Three layer perovskite-like structured Pr3Ti2TaO11 ferroelectrics with super-high curie point

Abstract

© 2014 The American Ceramic Society. Pr3Ti2TaO11 was prepared by co-precipitation and subsequent solid-state reaction at 1300°C. The compound has a perovskite-like layered structure belonging to space group Pmc21 with unit cell parameters a = 3.8689(3) A˚, b = 20.389(2) A˚, c = 5.5046 (5) A˚. Second harmonic generation results confirm the structure of Pr3Ti2TaO11 as being noncentrosymmetric. Dense and textured ceramics were prepared by spark plasma sintering. Analysis of the X-ray diffraction and transmission electron microscopy results showed that Pr3Ti2TaO11 ceramics have an n = 3 (type II) heteroblock structure consisting of alternating n = 2 and 4 octahedral oxide layers. High-resolution electron microscopy revealed the layered structure to be highly disordered, with faulting of the heteroblock structure and the coexistence of a n = 4 phase on a fine scale (nm), which was evident as a broadening of the X-ray diffraction peaks of the ceramics. Pr3Ti2TaO11 ceramic exhibits a super-high Curie point (1415 ± 5° C). A small, but measurable piezoelectric constant d33 between 0.1 and 0.2 pC/N was detected for the samples poled above 900°C under an electric field of 100-200 V/cm.