Preparation and characterization of perovskite ceramic powders by gelcasting

Perovskite La0.6Sr0.4Co0.8Fe0.2O3-delta (LSCF) powders have been successful ly synthesized from oxide and carbonates based on the principle of gelcasti ng. Phase-forming temperature is very dependent on the ball-milling process during the suspension preparation. As the ball-milling time is increased, the temperature of phase formation decreases, therefore the perovskite powd er obtained has a larger Brunaver-Emmett-Teller (BET) specific surface area . The grain sizes were around 1 mu m at 1000 degrees C and 2 mu m at 1100 d egrees C from scanning electron microscopy (SEM) photographs. The perovskit e powders have good sinterability: the sintering densities of ceramic bodie s shaped with as-prepared powders were investigated. SEM photos show that s intered ceramics exhibit a well defined morphology in the packing and sinte ring of particles. The oxygen permeance of disc shaped samples, with a thic kness ranging from 1.02 to 1.98 mm was 6.39 x 10(-8) - 1.99 x 10(-8) mol cm (-2) s(-1) at 900 degrees C indicating that LSCF ceramics have high oxygen permeation. It can be concluded that gelcasting is a simple and effective m ethod for preparing practical multicomponent perovskite powders. (C) 1999 K luwer Academic Publishers.