常压固相反应合成 LaB6 粉末及其反应机理

doi:10.3724/SP.J.1077.2011.00417

无机材料学报 ›› 2011, Vol. 26 ›› Issue (4): 417-421.DOI: 10.3724/SP.J.1077.2011.00417

常压固相反应合成 LaB₆ 粉末及其反应机理

徐秀华 , 肖汉宁 , 郭文明 , 高朋召 , 彭苏华

湖南大学材料科学与工程学院 , 长沙 410082

收稿日期:2010-06-05 修回日期:2010-08-27 出版日期:2011-04-20 网络出版日期:2011-04-22
作者简介:徐秀华 (1984 - ), 男 , 硕士研究生 .
基金资助:
国家自然科学基金 (50972042)

Preparation and Reaction Mechanism of LaB₆ Powder by Solid-state Reaction at Atmospheric Pressure

XU Xiu-Hua,XIAO Han-Ning,GUO Wen-Ming,GAO Peng-Zhao,PENG Su-Hua

College of Materials Science and Engineering, Hunan University, Changsha 410082, China

Received:2010-06-05 Revised:2010-08-27 Published:2011-04-20 Online:2011-04-22
Supported by:
National Natural Science Foundation of China (50972042)

摘要/Abstract

摘要： 以La₂O₃和B₄C为原料, 在常压下合成了LaB₆粉末. 计算了常压合成LaB₆的热力学条件, 采用XRD、 SEM、激光粒度分析表征了不同温度和保温时间合成的LaB₆粉末的物相组成、颗粒形貌和粒度分布, 探讨了LaB₆粉末的合成反应机理. 结果表明, 常压下1650℃保温2h的产物经酸洗后, 能得到纯度为99.22%具有立方体结构的LaB₆粉末. 当La₂O₃颗粒尺寸远小于B₄C时, 合成过程中LaB₆首先在B₄C表面生成, 随温度升高和保温时间延长, 未反应的La₂O₃和LaBO₃通过LaB₆壳不断扩散到B₄C核表面直至反应完全. 合成LaB₆粉末的初始形貌和尺寸主要取决于反应物B₄C原料 .

关键词: LaB₆, 热力学, 固相反应, 反应机理

Abstract: The lanthanum hexaboride (LaB₆) powders were synthesized under atmospheric pressure using B₄C and La₂O₃ powder as the precursors. The thermodynamic conditions for preparing LaB₆ at atmospheric pressure were calculated. The effects of temperature and holding time on the phase composition, morphology, particle size and distribution of LaB₆ powders were characterized by X-ray diffraction (XRD), scanning electron microscope(SEM) and laser particle size anslyzer. The reaction mechanism was investigated. The results show that LaB₆powders obtained under atmospheric pressure at 1650 ℃ for 2h have cube structure with 99.22% purity after washed by hydrochloric acid. When the particle size of La₂O₃ powder is much smaller than that of B₄C particle, the synthesis of LaB₆ starts on the surface of B₄C particle, then the residual La₂O₃ and LaBO₃ will diffuse through LaB₆ shell onto B₄C core until the reaction is completely with the temperature rising and holding time prolonged. The initial shape and particle size of LaB₆ powders are depending on that of B₄C particles.

Key words: lanthanum hexaboride, thermodynamic, solid-state reaction, reaction mechanism

中图分类号:

TB321

徐秀华, 肖汉宁, 郭文明, 高朋召, 彭苏华. 常压固相反应合成 LaB₆ 粉末及其反应机理[J]. 无机材料学报, 2011, 26(4): 417-421.

XU Xiu-Hua,XIAO Han-Ning,GUO Wen-Ming,GAO Peng-Zhao,PENG Su-Hua. Preparation and Reaction Mechanism of LaB₆ Powder by Solid-state Reaction at Atmospheric Pressure[J]. Journal of Inorganic Materials, 2011, 26(4): 417-421.

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常压固相反应合成 LaB₆ 粉末及其反应机理

Preparation and Reaction Mechanism of LaB₆ Powder by Solid-state Reaction at Atmospheric Pressure

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