A three-phase magnetoelectric composite of piezoelectric ceramics, rare-earth iron alloys, and polymer

A class of multiferroic, three-phase particulate composites of Tb–Dy–Fe alloy, lead–zirconate–titanate (PZT), and polymer are investigated, in which a small volume fraction $f$ of Tb–Dy–Fe alloy particles are dispersed in a PZT/polymer mixture. The measured dielectric, piezoelectric, and magnetoelectric properties demonstrate that a percolation transition occurs at $\text{f∼0.12}$ in the composites. When $f$ is low (e.g., $\text{f<0.07),}$ the composites exhibit piezoelectric and increasing magnetoelectric response. In the critical $f$ range of $\text{0.07<f<0.12,}$ such piezo- and magnetoelectric responses sharply drop, and equal zero at the percolation threshold, above which the composite becomes a conductor and a magnetostrictive composite only.