Abstract: | The grain boundary resistivity problem of highly conductive bulk Li0.34La0.55TiO3 perovskite has been investigated by means of impedance spectroscopy and solid‐state NMR of samples processed in controlled atmospheres. The samples were sintered in air, synthetic air, and oxygen, in which the level of moisture varied. A dry atmosphere is critical to obtain dense ceramics with a low grain boundary resistivity. The grain boundary conductivity is five times higher for samples sintered in oxygen atmosphere due to the suppression of Li2CO3 secondary phase formation, which is responsible for low lithium ion diffusion at the grain boundary. |