A 20 MHz single-element ultrasonic probe using 0.91Pb(Zn/sub 1/3/Nb/sub 2/3/)O/sub 3/-0.09PbTiO/sub 3/ single crystal

A 20 MHz single-element ultrasonic probe using 0.91Pb(Zn_1/3Nb_2/3)O₃-0.09PbTiO₃ (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 k₃₃ > 90%, which is much larger than the k₃₃ = 70 to 80% of conventional Pb(Zr_1-x,Ti_x)O₃ (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.