Application of the model-free approach to the study of non-isothermal decomposition of un-irradiated and gamma-irradiated hydrated gadolinium acetylacetonate

作者：Mahfouz R M^*; Ahmed G A W; Alshammari M R

来源：Radiation Effects and Defects in Solids-Incorporating Plasma Science and Plasma Technology, 2014, 169(6): 490-498.

DOI：10.1080/10420150.2013.877909

• gamma-irradiation
• gadolinium acetylacetone
• non-isothermal decomposition
• Gd2O3 nanoparticles

The non-isothermal decomposition of unirradiated and gamma-irradiated hydrated gadolinium acetylacetone with 10(2)kGy gamma-ray absorbed dose was carried out in air and in nitrogen atmospheres and in the temperature range of 25-1000 degrees C. The results indicate that gadolinium acetylacetonate decomposes through four main decomposition steps leading to the formation of intermediate products whose chemical structure is independent of the gas atmosphere applied and on the investigated absorbed dose. The final product at 820 degrees C was found to be Gd2O3 irrespective of the gas atmosphere and the irradiation conditions. The non-isothermal data were analyzed using linear Flynn-Wall-Ozawa and non-linear Vyazovkin (VYZ) iso-conversional methods. The results of the application of these free models on the present kinetic data showed that the activation energy, E-a is independent of alpha in a very wide conversion range (0.1-0.9) indicating that the decomposition process is controlled by a unique kinetic model. The results of the model-fitting analysis showed that the decomposition course of the four decomposition steps of hydrated gadolinium acetylacetone was controlled by the D-3 Jander diffusion model. Pure phase of Gd2O3 nanoparticles was obtained by thermal oxidation of gamma-irradiated GdAcAc.3 H2O at 800 degrees C for 6h. X-ray diffraction, transmission electron microscopy (TEM) and atomic force microscopy (AFM) techniques were employed for characterization of the as-synthesized nanoparticles. This is the first attempt to prepare Gd2O3 nanoparticles by solid-state thermal decomposition of gamma-irradiated hydrated gadolinium acetylacetone.

• 出版日期2014-6-3