Performance Analysis of Single Crystal PMN-PZT Unimorphs for Piezoelectric Energy Harvesting

This paper presents the performance analysis of the single crystal piezoelectric ceramic PMN-PZT (where PMN stands for lead magnesium niobate and PZT stands for lead zirconate titanate) for piezoelectric energy harvesting. Unimorph cantilevers using PMN-PZT layers with Al (aluminum) and SS (stainless steel) substrates are tested under base excitation for a wide range of load resistance (from 10 ohms to 2.2 Mohms). Electrical power generation performance of the unimorphs using PMN-PZT is compared against that of the unimorphs using the conventional piezoelectric ceramic PZT-5H with Al and SS substrates. For both substrates, it is observed that the power density (power output per device volume) and the specific power (power output per device mass) results of the unimorphs using PMN-PZT are about two orders of magnitude larger than those of the unimorphs using PZT-5H. Outstanding power generation performance of the unimorphs with PMN-PZT is associated with stronger resistive shunt damping effect compared to unimorphs with PZT-5H. In addition to the experimental analyses and comparisons, power generation and shunt damping results of a single crystal unimorph are successfully predicted by using a distributed parameter electromechanical model. Results show that single crystal PMN-PZT is a very strong interface for piezoelectric energy harvesting and shunt damping. However, the improved power generation and shunt damping performance of PMN-PZT comes with reduced robustness due to the brittle nature of the single crystalline structure.