In order to evidence the ligand influence on the thermal stability for Co(II) complex combinations, we have synthesized five
complex combinations of this metal with Schiff bases obtained by condensation of ethylenediamine with acetylacetone and benzoylacetone;
phenylenediamine with benzoylacetone and also anthranilic acid with benzaldehyde.
Kinetic parameters were determined for the decomposition reactions of some com plexes of cobalt, nickel, manganese, copper and cadmium halides and pseudohalides with ammonia, pyridine and substituted pyridines. For the zero order reactions, the values of the pre-exponential factors calculated assuming as limiting step the diffusion of the volatile component through the layer of the decomposed substance, are in satisfactory agreement with the experimental values.
A method is proposed for evaluation of the activation parameters for reactions which occur under non-isothermal conditions.
This method can discriminate between possible differential conversion functions. The proposed method, which was coded into
a software package available to the scientific community, is designed to solve an overdetermined systems of equations: dai/dt=k(Ti)f(ai) where i equations are to be considered (i can be the number of experimental points). Solution of this overdetermined system
with a pseudo-inverse matrix method furnishes the activation parameters and the parameters of the conversion function f(a).
Some examples of application of this method in non-isothermal kinetic analysis are presented.
The results obtained by studying zinc oxide non-stoichiometrization are presented. The kinetic parameters values under nonisothermal conditions were calculated too. Both the nonstoichiometric zinc oxide composition and the kinetic parameter values are depending on the generating substances.
A program for the evaluation of non-isothermal kinetic parameters is presented. The program allows evaluation of the kinetic
parameters under constant heating rate or constant reaction rate conditions. The simulation of temperature vs. conversion
curves is also possible. A regression method is included, which allows a discrimination between various conversion functions
and also evaluation of the activation parameters.
The program was tested with various simulated decomposition curves and the non-isothermal decomposition curves of calcium
oxalate. The program is written in Visual BASIC 4.0 and can be run under Windows 95 .
Authors:C. Popescu, I. Voicu, R. Alexandrescu, I. Morjan, D. Dumitras, M. Popescu, and D. Fatu
This paper reports on the synthesis of various iron oxides by the IR laser processing of different iron salts. X-ray diffraction
techniques were used to characterize the reaction products. Some differences in terms of crystallite size and isotropy between
these oxides and those obtained from the same salt by thermal means are described and explained.
Authors:A. Braileanu, M. Zaharescu, D. CriŞan, D. FĂtu, E. Segal, and C. Danciulescu
Former studies concerning the formation of the compounds in the pseudobinary systems of Bi2O3-MO type (M =Ca, Sr, Ca+Sr) have shown that the reaction which occurs with the highest rate is that between Bi2O3 and CaO. In the present work CaCO3 was used as CaO source. We carried out an investigation of the thermal decomposition of CaCO3 in the presence of Bi2O3 in comparison with the decomposition of pure CaCO3.