Thermal studies on beryllium titanyl/zirconyl oxalates

Abstract

Beryllium titanyl oxalate tetrahydrate and beryllium zirconyl oxalate tetrahydrate were prepared in aqueous medium and characterized by elemental analyses, magnetic susceptibility measurements and IR spectral studies. The thermal behaviour of these compounds under non-isothermal conditions was investigated by thermogravimetric, derivative thermogravimetric and differential scanning calorimetric (DSC) techniques. The intermediates obtained at the end of the various thermal decomposition steps were identified on the basis of elemental analyses and IR spectral studies. The decomposition proceeds through three major steps, viz, dehydration of the hydrate, decomposition of the oxalate to carbonate and decomposition of the carbonate to oxide. The graphical method of Coats and Redfern was employed to calculate kinetic parameters such as apparent activation energy and order of reaction. Heats of reaction for the different decomposition steps were calculated from the DSC curves.