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This paper presents a thorough study of the strain response of different types of electroceramics during dynamical electrical loading. It highlights important aspects to take into account in the experimental methodology and outlines general guidelines for the discussion and interpretation of the results. The contributions of piezoelectric effect, electrostriction and ferroelectric/ferroelastic domain switching to the strain produced during the application of an alternating electric field are discussed by describing the strain-electric field (S-E) loops of different dielectric ceramics in which each of these contributions are predominant. In particular, attention is given to the description of the strain evolution in the characteristic "butterfly loops" typically shown by ferroelectric materials. The strain-polarization loop is indicated as a useful means to reveal the interconnection between strain and polarization state during dynamical electrical loading. Strain rate is suggested as a powerful tool to obtain more detailed information regarding the mechanisms of the electric field-induced strain.

A three-dimensional mathematical model is proposed that describes the ferroelectric response of polycrystalline ferroelectrics to an electric field in the absence of mechanical stresses. It is based on the separation of the switching process into two related parts: the rotation of the spontaneous polarization vectors and the destruction of the domain wall fixing mechanisms. For each of the parts, the energy costs are calculated, which are the components of the energy balance in the real polarization process. The constitutive relations for the induced and residual components of the polarization vector of the representative volume are obtained. A number of numerical experiments were performed, which showed good agreement with the experimental data.