Direct Observation of the Polar State in the Relaxor Ba(Ti1-xZrx)O-3 by Transmission Electron Microscopy

作者：Tsukasaki H^*; Inoue Y; Koyama Y

来源：Ferroelectrics, 2014, 460(1): 18-33.

DOI：10.1080/00150193.2014.874888

• polar nanometer-sized region
• transmission electron microscopy
• domain structure
• Ba(Ti1-xZrx)O3
• relaxor ferroelectrics

In the ferroelectric mixed-oxide system Ba(Ti1-xZrx)O-3 (BTZ), an increase in Zr content results in the crossover from the ferroelectric M-A-type state with monoclinic symmetry to the relaxor state around x = 0.28. As a result of the crossover, BTZ is identified as the relaxor for x > 0.28. To understand the nature of the relaxor in BTZ, direct observations of the paraelectric (PE), M-A, and relaxor states for 0.17 <= x <= 0.40 was carried out between 400K and 87K by transmission electron microscopy with the help of the failure of Friedel's law. The observations indicated that polar nanometer-sized regions with (PE) and (PE) components were separately observed in the PE state above both T-c and T-m , which are, respectively, a transition temperature of the direct (PE -> M-A) transition and a maximum temperature of the real dielectric permittivity for the relaxor. During cooling from the paraelectric state above T-m in the relaxor, in the relaxor state below it, (PC)-component regions locally formed a 180 degrees domain structure, together with no coalescence of (PC) regions. It is thus understood that the M-A-to-relaxor crossover is characterized by the complete suppression of the coalescence of polar nanometer-sized regions with (PE) components. The relaxor state below T-m for 0.29 <= x <= 0.40 could be, as a result, identified as an assembly of polar nanometer-sized domains, presumably with monoclinic symmetry.

• 出版日期2014-2-17