Layer structured calcium bismuth titanate by mechanical activation

Abstract

Nanocrystalline calcium bismuth titanate (CaBi 4Ti 4O 15), which exhibits a layer structure, has been successfully synthesized by mechanical activation of constituent oxides of CaO, Bi 2O 3 and TiO 2 in a nitrogen atmosphere at room temperature. The phase-forming calcination at elevated temperatures that is always required is skipped. CaBi 4Ti 4O 15 derived from mechanical activation consists of nanocrystallites, which occur as aggregates of ∼50 nm in sizes. It demonstrates an improved sinterability and was sintered to a density of 93.4% theoretical density at 1175°C for 2 hours. Ferroelectric properties of sintered CaBi 4Ti 4O 15 derived from mechanical activation have been studied. A peak dielectric constant of 1049 at the Curie temperature of 774°C was measured at 1MHz for CaBi 4Ti 4O 15 sintered at 1175°C.