Solid state decomposition studies on tetraperoxo species of transition metals. Kinetics of the isothermal decomposition of K3Nb(O2)4 and K3Ta(O2)4

The kinetics of the isothermal decomposition of K₃Nb(O₂)₄ and K₃Ta(O₂)₄ have been investigated using a constant volume apparatus in the temperature ranges 428–451 and 416–464 K, respectively. The α-time plots for both these solids are predominantly deceleratory in nature. They obey the unimolecular decay law ?log(1 ? α) = kt over a long period of time. Facile nucleation has been attributed to two factors, namely the fine size of the crystallites of the reactants and the strain imposed by four peroxide rings. The activation energies for K₃Nb(O₂)₄ and K₃Ta(O₂)₄ are 126.53 and 95.86 kJ mole^?1 respectively.