Piezoelectric Performance and Hydrostatic Parameters of Novel 2–2-Type Composites

This paper provides a detailed study of the structure-piezoelectric property relationships and the hydrostatic response of 2-2-Type composites based on relaxor-ferroelectric 0.72 Pb (Mg
_1/3
Nb
_2/3
)O
₃
-0.28PbTiO
₃
single crystal (SC) material. Type I layers in the composite system are represented by a single-domain [111]-poled SC. Changes in the orientation of the crystallographic axes in the Type I layer are undertaken to determine the maximum values of the hydrostatic piezoelectric coefficients d
_h
*, g
_h
*, and e
_h
*, and squared figure of merit d
_h
* g
_h
* of the composite. The Type II layers are a 0-3 composite whereby inclusions of modified PbTiO
₃
ceramic are distributed in a polymer matrix. A new effect is described for the first time due to the impact of anisotropic elastic properties of the Type II layers on the hydrostatic piezoelectric response that is coupled with the polarization orientation effect in the Type I layers. Large hydrostatic parameters g
_h
* ≈ 300-400 mV · m/N, e
_h
* ≈ 40-45 C/m
²
, and d
_h
* g
_h
* ~ 10
^-11
Pa
^-1
are achieved in the composite based on the 0.72 Pb(Mg
_1/3
Nb
_2/3
)O
₃
-0.28PbTiO
₃
SC. Examples of the large piezoelectric anisotropy (|d
₃₃
*/d
_3f
*| ≥ 5 or |g
₃₃
*/g
_3f
*| ≥ 5) are discussed. The hydrostatic parameters of this novel compositesystem are compared to those of conventional 2-2 piezocomposites.