The Use of in-situ Powder Diffraction in the Study of Intercalation and Hydrothermal Reaction Kinetics

摘要

In this paper we describe the use of energy dispersive diffraction techniques using 'white' synchrotron radiation to record time resolved in-situ diffraction data on a number of important solid state reactions including intercalation and hydrothermal syntheses. We will describe the construction of a number of special environmental cells for studying these systems. We will discuss the kinetics of the intercalation of guests into a number of lamellar hosts. The kinetic data obtained from these studies have been modelled using nucleation and two-dimensional growth models. In a number of these systems disorder-order transition have been observed. We have also studied the synthesis of the open framework sulfide, TMA-SnS-1, and the gallium fluorphosphate ULM-5, under hydrothermal conditions. The effect of varying the temperature of reaction, reactant source and pH of solution on the syntheses have been investigated. For TMA-SnS-1 is it found that temperature is the primary factor in determining whether crystalline products are formed, while the pH of solution and reactant source were found to be important in determining the rate of reaction and the polytypic structure produced. Evidence has been obtained that in cases where crystalline TMA-SnS-1 is formed, the reaction proceeds via an intermediate disordered lamellar phase, before reacting further to form the final product.