Abnormal grain growth and electrical properties of Ba-excessive La-doped BaTiO3 ceramics prepared from nanopowder synthesized by sol-gel method

Nanopowder is frequently employed in the fabrication of miniaturized multilayer devices due to the advantage of small particle size. In this work, sol-gel method was employed for the synthesis of Bax-0.003La0.003TiO3 nanopowders. Abnormal grain growth was observed in the Ba-excessive composition at a relatively low sintering temperature. This result was inconsistent with previous reports that grain growth was suppressed in the Ba-excessive BaTiO3 ceramics. Combining a comparison study, BaCO3, second phase in the powder with x = 1.03, was confirmed to be responsible for the abnormal grain growth. Based on the results of SEM, XRD, TG-DTA and electrical properties, it is reasonable to speculate that BaCO3 and oxygen vacancy formed during reduction sintering together triggered the reactive liquid-phase sintering in the Bax-0.003La0.003TiO3 ceramics with x = 1.03. Thus abnormal grain growth occurred, meanwhile, semiconducting grains was formed.