In this study, a series of (1 - x)(Ba0.95Ca0.05)(Ti0.95Zr0.05)O3-x(Bi0.5Li0.5TiO3) ceramics (x = 0-0.007) codoped with Bi and Li elements were prepared by solid-phase sintering. Bi/Li codoping induces lattice distortion, reduces domain size, and increases tetragonal phase content, thereby enhancing the comprehensive performance of the BCTZ ceramics. The 0.994BCTZ-0.006BLT ceramic exhibits optimal performance: piezoelectric coefficient d33 = 270 pC/N, remnant polarization Pr = 7.3 μC/cm2, Curie temperature Tc = 112 °C, electromechanical coupling factors kp = 0.19 and kt = 0.45, sound velocity c = 5200 m/s, and dielectric loss tan δ = 0.0222. A 10 MHz planar ultrasonic transducer fabricated from this ceramic shows a pulse-echo peak-to-peak voltage Vpp of 206.74 mV, center frequency fc of 11.01 MHz, -6 dB bandwidth of 57.9%, and lateral resolution Rlateral of 0.95 mm. After acoustic focusing, the transducer's performance is further improved: Vpp = 233.53 mV, fc = 10.25 MHz, -6 dB bandwidth = 72.48%, and the lateral resolution Rlateral = 0.64 mm. Imaging tests on coins and porcine eyeballs demonstrate clear surface details/patterns of coins and excellent visualization of the conjunctiva, cornea, lens, and iris. This demonstrates its potential in the nondestructive testing and biological imaging fields.
Dong et al. (Mon,) studied this question.