A 20 MHz single-element ultrasonic probe using 0.91Pb(Zn1/3Nb2/3)O3-0.09PbTiO3 single crystal

A 20 MHz single-element ultrasonic probe using 0.91Pb(Zn1/3Nb2/3)O-3-0.09PbTiO(3) (PZN-PT 91/9) single crystal has been fabricated. The single crystal of PZN-PT 91/9 orientated to the (001) plane has longitudinal coupling factor of k(33) > 90%, which is much larger than the k(33) = 70 to 80% of conventional Pb(Zr1-xTix)O-3 (PZT) based ceramics. A single crystal of PZN-PT 91/9 without inclusion or crack has been grown with dimensions of about 25 x 15 x 5 mm by the self-flux method. Because mechanical strength in the fabrication of disk transducers orientated to the (001) plane was sufficiently strong, under the same conditions as are applied to conventional PZT ceramics, a piston single-element probe with a diameter of 2.0 mm and a frequency of 20 MHz was successfully fabricated. The bandwidth of the PZN-PT 91/9 probe was 13-26 MHz, which was 4 MHz broader than that of the conventional PZT probe.