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1.
Field emission (FE) triode arrays with the anodic aluminum oxide (AAO) template carbon nanotubes (CNTs) as the field emitters
are successfully fabricated and analyzed. Both the experimental measurement and numerical calculation are conducted to examine
the electron conduction properties of AAO-CNTs. Using a three-dimensional finite-difference time-domain particle-in-cell method,
a set of Maxwell equations and Lorentz equation is solved self-consistently, where the FE current is computed with Fowler–Nordheim
equation. We explore the FE characteristics of AAO-CNTs in the triode structure. After calibration with the measured data,
we study the evolution of current density and the convergence of the electron beams on anode plate with different gate voltages,
anode heights, and SiO2 thickness. The current density and focus performance maintain a trade-off relationship, where a larger current density accompanies
more divergent electron beam. 相似文献
2.
Influence of different fluoride containing electrolytes on the formation of self-organized titania nanotubes by Ti anodization 总被引:1,自引:0,他引:1
J. M. Macak L. V. Taveira H. Tsuchiya K. Sirotna J. Macak P. Schmuki 《Journal of Electroceramics》2006,16(1):29-34
The formation of self-organized porous titania nanotubes is achieved by electrochemical anodization under specific experimental
conditions. In present work, the formation of porous titania nanotubes on titanium substrates is investigated in several SO42−/F− based electrolytes. The presence of some non-porous layers covering the porous layers and accompanying the pore growth is
observed. We discuss in details the influence of different electrolyte composition on the structure of self-organized porous
layers, investigate the conditions for ideal pore growth. SEM investigations and XRD, AES and EDX surface analyses are carried
out to characterize the self-organized porous layers. The results show that using SO42−/F− electrolytes with different cations can drastically influence the final morphology of the self-organized porous nanotubes.
We furthermore show that the nanotubes consist of TiO2 and that they remain unchanged when annealed. 相似文献
3.
Hong Yang He Wang Xiandao Lei Chuanke Chen Dingyue Cao 《International Journal of Numerical Modelling》2014,27(4):649-655
According to the potential barriers generated by the silver, glass layer, and N+ emitter, an analytical model is developed to explain interface contact performance between the printed thick‐film silver paste and emitter for crystalline silicon solar cells. According to the model, the front contact resistance between the sintered silver and N+ emitter is simulated at different doping concentrations, temperatures, and density of state. The quantitative expression of interface contact resistance between the printed thick‐film silver paste and N+ emitter is derived for the first time. The results in this study unify different viewpoints about the current transport mechanisms at the sintered silver–silicon interface. If the glass frit chemistry and silver particle size are carefully tailored, the silver consumption per watt can be reduced, and the efficiency of crystalline silicon solar cells can be further improved. The results lay the foundation for studying the screen‐printed crystalline silicon solar cell front contact metallization system. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
4.
5.
J. Honkamo J. Hannu H. Jantunen M. Moilanen W. Mielcarek 《Journal of Electroceramics》2007,18(3-4):175-181
Zinc oxide based ceramics are widely used materials in varistors because of their excellent nonlinearity. Traditionally these
ceramics are sintered at high temperatures (about 1,100–1,300°C). In this work a novel zinc oxide-based material with a low
sintering temperature (900–1,000°C) was investigated. This material can be used in varistors consisting of several ceramic
layers with embedded silver/palladium thick-film electrodes. This paper explains the research procedure employed with this
novel varistor material, including the effect of sintering aid addition on the final electrical properties and fired microstructure.
The electrical properties achieved are compared to the values measured from the original zinc oxide composition without sintering
aid addition. Especially the I–V characteristics, nonlinearity coefficient α, breakdown voltage V
bk and leakage current density J
L
are investigated. The sintering properties are also reported. It was found that by adding 10 wt.% of glass and using a 900
°C sintering temperature, the material had good varistor characteristics, as V
bk = 378 V/mm, α = 33 and J
L
= 15 μA/cm2. The investigated varistor material can be applied to protect electrical circuits against surges. 相似文献
6.
Magnetoelectric BiFeO3 (BFO) materials exhibit ferroelectric and ferromagnetic properties simultaneously, therefore they have a potential to be
applied in magnetic as well as ferroelectric devices. BFO thin films were formed by depositing sol-gel solutions on Pt-coated
r-plane sapphire dielectric substrates. We did not observe any secondary phase such as Bi2Fe4O9 on the r-plane sapphire substrates, which is generally observed on Si substrates. We observed small ferroelectric grains
of about 0.1 μm on Pt/sapphire structures. The leakage current density in BFO films was found to be decreased dramatically
after optimizing process conditions of stoichiometric BFO chemical solution. The leakage current densities were in the range
of 10− 7 A/cm2 at room temperature and 10− 9 A/cm2 at 80 K under 0.4 MV/cm applied electric field. The main reason for low leakage current is considered to be reduction of
oxygen vacancies due to the presence of exclusive Fe3 + valance state in the films. An applied electric field higher than 0.5 MV/cm was required to pole the BFO films, which made
it difficult to obtain the saturated polarization at room temperature. We could measure the saturated remanent polarization
in the BFO films at 80 K and the obtained remanent polarization was 100 μC/cm2. 相似文献
7.
Effect of vanadium doping on ferroelectric and electrical properties of Bi3.25La0.75Ti3O12 thin film
Bi3.25La0.75Ti3O12 (BLT) and V-doped BLT (BLTV) thin films were prepared on Pt/Ti/SiO2/Si substrates by a pulsed laser deposition method. The effects of V doping on ferroelectric and electrical properties were
investigated by polarization-electric field hysteresis loops and leakage current-voltage measurements. BLTV single phases
were confirmed by X-ray diffraction. Remnant polarization was increased and the leakage current density was decreased by V
doping. The leakage current density of BLT thin films suddenly increased at 100 kV/cm while that of BLTV thin films increased
at the higher electric field of 160 kV/cm. The power law relationship J α En of current density vs. applied electric field is estimated to be J αE2.0 for BLT and J αE1.0 for BLTV thin films. The leakage current of the BLT/Pt junction can be explained by space-charge-limited current. However,
that of the BLTV/Pt junction was characterized by the Schottky emission behavior. 相似文献
8.
9.
A 30-nm-thick Ni layer was deposited on top of the nc-Si:H (hydrogenated nanocrystalline Si) films by rf-magnetron sputter,
and then heat-treatments were carried out at temperatures of 350–500∘C. Si nanocrystallites were formed in the Ni/nc-Si:H bilayer films during the post-deposition heat-treatments. The intensity
of the photoluminescence spectra of the post-deposition heat-treated films gradually increased at wavelengths of ∼420 as well
as ∼580 nm with raising the annealing temperature from 350 to 500∘C. It is highly likely that the increase of the photoluminescence intensity is caused by the increase in the total volume
of the nanocrystallites in the films. It was found that the nickel-induced crystallization processing enhanced the formation
of Si cystallites with the size of ∼2 and ∼5 nm in the films. 相似文献
10.
Hidenori Mimura Kazufumi Shiozawa Yoichiro Neo Morihiro Okada Masafumi Takahasi Gen Hashiguchi 《IEEJ Transactions on Electrical and Electronic Engineering》2007,2(3):272-277
Sputter‐induced carbon nanoneedle field emitters and Si electron‐transparent films have been developed for electron‐beam‐pumped light sources. The sputter‐induced carbon nanoneedle field emitters exhibited a stable electron emission of 0.1 mA at an average field of 13 V/µm. The 1.5‐µm thick Si electron‐transparent films achieved an electron transmittance of about 60% at an acceleration voltage of 27 kV. An electron‐beam‐pumped light source was demonstrated from the excitation of N2 gas, and a N2 gas spectrum was clearly observed. The increase of the beam current is important for increasing the light intensity. Copyright © 2007 Institute of Electrical Engineers of Japan© 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
11.
滴灌是目前最有效的节水灌溉方式之一,而准确计算毛管水头损失是滴灌设计的前提。毛管沿程水头损失的计算已基本形成统一认识,而局部水头损失规律因滴头形状的复杂性和布置方式的多样性仍没形成一致认识。为探明滴头插入对毛管水流局部阻力及流动特性的影响,本文对两种插入式毛管进行灌水试验,同时采用计算流体力学(CFD)数值模拟并分析验证,结果表明数值模拟与试验吻合度较高,可用数值模拟研究插入式毛管局部水头损失。在此基础上对9组滴灌管进行模拟研究,分析了不同流态下毛管局部水头损失系数影响因素。结果表明层流和紊流流态下,毛管局部水头损失系数均随雷诺数的增大而减小,随滴头毛管断面面积比的增大而增大;毛管局部水头损失占沿程水头损失之比值与滴头间距和滴头流量有关;毛管层流段水头损失相对较小,在不需精确计算时可忽略不计。研究结果可为管网水力计算提供参考。 相似文献
12.
研究通过提高发射区的方块电阻和采用合适的工艺技术,制备了性能优良的单晶硅太阳电池。采用丝网印刷技术制备了40Ω/□常规发射区和60Ω/□高方块电阻发射区单晶硅太阳电池并对其性能进行了分析研究。扩展电阻法分析表明:60Ω/□发射区的表面活性磷杂质浓度和结深比40Ω/□发射区的分别降低了12.8%和14.9%。尽管60Ω/□发射区太阳电池的串联电阻增加了0.141Ω/cm2导致填充因子下降了1.24%,但是短路电流密度和开路电压分别提高了1.31 mA/cm2和1.2 mV,最终转换效率仍然提高了0.4%。 相似文献
13.
LaNi0.6Co0.4O3 (LNC) is a perovskite-type conducting ceramic oxide, which is an ideal electrode layer for perovskite ferroelectric and piezoelectric
thin and thick film devices, owing to its unique crystal structure that can facilitate film growth and improve fatigue behavior.
When used for thick films, however, one of the drawbacks is its high sintering temperature of above 1200∘C, which can lead to severe inter-diffusion. In an attempt to reduce the sintering temperature of LNC without substantially
deteriorating the electrical properties, we have investigated the effects of doping LNC with an appropriate glass addition.
LNC powder was synthesized through a solid state reaction process. Varying amounts of glass compositions were then introduced,
in order to study their effects on densification, microstructure and electrical properties of LNC. The glass compositions
exhibited a strong effect on the sintering behaviors and microstructure, where the density after sintering was improved with
increasing amount of glass addition. While the electrical conductivity was adversely affected by an increasing amount of glass
addition, the composition with optimal glass addition showed a lowered sintering temperature of 950∘C, and at the same time maintained a high conductivity of 117 S cm−1. 相似文献
14.
I. H. Kim D. Y. Ku J. H. Ko D. Kim K. S. Lee J.-h. Jeong T. S. Lee B. Cheong Y.-J. Baik W. M. Kim 《Journal of Electroceramics》2006,17(2-4):241-245
To improve the stability of sputter-deposited ZnO:Al (AZO) films at high temperature above 300∘C, an amorphous Zn-Sn-O (ZTO) film was deposited on the top of AZO films as an protective layer by co-sputtering of pure ZnO
and SnO2 targets. Amorphous ZTO films had resistivity in the range from 10−2 to 10−3 Ωcm and were stable up to temperature of 400∘C. Heat treatments of bare AZO films in the atmosphere at 400∘C resulted in a dramatic increase in the resistivity accompanied by substantial decrease in carrier concentration and Hall
mobility. The AZO films covered with the ZTO film showed remarkable improvement in thermal stability for subsequent heat treatments
in the temperature range from 200 to 400∘C in the atmosphere as well as chemical stability in weak acidic solution. X-ray photoelectron spectroscopy analysis showed
that the improvement was attained by ZTO layer acting as diffusion barrier of oxygens and/or water vapors. 相似文献
15.
In this work, Pb0.97La0.02(Zr x Sn0.95?x Ti0.05)O3 (PLZST) (0.5?<?x?<?0.9) tetragonal antiferroelectric (AFET) and orthogonal antiferroelectric (AFEO) ceramics were successfully fabricated by screen printing process. The ceramic materials were in thick-film form bonded with a small amount of glass. The electric field up to 400 kV/cm was presented for antiferroelectric ceramics. Besides, in order to reduce the energy loss of ceramics, the effects of Sn content and temperature on the dielectric properties and energy storage performance of AFE ceramics were investigated. With the increase of Sn content, the forward threshold electric field (E AF) and backward threshold field (E FA) decreased and the energy storage density increased obviously. The maximum energy storage density of 5.6 J/cm3 (30 °C) and 4.7 J/cm3 (120 °C) with corresponding energy efficiency of 67 % and 73 % were obtained in Pb0.97La0.02(Zr0.5Sn0.45Ti0.05)O3 ceramic, which makes this material a promising potential application in capacitors for pulsed power systems. 相似文献
16.
Kazuaki Arai Hiroshi Tateishi Ko Agatsuma Takashi Saito Nobuyuki Sadakata Mikio Nakagawa 《Electrical Engineering in Japan》1995,115(4):1-13
A new type of superconductor is being developed for the application of high-field pulsed superconducting magnets, which are called fiber-reinforced-superconductors (FRS). A filament of FRS consists of a reinforcement fiber with high elastic modulus and a superconducting layer around it. The strain can be reduced against electromagnetic force because of highelastic modulus fibers. If Nb3Sn target is utilized, the preparation process of FRSs is shortened and there is the possibility to produce Nb3Sn layer which leads to high current density because of its uniform stoichiometric Nb3Sn layer. This paper presents first a technique of preparing a single-phase target of Nb3Sn to produce superconducting layers on reinforcement fibers of FRSs. Mixture of niobium and tin powder was reacted in a furnace filled with argon gas to be Nb3Sn, and then it was broken and cast into a stoichiometric target with a diameter of 77 mm. The critical temperature of the target itself was 17.5 K. The thin film deposited with the target showed no superconductivity without post annealing, but it had critical temperature from 14.5 K to 12.5 K after heat treatment. Second, a new target containing rich tin was prepared and the film deposited with it had superconductivity without post annealing. 相似文献
17.
Jong-Yoon Ha Ji-Won Choi Chong-Yun Kang Seok-Jin Yoon Doo Jin Choi Hyun-Jai Kim 《Journal of Electroceramics》2006,17(2-4):399-403
The effect of the addition of glass on the densification, low temperature sintering, and microwave dielectric properties of
the Ca[(Li1/3Nb2/3)1−x
Tix]O3−δ(CLNT) was investigated. Addition of glass (B2O3-ZnO-SiO2-PbO system) improved the densification and reduced the sintering temperature from 1150∘C to 900∘C of Ca[(Li1/3Nb2/3)1−x
-Tix]O3−δ microwave dielectric ceramics. As increasing glass contents from 10 wt% to 15 wt%, the dielectric constants (εr) and bulk density were increased. The quality factor (Q⋅f0), however, was decreased slightly. The temperature coefficients of the resonant frequency (τf) shifted positive value as increasing glass contents over Ti content is 0.2 mol. The dielectric properties of Ca[(Li1/3Nb2/3)0.75Ti0.25]O3−δ with 10 wt% glass sintered at 900∘C for 3 h were εr = 40 Q·f0 = 11500 GHz, τf = 8, ppm/°C. The relationship between the microstructure and dielectric properties of ceramics was studied by X-ray diffraction
(XRD), and scanning electron microscope (SEM). 相似文献
18.
Bo-Yun Jang Beom-Jong Kim Young-Hun Jeong Sahn Nahm Ho-Jung Sun Hwack-Ju Lee 《Journal of Electroceramics》2006,17(2-4):387-391
BaTi4O9 thin films were grown on a Pt/Ti/SiO2/Si substrate using RF magnetron sputtering. A homogeneous BaTi4O9 crystalline phase developed in the films deposited at 550∘C and annealed above 850∘C. When the thickness of the film was reduced, the capacitance density and leakage current density increased. Furthermore,
the dielectric constant was observed to decrease with decreasing film thickness. The BaTi4O9 film with a thickness of 62 nm exhibited excellent dielectric and electrical properties, with a capacitance density of 4.612
fF/μm2 and a dissipation factor of 0.26% at 100 kHz. Similar results were also obtained in the RF frequency range (1–6 GHz). A low
leakage current density of 1.0 × 10−9 A/cm2 was achieved at ± 2 V, as well as small voltage and temperature coefficients of capacitance of 40.05 ppm/V2 and –92.157 ppm/∘C, respectively, at 100 kHz. 相似文献
19.
Young-Bae Kim Jeong-Ung Kim Duck-Kyun Choi Jae-Min Hong Il-Doo Kim 《Journal of Electroceramics》2009,23(1):76-79
We report on the fabrication of low-voltage ZnO thin-film transistors using 1% Ni-doped Ba0.6Sr0.4TiO3 as the gate insulator. The Ni-doped BST, deposited by RF magnetron sputtering at room temperature, significantly reduced
leakage current density to less than 6 × 10−9 A/cm, as compared to a current density of 5 × 10−4 A/cm for undoped BST films at 0.5 MV/cm. The ZnO thin-film transistor with the Ni-doped BST gate insulator exhibited a very
low operating voltage of 4 V. The field-effect mobility, the current on/off ratio and subthreshold swing were 2.2 cm2 V/s, 1.2 × 106, and 0.21 V/dec respectively. 相似文献
20.
Cathodic material La1.0Sr1.0FeO4+δ for an intermediate temperature solid oxide fuel cell (IT-SOFC) was prepared via the glycine-nitrate process and characterized
by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM). XRD results
showed that no reaction occurred between the La1.0Sr1.0FeO4+δ electrode and Sm0.2Ce0.8O1.9 (SDC) electrolyte at 1000 °C. SEM results showed that the electrode formed good contact with the SDC electrolyte after sintering
at 1000 °C for 2 h. The electrochemical properties of La1.0Sr1.0FeO4+δ were measured using electrochemical impedance spectroscopy (EIS) and steady state polarization measurement. At 700 °C, the
polarization resistance was about 3.90 Ωcm2, and the lowest polarization overpotential was 57 mV at a current density of 55 mA cm−2. 相似文献