THERMAL STABILITY OF NICKEL AZIDES

Abstract

Thermal decomposition studies were carried out on three samples of nickel azide. The samples, prepared using different methods, are fresh nickel azide, fresh nickel hydroxy axide and the third sample was obtained by ageing fresh nickel hydroxy azide for almost one year. Thermal decomposition of the samples at different temperatures was carried out using a locally designed apparatus. The decomposition patterns of each of the samples cannot be explained by a single kinetic law as each of them comprises more than one region or stage of decomposition. Ni(II)N₃ and aged Ni(OH)N₃ decompose with maximum rate from the beginning of the decomposition at all temperatures considered. Ni(OH)N₃ however shows an initial induction period and considerable acceleratory rates before the decay starts. Activation energies calculated from appropriate rate constants gave similar values for the exponential and decay regions for Ni(II)N₃ and aged Ni(OH)N₃ (147( 3 and 74(6KJ mol^-1 respectively) while those for Ni(OH)N₃ in the acceleratory and decay regions are 106KJ mole^-1 for both regions. The overall observation is that ageing of Ni(OH)N₃ brings about the removal of the induction period in the decomposition kinetics similar to fresh Ni(II)N₃.


KEY WORDS: Ageing, activation Energy, Thermal Conductivity, order of Symmetry, Azides


Global Jnl Pure & Applied Sciences Vol.10(1) 2004: 169-178