纳米氧化物La0.8Sr0.2MnO3的制备研究

用添加表面活性剂的苹果酸溶胶凝胶法制备出纳米钙钛石型氧化物La0.8Sr0.2MnO3。通过差热热失重分析,确定了氧化物的焙烧制度。XRD分析表明,所烧制的氧化物样品特征衍射峰明显,杂峰少,晶形完整,其物相为钙钛石结构。表面活性剂因其亲油基团和亲水基团与胶体粒子可以发生复杂的相互作用,形成胶束和胶团,保护了胶体粒子不长大,从而有效地减小氧化物粉料的颗粒粒径,并且在纳米材料的制备过程中能显著降低纳米微粒的表面张力,从而可防止原生粒子团聚,所以在溶胶的制备过程中添加了表面活性剂聚乙烯醇(PVA)。根据谢乐公式计算得出,添加了PVA后,氧化物粉料的粒径约为17nm。TEM分析表明,聚乙烯醇可以作为纳米氧化物粉体La0.8Sr0.2MnO3的分散剂,添加适量的PVA可使纳米粒子的团聚现象得到了明显改善。

Preparation of Nanometer Oxide La0.8Sr0.2MnO3

Nanometer perovskite oxide La_(0.8)Sr_(0.2)MnO_3 is prepared by malic acid sol-gel method with adding surface active agent. The agglomeration method of perovskite oxide is confirmed by means of differential thermal gravimetry (DTA). X-ray diffraction verified the oxide materials prepared have obvious characteristic diffraction peaks, less mixed peaks and perfect crystalline phase. Surface active agent can prevent colloid particles from growing up and minish effectively size of oxide particle because of oleophylic and hydrophil gobbet and complicated interaction with colloid particle. Surface active agent may prevent original particle reuniting for reducing notabely surface tention of nanometer particle in preparation of nanophase materials. Surface active agent PVA are added during preparation of sol. The particle size of oxide is about 17 nm by Scherrer formula after adding PVA. The analysis of TEM indicates that PVA may be dispersants to nanometer oxide La_(0.8)Sr_(0.2)MnO_3,and proper PVA addition may improve greatly the dispersion of nanometer particle.