Effect of phase transitions on thermoluminescence characteristics of nanocrystalline alumina

Nanocrystalline boehmite (gamma-AlOOH) was synthesized by hydrothermal method using AlCl3 center dot 6H(2)O and Urea as precursors. The material gets decomposed to form the gamma-Al2O3 phase at around 873 K on annealing in air. On annealing further at higher temperatures it gets converted into different phases, such as, delta, theta and the most stable alpha-phase. Not only the phase changes but the annealing has also changed the morphology of the nanomaterial, i.e. it has changed from spindle like edges to vermicular structures and also grew bigger in sizes. The formations of different phases were confirmed by the X-ray diffraction (XRD) patterns and the changes in the morphology were seen through the TEM images. Further the effect of different phases on the thermoluminescence (TL) glow curve structures was studied and it is also shown that the TL glow curves structures do change due to phase transformations. To investigate further and to determine trapping parameters, different glow curves have been theoretically deconvoluted using computerized glow curve deconvolution (CGCD method) into simple glow peaks. The values of different trapping parameters also change as the glow curve structures on phase transformations due to reorganization of energy levels and the stress/strain generated by some intermediate phases. (C) 2013 Elsevier B.V. All rights reserved.