Characterization of (Fe_Zr,Ti-V_o ^ldrldr)^ldr defect dipoles in (La,Fe)-codoped PZT 52.5/47.5 piezoelectric ceramics by multifrequency electron paramagnetic resonance spectroscopy

Ferroelectric 1 mol.% La3+ and 0.5 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 (FeZr,Ti - Vo ldrldr)ldr 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 Vo ldrldr 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 (FeZr,Ti - Vo ldrldr)ldr defect associate, which may give rise to an internal bias field that is discussed being responsible for ferroelectric aging