Revealing the role of the constant phase element in relaxor ferroelectrics

Relaxor ferroelectrics exhibit both static and dynamic local structural order which controls their frequency-dependent electrical properties. A combination of advanced scattering and microscopy techniques have been used recently to determine the local structure of relaxors. To complement these, here we show an approach to electrical property measurements which identifies local dipoles whose switching is co-operative, temperature-dependent and responsible for the observed dispersion in dielectric properties. Impedance measurements and equivalent circuit analysis of a canonical relaxor, Pb(Mg1/3Nb2/3)O-3 single crystal, over the ranges 180-1050 K and 100 Hz-1 MHz, show that incorporation of a single constant phase element into the equivalent circuit used to fit experimental data is able to account fully for the dispersions that characterise the relaxor response, over this frequency range. This allows parametrisation of the relaxor behaviour, gives increased understanding of the relaxation mechanisms responsible and forms the basis for modifying and controlling relaxor characteristics. Relaxor ferroelectrics are a type of material exhibiting electrostriction whereby a change in the material shape occurs under an applied electric field; however, although known by the community for many years the underlying mechanisms of the phenomenon and the characteristic relaxations still remain under debate. To help address this issue, the authors report an equivalent circuit analysis revealing the key role of a constant phase element in the behaviour of relaxor ferroelectric single crystals.

Automated summary

In this study, impedance measurements and equivalent circuit analysis were used to reveal the key role of a constant phase element in the behavior of relaxor ferroelectric materials. This finding is significant for understanding the relaxation mechanisms and controlling the characteristics of relaxor materials.