Synthesis of Li-doped gamma-alumina nanopowders

Reference	Presenter	Authors (Institution)	Abstract
12-012	Rahpael Anacleto Martins Pires de Oliveira	de Oliveira, R.M.(Universidade de são Paulo); Gouvêa, D.(Universidade de São Paulo); Caliman, L.B.(Universidade de São Paulo);	Alumina is one of the main traditional ceramic materials. It that has several interesting characteristics, such as high melting point (2072°C), low density (3.95 g/cm3) and low refractive index (n=1.7282). Due to these characteristics, it is usually used for manufacturing refractory, polishing materials, sodium lamps among others. The nanoscale technology has made possible to obtain nano-Al2O3 pellets with high transparency. However, residual porosity and large grain size after sintering are problems that still need to be overcome. Thus, this project proposes the use of lithium as additive in order to manufacture transparent alumina. Lithium doping is expected to act in the transformation phase of gamma-alpha alumina. Nanometric powders were synthesized by the Pechini, with different LiCl molar concentrations (0.1, 0.5, 1, 3, 5 and 10 mol%), followed by calcination at 650ºC for 15h. The powders were characterized by XRD, XFR and BET specific surface area (SSA), and the lithium segregation, i.e., surface excess and grain boundaries excesses of nano alumina were determined by the lixiviation method. The DRX results show that the powders are majorly amorphous after calcinations and SSA values are between 85 and 150 m²/g.
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