Electromechanical Properties of PbTiO3 Ceramics Containing La and Mn

Abstract

A piezoelectric ceramic material having low dielectric constant, high thickness coupling factor, high mechanical quality factor, high stability, and high operating temperature, has been prepared from PbTiO3 incorporated with 2.5 mol% of LaO12 and 1.0 mol% of MnO2. Typical electromechanical constants of this material are as follows: dielectric constant ε11T/ε0 230, ε33T/ε0 170; coupling factor k33 0.46, kt 0.46, k15 0.28, kp 0.07, k31 0.04; mechanical quality factor Q 1100, Poisson's ratio σE 0.20. Frequency constants Nt and N3t of the fundamental and third-harmonic thickness vibrations have temperature coefficients of −1.1 × 10−4°C−1 and −2 × 10−5°C−1, respectively. Aging rates of Nt and N3t, are +0.02% and −0.02%/time decade at 30°C, respectively. The Curie point of this material exists at 470°C, and k33 and kt increase gradually with temperature up to 400°C. This material has grain size of 2–3 μ and bending strength of 2 × 107 kg/m2, and can be polished into very thin plate. The PbTiO3 ceramics have a high potential for use in electromechanical devices at high frequency and high temperature.

First-principles Predictions of Structures and Piezoelectric Properties of PbTiO3Single Crystal

“…1. For the ferroelectric tetragonal phase of PbTiO 3 , the bulk modulus at the fully relaxed state is 0 104GPa K = which is comparable with the previous experimental results [12][13][14]. Based on the calculation data given in Fig.…”

“…In Table 3 we summarized all the values calculated with the various functionals, also the available experimental data were given [12][13][14]. As shown in this table, the calculated results strongly depend on the choice of the exchange-correlation functional.…”

Electromechanical Coupling Factors of Novel 0–3–0 Composites Based on PMN–xPT Single Crystals

“…2a-d) are comparable to those in anisotropic ferroelectric ceramics of modified PbTiO 3 (see, e.g., data in Ref. 9), however, in the wide m range, the values of ECFs k * 33 and k * t remain considerably larger than those of the aforementioned ceramics. As for the PMN-0.33PT SC, its ECFs k 33 and k t equal 0.94 and 0.64, respectively, and ratios of k 33 /k 31 = −1.59 and k t /k p = −0.674 are achieved [7].…”

90° domain wall relaxation and frequency dependence of the coercive field in the ferroelectric switching process

“…Then, it is possible to draw the following picture to explain the influence of defects on the coercive field behavior found in figure 3. When the domains are switched without the influence of defects (virgin sample), which means unpinned or weakly pinned by space charges, part of the 90 o domain walls 15 are able to follow the electric field switching up to high frequencies. However, the pinning of the 90° domain walls by space charges increases their coercivity, thus does not allowing their rearrangement at higher frequencies, which implies in a saturation of the coercive field at frequencies lower than that observed for an unpinned state.…”