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1.
Sandwiched structures (a-SiNx/a-Si/a-SiNx) have been fabricated by the plasma enhanced chemical vapour deposition technique. A Si nanocrystal (nc-Si) layer was formed by crystallization of an a-Si layer according to the constrained crystallization principle after quasi-static thermal annealing at 1100℃ for 30 min. Transmission electron microscopy (TEM) and Raman scattering spectroscopy clearly demonstrated that nc-Si grains were formed in the as-deposited a-Si layer after annealing. The density of nc-Si grains is about 1011cm-2 as shown by TEM photographs. Using capacitance-voltage (C-V) measurements we investigated the electrical characteristics of the sandwiched structures. The charge storage phenomenon of the nc-Si layer was observed from the shift of flat-band voltage (VFB) in C-V curves at a high frequency (1 MHz). We estimated the density of nc-Si grains to be about 1011cm-2 from the shift value of VFB, which is in agreement with the result of TEM photographs. At the same time, we found that the shift of VFB increased with the increase of the applied constant dc voltage or the thickness of the nc-Si layer. 相似文献
2.
Nano-structure thin film of tungsten nitride was deposited onto Si-substrate at room temperature using Mather-type plasma focus (3.3?kJ) machine. Substrate was exposed against 10, 20, 30, and 40 deposition shots and its corresponding effect on structure, morphology, conductivity and nano-hardness has been systematically studied. The X-ray diffractormeter spectra of the exposed samples show the presence of various phases of WN and WN2 that depends on number of deposition shots. Surface morphological study revealed the uniform distribution of nano-sized grains on deposited film surface. Hardness and conductivity of exposed substrate improved with higher deposition shots. X-ray photo-electron spectroscopy survey scan of 40 deposition shots confirmed the elemental presence of W and N on Si-substrate. 相似文献
3.
The nano-sized ZrO2-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO2 particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO2 particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO2 particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %. 相似文献
4.
设计了SiO2与电极间加入ZnS的复合加速层结构,进一步说明靠电子注入的增强来扩大初电子源.同时,在电子发生倍增前后的电压下,对比了单层和夹层结构的不同加速层的发光性能.得到在低压直流下单侧复合加速层器件的发光优于单层SiO2加速层器件而劣于单层ZnS器件;在高压交流下复合加速层表现出明显的优势,在复合加速层中,ZnS不仅对电子有加速作用,而且对增强电子注入贡献很大,同时ZnS和SiO2/ZnS界面还提供了初电子源.另外,与SiO
关键词:
电致发光
复合加速层
过热电子
固态阴极射线 相似文献
5.
Influence of the ultrasound intensity (28 kHz, 1.1–7.5 W/cm2) on CaCO3 nucleation-growth on the surface of a cylinder mild steel electrode rotating at 500 rpm was studied in tap water. The deposition kinetics was analyzed by chronoamperometry; the calcareous layer was characterized by gravimetry, scanning electron microscopy and XRD. Application of ultrasound to calcium carbonate crystallization affects nucleation site density, mass-transport rate and cavitation erosion of the deposits. Lower intensity ultrasound reduces scale porosity and area density by increasing nucleation site density and accelerating the mass transport. Higher intensity ultrasound promotes cavitation erosion of the formed layer, thus cleaning the surface from the scale. A scale layer with the highest blocking properties formed under applied ultrasound intensity of 1.9 W/cm2. The ultrasound doubled crystallization rate, reduced the scale porosity 5 times and halved its area density compared to non-sonicated conditions. Ultrasound of controllable intensity can solve both scale and corrosion problems of industrial heat-exchange equipment by forming a protective scale layer and removing excessive deposits. 相似文献
6.
T. Car N. Radić J. Ivkov E. Babić A. Tonejc 《Applied Physics A: Materials Science & Processing》1999,68(1):69-73
82 W18 to Al62W38 compounds ranged from 800 K to 920 K. The activation energy for the crystallization and the Avrami exponent were determined.
The results indicated that the crystallization mechanism in films with higher tungsten content was a diffusion-controlled
process, whereas in films with the composition similar to the stoichiometric compound (Al4W), the interface-controlled crystallization probably occurred.
Received: 30 March 1998/Accepted: 9 September 1998 相似文献
7.
M. Song K. Mitsuishi M. Tanaka M. Takeguchi M. Shimojo K. Furuya 《Applied Physics A: Materials Science & Processing》2005,80(7):1431-1436
Self-standing tungsten nanowires, nanodendrites, and nanofractal-like trees were fabricated on insulator (Al2O3) substrates with a process of electron-beam-induced decomposition in a transmission electron microscope. The conditions for fabricating different morphologies are described. The fabricated structures are characterized with high-resolution transmission electron microscopy and X-ray energy-dispersive spectroscopy. A high concentration of tungsten and a high crystallinity of the structure are confirmed. The growth process is discussed, involving charges produced on the surface of the substrate and the behavior of precursor molecules under electron-beam irradiation. The formation of these structures is considered to relate to nanoscaled unevenness of the charge distribution on the surface of the substrate, movement of charges to the convex surface of the substrate, and accumulation of charges at the tips of the grown structures. PACS 81.07.-b; 07.78.+s; 81.15.Gh; 81.16.-c 相似文献
8.
Surachet Phadungdhitidhada Suvit Thanasanvorakun Pongsri Mangkorntong Supab Choopun Nikorn Mangkorntong Duangmanee Wongratanaphisan 《Current Applied Physics》2011,11(6):1368-1373
Mixed morphology of SnO2 nanowires and nanodendrites was synthesized on the gold-coated alumina substrates by carbothermal reduction of SnO2 in closed crucible. The products were characterized by scanning electron microscopy, x-ray diffractometer, and transmission electron microscopy. Results showed the SnO2 nanowires and the SnO2 nanodendrites branched out from the main nanowires. Both SnO2 nanostructures were pure tetragonal rutile structure. The nanowires were grown in [101] and directions with the diameter of 50–150 nm and the length of a few 10 μm. The nanodendrites were about 100–300 nm in diameter. The growth mechanism of the SnO2 nanostructures was also discussed. Characterization of ethanol gas sensor, based on the mixed morphology of the SnO2 nanostructures, was carried out. The optimal temperature was about 360 °C and the sensor response was 120 for 1000 ppm of ethanol concentration. 相似文献
9.
Regina Janet Sánchez-Leija Marta Riba-Moliner Diana Cayuela-Marín Octavio Domínguez-Espinós María Guadalupe Sánchez-Loredo 《Journal of Macromolecular Science: Physics》2014,53(2):173-190
Two different types of calcium fluoride (CaF2) particles were incorporated into a poly(ethylene terephthalate) (PET) matrix, fine particles (~350 nm), and nanoparticles (~70 nm). Both of them were synthesized by a chemical precipitation method using triethanolamine (TEA) as stabilizer. To obtain the nanoparticles, a greater amount of TEA was added during the synthesis in order to limit their growth. Therefore, unlike the fine particles, nanoparticles contained a greater amount of the stabilizer. Once CaF2 particles were obtained, the composite materials were prepared by melt-blending PET and particles at different filler loadings. The influence of both kinds of particles on the non-isothermal crystallization behavior of PET was investigated by using differential scanning calorimetry and field emission scanning electron microscopy. The Jeziorny-modified Avrami equation was applied to describe the kinetics of the non-isothermal crystallization, and several parameters were analyzed (half-crystallization time, Avrami exponent, and rate constant). According to the results, it is clear that CaF2 particles act as nucleating agents, accelerating the crystallization rate of PET. However, the effect on the crystallization rate was more noticeable with the addition of the fine particles where the surface plays an important role for epitaxial crystallization, while the addition of the nanoparticles with an organic surface coating resulted in a crystallization behavior similar to the observed for PET. 相似文献
10.
In the Ni–W system, a uniform amorphous Ni–W phase was obtained by ion irradiation of the nano-sized Ni–W multilayers at liquid-nitrogen
temperature. Interestingly, before undergoing complete amorphization, fractal patterns were observed at a relatively low irradiation
dose (3×1014 Xe+/cm2), and the patterns were characterized to consist of crystalline grains of Ni-enriched solid solution. The fractal dimension
was measured to be about 1.68±0.05, which was very close to that expected by the cluster diffusion-limited aggregation model.
Received: 30 January 2002 / Accepted: 2 February 2002 / Published online: 3 May 2002 相似文献
11.
Anatase TiO2 and W doped TiO2 films were fabricated by micro-arc oxidation (MAO) on titanium substrates and their hydrogen sensing properties were investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the oxide films and electrochemical impedance spectroscopy (EIS) was applied to investigate the gas sensing mechanism. It is found that the conductivity of TiO2 films varies with the introduction of W dopant. EIS analysis reveals that the grains and especially the grain boundaries are mainly contributed to the hydrogen response and their equivalent circuits could be represented electrochemically by parallel resistor and constant phase element (CPE). The enhanced sensor signal at higher measuring temperature (300 °C) is observed with an optimal doping concentration of W ions (1.81 at.%). 相似文献
12.
The effects of microwave, ultrasound and combined ultrasound-microwave (UM) treatment with different intensities on structural and hydrolysis properties of myofibrillar protein (MP) were investigated. Free radical scavenging ability, angiotensin-I-converting enzyme (ACE) inhibitory activity, and cellular antioxidant and anti-inflammatory abilities of the related bioactive peptides were also evaluated. Raman spectroscopic analysis indicated that MP molecule tended to unfold and stretch with increasing in β-turn and random coil content under mild microwave (100 W), ultrasound (100–200 W) and combined UM treatments. Meanwhile, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) revealed these treatments could also improve the thermal stability against heat-induced denaturation and degeneration. The 200 W ultrasound treatment clearly increased MP solubility by disrupting the highly-ordered aggregates into smaller filament and fragment structures. The 300 W ultrasound coupled with 100 W microwave treatment further enhanced these effects. The resulting partially denatured structure induced by suitable ultrasound and combined UM treatments increased the susceptibility of MP to exogenous enzymes, thereby accelerating hydrolytic process and yielding a high peptide concentration in MP hydrolysates. MP peptides could effectively inhibit free radical and ACE activity, which also improved the ability of antioxidant defence system, and suppressed the production of proinflammatory cytokines in RAW 264.7 cells stimulated by H2O2. The combination of 100 W microwave and 300 W ultrasound treatment was optimal method for generating bioactive MP peptides with the strongest multi-activity effects against H2O2-induced cell damage. 相似文献
13.
R. T. Malkhasyan R. V. Arutyunyan L. V. Kamaeva E. I. Salamatov 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2014,49(1):34-38
We study thermal-physical characteristics of nano-sized amorphous tungsten and of its oxide. It is shown that a nano-size amorphous metal gets into a nano-size crystalline state after heating up to temperatures much lower than the half-temperature of melting, which is typical for all nano-size amorphous materials. Phase transition of amorphous nano-size WO2 into crystalline state occurs in the temperature range 350–520°C, while the same transition in case of W takes place in the range 1000–1370°C. The energy released at crystallization of nano-size amorphous metal amounts to 170±25 J/g coinciding practically with the value of specific melting heat of usual tungsten. Such a high additional energy of nano-size amorphous metals above the energy of nano-size crystalline metals is their main peculiarity which widens essentially the range of their practical applications. 相似文献
14.
采用掺镧锆锡钛酸铅反铁电陶瓷作为阴极材料,研究了脉冲电压激励下陶瓷的电子发射特性.当激励电压为800V、抽取电压为0V时,得到1.27A/cm2的发射电流密度;当抽取电压增加到4kV时,获得1700A/cm2的发射电流密度.分析了发射电流随抽取电压的变化关系,讨论了反铁电陶瓷强电子发射的内在机理.结果表明:掺镧锆锡钛酸铅反铁电陶瓷能够在较低的激励电压(400V)下实现电子发射,发射电流远大于按照Child-Langmuir定律计算出的电流,三接点附近局域反铁电—铁电相变产生初始电子发射,初始电子电离中性粒子形成等离子体,增强了电子发射.
关键词:
铁电阴极
反铁电体
电子发射 相似文献
15.
Charging artifacts and surface features of corn starch granules were investigated by scanning electron microscopy. Three types of industrial waxy corn starch granules with different levels of moisture content (0, 10.3, and 24.2%) were prepared and subjected to both secondary electron imaging and backscattered electron imaging. There were no significant charging artifacts in secondary electron images at 3 or 5 kV. However, imaging at higher magnifications and accelerating voltages much lower than 3 kV ranging from 0.1 to 1 kV did not show well-resolved structures. At higher accelerating voltages than 5 kV, charging was manifested as excessive brightness at specific areas and alteration of bright and dark lines in the direction of the raster pattern in secondary electron images of all the types of specimens tested. As the accelerating voltage increased up to 30 kV in secondary electron images, the charging also increased. Meanwhile, no charging was detected in all the backscattered electron images taken at different accelerating voltages. As the accelerating voltage increased in backscattered electron images, the resolution increased with less depth of focus. Consistent results were found in all the types of corn starch granules assayed in this study. These results suggest that a simple and rapid morphological analysis of moisturized starches can be performed by backscattered electron imaging without considerable heat drying of starches. Concomitantly, it allows for imposing a higher accelerating voltage to ensure better image resolution, facilitating morphological characterization of diverse starch granules as they are in native states. 相似文献
16.
采用化学镀的方法在363K和p型Si(100)衬底上制得非晶Ni88P12合金薄膜.利用X射线衍射、X射线光电子能谱、扫描隧道显微镜和原子力显微镜对非晶合金薄膜及其经处理后形成的氧化态、还原态和晶态的结构、组分和表面的形貌特征作了研究,并对它的晶化行为作了初步探讨.结果表明,非晶合金薄膜是由纳米级微粒聚集成微米级颗粒组成;在低于晶化温度条件下经氧化和还原处理后的薄膜表面晶化;在晶化过程中,合金薄膜的非晶纳米微粒转变为微晶后长大成晶粒,其表面结构光滑平坦,几何边界
关键词: 相似文献
17.
Ting Zhang Zhitang Song Mingda Sun Bo Liu Songlin Feng Bomy Chen 《Applied Physics A: Materials Science & Processing》2008,90(3):451-455
The Si2Sb2Te5 phase change material for applications of chalcogenide random access memory was investigated. Electron irradiation induced
crystallization in a nano-sized area was studied by means of in situ transmission electron microscopy and selected area electron
diffraction. Amorphous Si2Sb2Te5 film changes to a polycrystalline state after electron beam exposure with sufficiently high energy and after a long time.
Crystallization of the film strongly depends on the electron beam energy, current density, as well as exposure time. According
to our study, the electron beam induced crystallization is a displacement damage dominant process.
PACS 64.60.Cn; 71.55.Jv; 78.66.Jg; 68.37.Lp; 85.40.-e 相似文献
18.
Tellurite glasses of the system xWO3–75TeO2–(25 ? x)B2O3 (0 ≤ x ≤ 25 mol. %) were prepared and studied by differential thermal analysis to explore the effect of WO3 on their glass transition and crystallization kinetics. The crystallization kinetics was studied under non-isothermal conditions using the formal theory of transformations for heterogeneous nucleation. The crystallization results were analyzed and both the activation energy of the crystallization process and the crystallization mechanism characterized. The phases into which the glass crystallizes were identified by X-ray diffraction. Diffractograms of the transformed material indicate the presence of microcrystallites of α-tellurite, Te0.95W0.05O2.05, Te2W and B2O3 in the amorphous matrix. 相似文献
19.
W. XuH.C. Sun J. Xu W. LiW.W. Mu Y. LiuM.Y. Yan X.F. HuangK.J. Chen 《Applied Surface Science》2011,258(1):346-349
We report the fabrication of Si quantum dots (QDs)/SiO2 multilayers by using KrF excimer laser (248 nm) crystallization of amorphous Si/SiO2 multilayered structures on ITO coated glass substrates. Raman spectra and transmission electron microscopy demonstrate the formation of Si QDs and the size can be controlled as small as 1.8 nm. After laser crystallization, Al electrode is evaporated to obtain light emitting devices and the room temperature electroluminescence (EL) can be detected with applying the DC voltage above 8 V on the top gate electrode. The luminescent intensity increases with increasing the applied voltage and the micro-watt light output is achieved. The EL behaviors for samples with different Si dot sizes are studied and it is found that the corresponding external quantum efficiency is significantly enhanced in sample with ultra-small sized Si QDs. 相似文献
20.
Metin Usta Süleyman KahramanFatih Bayansal Hacı A. Çetinkara 《Superlattices and Microstructures》2012
Tungsten trioxide (WO3) thin films were prepared by thermal evaporation method onto quartz substrates at room temperature. Effect of annealing temperature (from 200 to 800 °C) to morphology, crystallographic structure and electrical properties were investigated. In order to investigate the temperature dependant resistivity properties of the films dark current–voltage measurements were done at the temperatures of 30, 60, 90, 120 and 150 °C. From the AFM pictures it is seen that the increasing annealing temperature causes an increase in grain sizes. At elevated temperatures the grains combine to each other and thus form continuous and homogenous surfaces. From the XRD patterns it was seen that the as-prepared and annealed films at 200, 300, 310 and 320 °C were amorphous. On the other hand at 330 °C and higher temperatures the films were found as in crystallized structures (monoclinic phase). From the current–voltage measurements it was seen that the contacts areohmic and the current increased with increasing temperatures. From the calculated values it was seen that the produced films shows good semiconducting nature. 相似文献