PZT8 and PZT4 (Navy Types III and I) are the common “hard” piezoceramic materials used in power ultrasonic transducers. PZT piezo materials are comprised from the inorganic oxide compounds of lead (Pb), zirconium (Zr)and titanium (Ti). Fig. 1(a) highlights the differences in the vendor provided material properties for PZT8 and PZT4 typically used by transducer designers. This research is a case study on the performance of identical ultrasonic transducers used for semiconductor wire bonding, assembled with either PZT8 or PZT4 materials. Fig. 1(b-c) shows the diced PZT parts used for these transducers, along with the d31 Bode plot technique and equivalent circuit (DeAngelis et al., 2014). Fig. 2 shows the typical d31 Bode plot results for the individually diced plates of PZT8 and PZT4 vibrating in the width “W” direction. The wave speed c (i.e. frequency) and mechanical quality factor Qm are lower for PZT4, but the effective electromechanical-coupling factor k is about the same (not higher for PZT4 as per vendor k33 properties); it should be noted that catalog properties have ±20% tolerance.