Comparison of mechanical cross talk in single crystal and ceramic periodic piezoelectric composite arrays

Ultrasonic array technology is used in many imaging applications across a wide range of industrial sectors, including underwater sonar. Lead based single crystal materials such as pzn-pt and pmn-pt provide the possibility of manufacturing sonar arrays with significantly increased sensitivity and bandwidth, compared to conventional arrays based on piezoelectric ceramic designs. To take full advantage of single crystal materials, it is essential that the active transducer array should be efficient, unimodal over the frequency range of operation and demonstrate a wide directional response from individual array elements. One solution, which offers significant advantages, involves piezoelectric composites, comprising a matrix of active piezoelectric elements embedded within a passive, usually polymeric, material. This paper describes a theoretical and experimental investigation into mechanical cross talk within 1-3 and 2-2 connectivity piezoelectric composite array configurations. The study incorporates both piezoelectric ceramic, lithium niobate and pmn-pt single crystal array designs, with the theoretical and experimental comparison based on impedance characteristics and cross talk between array elements. The electrical impedance and mechanical cross talk predicted using PZFlex with good agreement demonstrated. The design techniques obtained from PZFlex, are shown to produce arrays with low cross talk and therefore desirable beam patterns.