Hydrothermal Synthesis Of Ti - Based Perovskite - Type Oxide And Its Growth Mechanism

Perovskite-type oxide (ABO3) is a typical representative of the family of oxides, which can have great changes of the position of A and B elements, thereby change the structures and properties. It exhibits varied physical and chemical properties by altering different reaction conditions, since it has been found. The main topic is about reaction mechanisms of synthesis with different precursors, and about synthesis conditions of products with better photocatalytic properties, and thus provides a basis for targeted-preparation.(1) Hydrothermal syntheses are carried out between Ti precursors with different solubility, morphologies, exposed facets and Sr(OH)2. The similarities and differences of morphologies, exposed facets can be contrasted between the precursors and products, we can infer the reaction mechanisms by collecting intermediates using quenching experiments, and confirm the reaction mechanisms by kinetic analysis. And then testing optical properties of products, and selecting the synthesis conditions of products with high properties. The experimental results show that the reaction belongs to dissolution-recrystallization mechanism, and the products synthesized by TiO2precursor exhibits superior photocatalytic properties.(2) On the basis of hydrothermal synthesis and dissolution recrystallization mechanism, hydrothermal syntheses of SrTiO3are carried out via the use of inorganic additives and light additives as a tool of morphology control and a structure-directing template by changing the kinetics and stimulating reactions. The progresses of hydrothermal reactions with the aid of inorganic additives are explored. The inorganic ions and light conditions, which have significantly modifies with the structures and properties, are selected. The experimental results show that with the additive of NaCl or NaN03, the products synthesized by TiO2precursor are modified with structures, and the light additives can accelerate the reaction rate and lowering the reaction temperature.(3) Hydrothermal synthesis of PbTiO3, BaTiO3with a change of elements on the position of A, under the reaction conditions of SrTiO3with better photocatalytic properties. The differences of possibility among the three different perovskite oxides are compared. At the same time, preliminary explorations of the growth process of SrTiO3are carried out based on the synchrotron radiation. The experimental results show that with the same reaction conditions, we can synthesize BaTiO3and PbTiO3, and the syntheses of SrTiO3may be easier than BaTiO3and PbTiO3.