Mechanical and electrical properties of Na0.55K0.45NbO3 + 0.2% MnO/Al2O3 composites for energy harvesting applications

Abstract

Abstract To increase the power output of piezoelectric energy harvesters, there are several options that have been the focus in a number of scientific studies. This work explores a new concept, by using ceramic/ceramic composites (Na0.55K0.45NbO3 + 0.2% MnO/Al2O3) for energy harvesting applications. The idea of increasing the elastic properties to maintain a sufficient power output is used. Mechanical and electrical properties of these composites with varying Al2O3 content have been evaluated to determine the energy harvesting properties. Here, the measured power densities exceeded the predicted values with a decrease from 0.11 μW mm−3 at 0 vol% to approximately 0.09 μW mm−3 between 5 and 15 vol%. Observations on the dielectric, piezoelectric and elastic properties revealed a residual stress inside the piezoelectric matrix. Whereas residual stress had a negative effect on the piezoelectric properties due to domain clamping and direct measurements of the energy harvesting properties showed a positive enhancement.