Mechanosynthesis of perovskite LaGaO3 and its effect on the sintering of ceramics

Ceramic precursors with LaGaO3 composition have been obtained by mechanosynthesis of a stoichiometric mixture of La2O3 and Ga2O3 after 34 h of milling. Single and crystalline phase powders can be obtained at a temperature as low as 800 °C; while by classical solid state reaction the La4Ga2O9 secondary phase still appears after calcination at 1200 °C. The influence of the mechanosynthesis route on the sintering of the ceramics has also been studied. The reduction of the particle size by prolonged milling and the higher reactivity of the activated precursors cause a reduction of the maximum shrinkage rate temperature of 500 °C with respect to the solid state reacted precursors. Despite these facts, it is found that the ceramics sintered from classically obtained precursors have similar densities at the optimum conditions as the ones obtained by mechanosynthesis, but with lower purity. Mechanical activation is shown as a good alternative to synthesize LaGaO3 based ceramics with Sr and Mg doping, which are candidates for electrolytes in solid oxide fuel cells (SOFC), but care with the sintering strategies must be taken into account to assure a high density of the ceramics.