草酸盐沉淀法制备不同形貌粒度的La2O3粉体

Preparation of LaO Powder with Different Morphology and Particle Size by Oxalate Precipitation

对草酸盐沉淀法制备多种形貌粒度的前驱体草酸镧及La2O3粉体材料进行了研究。以LaCl3为原料,以Na2C2O4为沉淀剂,采用直接沉淀法制备前驱体草酸镧,再通过煅烧制备La2O3粉体。考察了起始溶液pH值、反应物浓度、加料速度、反应温度、表面活性剂等因素对草酸镧粒度及形貌的影响,研究了煅烧温度、煅烧时间和煅烧机制对La2O3粉体粒度及形貌的影响。结果表明:控制不同的结晶条件可制备四边形片状、层状六面体、四棱柱型六面体等多种形貌和多种粒度的前驱体草酸镧;草酸镧晶体随加料速度的变慢按照一维、二维、三维的空间顺序长大;煅烧过程中,随着草酸镧分解,前驱体会先裂解产生细颗粒La2O3,产物La2O3颗粒随着温度升高及时间延长出现"烧结"长大情况,控制合适的煅烧条件可制得平均粒度为1μm的类球状La2O3粉体。

The preparation of precursor lanthanum oxalate and lanthanum oxide by oxalate precipitation was studied.The precursor lanthanum oxalate was prepared by direct precipitation method with LaCl3 as raw material and Na2C2O4 as precipitant.Then lanthanum oxalate was calcined to prepare lanthanum oxide powder.The effects of pH value of initial solution,reactant concentration,feeding speed,reaction temperature and surfactant on the particle size and morphology of lanthanum oxalate were investigated.The effects of temperature,time and mechanism on the particle size and morphology of La2O3 powder during process of calcination were also studied.The results showed that various lanthanum oxalate crystals,such as quadrilateral lamellar hexahedron,layered hexahedron and tetra-prismatic hexahedron,can be obtained by controlling crystallization conditions.Lanthanum oxalate crystals grow up in the spatial order of one-dimensional,two-dimensional and three-dimensional as the feed rate slows down.In the calcination process,with the decomposition of lanthanum oxalate,the precursor would crack to generate lanthanum oxide fine particles,and lanthanum oxide particles in the product would also grow"sintered"with the increase of temperature and calcination time.Spherical La2O3 powder with an average particle size of 1μm can be obtained by controlling appropriate calcination conditions.