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.% La
³⁺
and 0.5 mol.% Fe
³⁺
codoped Pb[Zr
_0.54
Ti
_0.46
]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

^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 Fe
³⁺
-doped PZT compounds. The present results show, however, that a similar defect association of the Fe
³⁺
functional center with a V
_o

^ldrldr
also exists in soft, donor-acceptor (La
³⁺
,Fe
³⁺
)-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.