Anomalous pyroelectric effect

Anomalous pyroelectric effect has been repeatedly observed in ferroelectric films which were compositionally graded or in which strain gradient or temperature gradient was realized. The effect is represented by the shift of the hysteresis P(E) loop center due to the change of temperature. Here we propose a new interpretation of this property. It is based on the assumption that the concentration gradient induces additional polarization. This is characterized by macroscopic description based on the modified Landau-Devonshire thermodynamic potential f(P). The graphical representation of this modified potential is an asymmetric double-well. The hysteresis phenomenon is described by the motion of the representative Brown particle in this double-well; the shape of the latter is modulated by the time-dependent electric field. The observed anomalous pyroelectric effect is based on the coherence of the asymmetry and kinetic aspect of the phenomenon.