Thermal decomposition of BaC2O4•0.5H2O studied by stepwise isothermal analysis and non-isothermal thermogravimetry

Thermal decomposition of BaC2O4. 0.5H(2)O in air was studied by a combination of stepwise isothermal analysis (SIA) and non-isothermal thermogravimetry. The results from both techniques show that the crystal water is released in one step and that anhydrous barium oxalate is decomposed in one step, while BaCO3 decomposes in three steps to BaO, forming two intermediate compounds with the formulas of BaCO3.(BaO)(2) and (BaCO3)(0.5). (BaO)(2.5). Reaction mechanism analyses using the data from SIA measurements show that the controlling mechanism for all the five decomposition steps in isothermal conditions is a two-dimensional phase-boundary controlled process. Kinetic parameters are obtained for the five decomposition steps from the non-isothermal thermogravimetric data.