Influence of electrode contact arrangements on Polarisation-Electric field measurements of ferroelectric ceramics: A case study of BaTiO3

A range of partial top full bottom electrodes are used to explore the use of bi-polar Polarisation-Electric field (P–E) measurements to quantify recoverable energy (W_rec), energy loss (W_loss) and the efficiency (η) of ferroelectric BaTiO₃ ceramics. The values obtained are dependent on the ratio of sample thickness (S) and top contact radius (r). With increasing S/r from 0.17 to 1.96 the P–E responses become increasingly distorted and broader. Measurements show W_rec increases by a factor of ∼1.4 but W_loss increases by a factor of ∼7 with η decreasing from ∼29% to 8%. Finite element modelling was used to simulate the experimental set-up of the sample/electrode arrangements using the Jiles-Atherton model to replicate the ferroelectric behaviour of BaTiO₃. These models demonstrate the experimentally applied electric field using a simple geometric correction for sample thickness is an underestimation of the actual field experienced by the material under the top contact at high S/r values. We stress the importance of reporting the contact sizes and thicknesses of samples when using P–E measurements to assess W_rec, W_loss and η in non-linear dielectric materials. This will allow a fairer comparison of performances between various types of materials being considered for high-energy-density ceramic capacitors.