常压固相反应合成LaB_6粉末及其反应机理  

Preparation and Reaction Mechanism of LaB_6 Powder by Solid-state Reaction at Atmospheric Pressure

作　　者：徐秀华[1] 肖汉宁[1] 郭文明[1] 高朋召[1] 彭苏华[1] 

机构地区：[1]湖南大学材料科学与工程学院,长沙410082

出　　处：《无机材料学报》2011年第4期417-421,共5页Journal of Inorganic Materials

基　　金：国家自然科学基金(50972042)~~

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.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 LaB6 powders 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.

关 键 词：LaB6 热力学 固相反应 反应机理 

分 类 号：TB321[一般工业技术—材料科学与工程]