These components provide very high electromechanical coupling coefficient
, resulting in broader bandwidth and higher sensitivity than traditional piezoelectric bulk components.
Electromechanical Coupling Coefficients
. The electromechanical coupling coefficient
is an important characteristic of piezoelectric ceramics used to measure the energy conversion efficiency.
where [theta] is the electromechanical coupling coefficient
, [C.sub.p] is the capacitance coefficient, and V is the voltage.
The electromechanical coupling coefficient ([k.sup.2]) was obtained as follows:
The effect of thickness of Ti[O.sub.2] thin film on the phase velocity, electromechanical coupling coefficient, temperature coefficient of frequency, and ultraviolet sensitivity of device was investigated.
The property of importance is the electromechanical coupling coefficient
of the films, which is a function of the processing temperature.
The electromechanical coupling coefficient, kt, in the thickness direction, along with other characteristics, such as the mechanical quality factor, [Q.sub.m], and acoustic impedance, [Z.sub.a], have been found from measurements on the electrical impedance of the piezoelectric composites.
This discrepancy seen from the measurements of the electromechanical coupling coefficient may be because the composites consist of an electromechanical ceramic embedded into a polymer matrix.
The electromechanical coupling coefficient
, [k.sub.t], of the composites was found from an analysis of the impedance spectrum measured by a network analyzer (HP 8702A).
Trindade and Benjeddou  have discussed the critical evaluation and optimization of the effective electromechanical coupling coefficients of piezoelectric adaptive structures.
Benjeddou, "Effective electromechanical coupling coefficients of piezoelectric adaptive structures: critical evaluation and optimization," Mechanics of Advanced Materials and Structures, vol.
For applications requiring miniaturization, Morgan Technical Ceramics' PMN-PT28 single crystal piezoelectric material is manufactured in a high temperature crystal grown process, which exhibits very large electromechanical coupling coefficients
as well as high dielectric constants and low dielectric losses, resulting in more sensitive sensors and more efficient transducers and actuators.