共查询到20条相似文献,搜索用时 31 毫秒
1.
Xiangping JiangMei Lin Na TuChao Chen Shulan ZhouHongquan Zhan 《Journal of Alloys and Compounds》2011,509(38):9346-9350
Single-crystalline Na0.5Bi0.5TiO3 (NBT) nanowires, with diameters of 100 nm and lengths of about 4 μm, were synthesized by using a simple hydrothermal method. Phase composition, morphology and microstructure of the as-prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The effects of reaction temperature and reaction time on precipitation of the NBT nanowires were investigated. It was found that reaction time significantly influenced the growth behavior of the powders in the hydrothermal system. Based on the experimental results, the one-dimensional (1D) growth mechanism of the NBT was governed by a dissolution-recrystallization mechanism. NBT ceramics derived from the nanowires showed typical characteristics of relaxor ferroelectrics, with diffuseness exponent γ of as high as 1.73. 相似文献
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A novel lanthanon seed was employed as the catalyst for the growth of GaN nanowires. Large-scale GaN nanowires have been synthesized
successfully through ammoniating Ga2O3/Tb films sputtered on Si(111) substrates. Scanning electron microscopy, x-ray diffraction, high-resolution transmission electron
microscopy, and Fourier transform infrared spectroscopy were used to characterize the samples. The results demonstrate that
the nanowires are single-crystal hexagonal wurtzite GaN. The growth mechanism of GaN nanowires is also discussed. 相似文献
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采用射频磁控溅射技术在硅衬底上制备Ga2O3/Nb薄膜,然后在900℃下于流动的氨气中进行氨化制备GaN纳米线.用X射线衍射(XRD)、透射电子显微镜(TEM)和高分辨透射电子显微镜详细分析了GaN纳米线的结构和形貌.结果表明:采用此方法得到的GaN纳米线有直的形态和光滑的表面,其纳米线的直径大约50nm,纳米线的长约几个微米.室温下以325nm波长的光激发样品表面,只显示出一个位于367 nm的很强的紫外发光峰.最后,简单讨论了GaN纳米线的生长机制. 相似文献
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YANG Li XUE Chengshan WANG Cuimei LI Huaixiang REN Yuwen) Chemistry Function Materials Lab Institute of Semiconductors Shandong Normal University Jinan China) Physics Department Shandong Normal University Jinan China) Inspection Institute for Electronic Products of Shandong Jinan China 《稀有金属(英文版)》2003,22(3)
Hexagonal gallium nitride films were successfully fabricated through ammoniating Ga2O3 films deposited on silicon (111) substrates by electrophoresis. The structure, composition, and surface morphology of the formed films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The measurement results reveal that the polycrystalline GaN films with hexagonal wurtzite structure were successfully grown on the silicon (111) substrates. Preliminary results suggest that varying the ammoniating temperature has obvious effect on the quality of the GaN films formed with this method. 相似文献
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Nickel-cobalt alloys were deposited from sulfate electrolyte with oxalic, malonic and succinic acids as additives and their microstructure and mechanical properties were studied. The crystal structure, surface morphologies, and chemical composition of coatings were investigated using X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy. The crystal structure and surface morphology analysis showed that the addition of dicarboxylic acid leads to (2 0 0) crystal face and the surface were more compact and uniform due to the grain refining. Ni60-Co40 alloy was achieved when succinic acid is used as additive. 相似文献
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Xinjuan Wang Bingsuo Zou Qinglin ZhangAihua Lei Wenjie ZhangPinyun Ren 《Journal of Alloys and Compounds》2011,509(41):9959-9963
CdS and ZnS nanostructures with complex urchinlike morphology were synthesized by a facile solvothermal approach in a mixed solvent made of ethylenediamine, ethanolamine and distilled water. No extra capping agent was used in the process. The structure, morphologies and optical properties of these nanostructures were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. The as-synthesized urchinlike architectures were composed of nanorods with wurtzite structure. The preferred growth direction of nanorods was found to be the [0 0 1] direction. The PL spectrum of CdS nanostructures exhibited a highly intense red emission band centered at about 706 nm. On the basis of the experimental results, a possible growth process has been discussed for the formation of the CdS and ZnS urchinlike structures. 相似文献
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Huan MaDuanwei He Li LeiShanmin Wang Ying ChenHaikuo Wang 《Journal of Alloys and Compounds》2011,509(7):L124
GaN crystals are successfully obtained through solid-state metathesis (SSM) reaction between sodium gallium oxide (NaGaO2) and boron nitride (BN) under high pressure and high temperature. X-ray diffraction (XRD) pattern indicates that the attained GaN crystals possess a hexagonal wurtzite-type structure. Scanning electron microscopy (SEM) is used to estimate the size and morphology of GaN crystals, and results show that GaN grains with the size over 100 μm can be prepared at 5 GPa and 1600 °C. Moreover, pressure-temperature (P-T) formation region of GaN has been discussed. Our results suggest a promising novel route for synthesizing GaN crystals from SSM reactions under high pressure. 相似文献
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Rodrigo L.O. Basso Vanessa Schmidt Silvia A.C. Abarca Almir Spinelli Cristiano Giacomelli 《Corrosion Science》2010,52(9):3133-2731
The effect of pulsed plasma nitriding temperature and time on the pitting corrosion behaviour of AISI H13 tool steel in 0.9% NaCl solutions was investigated by cyclic polarization. The pitting potential (Epit) was found to be dependent on the composition, microstructure and morphology of the surface layers, whose properties were determined by X-ray diffraction and scanning electron microscopy techniques. The best corrosion protection was observed for samples nitrided at 480 °C and 520 °C. Under such experimental conditions the Epit-values shifted up to 1.25 V in the positive direction. 相似文献
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Of the many methods of laser treatment for improving materials surface properties that have been reported, very few have addressed laser-assisted chemical reaction. In this work laser deposition of metal-matrix composites is reported, using chromium oxide and silicon carbide powders mixed in silica sol-gel mixtures, on EN43 mild steel substrates. Very fine SiC particles ≤ 1 μm and M7C3 carbides were synthesised in situ and dispersed in ferrite matrix by this process. A diode laser at different powers and scanning speeds was applied to specimens coated with slurries of different chemical compositions. The effect of solution composition and bath depths were examined in order to achieve optimum experimental parameters. Surface morphology and microstructure of the deposited coatings and substrate surface layers were examined using optical microscopy, scanning electron microscopy (SEM) and field emission gun scanning electron microscope (FEG-SEM). Chemical composition was determined by energy dispersive X-ray analysis (EDX). The different phases were identified by X-ray diffraction (XRD). Results of microhardness measurements and wear properties of the coatings are also reported. Thermodynamic analysis of the reactions taking place is also given. 相似文献
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Seyed Hossein Hosseini S.H. MohseniA. Asadnia H. Kerdari 《Journal of Alloys and Compounds》2011,509(14):4682-4687
Conductive polyaniline (PANi)-manganese ferrite (MnFe2O4) nanocomposites with core-shell structure were synthesized by in situ polymerization in the presence of dodecyl benzene sulfonic acid (DBSA) as the surfactant and dopant and ammonium persulfate (APS) as the oxidant. The structure and magnetic properties of manganese ferrite nanoparticles were measured by using powder X-ray diffraction (XRD) and vibrating sample magnetometer (VSM), respectively. Its morphology, microstructure and DC conductivity of the nanocomposite were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and four-wire-technique, respectively. The microwave absorbing properties of the nanocomposite powders dispersing in resin acrylic coating with the coating thickness of 1.4 mm were investigated by using vector network analyzers in the frequency range of 8-12 GHz. A minimum reflection loss of −15.3 dB was observed at 10.4 GHz. 相似文献
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Kuang-Wei LiuSheng-Joue Young Shoou-Jinn Chang Tao-Hung HsuehHung Hung Shi-Xiang ChenYue-Zhang Chen 《Journal of Alloys and Compounds》2012,511(1):1-4
This study grew GaN epilayers on Si(1 1 1) substrate via molecular beam epitaxy, with a CrN interlayer fabricated through a nitridation process. The X-ray diffraction results showed two peaks corresponding to CrN(1 1 1) and GaN(0 0 0 2). The results of auger electron spectroscopy showed that the concentration of electrons was relatively low in the samples grown with a CrN interlayer, due to CrN preventing Si atoms from diffusing into the GaN epilayer, thereby reducing electron concentration. Photoluminescence spectra indicated that donor-accepter pair recombination (DAP) emission was not generated in the GaN with a CrN interlayer because of improved crystalline quality and a reduction in electron concentration. 相似文献
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Hematite (α-Fe2O3) nanowires were observed through directly annealing Ni81Fe19 foils at 600 °C for 120 min in atmosphere. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to characterise the nanowires. The results indicate that the growing mechanism includes iron segregation to the surface combined with an internal stress induced by the oxidation process. 相似文献
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Hui Xu Chengtang Liu Huaming Li Yuanguo XuJiexiang Xia Sheng YinLing Liu Xiangyang Wu 《Journal of Alloys and Compounds》2011,509(37):9157-9163
A series of NaNbO3/ZnO heteronanostructures were synthesized with the hydrothermal method. Various characterization methods such as X-ray powder diffraction (XRD), scanning electronic microscope (SEM) and energy dispersive X-ray spectrometer (EDS), transmission electron microscope (TEM), X-ray photoelectron spectra (XPS) and diffuse reflectance spectra (DRS) were employed to investigate the structure, morphology and photocatalytic properties. The photocatalytic activity of the catalysts was evaluated by the degradation of methylene blue dye and the highest photocatalytic efficiency was observed when the content of NaNbO3 was 10 wt.%. The photocatalytic mechanism of the heterojunction was also discussed. The effective transformation of the photoexcited electron and holes restricted the recombination of charges, which was regarded as the main reason of the high photocatalytic activity. 相似文献
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Fabrication of SiC particulate reinforced AZ91D composite by vacuum-assisted pressure infiltration technology 总被引:1,自引:0,他引:1
Bowen Xiong Huan Yu Zhifeng Xu Qingsong Yan Changchun Cai 《Journal of Alloys and Compounds》2011,509(29):L279
The AZ91D Mg matrix composites reinforced by SiC particulate with the sizes of 11 μm, 21 μm and 47 μm were successfully fabricated respectively by vacuum-assisted pressure infiltration technology. Microstructures and particulate distributions were analyzed with scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The coefficient of thermal expansion (CTE) measurements was performed from 75 °C to 400 °C at a heating rate of 5 °C/min. The results show that the uniform distribution of SiC particulate in metal matrix and density over 98% in theoretical density of composites were fabricated. Only MgO phase was detected at the interface and no brittle phases of Al4C3 and Mg2Si were discovered. The desirable coefficients of thermal expansion of composites were achieved. The intensity of dislocation generation nearby SiC particulate increases significantly with the increasing of SiC particulate size. Therefore, this technology is a potential method to fabricate Mg matrix composites reinforced by SiC particulates with the desirable microstructures and CTE. 相似文献
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Stoichiometric compound of copper indium sulfur (CuIn5S8) was synthesized by direct reaction of high purity elemental copper, indium and sulfur in an evacuated quartz tube. The phase structure of the synthesized material revealed the cubic spinel structure. The lattice parameter (a) of single crystals was calculated to be 10.667 Å. Thin films of CuIn5S8 were deposited onto glass substrates under the pressure of 10−6 Torr using thermal evaporation technique. CuIn5S8 thin films were then thermally annealed in air from 100 to 300 °C for 2 h. The effects of thermal annealing on their physico-chemical properties were investigated using X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), optical transmission and hot probe method. XRD studies of CuIn5S8 thin films showed that as-deposited films were amorphous in nature and transformed into polycrystalline spinel structure with strong preferred orientation along the (3 1 1) plane after the annealing at 200 °C. The composition is greatly affected by thermal treatment. From the optical transmission and reflection, an important absorption coefficient exceeds 104 cm−1 was found. As increasing the annealing temperature, the optical energy band gap decreases from 1.83 eV for the as-deposited films to 1.43 eV for the annealed films at 300 °C. It was found that CuIn5S8 thin film is an n-type semiconductor at 300 °C. 相似文献
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Alumina nanowires were synthesized on large-area silicon substrate via simple thermal evaporation method of heating a mixture of aluminum and alumina powders without using any catalyst or template. The phase structure and the surface morphology of the as-grown sample were analyzed by X-ray diffractometry(XRD) and scanning electron microscopy (SEM), respectively. The chemical composition and the microstructure of the as-grown alumina nanowires were characterized using transmission electron microscope(TEM). The nanowires are usually straight and the single crystalline has average diameter of 40 nm and length of 3 - 5μm. The growth direction is along the [002] direction. Well aligned alumina nanowire arrays were observed on the surface of many large particles. The catalyst-free growth of the alumina nanowires was explained under the framework of a vapor-solid(VS) growth mechanism. This as-synthesized alumina nanowires could find potential applications in the fabrication of nanodevices. 相似文献
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通过在不同温度下氨化ZnO/Ga2O3膜,在Si衬底上成功制备了GaN纳米结构材料。氨化前,ZnO层和Ga2O3膜分别通过射频磁控溅射法依次溅射到Si衬底上。用X射线衍射(XRD)、红外傅里叶变换光谱(FTIR)分析了GaN晶体的结构和组分,利用扫描电子显微镜(SEM)观察了样品的形貌。通过对测试结果的分析可知在Si衬底上由ZnO挥发辅助生长出六方纤锌矿GaN纳米结构晶体,并且ZnO/Ga2O3的氨化温度对形成GaN纳米材料具有明显的影响。 相似文献