Piezoelectric coupling coefficient

Analysts typically determine the piezoelectric properties of materials by studying the resonance characteristics of an appropriately shaped specimen subjected to a varied electric field. Details of the experimental setup are gjven in References 18 and 19- Investigations into the utility of PZT thin films for micromotors and other devices are also in progress. Fundamental properties of these films, such as piezoelectric coupling coefficients, have been measured by laser interferometry. ... 

Since pyroelectric ceramics are also piezoelectric, a temperature change also induces a change in the polarization due to the secondary pyroelectric effect, which is described by the product of the thermal expansion strain times the piezoelectric coupling coefficient. While this secondary effect can be large in polymers due to their large thermal expansion coefficients, in ceramics, it is typically small compared with the (first-order) pyroelectric effect. 

SAW component design is based on the application of an equivalent circuit model [29] using the values of the piezoelectric coupling coefficient of the material, Fo. and the static capacitance [30], The frequency at which the AW device operates depends on ... 

Due to the abandonment of piezoelectric properties for the matrix material, all of the piezoelectric coupling coefficients as well as the dielectric permittivity appear in a simplified form. 

Unlike the procedure laid out above, which introduces the factor C3, in the publications of Bent and Hagood [14,15] and Bent [13], the fraction is set to one only for the mechanical fields, while it is retained for the electrostatic fields. The resulting constitutive matrix of Eq. (5.27b) therefore becomes non-symmetric with respect to the piezoelectric coupling coefficients. Since the undermost line of the normal mode constitutive relation is not used there any further, this has no consequences. 

Fig. 5.11. Variation of the piezoelectric coupling coefficient 633 with the directional fiber fractions and V2. The values are normalized with respect to the bulk piezoelectric material and homogeneous electrostatic fields. Both substitution sequences are shown for different factors C3 the results are identical for the homogeneous conditions of C3 = 0.

Fig. 5.15. Variation of the induced strain piezoelectric coupling coefficient dss with the fiber volume fraction n experimental results from Chan and Unsworth [49] and finite element results from Poizat and Sester [143].

FIGURE 3.35 Dielectric constant and planar piezoelectric coupling coefficient for compositions near the morphotropic phase boundary in PZT. 

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