Lead Zirconate Titanate Hollow-Sphere Transducers

Millimeter-sized, hollow spheres of lead zirconate titanate were fabricated by blowing gas through a fine-grained slurry of PZT-5. After they were sintered, the spheres were poled in two ways: radially between inside and outside electrodes, and tangentially between two outside electrodes. The capacitance and vibration modes were modeled and measured for these two poling configurations. The two principal modes of vibration were a breathing mode near 700 kHz and a wall thickness mode near 10 MHz. These spheres have potential uses in medical ultrasound, nondestructive testing, and low-density transducer arrays.