Rayleigh analysis and dielectric dispersion in polycrystalline 0.5(Ba0.7Ca0.3)TiO3– 0.5Ba(Zr0.2Ti0.8)O3 ferroelectric thin films by domain-wall pinning element modeling

Rayleigh analysis and dielectric dispersion in polycrystalline 0.5(Ba0.7Ca0.3)TiO3– 0.5Ba(Zr0.2Ti0.8)O3 ferroelectric thin films by domain-wall pinning element modeling
Becker M, Burkhardt C, Schröppel B, Kleiner R, Koelle D
J. Appl. Phys. 128, 154103 (2020); https://doi.org/10.1063/5.0025109

We use impedance spectroscopy to investigate the dielectric response in polycrystalline, lead-free 0.5(Ba0:7Ca0:3)TiO3–0.5Ba(Zr0:2Ti0:8)O3
(BCZT) ferroelectric thin films as a function of amplitude E0 and frequency f of an applied ac electric field. Impedance spectra from
f ¼ 10 Hz to 1 MHz were collected at different E0 on polycrystalline BCZT capacitor stacks, grown by pulsed laser deposition on platinized
Si substrates and covered with Au electrodes. Deconvolution of the spectra is achieved by fitting the measured impedance to the impedance
of an equivalent-circuit model of the capacitor stacks, including a recently proposed domain-wall pinning element ZDW. From an extended
data analysis, we quantify the coupling strength between dielectric nonlinearity and frequency dispersion in the BCZT thin films, and we
obtain a schematic diagram of the different domain-wall-motion regimes. Our results indicate that the presence of grain boundaries in
BCZT reduces the coupling strength and suppresses the motion of internal domain-wall segments and also the irreversible center-of-mass
motion of the domain walls.