DTA STUDIES ON THE EFFECT OF IMPURITIES ON THE PHASE-TRANSFORMATIONS OF BARIUM CARBONATE

Orthorhombic (π) barium carbonate, undergoes a reversible transformation to hexagonal (β) form around 1093 K which in turn undergoes a reversible transformation to cubic (α) form around 1253 K. Cationic impurities such as Ca2+, Sr2+, Cd2+, Zn2+, have been doped in pure barium carbonate and their effect on the kinetics and energetics of its transformations were studied. By using DTA technique, the enthalpy and energy of activation for the transformation of pure and doped samples of barium carbonate have been calculated and compared. © 1979 Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest.