Electrical and physical properties of repoled PMN–PT single-crystal sliver transducer

Effects of the repoling process on the dielectric constant (ε33T/ε0) and electromechanical coupling factor bar mode (k′33) after array dicing for lead magnesium niobate–lead titanate (PMN–PT) single-crystal (SC) transducers of a rectangular bar (sliver) form have been investigated for the medical ultrasonic probe application. After the repoling a L 12.0×W 0.15×T 0.35mm sliver showed that ε33T/ε0 and k′33 increased from 4100 to 4500 and 87.2% to 88.6% on average, respectively. Cross-sectional observation of microstructure and a change of ε33T/ε0 values of the PMN–PT SC transducer revealed that the decreased properties of the sliver are attributable to partial depolarization, residual stress, and mechanical damage of the dicing surfaces. Thus, the repoling process of medical array probe is an effective method for improving the PMN–PT SC transducer.