Design of low-loss 1-3 piezoelectric composites for high-power transducer applications

Abstract

Lead zirconate titanate (PZT)/polymer 1–3 composites have improved electromechanical properties compared with monolithic counterparts, but possess a low mechanical quality factor, limiting their use in high-power transducer applications. The goal of this work was to improve the mechanical quality factor of 1–3 PZT/polymer composites by optimizing the polymer materials. Theoretical analysis and modeling were performed for optimum composite design and various polymers were prepared and characterized. 1–3 piezocomposites were constructed and their electromechanical properties were experimentally determined. The results demonstrated that the composites with high-thermal-conductivity polymers generally have degraded electromechanical properties with significantly decreased mechanical quality factors, whereas the composites filled with low-loss and low-moduli polymers were found to have higher mechanical quality factors with higher electrome-chanical coupling factors: Qm ~ 200 and kt ~ 0.68 for PZT4 composites; Qm ~ 400 and kt ~ 0.6 for PZT8 composites. The improved mechanical quality factor of 1–3 piezocomposites may offer improved performance and thermal stability of transducers under high-drive operation.

High Temperature, High Power Piezoelectric Composite Transducers

“…A low mechanical quality factor of the piezocomposites is due to the fact that high thermal conductivity polymers generally have relatively high values of elastic modulus, resulting in a high structural damping. In contrast, the composites filled with polymers that have low values of elastic modulus and losses offered relatively high mechanical quality factors, being >380–400, and consequently higher dynamic strains with respect to drive field under 50 °C isothermal condition [ 11 , 28 , 88 ], indicating that this kind of piezocomposites requires smaller input power to achieve the same level of output power compared to low mechanical quality factor counterparts, resulting in smaller heat generation, potentially overcoming the shortcoming of conventional piezocomposites.…”

Mechanically Rotating Intravascular Ultrasound (IVUS) Transducer: A Review

“…One of the inconveniences of employing composite structures is that it is difficult to secure the conditions of the composite structure, such as kerf and ceramic widths, to avoid lateral mode vibration as the frequency increases. For example, in a 1-3 composite structure, to avoid lateral mode vibration, the kerf and ceramic width should be less than v S /(2f) and v L /(2f), respectively, where v S , v L , and f are the shear wave velocity of the polymer filler, lateral wave velocity of the piezoelectric element, and thickness resonant frequency of the composites [ 155 ], respectively. For example, for an 1–3 piezo-composite structure for a center frequency of 60 MHz, a kerf width should be less than 10 μm.…”

Cold Sintering of PZT 2-2 Composites for High Frequency Ultrasound Transducer Arrays

“…The stopband edges are governed by the spatial scale, and lateral resonances (piezoelectrically coupled edge resonances). To avoid the lateral resonances, the width of the piezoelectric element and the kerf must be less than a fraction of the wavelength such that the stopband edge resonance frequency is well above the thickness mode resonance [21][22][23].…”