Characterization of (Fe′Zr,Ti-VO••)• defect dipoles in (La,Fe)-codoped PZT 52.5/47.5 piezoelectric ceramics by multifrequency electron paramagnetic resonance spectroscopy

Ferroelectric 1 mol.% La3+ and 0.15 mol.% Fe3+ codoped Pb[Zr0.54Ti0.46]O-3 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(center dot center dot))(center dot) 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(center dot center dot) also exists in soft, donor-acceptor (La3+,Fe3+) codoped PZT. According to models developed by Arlt et al. electric dipoles from defect associates, such as the (Fe '(Zr,Ti) - V-O(center dot center dot))(center dot) defect associate, which may give rise to an internal bias field that is discussed being responsible for ferroelectric aging.