Spatially-resolved relaxor to ferroelectric phase switching in 0.93Na1/2Bi1/2TiO3-0.07BaTiO3 ceramics

In situ, spatially-resolved synchrotron X-ray diffraction was utilized to investigate the electric field-induced heterogenous phase transformation of nonergodic relaxor 0.93Na1/2Bi1/2TiO3-0.07BaTiO3 ceramics. A Cu electrode was coated on one surface of a rectangular sample by aerosol deposition (AD), while a Pt layer was deposited on the opposite surface by sputter deposition. It is anticipated that a different stress state and/or domain morphology should occur on the AD deposited Cu electrode side due to the particle impact-consolidation deposition process. Under an electric field, different sample regions, i.e., AD, Middle, and Sputter sides, showed systematic changes in the relaxor to ferroelectric phase transition behavior. In particular, most <001> grains transformed at a sub-coercive field of 0.8 kV/mm, while the majority of the <111> grains only appeared to undergo transitions at a higher field (2.4 kV/mm). Also, the tetragonal phase became the dominant structure at higher field levels. Importantly, both <111> and <001> grains undergo phase switching at lower fields in the region close to the AD-processed layer. The study indicates that the AD process-induced stress can facilitate the electric field-induced relaxor to ferroelectric phase transition, i.e., the AD Cu side showed more significant lattice strain and domain texture than the sputter Pt side.