Dielectric and Ferroelectric Properties of Na_(0.42)K_(0.08)Bi_(0.5)TiO_3 and Na_(0.25)K_(0.25)Bi_(0.5)TiO_3 Relaxor Ceramics

摘要

Na_(0.42)K_(0.08)Bi_(0.5)TiO_3 (NKBT16) and Na_(0.25)K_(0.25)Bi_(0.5)TiO_3 (NKBT50) ceramics have been fabricated by the solid-state reaction. The dielectric responses show a tandem of relaxor-like anomalies, a broad maximum and a lower temperature hump. Temperature dependences of depolaration current of poled ceramics indicate that the lower temperature hump corresponds to the decay of spontaneous polarization. It is believed that at room temperature the ceramics would present polar clusters in a antiferroelectric matrix and electric field can suppress the relaxor behavior. NKBT50 exhibits a higher piezoelectric constant and a higher depolarization temperature. The use for device application has been indicated.