Papers by Keyword: CaBi₄Ti₄O₁₅

Abstract: Thin films of MBi₄Ti₄O₁₅ (M = Ca and Sr) with preferential crystal orientation were fabricated using underneath perovskite layers on various substrates. One-axis BLSD films on (100)LaNiO₃/(111)Pt/Ti/(100)Si and epitaxial BLSD films on (100)SrRuO₃//(100)SrTiO₃ were fabricated by chemical solution deposition (CSD). Dielectric constants of the CaBi₄Ti₄O₁₅ and SrBi₄Ti₄O₁₅ films on (100)LaNiO₃/(111)Pt/Ti/(100)Si were approximately 250, while those on (100)SrRuO₃//(100)SrTiO₃ were 220, respectively. The temperature coefficients of capacitance (TCCs) of these films were below 10% in atmospheric temperature range between R.T. and 300°C, which is significantly smaller than those of conventional (Ba,Sr)TiO₃-based capacitors.

Abstract: CaBi4Ti4O15 based thick films were prepared by screen-printing method on Si substrates. Screen-printable pastes were prepared by kneading the CaBi4Ti4O15 powder in a three-roll mill with an organic vehicle. The remanent polarization of 6.3 C/cm2 and coercive field of 130kV/cm were obtained for the CaBi4Ti4O15 with Nb2O5 1wt% thick film fired at 1130°C. The cavity structure was prepared by etching of Si substrate. The displacement-electric field butterfly curves were obtained.

Abstract: MBi4Ti4O15 (M=Ba,Ca) thick films were prepared by screen printing and firing using Pt bottom electrodes and ZrO2 substrates. Screen-printable pastes were prepared by kneading the MBi4Ti4O15 powder in a three-roll mill with an organic vehicle. The microstructures and electric properties of the thick films were examined in comparison with bulk ceramics. The remanent polarization of 6.2 9C/cm2 and coercive field of 130kV/cm were obtained for the CaBi4Ti4O15 thick film fired at 1130OC. The Curie points of MBi4Ti4O15 (M=Ba,Ca) thick films from dielectric peaks were 450OC and 790 OC for M=Ba and M= Ca.

Abstract: Nanocrystalline calcium bismuth titanate (CaBi4Ti4O15), which exhibits a layer structure, has been successfully synthesized by mechanical activation of constituent oxides of CaO, Bi2O3 and TiO2 in a nitrogen atmosphere at room temperature. The phase-forming calcination at elevated temperatures that is always required is skipped. CaBi4Ti4O15 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 1175oC for 2 hours. Ferroelectric properties of sintered CaBi4Ti4O15 derived from mechanical activation have been studied. A peak dielectric constant of 1049 at the Curie temperature of 774oC was measured at 1MHz for CaBi4Ti4O15 sintered at 1175oC.