Journal of Thermal Analysis and Calorimetry

, Volume 87, Issue 3, pp 841–845 | Cite as

Study of isothermal decomposition of lanthanide mixed complexes with 2,2,6,6-tetramethyl-3,5-heptanodione and 1,10-phenanthroline

  • W. S. Lopes
  • Crislene R. S. Morais
  • A. G. Souza
  • V. D. Leite
  • B. D. de A. Firmo


Isothermal decomposition kinetic of three lanthanide mixed complexes with the general formula of Ln(thd)3phen (where Ln=Nd3+, Sm3+ or Er3+, thd=2,2,6,6-tetramethyl-3,5-heptanodione and phen=1,10-phenanthroline) has been studied in this work. The powders were characterized by their melting point, elemental analysis, FTIR spectroscopy and thermogravimetry. The isothermal TG curves have been recorded under the same conditions at 265–285, 265–285 and 250–270°C for Nd(thd)3phen, Sm(thd)3phen and Er(thd)3phen, respectively.

The kinetic parameters, i.e. activation energy, reaction order and frequency factor were obtained through the technique of lineal regression using the relation g(α)=kt+g 0. The analysis was done at decomposed fractions between 0.10–0.90. The values of activation energy were: 114.10, 114.24 and 115.04 kJ mol–1 for the Nd(thd)3phen, Sm(thd)3phen and Er(thd)3phen complexes, respectively. The kinetic models that best described the isothermal decomposition reaction the complexes were R1 and R2. The values of activation energy suggests the following decreasing order of stability: Nd(thd)3phen<Sm(thd)3phen<Er(thd)3phen.


activation energy β-diketone isothermal kinetic lanthanide mixed complexes 


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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • W. S. Lopes
    • 1
  • Crislene R. S. Morais
    • 2
  • A. G. Souza
    • 3
  • V. D. Leite
    • 1
  • B. D. de A. Firmo
    • 1
  1. 1.Departamento de Química, Centro de Ciências e TecnologiaUniversidade Estadual da ParaíbaBodocongóBrazil
  2. 2.Departamento de Engenharia de Materiais, Centro de Ciências e TecnologiaUniversidade Federal de Campina GrandeBodocongóBrazil
  3. 3.LTM, Departamento de Química, Centro de Ciências Exatas e da NaturezaUniversidade Federal da ParaíbaJoão PessoaBrazil

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