Kinetic study of isothermal crystallization process of Gd2Ti2O7 precursors powder prepared through the Pechini synthetic approach
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Crystallization process of Gd2Ti2O7 precursors powder prepared by Pechini-type polymerized complex route has been studied under isothermal experimental conditions in an air atmosphere. It was found that the crystallization proceeds through two-parameter Sestak-Berggren (SB) autocatalytic model, in the operating temperature range of 550 degrees C LT = T LT = 750 degrees C. Based on the behavior of SB parameters (M, N), it was found that in the lower operating temperature range, the crystallites with relatively low compactness exist, which probably disclosed low dimensionality of crystal growth from numerous nucleation sites, where the amorphous solid is produced. In the higher operating temperature region (above 750 degrees C), it was established that a morphological well-defined and high-dimensional particles of the formed pyrochlore phase can be expected. It was found that at T=850 degrees C, there is a change in the rate-determining reaction step, from autocatalytic into the contract...ing volume mechanism. (C) 2015 Elsevier Ltd. All rights reserved.