A-site cation ordering and the glassy polarization behavior of lanthanum-modified lead zirconate titanate

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Abstract
The microstructure and dielectric behavior of lanthanum-modified lead zirconate titanate with 9 at.% lanthanum and a Zr/Ti ratio of 65/35 (PLZT 9/65/35) were investigated. By analyzing the frequency dependence of the temperature of the dielectric maximum (Tm) using the Volgel-Fulcher relationship, an activation energy and freezing temperature of 0.0393 ev and 347.4 K respectively, were obtained, showing that the polarization behavior of the sample bears resemblance to spin and dipolar glasses. Both selected-area diffraction (SAD) and high-resolution electron microscopy (HREM) reveal that {h+1/2, k+1/2, 0}-type superlattice exists in the sample. The lattice images of the ordered and the disordered regions were shown directly by HREM. The size of the ordered domains is from 10-20 nm. An ordered model with body-centered cubic superstructure on A-site cations was proposed. Based on the A-site cations ordering, the dielectric polarization behavior in different temperature range was discussed.