Layer structured calcium bismuth titanate by mechanical activation

Nanocrystalline calcium bismuth titanate (CaBi4Ti4O15), which exhibits a layer structure, has been successfully synthesized by mechanical activation of mixed oxides of CaO, Bi2O3 and TiO2 for 30 h in a nitrogen atmosphere at room temperature, and therefore, the phase-forming calcinations that is always requested at an elevated temperature is skipped. The resulting CaBi4Ti4O15 phase is composed of fine particles of about 50 nm in size. It was sintered to a density of 93.4% theoretical density at 1175 degreesC for 2 h. Sintered CaBi4Ti4O15 exhibits a maximum dielectric constant of 1049 at the Curie point of 774 degreesC, when measured at 1 MHz. (C) 2004 Elsevier B.V. All rights reserved.