Chemical reactions and structural phase transitions of sodalites and cancrinites in temperature dependent infrared (TIR) experiments

The infrared absorption of a solid highly diluted within an infrared transparent pellet (e.g., KBr, NaCl, etc.) is easily measured as a function of the temperature up to the melting point of the matrix. A disadvantage could be any interaction or chemical reaction between the matrix and the sample. However, such reactions and reactions within the embedded sample can be used in a systematical way for the investigation of the creation of new materials. Here, four types of working examples will be given. Starting with typical temperature dependent (TIR) investigations on the phase transition characteristics of a NaNO3-sodalite it is shown how this intrinsic property is effected by an exchange of Na/K between the matrix and the sodalite. Secondly, the effect of dehydration on NaB(OH)4-sodalite as studied in situ in the KBr pellet is considered. Thirdly, in situ investigations of the formation of new compositions within the family of cancrinites are described. Here, the effect of dehydration, and the combined exchange of Na/K and Cl/Br/NO3 of this typical microporous material is reported. Finally, the first steps of the soft chemically formed sodalite from the sol-gel liquid in the KBr container will be outlined briefly.