Phase transition temperatures and electrical properties of divalent ions (Ca2+, Sr2+ and Ba2+) substituted (Bi1/2Na1/2)TiO3 ceramics

Phase transition temperature and electrical properties of divalent ions (Ca 2+ , Sr 2+ and Ba 2+ ) substituted (Bi 1/2 Na 1/2 )TiO 3 (BNT)-based ceramics were studied to investigate the relationship between the substituted ion and the effect on various characteristics. These ceramics were prepared by a conventional ceramic fabrication process. The behavior of the depolarization temperature, T d , slope depends on the substituted ionic radius before correspondence of the T d to the rhombohedral-tetragonal phase transition temperature, T R-T (0-3 at% for Ba 2+ -substituted BNT). The piezoelectric constant, d 33 , of Ca 2+ and Sr 2+ increased because of the increase of their free permittivity, e T 33 /e 0 , accompanying a decrease of T d . On the other hand, the d 33 of Ba 2+ -substituted BNT increased with increasing amount of Ba 2+ below 7 at% because Ba 2+ -substituted BNT has a MPB composition. Therefore, the d 33 of Ba 2+ 7 at% substituted BNT had a maximum of 152 pC/N. T d has a trade-off relationship with d 33 .