Proton Conducting Ceramic Powder Synthesis by a Low Temperature Method

Molten salt synthesis (MSS) is a simple method for the preparation of ceramic powders with specific morphology. The main role of the molten salts is to increase the reaction rate and lower the reaction temperature. It occurs because of much higher mobility of reactants in the liquid medium than in the solid state. In this work the molten salt synthesis was applied to produce ceramic powders of La_0.995Ca_0.005NbO₄ and BaCe_0.9−x Zr _x Y_0.1O₃. Single-phase lanthanum niobate formed in all studied conditions of the synthesis, whereas in the case of barium cerate-zirconate MSS led to forming two crystalline phases: barium cerate and barium zirconate. The heating temperature and time as well as the salt content most strongly influenced the shape and size of particles. The influence of other parameters on the powder morphology was weaker. Despite differences in size and morphology, all groups of the La_0.995Ca_0.005NbO₄ powder obtained with the MSS method pressed into pellets and sintered gave a dense ceramic material. On the other hand in the case of barium cerate-zirconate regardless of synthesis and sintering conditions the ceramics were porous.