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Influence of Lanthanum on Synthesizing of SiC nanometer powder

Journal of Rare Earths 2007年第S2期25卷 98-103页

作者：张宁龙海波王柳燕才庆魁 Scientific Technology Research Center Shenyang University

Low cost silicon carbon nanometer powder was synthesized by carbothermal reduction method with nanometer SiO2 and carbon as raw material. Its synthesis thermodynamics were discussed. The influence of La on TG-DSC curve was also analyzed. It indicated that the synthesis process of SiC powder had two steps. In the first step two medial productions of SiOg and COg formed, and in the second step, β-SiC was finally synthesized. After 0.3% La added, at the first step, the initiatory forming temperature of producing SiO(g) and CO(g) declined from 1351.4 to 1250.9 ℃, and the thermal activation energy decreased from 223.6 to 34.7 J·g-1; at the second step the initiatory forming temperature of synthesizing β-SiC powder declined from 1526.5 to 1357.8 ℃, and the thermal activation energy decreased from 693.7 to 295.7 J·g-1. Without La added, the best synthesis technology for β-SiC powder was 1550 ℃ for 120 min, average powder diameter was bigger about 150 nm. With La added, the best synthesis technology was 1500 ℃ for 120 min, average powder diameter was about 100 nm.

关键词： lanthanum SiC synthesis temperature low cost nanometer powder rare earths

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Phase formation regularities in Fe-based nanometer powders prepared by gas evaporation process

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中国有色金属学会会刊：英文版 2001年第5期11卷 725-728页

作者：陈振华严红革陈刚康智涛黄培云 Cent S Univ Dept Mat Sci & Engn Changsha 410083 Peoples R China

A serials of Fe based nanometer powders were fabricated by reduced pressure gas evaporation process with induction current as the heating source. The formation regularities of the phases in as prepared powders and the structures of the nanometer particles were investigated. Pure Fe nanometer powders with about 70% γ Fe phase is prepared in present study by using the powder collector with good cooling effect. In the nanometer powders of Fe Ni alloy, solid solution phase γ (Fe,Ni) and α Fe phase form, but for Fe Cr alloys only solid solution phase α (Fe,Cr) forms. In the nanometer powders of Fe Cu alloy, only pure metal phases of γ Fe and Cu form, and no compound or solid solution phase exists. The formation regularity of the phases in the nanometer powders of alloys obeys the common phase laws in bulk alloy state.

关键词： gas evaporation nanometer powder Fe based powder

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Hydrothermal Synthesis and Characterization of Iron Doped near-stoichiometric LiNbO3 nanometer powders

Hydrothermal Synthesis and Characterization of Iron Doped ne...

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第14届全国晶体生长与材料学术会议

作者： CHEN Zhe-ning CHENG Shi-jing① Liu Xin-rong (Department of Applied Chemistry Harbin Institute of Technology , Harbin 150001)

With Nb2O5, Li2CO3, Fe2O3 as the basic raw materials, iron doped lithium niobate nanometer powders were prepared at 240℃ for 12h by the hydrothermal method. The crystal phase compositions, chemical el

关键词： lithium niobate nanometer powder hydrothermal synthesis Fe-doped

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Study on Properties of Composite Oxides TiO_2/SiO_2

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Chinese Journal of Chemical Engineering 2002年第3期10卷 349-353页

作者：周亚松姜国伟 University of Petroleum(Beijing) State Key Laboratory of Heavy Oil Processing 北京 102200

The nanometer particles of TiO_2 and TiO_2/SiO_2 oxides wereprepared by sol-gel supercritical fluid drying method. The propertiesof TiO_2 and TiO_2/SiO_2 were characterized by means of BET(Brunner-Emmett- Teller method), TEM (transmission electronmicroscopy), SEM (scanning electron microscopy), XRD (X-ray diffrac-tion) and FTIR (Fourier transform-infrared) techniques. The effectsof different preparation route, prehydrolysis and non-prehydrolysis,on the properties of TiO_2/SiO_2 oxide were also examined.

关键词： sol-gel CO_2 supercritical fluid drying nanometer powder TiO_2/SiO_2

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