Kinetic analysis of the phase transformation from α- to β-copper phthalocyanine: A case study for sequential and parametric Rietveld refinements

The solid-state phase transformation from alpha- to beta-copper phthalocyanine, using isothermal data obtained at T=250 degrees C and nonisothermal data obtained in the temperature range of 30 degrees C <= T <= 330 degrees C with a constant heating rate of 1.67 degrees/min, was investigated by sequential and parametric full quantitative Rietveld analyses. Results obtained in this Study show that the parametric Rietveld refinement technique is most suitable and applicable for kinetic studies of isothermal powder diffraction data. On the other hand, the sequential Rietveld refinement technique can give reliable results for the kinetic analysis of nonisothermal data. The main advantages of the parametric Rietveld refinement over the sequential Rietveld refinement are increased robustness against outliers, low weight fractions, and noisy data and an increase in computational speed. (C) 2009 International Centre for Diffraction Data. [DOI: 10.1154/1.3194111]