Piezoelectric Properties of Pb1−xLax(Zr0.52Ti0.48)1−x/4O3 Thin Films Studied by In Situ X-ray Diffraction

Abstract

The piezoelectric properties of lanthanum-modified lead zirconate titanate Pb1−xLax(Zr0.52Ti0.48)1−x/4O3 thin films, with x = 0, 3 and 12 mol% La, were studied by in situ synchrotron X-ray diffraction under direct (DC) and alternating (AC) electric fields, with AC frequencies covering more than four orders of magnitude. The Bragg reflections for thin films with low lanthanum concentration exhibit a double-peak structure, indicating two contributions, whereas thin films with 12% La possess a well-defined Bragg peak with a single component. In addition, built-in electric fields are revealed for low La concentrations, while they are absent for thin films with 12% of La. For static and low frequency AC electric fields, all lanthanum-modified lead zirconate titanate thin films exhibit butterfly loops, whereas linear piezoelectric behavior is found for AC frequencies larger than 1 Hz.

Time-resolved piezoelectric response in relaxor ferroelectric (Pb0.88La0.12)(Zr0.52Ti0.48)O3 thin films

“…S6 in the supplementary material and which are similar to the results reported in ref. [32]. The strain increases, particularly for negative voltage pulses, with increasing applied voltage agreeing with the inverse piezoelectric effect:   = d33 E3.…”

“…In the present study, a polycrystalline relaxor ferroelectric PLZT 12/52/48 thin film was investigated by time-resolved synchrotron X-ray diffraction. These studies built on in situ X-ray diffraction during the application of DC and AC voltages revealing asymmetric butterfly loops of the piezoelectrically-induced strain as a function of the applied electric field, which evidence a built-in electric field in the thin film, which is oriented from the top electrode towards the bottom electrode [32]. Applying PUND (Positive-Up Negative-Down) pulse sequences with frequencies ranging from 15 precursors.…”

On the photovoltaic effect asymmetry in ferroelectrics

“…This asymmetry can be further increased by the asymmetry in coercive electric fields after positive and negative poling known as internal bias field (figure 2(c) (inset)). As a result, the measured deformation along the poled direction exhibits remanent tension The resulting piezoelectric loop is therefore not symmetric (figure 2(d)) as often reported for many piezoelectric samples [56][57][58][59][60]. From the comparison between deformation measurements and PV responses it is evident that a tension along the polarization direction (state 1, obtained after positive poling) is more favourable for PV effect, in contrast to compression (state 16).…”