Influence of precursor calcination temperature on sintering and conductivity of Li1.5Al0.5Ti1.5(PO4)3 ceramics

ABSTRACT Li1.5Al0.5Ti1.5(PO4)3 (LATP) is the most promising electrolytes. LATP precursor was prepared by the co-precipitation method and calcined at 500–900°C to examine the influence of the calcination temperature on LATP pellets sintered at 1000°C. The calcination temperature exerted a large effect on the morphology of sintered LATP pellets, even though the sintering temperature was same for all the samples. Formation of voids was observed in the precursor powders calcined at 500, 600, 700, and 900°C, while no void was formed in the powder calcined at 800°C. The precursor powders calcined at low temperatures (500–700°C) were crystallized during sintering. This caused shrinkage of the particles, leading to the void formation. The precursor powder calcined at 900°C was more stable at the sintering temperature. Resulting in formation of porous pellets. These voids increase the grain-boundary resistance. As a result, the LATP pellets prepared from the precursor powder calcined at 800°C showed the highest conductivity (σtotal = 5.1 × 10？4 S cm？1) due to the relatively high crystallinity and stability of the precursor powder. It was concluded the calcination temperature applied to the precursor powders influences the properties of final sintered LATP pellets. The calcination temperature must thus be chosen carefully