Comparing Different Electrodes of Piezoelectric Single Crystal Composites for Underwater Acoustic Transducers

Electrodes are critical to piezoelectric single crystal composites (PSCCs) as they directly determine the efficiency and reliability of piezoelectric devices. Currently, a comprehensive comparison of the major properties of different electrodes on PSCCs, particularly their adhesive performance, is highly needed because the cross-linked structure and large surface-displacement fluctuations of PSCCs likely cause the peeling and failure of electrodes. Herein, we compared electronic conductivity and adhesive performance of different electrodes for PSCCs including magnetron sputtering Au (MS Au), electron beam evaporation Au (BE Au), and low-temperature silver paste (LTSP) electrodes. The results demonstrate that the LTSP electrodes exhibited the highest adhesion strength of 3.5 MPa compared to MS Au (2.1 MPa) and BE Au (0.9 MPa) electrodes on PSCCs. In addition, the adhesion strength of electrodes on PSCCs was lower than that on piezoelectric single crystals owing to the existence of the polymer phase. In terms of electrical conductivity, the LTSP electrodes displayed the highest resistivity of 2.25 × 10–6 Ω·m, and MS Au and BE Au electrodes showed similar resistivities of 6.8 × 10–8 and 7.6 × 10–8 Ω·m, respectively. This work provides important information in choosing electrodes for PSCCs, thus benefiting the design for underwater acoustic transducers.