GUSTAVO CARNEIRO CARDOSO DA COSTA
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Artigo IPEN-doc 16257 Comparative studies on properties of scandia-stabilized zirconia synthesized by the polymeric precursor and the polyacrylamide techniques2010 - COSTA, G.C.C.; MUCCILLO, R.ZrO2:Sc2O3 powders were synthesized by the polyacrylamide and the polymeric precursor techniques. The powder particles had the state of agglomeration analyzed by laser scattering, the structural phases by X-ray diffraction, and the morphology by scanning electron microscopy. The polyacrylamide and the polymeric precursor techniques produced stable transparent gels and polymeric resins, respectively. Upon calcination the gels and the resins yielded high surface area powders, fully stabilized in the cubic fluorite structure. The crystalline phases, grain morphology and electrical behavior of sintered pellets using powders synthesized by both techniques were analyzed. The amount of organics in the precursors was found to be responsible for the state of agglomeration of the particles, producing pellets with different electrical behavior.Artigo IPEN-doc 13764 Synthesis of scandia-stabilized zirconia nanoparticles by the polyacrylamide technique2008 - COSTA, G.C.C.; MUCCILLO, R.The synthesis of ZrO2:10 mol% Sc2O3 powders by the polyacrylamide technique was carried out using zirconium and scandium precursor solutions, acrylamide, N,N′-methylene-bisacrylamide and ammonium persulfate. The polymerization process occurred in few seconds and, without any precipitation, transparent polymeric gels were obtained. Calcination of the gels produced nanosized ceramic powders fully stabilized in the cubic fluorite structure. High specific surface area powders of 78 m2/g, corresponding to ~ 13 nm average particle size for an average crystallite size of 5 nm, evaluated by X-ray diffraction, were obtained after calcination at 500 °C. The powders were characterized by in situ high temperature X-ray diffraction and scanning electron microscopy. Pellets sintered at 1500 °C show high values of oxide ion conductivity.Artigo IPEN-doc 14732 High-temperature electrical properties of lanthanum beta-alumina solid electrolytes2009 - COSTA, G.C.C.; MUCCILLO, R.