Piezoelectric and dielectric properties of PZT–cement–aluminum nano-composites

Three-phase piezoelectric composites that were comprised of PZT, nano-sized aluminum (18 nm) and Portland cement were prepared via a normal mixing and spreading method. The volume fraction of Al was held constant at 0.02, while the volume fraction of PZT was varied from 0.10 to 0.70. The dielectric constant, tan (δ), and piezoelectric coefficient were experimentally investigated as a function of PZT volume fraction were found to possess higher dielectric constants, than their two-phase counterparts (PZT and Portland cement). A comprehensive age study of the piezoelectric and dielectric properties is presented, where significant reductions in material performance occurred within 2 days of sample preparation, and to a lesser degree after 400 days for piezoelectric properties. Properties of the composites are believed to be influenced by the oxidation of aluminum by the alkaline constituents in the cement matrix, distribution of fillers within the cement matrix and air voids.