Kinetics and Mechanism of the Reaction Between Zinc Oxide and Barium Carbonate

The kinetics of reaction between BaCO 3 and ZnO were studied using thermogravimetric analysis to monitor the percent reaction versus time. Solid state reaction models based on ( a ) product growth controlled by diffusion through a continuous product layer, ( b ) product growth controlled by phase boundary reactions, and ( c ) the concept of an order of reaction, were invalid for the reaction studied. The kinetics of the reaction were described by the kt =–ln (1 – x )⅔ nuclei growth equation. The defect nature of the zinc oxide studied was altered by doping with Li2 O and Cr 2 O 3 . The activation energy for the reaction of BaCO 3 and pure ZnO was 54.6 kcal/mole. The changes in activation energy with the type and amount of ZnO doping cannot be accounted for by the quasi‐chemical theory of solids.