Processing》2010,98(3):635-641
Ultralong ZnO nanowires were successfully synthesized by a simple hydrothermal reaction of Zn foil and aqueous Na2C2O4 solution at 140°C. The as-synthesized ZnO nanowires are single crystalline with the wurtzite structure and grow in the [0001]
direction. The role of Na2C2O4 in the formation of ultralong ZnO nanowires was investigated, and a possible mechanism was also proposed to account for the
formation of the ultralong ZnO nanowires. The gas sensor fabricated on the basis of the ultralong ZnO nanowires showed excellent
response characteristics towards NH3 and N(C2H5)3 vapors with low concentration, and its detection limits for NH3 and N(C2H5)3 are about 0.2 and 0.15 ppm at the working temperature of 180°C, respectively. This result suggests potential applications
of the ultralong ZnO nanowires in monitoring flammable, toxic and corrosive gases. 相似文献
10.
Martins MA Rossatto M Prola LD Pizzuti L Moreira DN Campos PT Frizzo CP Zanatta N Bonacorso HG 《Ultrasonics sonochemistry》2012,19(2):227-231
The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalomethyl[carboxyethyl] ketones [R3C(O)CHC(R1)OMe, where R3 = CF3, CCl3, CO2Et and R1 = Me, Et, Pr, Bu, i-Pent, CH2CH2CO2Me] with propargyl amines [R2NHCH2CCH, where R2 = Pr, PhCH2] is reported. Yields, solvents and reaction times needed for reaction completion, by microwave irradiation (MW), conventional thermal heating (TH) and under ultrasound irradiation (US) are compared. The best results were obtained under US irradiation in good to excellent yields (70-93%). 相似文献
11.
S. Mátéfi-Tempfli M. Mátéfi-Tempfli L. Piraux 《Applied Physics A: Materials Science & Processing》2009,96(3):603-608
We report on different approaches that we have adopted and developed for the fabrication of nanowires and nanostructures.
Methods based on template synthesis and on self organization seem to be the most promising for the fabrication of nanomaterials
and nanostructures due to their easiness and low cost.
The development of a supported nanoporous alumina template and the possibility of using this template to combine electrochemical
synthesis with lithographic methods open new ways for the fabrication of complex nanostructures. The numerous advantages of
the supported template and its compatibility with microelectronic processes make it an ideal candidate for further integration
into large-scale fabrication of various nanowire-based devices. 相似文献
12.
Mohammad Yuonesi Mojtaba Yaghobi Hamid Reza Alae 《Physica B: Condensed Matter》2011,406(15-16):2962-2966
The electronic structure, magnetic properties and also the bonding mechanism of the pure SiC and compounds SiC:Cr and SiC:Cr:Al have been studied using the Quantum SPRESSO Software within the density-functional theory (DFT). β-SiC, which is a nonmagnetic semiconductor, has more applications in industry. For the magnetic property, it is alloyed with transition metal. One of the transition metal is chromium. The calculations showed that its alloy at both Si site and C site (SiC:Cr) changes the physical properties of the host material and contributes in the molecular bond. It is seen that if the Al atom was doped in the compounds, SiC:Cr will produce hole carriers and the magnetic properties will thus increase to the considerable values due to the mediation effect. The magnetic property will create the up and down spin band gap to filter carriers. The charge density distribution illustrates that the Al atom has the atomic behavior in the compounds Sic:Cr:Al and does not contribute in the molecular bond. For comparison, the calculations were performed for the pure β-SiC. 相似文献
13.
Dang Thi Thanh Le Do Dang Trung Nguyen Duc Chinh Bui Thi Thanh Binh Hoang Si Hong Nguyen Van Duy Nguyen Duc Hoa Nguyen Van Hieu 《Current Applied Physics》2013,13(8):1637-1642
The design of core–shell heteronanostructures is powerful tool to control both the gas selectivity and the sensitivity due to their hybrid properties. In this work, the SnO2–ZnO core–shell nanowires (NWs) were fabricated via two-step process comprising the thermal evaporation of the single crystalline SnO2 NWs core and the spray-coating of the grainy polycrystalline ZnO shell for enhanced ethanol sensing performance. The as-obtained products were investigated by X-ray diffraction, scanning electron microscopy, and photoluminescence. The ethanol gas-sensing properties of pristine SnO2 and ZnO–SnO2 core–shell NW sensors were studied and compared. The gas response to 500 ppm ethanol of the core–shell NW sensor increased to 33.84, which was 12.5-fold higher than that of the pristine SnO2 NW sensor. The selectivity of the core–shell NW sensor also improved. The response to 100 ppm ethanol was about 14.1, whereas the response to 100 ppm liquefied petroleum gas, NH3, H2, and CO was smaller, and ranged from 2.5 to 5.3. This indicates that the core–shell heterostructures have great potential for use as gas sensing materials. 相似文献
14.
K. V. Frolov D. L. Zagorskii I. S. Lyubutin M. A. Chuev I. V. Perunov S. A. Bedin A. A. Lomov V. V. Artemov S. N. Sulyanov 《JETP Letters》2017,105(5):319-326
Fe1-x Co x nanowires are obtained by electrochemical deposition into the pores of track-etched membranes. The characteristics of the growth process that allow controlling the length and aspect ratio of the nanowires are established. The elemental composition and magnetic properties of the nanowires depend on the diameter of the track-etched pores, which varies from 30 to 200 nm, and the electrochemical potential U (650–850 mV), which determines the nanowire growth rate. According to the results of elemental analysis and the Mössbauer spectroscopy data, the Co content in Fe1-x Co x lies in the range of x=0.20?0.25. It is found that the orientation of the magnetic moment of Fe–Co nanoparticles in the wires depends both on the track pore size d and on the nanowire growth rate. Thus, the magnetic moments in nanowires grown in 50-nm-diameter pores are oriented within 0°–40° with respect to the nanowire axis. The magnetic properties of the nanowires are explained in the framework of a theoretical model describing the magnetic dynamics of nanocomposites, which was extended to include the relaxation of the magnetization vector and to take into account interaction between the particles. The key physical parameters important for the technological applications of the nanowires are determined, their dependence on the nanowire growth conditions is traced, and the possibility of controlling them is established. 相似文献
15.
The quantum properties of Au–Mn nanowires are analyzed theoretically from first principles. The emergence of magnetic properties in these nanowires, consisting of nonmagnetic elements, is demonstrated. It is shown that the manganese atoms carry fairly large magnetic moments (~4.3 μB), although crystalline Mn is a paramagnet. Analysis of the electronic structure of these bimetallic nanowires indicates that the magnetic moments at the Mn atoms arise owing to the formation of a complicated structure of hybrid orbitals. Furthermore, it is found that the antiferromagnetic state in Au–Mn nanowires is stabilized by the occurrence of indirect exchange interaction between Mn atoms. 相似文献
16.
M. Milosavljevic S. Dhar P. Schaaf N. Bibic M. Han K.-P. Lieb 《Applied Physics A: Materials Science & Processing》2000,71(1):43-45
The iron di-silicide #-FeSi2 is a promising direct band gap semiconductor but difficult to produce. Here, the successful direct synthesis of this phase by ion beam mixing of Fe/Si bilayers at temperatures in the range of 450 to 550 °C is reported. The obtained single-phase #-FeSi2 layers and their structure are confirmed by Rutherford backscattering spectrometry, X-ray diffraction and conversion electron Mössbauer spectroscopy. 相似文献
17.
The intensities of Si X-ray emission spectra of Si, β-SiC, stishovite, and β-cristobalite crystals are calculated. The wave
functions of the initial and final states are obtained in the framework of the density-functional theory with the use of the
norm-conserving and ultrasoft pseudopotentials. The all-electron crystal orbitals are reconstructed from the one-electron
pseudowave functions. The probabilities of X-ray emission transitions are calculated by reconstructing the all-electron orbitals
in two different gauges, namely, the length and velocity gauges. The calculated intensities are compared with the experimental
spectra and the partial densities of states. 相似文献
18.
M. Nowak B. Kauch P. Szperlich D. Stró? J. Szala T. Rzychoń ?. Bober B. Toroń A. Nowrot 《Ultrasonics sonochemistry》2010,17(2):487-493
A sonochemical method for direct preparation of nanowires of SbS1?xSexI solid solution has been established. The SbS1?xSexI gel was synthesized using elemental Sb, S, Se and I in the presence of ethanol under ultrasonic irradiation (35 kHz, 2 W/cm2) at 50 °C for 2 h. The product was characterized by using techniques such as powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray analysis, selected area electron diffraction, and optical diffuse reflection spectroscopy. The SEM and HRTEM investigations exhibit that the as-prepared samples are made up of large quantity nanowires with lateral dimensions of about 10–50 nm and lengths reaching up to several micrometers and single-crystalline in nature. The increase of molar composition of Se affects linear decrease of the indirect forbidden optical energy gap as well as the distance between (121) planes of the SbS1?xSexI nanowires. 相似文献
19.
Large-scale silver nanowires with controlled aspect ratio were synthesized via reducing silver nitrate with 1, 2- propanediol in the presence of poly (vinyl pyrrolidone) (PVP). Scanning electron microscopy, transmission electron microscopy and x-ray powder diffraction were employed to characterize these silver nanowires. The diameter of the silver nanowires can be readily controlled in the range of 100 to 400 nm by varying the experimental conditions. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy results show that there exists no chemical bond between the silver and the nitrogen atoms. The interaction between PVP and silver nanowires is mainly through the oxygen atom in the carbonyl group. 相似文献