Evaluation of PbTiO3‐based piezoelectric ceramics for hydrophone applications

Abstract

PbTiO3‐based ceramics recently developed by Toshiba scientists have interesting implications for conventional hydrophone design. They exhibit virtually no coupling in the 31‐mode while the 33‐mode is strongly coupled, yielding a high hydrostatic voltage coefficient (gh). The possible application of this material in hydrophones was investigated by comparing the theoretical performance of a PZT‐5H cylinder with capped ends to a PbTiO3 disk. Particular attention is paid to calculating the signal‐to‐noise performance because of the low permittivity of this material. It was found that this parameter is only slightly affected in the presence of a low‐noise preamplifier, but it will probably not be acceptable for measuring water noise levels. Sensitivity measurements obtained from a PbTiO3 disk suspended in a rubber boot filled with castor oil gave predictable results. The responses were flat to within ±2 dB up to the thickness resonance. It is indicated that the PbTiO3‐based hydrophone generally compares favorably with the conventional PZT designs. The PbTiO3‐based hydrophone offers the advantages of a superior wideband performance and a very simple construction. It should also be ideally suited to deep submergence applications.