V. Yu. Topolov

Piezoelectric sensitivity of PbTiO3-based ceramic/polymer composites with 0-3 and 3-3 connectivity

This paper describes the modelling and comparison of piezoactive composites of 0–3 and 3–3 geometry. Algorithms for the evaluation of effective elastic, piezoelectric and dielectric constants are proposed which can be used for the prediction of piezoelectric sensitivity and optimisation of properties. The hydrostatic piezoelectric voltage coefficient gh, figure of merit d33·g33 and hydrostatic figure of merit dh·gh are calculated for PbTiO3 based piezocomposites in which the anisotropy factor d33 / d31 of the piezoelectric phase can be varied from small to infinitely large values. Maxima of these parameters are determined and factors influencing piezoelectric sensitivity of the composites are analysed.

The role of 90° domain wall displacements in forming physical properties of perovskite ferroelectric ceramics

Abstract A proposed model which takes into account an elastic interaction between a polydomain grain and a surrounding ceramic matrix under weak external mechanical stresses has been used for evaluating a contribution from 90° domain wall displacements to piezoelectric and elastic constants of the perovskite ferroelectric ceramics. A difference between experimental and averaged constants of BaTiO3 ceramics can be explained by the estimated contribution.

Ferroelectric ceramics with a large piezoelectric anisotropy

This review concerns the experimental and theoretical publications devoted to the important problem of the large piezoelectric anisotropy in -based polarized ferroelectric ceramics.

High-performance 1-3-type composites based on (1 − x)Pb(A 1/3 Nb 2/3 )O 3 - xPbTiO 3 single crystals (A = Mg, Zn)

This paper describes the concentration dependences of piezoelectric coefficients, squared figures of merit and electromechanical coupling factors which have been calculated for 1–3 and 1–0–3 piezo-active composites based on single crystals of relaxor-ferroelectric solid solutions of (1 − x)Pb(A1/3Nb2/3)O3–xPbTiO3 where A = Mg, Zn. The role of the single-crystal component, its electromechanical properties and the polymer matrix (monolithic or porous) in forming these concentration dependences is analysed to demonstrate the ranges in which effective composite parameters are most sensitive to material properties and composite architecture, with particular emphasis on where their maximum values are attained. The basic variables in this study are the chemical composition (x and A), volume concentrations of the single-crystal component, the presence of pores in the polymer matrix and the aspect ratio of the spheroidal pores. It has been shown that particularly high values of piezoelectric coefficient g ∗ ∼ 10 2 mV mN −1 and hydrostatic piezoelectric coefficients g ∗ ∼ 10 2 mV mN −1 and d ∗ h ∼ (10 2 –10 3 ) pC N −1 are expected in the 1–0–3 0.67Pb(Mg1/3Nb2/3)O3– 0.33PbTiO3 single crystal / porous araldite composite with spheroidal pores in the matrix.

A comparative study of different methods of evaluating effective electromechanical properties of 0-3 and 1-3 ceramic/polymer composites

The results of the evaluation of different effective parameters of 0-3 and 1-3 piezoactive composites are reported. For this, a matrix method previously developed for 2-2 connectivity is used and its application extended to 1-3 and 0-3 connectivities. Simulations are made with three perovskite-type ferroelectric ceramics and a vinylidene fluoride/trifluoroethylene piezoelectric polymer. Comparisons are shown and discussed between the different compositions, connectivities and other models and calculation methods. Particular attention is focused on factors leading to the appearance of extreme, discontinuity points and other features of effective parameters which are functions of volume concentrations of components (phases).

Polarization orientation effect and combination of electromechanical properties in advanced 0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 single crystal/polymer composites with 2–2 connectivity

A comparative study on the effective piezoelectric properties and hydrostatic piezoelectric response is first carried out for advanced 2?2 composites based on single crystals of relaxor-ferroelectric solid solutions. Different orientations of domains and different poling directions of components are taken into consideration in the analysis of the effective longitudinal piezoelectric coefficients d33*, e33*, g33* and hydrostatic piezoelectric coefficients dh*, eh* and gh*. The important role of the polarization orientation effect and the effect of combination of the electromechanical properties in attaining the large effective parameters is shown for the parallel-connected 2?2 single-domain 0.67Pb(Mg1/3Nb2/3)O3?0.33PbTiO3/polyvinylidene fluoride composite. In particular, near extremum points of the effective parameters, this composite is characterized by the piezoelectric coefficients g33*?500?mV?m?N?1, |dh*|?400?pC?N?1, |eh*|?40?C?m?2, and gh*?400?mV?m?N?1. Three piezo-sums are first found to describe major contributions of the piezoelectric coefficients dij*, eij* and gij* to dh*, eh* and gh*, respectively, in the vicinity of absolute maxima (minima) of the aforementioned hydrostatic parameters. Advantages concerned with the presence of the single crystal (either single-domain or polydomain) in the studied 2?2 composites are discussed in connection with their piezoelectric activity, sensitivity and hydrostatic response.

On the remarkable performance of novel 2–2-type composites based on [0 1 1] poled 0.93Pb(Zn1/3Nb2/3)O3–0.07PbTiO3 single crystals

The important role of the anisotropy of elastic and piezoelectric properties in the relaxor-ferroelectric 0.93Pb(Zn1/3Nb2/3)O3?0.07PbTiO3 single crystal poled along [0?1?1] of the perovskite unit cell has been stated in connection with the formation of the piezoelectric response of the 2?2-type piezo-active composites based on this single crystal. Different examples of the 2?2 single crystal/polymer and 2?2?0 single crystal/porous polymer composites have been studied in this work. Based on the non-monotonic volume fraction and orientation dependences of effective piezoelectric coefficients and figures of merit of the 2?2-type composites, we have shown their advantages. These advantages are associated with a presence of high piezoelectric activity and sensitivity, with variations of the effective piezoelectric coefficients , , and within wide ranges along with signs of the piezoelectric coefficients of the 0.93Pb(Zn1/3Nb2/3)O3?0.07PbTiO3 single crystal. Experimental values measured by Zhang et al (2006 Appl. Phys. Lett. 89 242908) obey the condition sgn 0 SRC=http://ej.iop.org/images/0022-3727/40/22/038/jphysd249720in006.gif/> that has a considerable influence on the piezoelectric performance and hydrostatic parameters of the studied 2?2 and 2?2?0 composites.

The remarkable orientation and concentration dependences of the electromechanical properties of 0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 single crystals

The present paper is devoted to evaluations of electromechanical constants of single-domain and multidomain relaxor-ferroelectric 0.67Pb(Mg1/3Nb2/3)O3– 0.33PbTiO3 single crystals near the morphotropic phase boundary. For the rhombohedral single crystal (3m class), piezoelectric coefficients and electromechanical coupling factors are calculated as functions of Euler angles. Features of orientation dependences of the piezoelectric coefficients and electromechanical coupling factors are first formulated and analysed. Two variants of concentration dependences of effective piezoelectric strain coefficients and electromechanical coupling factors are also first calculated, and the features of the piezoelectric activity of multidomain 0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 single crystals are discussed.

Porous piezoelectric composites with extremely high reception parameters

The reception parameters Q33* and Qh* of modified fiber composites based on high-e33FC/c33FC, E ferroelectric piezoceramics (e33FC is the piezoelectric constant, c33FC, E is the elastic modulus) are considered as functions of the electromechanical properties and the porosity of the components. Pore configurations at which the values (Q33*)2≈(Qh*)2≈7×10−9 Pa−1 for the polymer matrices of 1-0-3 composites are much higher than for conventional ternary composites are analyzed.

On a correlation between remanent polarization and piezoelectric coefficients of perovskite-type ferroelectric ceramics

It is shown that the dependence of the piezoelectric coefficients of BaTiO3 ferroelectric ceramics on the remanent polarization is monotonic due to the influence of the domain structure of the grains. The effect of the 90° domain structure of the grains on the non-monotonic behaviour of the piezoelectric coefficients and their anisotropy in PbTiO3 ceramics is discussed. It is established that contradictions between results of some recent papers are removed by taking into account the role of the domain structure in forming the piezoelectric response of ferroelectric ceramics.