14:45 〜 15:00
▲ [19p-W833-5] Electrical and Structural Properties of BiFeO3-BaTiO3 lead-free piezoelectric ceramics
キーワード：BiFeO3-BaTiO3 solid solution,lead-free
Lead-based piezoelectric bulk ceramics, such as Pb(Zr,Ti)O3, are used for various devices, because of their excellent piezoelectric properties. However, the toxicity of lead and its high vapor pressure have led to a demand for alternative lead-free piezoelectric materials that are environmentally benign from the viewpoint of sustainable development. Recently, the BiFeO3-BaTiO3 ceramics are kind of replacement lead-based piezoelectric materials. The BiFeO3-BaTiO3 lead-free piezoelectric ceramics have a potential to be applied at high operation temperature, because of their high curie temperature. The phase diagrams of BiFeO3-BaTiO3 lead-free ceramics were reported two different phase diagram. M. M. Kumar et al. reported that structure was changed from rhombohedral to cubic at 0.67BiFeO3-0.33BaTiO3 composition. On the other hand, S. O. Leontsev and R. E. Eitel reported that structure was changed from rhombohedral to pseudo-cubic structure at 0.75BiFeO3-0.25BaTiO3 composition. The information of phase transition composition is unclear in BiFeO3-BaTiO3 system.
In this study, (1-x)BiFeO3-xBaTiO3 (x = 0.25, 0.30, 0.33, 0.35, and 0.40) bulk ceramics were formed using solid state reaction method. The crystal structures were investigated using x-ray diffractometer. The crystal structures of solid solution ceramics are rhombohedral for 0.80BiFeO3-0.20BaTiO3, an intermediate structure between rhombohedral and pseudo-cubic for 0.75BiFeO3-0.25BaTiO3 and a pseudo-cubic structure from x = 0.30 to 0.40, respectively. The lattice parameters and cell volumes were increased with increasing BaTiO3 contents. The shapes of polarization-electric field hysteresis loops were changed from hard-type to soft-type, because BiFeO3 and BaTiO3 are hard-type and soft-type ferroelectrics. The remanent polarization were highest observed ~34 mC/cm2 at 0.75BiFeO3-0.25BaTiO3 composition. The coercive field were decreased with increasing BaTiO3 contents. The piezoelectric properties, strain value from Strain – Electric filed curves, were observed ~ 0.20% with 60 kV/cm in 0.70BiFeO3-0.30BaTiO3 composition. The negative strain were decreased with increasing BaTiO3 contents, because of decreasing coercive field. More detailed properties will be discussed in presentation.
In this study, (1-x)BiFeO3-xBaTiO3 (x = 0.25, 0.30, 0.33, 0.35, and 0.40) bulk ceramics were formed using solid state reaction method. The crystal structures were investigated using x-ray diffractometer. The crystal structures of solid solution ceramics are rhombohedral for 0.80BiFeO3-0.20BaTiO3, an intermediate structure between rhombohedral and pseudo-cubic for 0.75BiFeO3-0.25BaTiO3 and a pseudo-cubic structure from x = 0.30 to 0.40, respectively. The lattice parameters and cell volumes were increased with increasing BaTiO3 contents. The shapes of polarization-electric field hysteresis loops were changed from hard-type to soft-type, because BiFeO3 and BaTiO3 are hard-type and soft-type ferroelectrics. The remanent polarization were highest observed ~34 mC/cm2 at 0.75BiFeO3-0.25BaTiO3 composition. The coercive field were decreased with increasing BaTiO3 contents. The piezoelectric properties, strain value from Strain – Electric filed curves, were observed ~ 0.20% with 60 kV/cm in 0.70BiFeO3-0.30BaTiO3 composition. The negative strain were decreased with increasing BaTiO3 contents, because of decreasing coercive field. More detailed properties will be discussed in presentation.