Dipoles in (La,Fe)-Codoped PZT 52.5/47.5 Piezoelectric Ceramics by Multifrequency Electron Paramagnetic Resonance Spectroscopy

Ferroelectric 1 mol.% La3+ and 0.5 mol.% Fe3+ codoped Pb[Zr0 54Ti0 46]O3 ceramics were studied by means of multifrequency electron paramagnetic resonance (EPR) spectroscopy. The obtained results prove that iron is incorporated at the [Zr,Ti]-site, acting as an acceptor and building a charged (Fe Zr,Ti V O ) defect dipole with a directly coordinated oxygen vacancy for partial charge compensation. This feature of the defect associates has hitherto been identified only in hard, exclusively Fe3+-doped PZT compounds. The present results show, however, that a similar defect association of the Fe3+ functional center with a V O also exists in soft, donor-acceptor (La 3+,Fe3+)codoped PZT. According to models developed by Arlt et al. electric dipoles from defect associates, such as the (Fe Zr,Ti V O ) defect associate, which may give rise to an internal bias field that is discussed being responsible for ferroelectric aging.