POLYMORPH TRANSITION KINETICS BY DTA

The polymorph transition kinetics of the changes vaterite to calcite and aragonite to calcite have been followed using a DTA technique. The method eliminates the grinding process present in other analytical techniques and so has certain advantages. For both transitions the kinetic equation describing the process is found to be: {Mathematical expression} Values of activation energy were found to be 452±19 KJ mole-1 and 208±8 KJ mole-1 for aragonite and vaterite transitions respectively using a procedure which enabled the calculation of kinetic parameters from a rising temperature experiment. © 1978 Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest.