| 摘要 |
PURPOSE: A lead-free piezoelectric ceramics for a sensor and an actuator is provided to improve dielectric ratio and piezoelectric constant by arranging paraelectric materials of small sizes around ferroelectric materials of large sizes and forming the trap structure. CONSTITUTION: A lead-free piezoelectric ceramics for a sensor and an actuator is composed of paraelectric materials and ferroelectric materials. The paraelectric materials and the ferroelectric materials are mixed at the volume ratio of 1 : 5-20. The sizes of the paraelectric materials are smaller than the sizes of the ferroelectric materials. The paraelectric materials are piezoelectric materials which are arranged around the ferroelectric materials. When electric field is generated in the piezoelectric materials, the paraelectric phase is changed into ferroelectric phase and the domain of the ferroelectric phase is changed. The ferroelectric material is composed of (Bi0.5Na0.5)TiO3 or (Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3-based materials. The paraelectric material is obtained by mixing an additive for lowering phase-change temperatures into the ferroelectric materials. |
