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Synthesis and Determination of the Kinetic Parameters for Non-Isothermal Decomposition of Complexes Ln(thd)3phen

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Abstract:

In this work the kinetics of the thermal decomposition of two ß-diketone lanthanide complexes of the general formula Ln(thd)3phen (where Ln = Nd+3 or Tm+3, thd = 2,2,6,6- tetramethyl-3,5-heptanodione and phen = 1,10-phenantroline) has been studied. The powders were characterized by several techniques. Thermal decomposition of the complexes was studied by non-isothermal thermogravimetry techniques. The kinetic model that best describes the process of the thermal decomposition of the complexes it was determined through the method proposed by Coats-Redfern. The average values the activation energy obtained were 136 and 114 kJ.mol-1 for the complexes Nd(thd)3phen and Tm(thd)3phen, respectively. The kinetic models that best described the thermal decomposition reaction the both complexes were R2. The model R2 indicating that the mechanism is controlled by phase-boundary reaction (cylindrical symmetry) and is defined by the function g(α) = 2[1-(1-a)1/2], indicating a mean reaction order. The values of activation energy suggests the following decreasing order of stability: Nd(thd)3phen > Tm(thd)3phen.

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Periodical:

Materials Science Forum (Volumes 530-531)

Pages:

506-512

DOI:

https://doi.org/10.4028/www.scientific.net/MSF.530-531.506

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Online since:

November 2006

Authors:

Wilton Silva Lopes, Crislene Rodrigues da Silva Morais, A.G. de Souza

Keywords:

Coats-Redfern, Lanthanide, Non-Isothermal Thermogravimetry, β-Diketone

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© 2006 Trans Tech Publications Ltd. All Rights Reserved

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