Design and fabrication of non-polymer transducers in the frequency range from 30 to 80 MHz [for biomedical imaging]

The material properties of coarse and fine grained lead zirconate titanate (PZT) materials in the frequency range from 30 to 80 MHz are examined. Mechanical losses increase rapidly and k_t (the thickness mode coupling coefficient) drops as the thickness mode resonator width approaches the grain size. At 50-MHz coarse-grained PZT exhibited a k_t of 0.38 and had mechanical losses of 11.0 dB/mm, while a fine-grained (high-density) PZT exhibited a k _t of 0.47 with mechanical losses of 6.2 dB/mm. Experimental and theoretical analysis of the performance of a 1×1 mm coarse-grained PZT device is presented. Two-way insertion loss of as little as 17.5 dB has been achieved for this device operating at 45 MHz. Fabrication methods are described