Lead zirconate titanate thick‐film ultrasonic transducer for 1‐ to 50‐MHz frequency bands fabricated by hydrothermal method

Abstract

This prototype ultrasonic transducer had about a 30‐μm thick hydrothermal PZT layer on a 50‐μm thick titanium substrate. An active area of this transducer was 3.5 mm in diameter. Material constants of this hydrothermal PZT thick film were measured. Electromechanical coupling coefficient kt was over 0.25 and acoustic impedance was 6 Mrayl. A mechanical resonance frequency in the thickness mode of the prototype ultrasonic transducer was approximated by a mason’s equivalent circuit using the thickness and the material constants of the hydrothermal PZT film and the Ti substrate. The prototype ultrasonic transducer had a double broad peak spectrum of about 15 and 30 MHz in simulation. Also, these broad peaks were a half wavelength and a quarter wavelength resonance frequency in a combined structure of the hydrothermal PZT thick film and the Ti substrate. The prototype ultrasonic transducer transmitted ultrasound in water. Experimental results were the prototype ultrasonic transducer radiated ultrasound at the frequency range from 1 to 50 MHz as wideband using respective resonance frequency. A reason for the wideband characteristics radiation of ultrasound was the prototype ultrasonic transducer has low acoustic impedance and double broad peak.