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 (Wrec), energy loss (Wloss) 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 Wrec increases by a factor of ∼ 1.4 but Wloss 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 Wrec, Wloss 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.