Vitaly Yu. Topolov

Orientation Effects in 1–3 Composites Based on 0.93Pb(Zn1/3Nb2/3)O3– 0.07PbTiO3 Single Crystals

This paper studies polarisation orientation effects in 1–3 composites with two piezo-active components. It is shown how the orientation of the main crystallographic axes in 0.93Pb(Zn 1/3 Nb 2/3 )O 3 –0.07PbTiO 3 single-crystal rods and the poling direction of a polyvinylidene fluoride matrix affect the volume fraction behaviour of the piezoelectric coefficients, squared figure of merit and hydrostatic parameters of the composites. For a fixed orientation, effective parameters calculated using the matrix approach are compared with those evaluated by the finite element method. Possible property advantages concerned with orientation effects, maxima of effective parameters and high performance of these composites are analysed taking into consideration the electromechanical properties of the components.

Analysis of the piezoelectric performance of modern 0–3-type composites based on relaxor-ferroelectric single crystals

Effective piezoelectric coefficients e 33*, d 33*, g 33*, and h 33*, squared figures of merit d 33*g 33* and dh *gh *, and other related parameters of novel 0–3 and 0–3–0 composites based on single crystals of relaxor-ferroelectric solid solutions of (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 are studied using the effective field method, effective medium method and finite element method. The volume-fraction dependences of a number of parameters and figures of merit are determined using the above methods and compared for composites with aligned prolate spheroidal inclusions. Four parameter ratios that determine interconnections between the effective electromechanical constants of the 0–3-type composites are first introduced. These parameter ratios are used to interpret the longitudinal dielectric and piezoelectric response of composite structures with prolate inclusions that exhibit high piezoelectric activity. The role of piezoelectric anisotropy and activity of the composite components in forming the longitudinal piezoelectric effect is analysed. Specific novel composite architectures with high piezoelectric sensitivity (longitudinal and hydrostatic) are identified and discussed.

Hydrostatic Piezoelectric Coefficients of the 2–2 Composite Based on [011]-poled 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 Single Crystal

The effect of the polarisation orientation of [011]-poled polydomain PMN-0.29PT single crystal on the hydrostatic piezoelectric coefficients and of a parallel-connected 2–2 composite has been analysed. Orientation and volume-fraction dependences of the piezoelectric coefficients of the 2–2 PMN-0.29PT/polymer composite have been studied to determine extreme points of and in three cases of rotations of the main crystallographic axes of the PMN-0.29PT single crystal. The largest values of the hydrostatic piezoelectric coefficients = 444 pC/N and = 33.1 C/m2 are of interest for hydroacoustic applications. Important contributions from the piezoelectric coefficients and into and , respectively, have been determined near the extreme points of the hydrostatic parameters.

Microgeometry, piezoelectric sensitivity and anisotropy of properties in porous materials based on Pb(Zr, Ti)O3

Relations between the microgeometry, piezoelectric sensitivity and piezoelectric anisotropy are studied in porous composite materials based on Pb(Zr, Ti)O3 ceramics. Systems of micrographs of cuts being parallel and perpendicular to the polarization direction are first shown for the porosity range vp = 0.05 - 0.57, and examples of microcracking at vp = 0.57 are considered. Experimental data on longitudinal and hydrostatic piezoelectric coefficients and squared figures of merit are represented as functions of vp, and nonmonotonic behavior of the piezoelectric anisotropy factor with increasing vp is analyzed in the context of changes in the microgeometry. Experimental results are compared to those derived from approximation formulae for the related porous ceramic.

Problem of Piezoelectric Sensitivity of 1–3-Type Composites Based on Ferroelectric Ceramics

A new anisotropic 1–3-type composite with high piezoelectric sensitivity is put forward, and trends in increasing the effective parameters characterising piezoelectric sensitivity are analysed. Effective piezoelectric coefficients and , squared figure of merit and related hydrostatic parameters , and are studied within the framework of the proposed model of the ferroelectric ceramic/porous polymer composite with 1–3–0 connectivity. Effects of porosity, microgeometry of pores and their orientation on the aforementioned piezoelectric coefficients and figures of merit of the 1–3–0 composite are studied to show its piezoelectric performance and high piezoelectric sensitivity. A comparison of the effective parameters to those known for the related 1–3-type composites based on ferroelectric ceramics is carried out, and some advantages concerning high piezoelectric sensitivity of the studied 1–3–0 composite are emphasised.

Maxima of Effective Parameters of Novel Piezo-Composites Based on Relaxor-Ferroelectric Single Crystals

This paper is devoted to the analysis of effective electromechanical properties and their maxima in 0–3-type composites based on (1 − x)Pb(Mg1/3Nb2/3)O3 − xPbTiO3 single crystals. It is shown that the electromechanical interaction between the single-crystal and polymer components with the anisotropy of their piezoelectric coefficients e33 (n)/|e31 (n)| ≥ 5 results in relations d33* ≈ e33*s33* E , g33* ≈ h33*s33* D , and k t * ≈ k33* for the electromechanical constants. These relations hold in a wide range of volume fraction and aspect ratio of the spheroidal inclusions in the 0–3 composite. An increase in the maximum values of different effective parameters is expected by forming a system of oblate air pores in the matrix.

Effect of the matrix subsystem on hydrostatic parameters of a novel 1–3-type piezo-composite

The influence of the aspect ratio and volume fraction of ferroelectric ceramic inclusions in a 0–3 matrix on the hydrostatic parameters of a three-component 1–3-type composite is studied to demonstrate the important role of the elastic properties of the two-component matrix on the composite performance. Differences in the elastic properties of the 0–3 matrix and single-crystal rods lead to a considerable dependence of the hydrostatic response of the composite on the anisotropy of the matrix elastic properties. The performance of a 1–0–3 0.92Pb(Zn1/3Nb2/3)O3–0.08PbTiO3 SC/modified PbTiO3 ceramic/polyurethane composite suggests that this composite system is of interest for hydroacoustic applications due to its high hydrostatic piezoelectric coefficients

Features of the Piezoelectric Response for a Novel Four-Component Composite Structure

d_{h}^{\ast} \approx \;

High Performance of Novel 1–3-Type Composites Based on Ferroelectric PZT-Type Ceramics

(400--500)

Piezoelectric Activity and Sensitivity of Novel Composites Based on Barium Titanate-Hydroxyapatite Composite Ceramics

\; \textrm{pC/N}