Acoustical transduction in two-dimensional piezoelectric array

Abstract

The acoustical transduction in an array of ferroelectric domains with alternating piezoelectric coefficients is characterized by multi-frequency resonances, which occur at the boundary of the acoustic Brillouin zone (ABZ). The resonances correspond to two successive domain excitations in the first and second ABZ correspondingly, where the speed of ultrasound is somewhat different. An important parameter for acoustical transduction is the electric impedance Z. The results of the theoretical and experimental investigations of Z in a periodically poled LiNbO3 are presented. The magnitude and phase of Z depend on the array parameters including domain resonance frequency and domain number; Z of arrays consisting of up to 88 0.45-mm-long domains in the zx-cut crystal are investigated. The strong changes in Z-magnitude and phase are observed in the range of 3–4 MHz. The two resonance zones are within 3.33 ± 0.05 MHz and 3.67± 0.05 MHz. The change in domain number influences Z and its phase. By varying the number of inversely poled domains and resonance frequencies, one can significantly control/change the electrical impedance of the multidomain array. The findings may be used for developing new acoustic sensors and transducers.