Studies of Perovskite Materials for High Performance Piezoelectrics and Non- Volatile Memory

Perovskite materials are crucial in a variety of important technological applications. Using quantum-mechanical simulations, we have computationally investigated ferroelectric materials for applications in computer memory and piezoelectric devices. We have determined that tetragonality of perovskite ferroelectrics, which is crucial for high piezoelectric performance, exhibits a quadratic dependence on the displacement of the B-site cations only. This provides guidance for the design of ferroelectrics and piezoelectrics with desired properties. We have also shown that a high piezoelectric response is likely to be present in lead-free, environmentally-friendly Sn(Al1/2Nb1/2O₃) solid solutions. In a study of ultrathin ferroelectric films, we have shown that the details of metal-oxide bonding at the electrode-ferroelectric interface such as oxide termination play an important role in determining polarization stability and the miniaturization limit of ferroelectric devices. :subscript