Grain boundary and surface area evaluation of Ca or Mg-doped SnO2 nanopowders

Reference	Presenter	Authors (Institution)	Abstract
12-059	Gilberto José Pereira	Pereira, G.J.(Centro Universitário da FEI); Batista, F.(Centro Universitário da FEI);	Tin oxide powders doped with different amounts of $M{g}^{2+}$ or $C{a}^{2+}$ were synthesized by the polymeric precursor method (modified Pechini). Previous works in the literature point out to additive segregation onto the particles surfaces, leading to macroscopic characteristics similar to MgO or CaO. The powders were submitted to acid washing in order to remove segregated cations from the surface. Lixiviated powders were calcined at different temperatures up to 500°C and specific surface area has decreased pronouncedly between 450 and 500°C. Since a fraction of the cations was removed, the responsible for reduction on total area was the free surface. The washing procedure showed that in concentrations about 1% molar ratio, cations probably are located at solid-solid interfaces and, grain boundary area (calculated to be about 15 $m^2.g^{-1}$) kept constant, because the most probable location for dopants is the solid-solid interfaces, which can not be reached by lixiviation solution. Also, total surface area was proportionally increased with the temperature calcination.
<< Back