Characterization of (FeZr,Ti-Vo 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[Zr_0.54Ti_0.46]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 ^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 V_o ^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 (Fe_Zr,Ti - V_o ^ldrldr)^ldr defect associate, which may give rise to an internal bias field that is discussed being responsible for ferroelectric aging.