pH值对溶胶-凝胶法制备La0.65Sr0.35MnO3的影响

Effects of pH Value on Preparation of La0.65Sr0.35MnO3 by Sol-Gel Process

摘要:

利用溶胶-凝胶法制备亚锰酸盐化合物La0.65Sr0.35MnO3，通过XRD和SEM研究不同pH值对合成粉体相组成和微观形貌的影响。结果发现：在pH值为0.5的酸性环境和pH为8.0的弱碱性环境中，均可以获得具有钙钛矿结构且尺寸均匀的La0.65Sr0.35MnO3粉体。在pH值为0.5的酸性环境中，有利于形成二维层状结构的凝胶，而在pH为8.0的弱碱性环境中，有利于形成三维空间网络结构的凝胶，金属离子可以有效地分散于这两种凝胶中，避免了后期热处理过程中化学组分的偏差及团聚的生成

Abstract:

La0.65Sr0.35MnO3 was prepared at different pH values by sol-gel method. The phase composition of the as-received powder was measured using X-ray diffraction. The particle size and morphology were observed by SEM. The results show that the samples called manganites have single perovskite structure and homogeneous particle size distribution when the pH value is controlled near 0.5 and 8.0 during the sol-gel process. The layer-shaped gel forms in the system when pH=0.5. However, the three-dimensional reticulate gel occurs when pH=8.0. The homogeneous distribution of La, Sr and Mn ions in the gel benefits avoiding the deviation of the chemical composition of manganites and the agglomeration of the powder in the following heat treatment.