Influence of gamma-irradiation and Dy2O3 on the decomposition of barium oxalate: A thermogravimetric study

Effect of gamma -irradiation (410-MGy) and the presence of DY2O3 (10 mol%) on the decomposition of anhydrous barium oxalate has been investigated by t he rising temperature technique. It is evident from the data that in all th e materials, decomposition occurs through (i) a slow reaction stage and (ii ) a fast stage followed by a decay period. The loss of 'CO' from the oxalat e is governed by a two-dimensional phase boundary reaction with cylindrical geometry, the power law of the reaction order, 0.5, in the irradiated salt and three-dimensional nuclei growth in case of mixture. The data were well explained by the contracting area (R-2) model indicating that irradiation as well as mixing enhanced the rate of reaction and decreased the energy of activation, the effect being more prominent in the latter case. (C) 2000 E lsevier Science B.V. All rights reserved.