Ferroelectric Domain Morphology Evolution and Octahedral Tilting in Lead-Free (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-(Bi1/2Li1/2)TiO3-BaTiO3 Ceramics at Different Temperatures

摘要

Observations by in-situ transmission electron microscopy (TEM) reveal thechanges in domains morphology in0.885(Bi1/2Na1/2)TiO3-0.05(Bi1/2K1/2)TiO3-0.015(Bi1/2Li1/2)TiO3-0.05BaTiO3ceramics. Evolution of the macroscopic ferroelectric domains has been observedat 25 oC to 180 oC. The ferroelectric domains and their walls reduceprogressively with increasing temperature. In the selected-area electrondiffraction (SAED) patterns the crystallographic evidence of antiferroelectricdomain is not found over the temperature range, which provides the evidencethat the ferroelectric-antiferroelectric transition does not occur in theceramic. The temperature-dependent forbidden 3/2 1/2 0 and superstructure 3/21/2 1/2 reflections indicate the presence of an in-phase and anti-phaseoctahedral tilting in the ceramic, respectively. Dark-field TEM images showthat the size of the octahedral tilted domains is smaller than 30 nm across andthese domains are uniformly distributed in the grains. The influence of thelocalized octahedral titling on the stability of ferroelectric domains and thetemperature-dependent properties is discussed in this paper.