Study On Soft-chemistry Method Fabrication, Structure And Property Of Inorganic Layered Nanocomposites

Recently, synthesis and creation of novel nanometer and micro-sized materials are extensively studied in material field. Soft-chemistry method is considered as one of the most outlook method in fabricating new materials because of its unique reacting characteristics, such as mild reaction condition, lower reaction speed, controllable process. In this Ph. D. dissertation, soft-chemistry law was fully used in fabricating and modifying perovskite-type layered lanthanon titanates, including synthesis of ultrafine layered K₂Ln₂Ti₃O₁₀ and nanocomposites based on it. The influence of the particle size on the crystal structure, micrograph and interlayer soft reaction properties, such as exchanging/intercalating reaction and photocatalytic activity was studied. The dissertation was mainly focused on:Two kinds of soft-chemistry method---stearic acid method (SAM) and citric acid sol-gel method were successfully adopted to fabricated ultrafine layered K₂Ln₂Ti₃O₁₀ and K₂Ln_2-xLn'_xTi₃O₁₀ (Ln, Ln'=La, Pr, Nd, Sin, Eu, Gd, Dy) compounds under relatively lower temperature. The impact of Ln on the K₂Ln₂Ti₃O₁₀ crystal structure was also systemic investigated. Results showed that the radius of Ln³⁺ determined whether the layered perovskite structure could be formed. The formation mechanism of K₂Ln₂Ti₃O₁₀ was discussed. It was shown that the K₂Ln₂Ti₃O₁₀ was changed from a mediate state— KLn₂Ti₃O_9.5 for the first time. And the KLn₂Ti₃O_9.5 series were newly synthesized by SAM. It was found that KLn₂Ti₃O_9.5 is square-like and the average size is ca.20nm, has higher BET surface area and unique layered structure similar to the aim products. The obtained products are a new kind of perovskite-type layered compounds. The photocatalytic properties of K₂Ln₂Ti₃O₁₀ and K₂Ln_2-xLn'_xTi₃O₁₀ were studied and results showed that the photoactivities of samples obtained by SAM are all better than those of SSR (solid state reaction), the photocatalytic activity of K₂Ln₂Ti₃O₁₀ was strongly dependent on Ln, decreasing in the sequence of Dy> Gd>Nd>Sm >La by the same method and this sequence was successfully explained by analyzed the energy gap of each K₂Ln₂Ti₃O₁₀. At the same time, the adulteration of Ln helps to improve its catalytic activity.The interlayer soft reaction process, such as acid-exchanging and alkylamine intercalating process of K₂La₂Ti₃O₁₀ was systemic studied. The influence of particle sizes of K₂La₂Ti₃O₁₀ and the kind of acid on the products of exchanged by H+, intercalated by...