Structural phase stability and electric field induced relaxor–ferroelectric phase transition in (1 − x)(Bi0.5Na0.5)TiO3–xBaTiO3 ceramics

Abstract Structure, phase transition, and dielectric relaxor behavior have been investigated in morphotropic phase boundary compositions of (1 −  x )(Bi 0.5 Na 0.5 )TiO 3 - x BaTiO 3 ceramics for x  = 0.06, 0.07, and 0.075. In-situ structural thermal stability has been analyzed by using high-resolution synchrotron X-ray diffraction as a function of temperature. A transition sequence of rhombohedral + tetragonal − tetragonal − cubic phases is observed upon heating. The “rhombohedral + tetragonal” indicates a coexistence of rhombohedral R3c and tetragonal P4bm phases. The two-phase coexistence extends from room temperature to 200 °C. Zero-field dielectric permittivity reveals a frequency dispersion at low temperature region ( T T m ) and polar nanoregions below Burns temperature ( T B ). The two-phase coexistence plays a vital role for frequency dispersion below T m . Dielectric spectra of pre-poled samples reveal a field-induced ferroelectric−relaxor phase transition at depolarization temperature T d .