Bismuth aluminate:: A new high-Tc lead-free piezo-/ferroelectric

Ferroelectric materials, which have a reversible spontaneous polarization and generate an electric potential when subjected to a mechanical stress (piezoelectricity), have applications in nonvolatile random access memory devices and micro-electromechanical systems. For such applications, materials that remain ferroelectric up to high temperatures are desired. Bismuth aluminate has been predicted to be one such material. We present herein the first characterization of the dielectric, ferroelectric, and piezoelectric properties of the ceramic BiAlO3 synthesized by the high-pressure method. It is demonstrated that BiAlO3 is indeed a lead-free ferroelectric with a Curie temperature T-c > 520 degrees C, a piezoelectric coefficient d(33) = 28 pC/N, and a room-temperature remnant polarization P-r = 9.5 mu C/cm(2). P-r increases with temperature, reaching 26.7 mu C/cm(2) at 225 degrees C.