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the application of the so called “third–law methodology” which reflects a marked difference in research philosophy. The PA theory basically assumes (among other assumptions) that the primary step of thermal decomposition consists in the nonequilibrium congruent dissociative evaporation of the reactant. These assumptions seem somewhat questionable inasmuch as they are not fully substantiated by experimental facts Indeed it is extremely difficult to test experimentally the conjectured primary congruent step, even in high vacuum, considering the extremely low volatility of the oxide products at decomposition temperatures. Thus although the author claims that the PA theory is generally better than the traditional Arrhenius-plot and second-law method, at least for a great part of ceramic oxides obtained from the thermal decomposition of their inorganic salts, the PA analysis can lead to results that are too speculative. In such a cases for the understanding of the kinetics of the thermal decomposition reaction it appears mandatory to couple the kinetics data from the thermal decomposition curves with the microstructure evolution of the produced oxides.

Useful bibliography

Papers

D.T. Beruto, Alan W. Searcy, Mun Gyu Kim, “Microstructure, kinetic, structure, thermodynamic

analysis for calcite decomposition: free-surface and powder Thermochimica Acta 424 (2004) 99-109 and references cited therein

bed

experiments”,

Boris V. L’vov “Application of the third-law methodology to the investigation of decomposition kinetics”, Thermochimica Acta 424 (1-2) (2004) 183-199. A review and refs cithed therein D.L. Hildebrand, K. H. Lau, R. D. Brittain,” Mechanistic aspects of metal sulfate decomposition

processes” High Temp. Science 26 (1988-1989) 427-440. B.V. L’vov, “The physical approach to the interpretation of the kinetics and mechanism thermal decomposition of solids: state of the art”, Thermochimica Acta 272 (2001) 97-124

of

C.H.Bamford,

C.F.Tipper,

“Comprehensive

chemical

kinetics,

Vol.22.

Reactions

in

the

solid

state”, Elsevier, Scientific Publishing Co.,1980

  • D.

    Beruto, J. Ewing, A.W. Searcy: “The nature of the CaO produced by calcite decomposition in vacuum and in CO2 , J. Amer. Cer. Soc. 62 (1979), 580

  • D.

    Beruto, L. Barco, A.W. Searcy,: “CO2-catalyzed surface area and porosity changes in high surface area CaO aggregates” J. Amer. Cer. Soc.67(1984)512.

  • A.

    Searcy and D. Beruto, “Kinetics of endothermic decomposition reactions.I. Steady-state chemical steps. II. Effects of solid and gaseous products”, Journal Physical Chemistry 80

    • (1976)

      425 ; ibidem 82 (1978) 163-67.

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