沉淀法制备纳米Al_2O_3过程中亚稳态相变温度的研究  

Metastable phases transformation temperature during Al_2O_3 synthesis using precipitation method

作　　者：黄可龙[1] 尹良果[1] 刘素琴[1] 樊新[1] 

机构地区：[1]中南大学化学化工学院,长沙410083

出　　处：《功能材料与器件学报》2007年第2期134-138,共5页Journal of Functional Materials and Devices

基　　金：863高技术资助项目(No.2002AA323100)

摘　　要：采用沉淀法以Al(NO3)3.9H2O和NH3.H2O为原料制备了Al(OH)3干凝胶,经过高温煅烧合成纳米级的α-Al2O3粉末,研究了不同的Al(OH)3干凝胶样品的TG/DTA变化和煅烧过程中亚稳态Al2O3的相变过程。试验证明,Al(OH)3干凝胶中NH4NO3和α-Al2O3籽晶的存在使θ→α成核势垒降低,从而使得相变温度也降低。NH4NO3的存在使θ-Al2O3→α-Al2O3的相变温度降低了40℃;NH4NO3和2wt%α-Al2O3籽晶的双重作用则使θ→α的相变温度约降低220℃。制备出的α-Al2O3粉末,粒径分布均匀,无明显团聚,近似六方球形,平均粒径为70nm。α- Al2O3 nanocrystalline powders were synthesized by calcining the dry Al （OH）3 gels prepared from aluminum nitrate and ammonia solution using precipitation method, and we studied TG/DTA and the transformation of metastables Al2O3 in the process of calcining different dry Al （OH） 3 gels. Because of NH4NO3 and α -Al2 O3 seed crystal, the nucleation barriers of θ→α reduced, consequently, the phase transformation temperature can be reduced for 40℃ by the effect of NH4NO3 ; and about 220℃ lower than the normal transformation temperature because of the dual role of the NH4NO3 and 2wt% α - Al2O3 seed crystal. The obtained α -Al2O3 powder has no obvious agglomeration, narrow particle size distribution, hexagonal spherical shape, and a mean particle size of 70nm.

关 键 词：沉淀法 Α-AL2O3 亚稳相 相变温度 形核势垒 

分 类 号：O648[理学—物理化学]