Pb displacements in Pb(Zr,Ti)O-3 perovskites

Electron-paramagnetic-resonance spectroscopy, band-structure calculations, polarization-voltage measurements, and charge injection experiments are used to show that Pb2+ ion displacements are critical to the ferroelectric behavior of Pb(Zr,Ti)O-3. The displacements of the Pb2+ ions are followed by analyzing the hyperfine and superhyperfine interactions of the photoinduced Pb3+ center. The ferroelectric contribution of Pb2+ arises because Pb retains its 6s valence electrons which then hybridize with the O 2p states to create a high effective charge. This contrasts with other perovskites in which the A ion in other ABO(3) perovskite structures possesses an inert gas configuration and retains its classical ion charge.