Piezoelectric Perovskite: Old and New Compounds

Marco Fornari

Department of Physics, Central Michigan University

Ab initio calculations have been used extensively to understand the microscopic physics of the lower temperature non-centrosymmetric phases in perovskite oxides. The presence of a reversible spontaneous polarization and large electromechanical coupling make these materials important in a variety of applications including memories, transducers and actuators.

The understanding of the interplay between structural instabilities in perovskite alloys is the key to unveil the microscopic physics behind the soft polarization rotation in PZT and related systems. I will present results which show the pressure effect on rotational and displacive instabilities and speculate that local stress induced by B-site disorder can favor the octahedral rotation. Recent TEM experiments support our findings and further underline the importance of the local structure.

In order to enhance the electromechanical properties we will also show how alloying on the A-site add an additional mechanism to bring different lattice instabilities on the same energy scale. Analyzing such a mechanism we will present our predictions for the piezoelectric potentials of novel compounds.