oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Production of Nanometer Powders with an Electrohydrodynamic Technique
Xifeng YU,Zhuangi HUXiang LIU,Lizhi CHENG,
材料科学技术学报 , 1997,
Abstract: The principle of producing nanometer powders with the electrohydrodynamic technique and the apparatus were described. The effects of the geometry and size of the cathode and anode. and the applied voltage on the emitted current and the mean size of the nanometer powders were Studied.Experimental results show that with the decreasing in the diameter of the cylindrical cathode and in the calibre of the spiral cathode, the mean size of the nanometer powders decreases. The effect of the calibre of the spiral cathode is more remarkable. In addition, the mean size of the nanometer powders decreases with decrease in the internal and external diameter of the anode and the increase in the applied voltage.
Piezochromic Phenomena of Nanometer Voids Formed by Mono-Dispersed Nanometer Powders Compacting Process  [PDF]
Lihong Su, Caixia Wan, Jianren Zhou, Yiguang Wang, Liang Wang, Yanling Ai, Xu Zhao
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072964
Abstract: Piezochromism describes a tendency of certain materials changing colors when they are subjected to various pressure levels. It occurs particularly in some polymers or inorganic materials, such as in palladium complexes. However, piezochromism is generally believed to work at high pressure range of 0.1–10 GPa. This research work focused on unique piezochromism responses of the nanometer voids formed by the 5–20 nm inorganic ISOH nanometer powders. It was discovered that microstructures of the nanometer voids could change color at very low pressures of only 0.002–0.01 GPa; its sensitivity to pressure was increased by tens of times. It is believed that the uniform microstructures of nanometer powders contributed to the material's high sensitivity of piezochromic phenomena. One factor which quantum optical change caused by nanometer voids affected the quantum confinement effect; another is surface Plasmon Resonance of great difference dielectric property between conductive ITO powder and insulation hydroxide.
Synthesis and Properties of Cerium Oxide Nanometer Powders by Pyrolysis of Amorphous Citrate
Xiangting DONG Guangyan HONG,Decai YU,Dashu YU,
材料科学技术学报 , 1997,
Abstract: CeO2 nanometer powders of different sizes were prepared at low temperature by pyrolysis of amorphous citrate. XRD patterns show that CeO2 is cubic in structure, space group Oh5-FM3M·TEM indicates that the prepared CeO2 is spherical in shape, and the particle size distribution is in narrow range. It was found that calcination temperature is a more important factor affecting the crystallite size of CeO2 than calcining time, the smaller the particle. the bigger the crystallattice distortion, the worse the crystal growth. Solubility test of CeO2 in nitric acid reveals that the surface activity of CeO2 decreases with the increasing particle sizes. IR spectra analysis shows that the absorption of Ce-O bond is shifted to higher energy with the decrease of CeO2 particle sizes.
PREPARATION OF NANOMETER ZINC OXIDE BY EVAPORATION METHOD
AAASaleh,XJZhai,YCZhai,YFu,
A.A.A. Saleh,X.J. Zhai,Y.C. Zhai and Y. FuSchool of Materials and Metallurgy,Northeastern University,Shenyang,China
金属学报(英文版) , 2002,
Abstract: Nanometer ZnO particles were synthesized by evaporating of zinc powders of averageparticle size of 370μm studied by XRD, TEM and electron diffraction. The particleswere formed by the oxidation of evaporated zinc vapor in the air. It was found that theparticles range from 70 to 100nm in average particle size. The effect of experimentalparameters was investigated, the increase of the air flow-rates reduced the averageparticle size, while increasing the evaporation temperature and the amount of metalcharged increased the average particle size. TEM of the particles collected showedthat the crystal habits of particles have a tetrapod-like of wurtzite structure consists offour needle crystals. It was found by electron diffraction that all particles were singlecrystal.
Preparation and characterization of nanostructured powders of hydroxyapatite
Martínez-Casta？ón, G. A.;Loyola-Rodríguez, J. P.;Zavala-Alonso, N. V.;Hernández-Martínez, S. E.;Ni？o-Martínez, N.;Ortega-Zarzosa, G.;Ruiz, F.;
Superficies y vacío , 2012,
Abstract: in this work, hydroxyapatite nanostructured powders were prepared with different crystallinity degree, crystal size and morphology using a simple aqueous precipitation method varying the ph and temperature parameters. we found that at higher ph values the crystal size grows and crystallinity was improved; at higher temperatures there is also a crystal size growth and crystallinity improving but this change is more significant, a change in the morphology of the nanopowders was also observed. using xrd patterns and rietveld analysis we found that the crystal size change from 9.15 to 26.4 nm. the prepared powders are highly agglomerated with a pseudo-spherical and rod-like morphology.
Sonocatalytic degradation of methyl orange in the presence of (nanometer and ordinary) anatase TiO2 powders
WANG Jun,GUO Bao-dong,ZHANG Zhao-hong,ZHANG Xiang-dong,WU Jing,LI Hong,
WANG Jun,GUO Bao-dong,ZHANG Zhao-hong,ZHANG Xiang-dong,WU Jing,LI Hong
环境科学学报(英文版) , 2005,
Abstract: The nanometer and ordinary anatase titanium dioxide (TiO2) powders were adopted as the sonocatalysts for the degradation of methyl orange used as a model compound for the first time. It was found that the sonocatalytic degradation effect of methyl orange in the presence of TiO2 powder were much better than that without TiO2, but the sonocatalytic activity of the nanometer anatase TiO2 particle was obviously higher than that of ordinary anatase TiO2 particle. Although there are many factors influencing sonocatalytic degradation of methyl orange, the experimental results showed that the best degradation ratio of methyl orange could be obtained when the experimental conditions were: initial concentration 15 mg/L, nanometer anatase TiO2 adding amount 750 mg/L, ultrasonic frequency 40 kHz, output power 50 W, pH = 3.0 and temperature 40 degrees C within 150 min. In addition, the catalytic activity of reused nanometer anatase TiO2 catalyst was also studied and found to decline gradually comparing with initial nanometer anatase TiO2 catalyst. All experiments indicated that the method of the sonocatalytic degradation of organic pollutants in the presence of TiO2 powder was an advisable choice for non- or low-transparent organic wastewaters.
Grain Growth Kinetics and Debye Temperature of Nanometer TiO_2 Powders Prepared by a Sol-gel Process
Ju LUO,Xingzhao DING,Benpei CHEN,Jie KONGYuanda DONG,
材料科学技术学报 , 1994,
Abstract: The development of microstructure of nanometer TiO2 powders prepared by a sol-gel process was systematically studied. Grain growth was mon itored using X-ray diffraction (XRD) and transmission electron microscopy (TEM). and the Debye temperature of anatase crystallites was determined. It was found that the grain size of the powders increased slowly with annealing temperature up to 773 K. but grew rapidly in the temperature range of 773-1273K. The activation energies (Ea) for the growth of anatase crystallites in the two temperature regions were calculated to be 16 and 90 kJ / mol, respectively. The Debye temperatures of nanocrystalline anatase powders were all lower than that of microcrystalline anatase. which implies that the bonding force between Ti and O atoms in nanocrystalline TiO2 shourd be smaller than that in microcrystalline state. However. it was noted that the Debye temperature of nanocrystalline anatase increased with the decrease of grain size. This may be attributed to the enhancement in atomic bonding force due to the existence of high surface tension in nanocrystalline powders
Preparation and Properties of Nano-TiO_2 Powders
Zhe SONG,Qing LI,Lian GAO,
材料科学技术学报 , 1997,
Abstract: This paper reports the preparation of nano-TiO2 (about 10 nm) powder by the method of precipitation. In detail, some breparation conditions were investigated in order to find out how to control the grain size and reduce the agglomeration of powders. Also, the reflex spectra of nano-scale powders with different grain size were studied. It tvas found that the wave length and width of reflex spectra are connected with the grain size of nano-TiO2 powders
INFLUENCE OF ZnO NANOMETER POWDERS ON MICROSTRUCTURE AND ELECTRICAL PROPERTIE OF VARISTOR MATERIAL
ZnO纳米粉对压敏陶瓷材料显微结构和电学特性的影响
KANG Xueya,SONG Shigen,HAN Ying,TU Miniing,TAO Minde,
康雪雅,宋世庚,韩英,涂铭旌,陶明德
材料研究学报 , 1996,
Abstract: A sol-gel method for the preparetion of doped ZnO varistor nanometer powders was described.The influence of the ZnO nanometer powders on the microstrue, the nonlinear parameter,the breakdown voltage, and the dielectric properties of ZnO varistor was investigated. Compared to the conventional mixed oxide technique, varistor ceramics made from sol-gel powders with a more homogeneous distribution of dopants, a regular microstructure and show improvement electrical properties.
Preparation of nanosized non-oxide powders using diatomaceous earth  [PDF]
？aponji？ A.,Babi？ B.,Deve？erski A.,Matovi？ B.
Science of Sintering , 2009, DOI: 10.2298/sos0902151s
Abstract: In this paper the nanosized non-oxide powders were prepared by carbothermal reduction and subsequent nitridation of diatomaceous earth which is a waste product from coal exploitation. Our scope was to investigate the potential use of diatomaceous earth as a main precursor for low-cost nanosized non-oxide powder preparation as well as to solve an environmental problem. The influence of carbon materials (carbonized sucrose, carbon cryogel and carbon black) as a reducing agent on synthesis and properties of low-cost nanosized nonoxide powders was also studied. The powders were characterized by specific surface area, X-ray and SEM investigations. It was found that by using diatomaceous earth it is was possible to produce either a mixture of non-oxide powders (Si3N4/SiC) or pure SiC powders depending on temperature.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.