Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p> The predictions obtained with a thermodynamical method are compared with experimental results. Several materials which pass a ferroelectric phase transition of first or second order are investigated. The predictions correspond well with the experimentaly determined qualitative and quantitative features as to the field and temperature dependence. Finally, extraordinary strain-field curves are predicted and proved.</jats:p>